0648 (114927)

Dental Visits of Socioeconomically Disadvantaged Children – African American Parents' Perspectives. S.R. REYES, M. WOOLFOLK, and M.R. INGLEHART, University of Michigan, Ann Arbor, MI

Objectives: To explore which parent factors are correlated with socioeconomically disadvantaged children's utilization of oral health care services. Specifically, it was assessed whether parents' background factors, their oral health-related experiences, and oral health-related knowledge affect whether they bring their child(ren) for a dental visit.

Methods: Data were collected from 104 African American parents (average age: 28.88 years; age range: 16 to 57 years) who visited a WIC clinic. They volunteered to respond to a self-administered anonymous survey. All parents lived in a county with a pediatric community dental clinic that offered free treatment for children in families whose income was 200% under the poverty level.

Results: While 33% of the parents had not taken their child(ren) for a dental visit during the past year, 26.1% had taken at least one of their children, and 40.9% had taken all their children for a dental visit. The parents were more likely to have taken their children for a dental visit, the older the parents were (r=.238; p=.026) and the more children they had (r=.32; p=.003). Parents who had had a tooth ache in the past or who had had a root canal before, were more likely to have taken their child for a dental visit during the past year (contingency coefficient=.299; p=.017 / cc=.250; p=.054). The more oral health-related knowledge the parents had, the more likely they were to have taken their child for a dental visit. The number one reason for parents of younger children for not visiting the dentist was that they thought their children were too young and had too few teeth to need to see a dentist.

Conclusions: These results showed that parents' own oral health-related experiences as well as their knowledge determined whether they were likely to bring their children for dental visits.


0649 (116361)

Dental service utilization in remote rural and low-income urban areas. T.P. WALL, W.R. WENDLING, and L.J. BROWN, American Dental Association, Chicago, IL

Objectives: We investigated dental service utilization among remote rural and low-income urban populations. For those who did not report a dental visit, we examined reasons for no visit.

Methods: Dental service utilization estimates were based on the 1999 National Health Interview Survey. Assignment of NHIS respondents into three geographic areas was based on Rural Urban Commuting Area codes and HUD income classification information assigned at the census tract level.

Results: Those living in rural and low-income urban areas were found to be less likely to report a preventive dental visit than a baseline comparison group, after controlling for covariates such as education, income and dentate status. Among those with no visit, “No problem” was the most common reason given for no dental visit during the past year in all geographic areas. The percent who mentioned “Cost/no insurance” was 30.1 percent among those living in a low-income urban area and just over 25 percent in rural and baseline areas. Reasons related to dentist availability (“don't know dentist”, “dentist too far” and “can't get there”) were reported by relatively small percentages of respondents.

Conclusion: Those living in rural and low-income urban areas were less likely to utilize dental services than those living in a baseline comparison population. Demand side variables such as income and education were found to be strong predictors of dental service utilization. Among those with no visit, reasons related to dentist availability were reported by a small percentage of respondents in all geographic areas.


0650 (116815)

Assessing income, dental insurance and cost barriers to dental care. D. LOCKER, C. QUINONEZ, and J. MAGGIRIAS, University of Toronto, Toronto, ON, Canada

Objectives: To assess the associations between income, dental insurance and cost barriers to dental care. Methods: Data were collection from a national sample of Canadian adults 18 years and over using a telephone interview survey based on random digit dialing. Questions were asked about household income and dental insurance coverage along with three questions concerning cost barriers to accessing dental care. These were: “In the past three years…has the cost of dental care been a financial burden to you?...have you delayed or avoided going to a dentist because of the cost?...have you been unable to have all of the treatment recommended by your dentist because of the cost?”. Results: The survey was completed by 2027 subjects. Just over half (59.1%), were covered by private dental insurance and five percent by public dental programs. The remainder, 35.9%, paid for dental care out-of-pocket. Only 19.3% of the lowest income group had private coverage compared with 80.5% of the highest income group (p<0.001). Half (48.1%) responded positively to one of the three questions concerning cost barriers and 14.8% responded positively to all three. Low income subjects (p<0.001) and those without dental insurance (p<0.001) were most likely to report cost barriers to care. Having private dental insurance did not entirely eliminate cost barriers for the low income group. Among the low income insured 31.0% reported dental care imposing a financial burden, 36.0% had delayed or avoided care because of the cost and 39.9% had not been able to have all treatment recommended. For the high income insured, the percentages were, 13.0%, 14.0% and 20.9% respectively. Conclusions: While private dental insurance reduces, it does not entirely eliminate, cost barriers to dental care, particularly for those with low incomes. Supported by Ontario Ministry of Health and Long Term Care.


0651 (116919)

Oral health status among low-income kindergarten school children in Peru. A.L. SEMINARIO1, J. BERG1, and P. SANCHEZ2, 1University of Washington, Seattle, WA, 2Universidad Peruana Cayetano Heredia - Facultad de Estomatologia, Lima, Peru

OBJECTIVES: To determine the baseline oral health status in kindergarten schoolchildren from low-income communities in Peru in an oral health-promoting school program. METHODS: Children (n=276), their parents and schoolteachers of 4 kindergartens in the city of Chiclayo, Peru, participated in this study. The criteria for the kindergartens' selection were that: (a) they belonged to low-income communities, (b) they were not participants of any previous dental program, (c) parents and schoolteachers realized the urgency of an oral health program by notifying their interest in our study, (d) kindergartens had utilities adequate for young children, and e) they had previously participated in a medical program so that the behavior and collaboration of parents and schoolteachers with regard to this kind of experience was demonstrated. Children, all in generally good health, were divided into: primary dentition phase (group A, n=264, mean age 3.9 years) and early mixed dentition phase (group B, n=12, mean age 5.1 years). DMFT, dmft, plaque score, Significant Caries Index (SiC), and SiC10 were recorded. One examiner conducted oral examinations in both groups throughout the study using the World Health Organization (WHO) diagnostic criteria (WHO, Oral Health Surveys, 4th Edition, 1997). RESULTS: Group A: The percentage of caries was 53.03%. The dmft was 2.27 and dental plaque 1.46. However, SiC was 5.97 and SiC10 was 8.73. Group B: The percentage of caries was 75%. DMFT was 3.75 and dental plaque 1.61. Nonetheless, SiC was 7.25 and SiC10 was 10. CONCLUSIONS: The data obtained demonstrated the need to improve the oral health status in these low-income communities, especially in groups with poorest oral health conditions. The willingness of parents and schoolteachers to improve the situation by participating in an oral health-promoting school program may be a strong factor in the success of the next stage of our study.


0652 (117604)

Racial Disparity in Maternal Oral Health Behavior and Practices. D. URLAUB, K. BOGGESS, M.K. MOOS, and C. LORENZ, University of North Carolina, Chapel Hill, NC

Objectives: We have previously reported an association between maternal periodontal disease and preterm birth. The objective of this study was to determine oral health behavior/practice among pregnant women and to identify groups who may benefit from oral health behavior education.

Methods: A written, validated questionnaire designed to assess maternal knowledge, beliefs, and behavior regarding oral health was administered to pregnant women attending the University of North Carolina Women's Clinic. Demographic information was also collected. Chi square test was used to compare knowledge/beliefs among racial/ethnic groups.

Results: 599 women completed the survey (31% Hispanic, 20% African American, 42% Caucasian, 7% other). 246 (41%) reported fair/poor/very poor oral health. 50% reported a dental visit within the past 12 months; 25% during the current pregnancy. White women were more likely to have been to the dentist within the past 12 months and during pregnancy compared to Blacks and Hispanics (65% vs. 43% vs. 23% P=.0001 and 35% vs. 20% vs. 20% P=.0001 respectively). Hispanic women were more likely than Blacks or Whites to cite ‘can't afforde' or ‘no insurance' as reason for not seeing a dentist within last 12 months (28% vs. 8% vs.8%, P=.0001 and 34% vs. 13% vs. 15% P=.0001, respectively). Hispanic women were more likely than Blacks or Whites to never receive dental care (25% vs. 16% vs. 5%, respectively, P<.0001). 147(25%) reported brushing once/day, 351(59%) reported brushing 2x/day, with no significant differences among race/ethnicity groups. Hispanics and Blacks were more likely to report never flossing than whites (27% vs. 26% vs. 10%, respectively, P<.0001).

Conclusion: Dental care utilization and oral health practices vary by race/ethnicity among pregnant women. Given the role of proper oral hygiene and control of the biofilm in reducing gingivitis and periodontitis, exploration of the reasons for these differences merits further study. Funded by NIH DE018642.


0653 (117703)

Social Inequities and Oral Health Conditions in Curitiba, Brazil. B.H.S. FRANÇA, V. SPIRANDELLI, J.C. BISINELLI, S.T. MOYSES, S.J. MOYSES, S. GUIOTOKU, V. BACELAR, and M.L. CARVALHO, Pontificia Universidade Catolica do Parana, Curitiba, Brazil

Objectives: Identify the oral health conditions in a population of individuals who collect recyclable materials and their relationship with health determinants and social exclusion. Methods: a quantitative population-based cross-sectional study. The sample was composed of 367 subjects aged between 12 and 65 yrs, residents in an ‘irregular occupation' area. Socio-economic conditions, dental loss, pain, self-perception of dental health, and access to health services were investigated. Oral examination by a dentist in homes and interviews by structured questionnaires were performed. Results: 43% had average family incomes of up to the minimum wage, 74% had not completed an elementary education, and 14.4% were illiterate. 92% up to 19 yrs of age had all their teethl 19.5% of those between 20 and 64 years had all their teeth; 21% showed fewer than 20 teeth; and 8% were edentulous. The dental losses were greater in subjects who were not born in Curitiba (p = 0.00) and higher in illiterate persons and those with up to three years of study (p = 0.00). A statistically significant association was found between dental loss and self-perception in relation to appearance and mastication (p = 0.00). During interviews, 6% stated that they had never visited a dentist, 81% had access to public health services, and 33% said that they had dental and/or gum pain in the preceding four weeks. Conclusions: Dental loss is one of the hallmarks of social inequities that may generate suffering, feelings of inferiority, and discrimination.


0654 (118496)

Oral Health Behaviours of Iranian adolescents: Socioeconomic and Psychological factors. V. RAVAGHI1, V. MARINHO2, M. UNDERWOOD3, and S. ELDRIDGE1, 1Centre for Health Sciences, Barts and The London School of Medicine and Dentistry, London, United Kingdom, 2Institute of Dentistry, Barts and The London School of Medicine and Dentistry, London, United Kingdom, 3Health Sciences Research Institute, Warwick Medical School, University of Warwick, Warwick, United Kingdom

Objectives: This study investigated the links between adolescent oral health behaviours and two sets of variables: socioeconomic status, and psychological variables.

Methods: We used a two-stage random-cluster sampling to identify 654 high school students (15-17 year old) studying in urban area of Sanandaj, the centre of Kurdistan, Iran. Out of those, 639 students (324 girls, 315 boys) completed the questionnaires. The outcomes of the study were tooth brushing and dental flossing frequency and these were dichotomised into “once a day and more” and “less than once a day”. Socioeconomic status was examined using four social indicators: wealth index (WI), subjective socioeconomic status (SSES), mother's and father's education. Depression and anxiety were measured using the subscales of the HADS, and self-esteem was evaluated using the Rosenberg self-esteem scale. Gender was the only demographic variable examined. Data analysis was done at two stages: bivariate (chi-squared test) and multivariate (binary logistic regression) using SPSS.

Results: Logistic regression analysis adjusting for all variables indicates that toothbrushing frequency is positively associated with having a mother with university education, having mild and high level of self esteem, and being female, and inversely related with having possible or probable depression. The frequency of dental flossing was related positively with highest level of self-esteem and inversely with the highest level of depression. No further associations were detected. Girls showed higher prevalence of “once a day and more” toothbrushing, but no significant difference was found for flossing.

Conclusion: Toothbrushing and dental flossing frequency had limited relationships with certain levels of socioeconomic status. Depression and self-esteem were associated with adolescent oral health behaviours while anxiety was not.


0656 (119596)

Socio-demographic inequality in children's oral health – a comparative study. J. DAVID1, S.N. KIWANUKA2, and A.N. ÅSTRØM1, 1University of Bergen, Bergen, Norway, 2Institute of Public health, Makerere University, Kampala, Uganda

Objective: to examine inequality in children's oral health related to socio-economic factors; socioeconomic status (SES), country of residence, household wealth and parental education and 2) assess whether SES related inequality was consistent in direction and magnitude across two culturally diverse child populations. Methods: Two cross-sectional studies were conducted during 2003 and 2004, focusing on 12-yr-old primary school children in the state of Kerala, India and in Kampala, Uganda. 838 Indian (participation rate 100%) and 614 Ugandan (participation rate 74%) school children completed questionnaires regarding self-rated oral health, oral health attitudes and behaviors and were also subjected to an oral health examination. Results: The prevalence of dental caries in the permanent dentition was 27% and 40% in Kerala and Kampala, respectively. Corresponding figures for reported oral problems, teeth dissatisfaction, negative oral health attitudes and frequent sugar consumption were 73% versus 55%, 78% versus 54%, 32% versus 21% and 33% versus 73%. General Linear Models (ANCOVA) revealed that country differences persisted across oral health indicators after adjusting for SES variables. Kampala children had on average higher DMFT scores, were more satisfied with teeth, reported less oral problems and had favorable oral attitude than their Kerala counterparts. Children having mothers of higher education had on average lower DMFT, more positive attitudes and less frequent sugar intake than their counterparts. In Uganda and India children in the poorest wealth group were on average more dissatisfied with oral health than less poor children, the magnitude of this inequality was largest in India. Conclusion: Substantial inequalities, favoring high SES groups, exist in clinically assessed- and self reported oral health of children across two culturally diverse countries. Between country differences in the magnitude of children's oral health inequalities were generally small. Possible mechanisms linking social inequality and oral health should be addressed in further studies.


0657 (119724)

Parents' educational level and dental care of CP children. A. WYNE, King Saud University, Riyadh, Saudi Arabia

Objectives: To determine the role of the age group, gender and educational level of parents of Saudi cerebral palsy (CP) children in dental care of their CP children. Methods: A specially designed self-administered questionnaire was utilized to collect the required demographic information from the parents in Riyadh, the Capital city of Saudi Arabia. A total of 124 questionnaires were distributed among the randomly selected CP children's parents, out of which 106 parents, 73 (68.9%) mothers and 33 (31.1%) fathers completed the questionnaires giving a response rate of 85.5%. Results: The mean age of the parents was 34.0 (SD 8.6) years, ranging from 21 to 70 years. About six in ten (58.5%) parents' had “high school or above” education and the rest (41.5%) had “middle school or lower” education. There was no correlation (p>.05) between the parent's age group and gender with dental care of CP children. However, the parent's response about various aspects of CP children's dental care differed significantly in relation to their educational status. A significantly (p<.05) higher percentage (11.4%) of parents with “middle school and lower” education thought that one should visit a dentist only in case of pain as compared with 3.2% of parents with education “high school or above”. A significantly higher (p<.05) percentage (96.8%) of parents with education “high school and above” had heard about fluoride as compared to low education parents (79.5%). Similarly, all the parents with education “high school and above” reported as being educated about dental health of their children by some one as compared with 86.0% of parents in low education category. Conclusion: The educational status of parents seems to affect the dental care of their CP children.


0658 (119741)

Inequalities in Oral Health CARE in Nigeria. O.A. ADELEKE, I.S. DANFILLO, G.A. CHUKWU, M.F. GYANG, P.H. JALO, and J.P. STEVE, InterCountry Centre for Oral Health (ICOH) for Africa, Jos, Nigeria

OBJECTIVES: - Nigeria has always focused on inequalities in the distribution of health facilities and health manpower; aimed to reduce the imbalance in the distribution of facilities and ensure a more equitable distribution of health facilities and manpower for every part of the Country in all the previous National Health development plans. The study determined the spread of Oral health manpower and facilities in the Country.

METHODS: Cross sectional study. Data on the number of dental health training institutions, dental manpower and facilities were collected using an interviewer administered questionnaire from the 36 States of the Country and Federal Capital Territory.

RESULTS: There was a predominance of training institutions for Dental surgeons in the Southern (87.5%) part of the Country. The only training institution for Dental therapist is in the Southern part. The Southern part also has more of the dental facilities, with more than half, either as Federal, Private, Mission and Military. There were more oral health personnel in the Southern part, with more than 75% in the urban areas across the country.

CONCLUSION: Despite the desire of the Federal and State Governments to ensure a more equitable distribution of health manpower and facilities, glaring disparities are still evident. There is a marked growth in private facilities and manpower is still skewed towards urban areas.

*The study was funded by the Federal Ministry of Health,to InterCountry Centre For Oral Health (ICOH)for Africa, Jos.


0659 (118791)

Design and Programming Challenges of an Interactive Dental Educational Module. R. AMER1, G. DENEHY1, D.S. COBB1, D. DAWSON1, M. CUNNINGHAM-FORD1, and C. BEGERON2, 1University of Iowa, Iowa City, IA, 2University of Iowa, IOWA City, IA

OBJECTIVES: Simulation is a proven method of teaching dental students the psychomotor skills necessary to properly prepare them for patient based clinical procedures. Dental techniques such as the proper application of a 3-step etch-and-rinse resin bonding system, require proper handling of the multiple components of the system and proper sequencing in order to achieve clinically acceptable results. This skill set becomes second nature to new dental students only by supervised repetition. Learning by repetition lends itself well to the media format today's students are so familiar with; the interactive computer “gaming” format. METHODS: The research team defined the important steps for the successful placement of a 3-step resin bonding system to be included in a teaching module: These included the proper sequence, placement times, appropriate applications of air and water, and correct application of light polymerization. These elements were programmed into an interactive computer game using Adobe Flash CS3 and incorporated into a clinical scenario. RESULTS: The lack of a standardized computer platform for educational simulators required the project developer to construct all the components for this program. The result is a prototype computer game that provides the students reinforcement, motivation and repetition in correctly learning the bonding process in an updated interactive simulation format using a clinical scenario. CONCLUSION: This interactive teaching module once developed has the potential to be applied to a variety of clinic based procedures. It can possibly provide the feedback normally received only from an observing faculty member. The effectiveness of this interactive computer simulator will be statistically compared to a traditional clinical demonstration using freshman dental students in December of 2008.


0660 (116641)

User Acceptance Testing of an Online Electives Component in IVIDENT. P.A. REYNOLDS1, B. QUINN1, S. STAGNELL1, J. CORNFORTH2, J. HARPER1, S. HOLMES1, D. BYRNE1, and C. PAGANELLI3, 1King's College London, London, United Kingdom, 2Tier2 Consulting Ltd, Hertford, United Kingdom, 3Faculty of Dentistry, University of Brescia, Brescia, Italy

Objectives:

• To test the integration, business process models and functionality of the online electives component in IVIDENT (International Virtual Dental School)

• To assess student use and preferences for the online electives component

• To propose further functionality for the electives system

Methods:

Following a user requirements analysis and elaboration for outgoing and incoming electives in an undergraduate dental course, user acceptance testing was performed on students undertaking outgoing electives in their fourth year. 175 students were eligible for an outgoing elective in 2008.

Assessments of the following were made:

a) Secure login through the Dental Electives Abstract System (DEARS), use of IVIDENT business processes for permissions on health and safety, upload of abstract, verification process, and submission of initial short and final electives report.

b) Student use and preferences through an online questionnaire and focus group qualitative methodology

c) Potential use of the business processes and databases for other functionalities within IVIDENT

Results:

163 students went on elective for seven days - four weeks in UK and to global destinations. All students accessed the DEARS system securely and submitted abstracts and initial reports to Registry and tutor verifiers. Final reports (1000 words) were securely uploaded into Vista8 WebCT Virtual Learning Environment.

Qualitative analysis of the questionnaires demonstrated a high level of satisfaction with the automated processes, with tutor availability as needed. The database of short reports to choose electives was most popular.

Conclusions:

The database of abstracts and short reports provided a global profile of countries visited, identified common problems, and began a community of users. The business processes worked securely and well and can be extended as an enrolment function for overseas students applying for courses, sabbaticals and exchanges. Founder members and partners of the IVIDENT project can use this component in the IVIDENT suite of tools.


0661 (113779)

Proper Diagnosis Records For ICD-10 Coding Systems In Dental Students. Y. CHANTRAVEKIN, Thammasat University, Pathumthani, Thailand

ICD-10 has been used in healthcare coding systems in most countries including Thailand. Diagnoses written by doctors are converted into 3 to 5-digit alphanumeric codes. These codes are parts of "Relative Weight" calculation in the DRG system and also relate to healthcare reimbursement. However, ICD studying in Thailand, especially in dentistry profession is not well established. Most dentists may not know how to record charts properly, so information in dentistry may not be reliable. Objectives: 1) to study a baseline ability of Thai Dental Students to select proper diagnoses for each ICD specific diagnosis terminology. 2) to evaluate achievement of 1-hour ICD-10 lecture. Methods: Forty-seven 5th year dental students were included in this study. The pre-test questionnaires composed of scenarios with ICD diagnoses of Diseases of Oral Cavity, and Jaws, Injuries to Head, and Transport Accidents. In each scenario, the students had to choose the proper Principal Diagnosis, Comorbidities, and Complications. Then the students attended the 1-hour ICD-10 Class composing of basic ICD-10 background, ICD modification, and principles of OPD and IPD records. The post-test examination with same questionnaires was performed. The post-test scores were compared to the pre-test with paired t-test. Results: In the pre-test, the mean scores of the student who could record the correct Principal Diagnosis, Comorbidities, and Complications were 32.33+/-19.24, 16.83+/-14.70, and 24.74+/-30.40 respectively, whereas the post-test scores were 45.75+/-26.75, 44.19+/-24.36, and 57.98+/-39.39 respectively. All scores of post-test were significantly different from pre-test (p<0.001), but only 61.70% of students could pass the post-test examination. Conclusion: Although 5th year dental students pass most of the lecture courses and have treated patients for a period of time, they still have minimal basic knowledge of ICD and cannot record the proper diagnoses. One-hour ICD-10 lecture can improve it partially. Longer ICD-10 Course with related workshops may be necessary.


0662 (119651)

Multiple Site Teaching in Oral Health Science Using Advanced Technology. I.M. MADDEN, A. GIBSON, F. SKINNER, A.F. HALL, and L.A. GUNN, UHI Millennium Institute, Inverness, United Kingdom

Innovative methods used by UHI to deliver learning and teaching allow student support wherever they live. “Blended learning” provides face to face, video-conference and online delivery selected to match the learner's individual needs.

The UHI aim of region-wide access to education is a central aim of the BSc Oral Health Science programme. Undergraduate training for Dental Therapists in rural Scotland is undertaken on two sites 250-miles apart, using online teaching material, synchronous real-time tutorials, clinical skills training by video-conferencing and medical observation technology (SMOTS) as well as face-to-face clinical teaching.

In order to assess the acceptance of these teaching methods, data were collected from tutors and students on online resources, communications and web technology for course delivery.

Aims and objectives: To assess the experience of and attitude to online teaching resources and synchronous presentations to distant sites using SMOTS and video-conferencing for Dental Therapy training.

Methods: Analysis of data collected from questionnaires and feedback forms provided by tutors and students.

Results: 66% of respondent tutors (n= 6) had never previously studied online; 83% had never taught using video-conferencing; 66% were unsure of using the UHI “Blackboard” online teaching programmes.

The group of twelve students studying at two separate sites rated their attitude to aspects of teaching and technology. Feedback forms were completed for 36 session episodes. Positives included “very good” rating for teaching methods (52%) student involvement (55%) and tutor's knowledge (83%).

Difficulties included lack of familiarity with equipment, lack of interaction between students and tutors on different sites and technical difficulties.

Conclusions: Despite the relative inexperience of tutors in these teaching methods, students showed enthusiasm to accept the teaching programme. Ongoing evaluation is required to demonstrate effectiveness of the training programme.


0663 (114859)

Effectiveness of Oral Health Education in Korean Elementary Students. S.J. MUN, N.H. KIM, J.H. BYUN, S.J. YANG, J.Y. YANG, and J.A. LEE, Yonsei University, Dental Hygiene, Wonju College of Medicine, Wonju Kangwondo, South Korea

Objectives: The purpose of this study was to compare effectiveness of the oral health education and the satisfaction of the two different education methods between SDL (Self-Directed Learning) and CCI (Conventional Classroom Instruction) on elementary school students.

Methods: The subjects were 233 elementary school students of 11years old (male: 56%, female: 44%) by cluster sampling. They are divided into two groups and received different type of the oral health education each of them SDL and CCI.

CCI is a conventional that one dental hygienist explains the oral health knowledge and behaviors with the power point presentation. In the SDL method, the computer flash animation program was used showing the same contents about the oral health knowledge and behaviors. The students put on the headset and they carried out the course themselves clicking the button on the screen. The survey was conducted before, just after and one week after the education with self-reported questionnaire consisted of oral health knowledge, behaviors and satisfaction of the education. Collected data were analyzed into Chi-square test, Independent t-test and repeated measure ANOVA using SPSS 12.0K program.

Results: 1. Oral health knowledge score went up significantly in both groups (p<0.001) after the education.

2. Oral health behavior score was recorded higher in SDL (p<0.001) just after the education.

3. Oral health education satisfaction rates were high (SDL: 88.9%, CCI: 99.1%) in both groups. In SDL, the students were interested in the fresh animation program due to the self-learning process, while they could not ask a question about the tooth brushing method.

Conclusion: It is concluded that SDL method has a lot of positive aspect performing the oral health education of the elementary school students in Korea. Although some problems were discussed in this study, the suggestion of more effective SDL computer programs would be possible.


0664 (119499)

Learning Styles, Approaches and Perception of Environment at KAUFD. A.M. SINDI1, E.S. DAVENPORT1, and J. FARSI2, 1Barts and The London School of Medicine and Dentistry, London, United Kingdom, 2King Abulaziz University Faculty of Dentistry, Jeddah, Saudi Arabia

Objectives:

Following the establishment of the School of Dentistry in Jeddah, Saudi Arabia little attention has been paid on students' perception of their environment. The aim was to assess the learning environment and understand how students learn to support academics in planning a curriculum to achieve optimum learning outcomes.

Methods:

Study was conducted at KAUFD during March/April 2008. 192 fifth and sixth year dental students were invited to participate. Three structured questionnaires were administered; Approaches to Learning/Studying (ALS) to assess learning approaches, Index of Learning Style (ILS) to assess learning styles, and Dundee Ready Education Environment Method (DREEM) to evaluate students' opinion of their learning environment. Demographic details and academic records were obtained.

Results:

85 fifth and 62 sixth year undergraduates consented to participate, 62% were females. Undergraduates with satisfactory grades were surface learners (p=0.003). The majority of learning preferences were visual (70%), sensing (58%) in contrast fewer active (25%)/reflective (6.3%) and sequential (21%)/global (10.3%) learners. Female students were more likely (p=0.003) to be verbal learners, there were no significant differences in age, socioeconomics or academic achievement. The mean overall DREEM score was 109.06 demonstrating positive feeling about the environment, learning, teachers, academic self perception and the school atmosphere. However, their social self-perception was not positive. Female students were more positive about their teachers than males (p=0.002). A third viewed the school to have plenty of problems.

Conclusion:

A variety of approaches are adopted which may be due to a mismatch between approach to studying and perception of the students' learning environment. Students adopt a surface approach to deal with the overloaded curriculum and the demanding assessment system. The profile of learning styles of dentists are: sensing learner, oriented towards facts and procedures, and visual learners. The students' perception of their dental education environment was acceptable but could be improved.


0665 (117890)

Considerable Variables for Selecting Self-directed Learners. B.Y. PARK, B.H. JIN, and K.K. KIM, Seoul National University, Seoul, South Korea

Objectives: In modern society, the object of dental education is to train dental students to become competent self-directed learning dentists, so it's very important for dental school to select learners who are ready for self-directed learning among many applicants. The purpose of this research is to explore the demographical and psychological factors affecting self-directed learning readiness(SDLR) of school of dentistry students.

Methods: 94 newcomers of school of dentistry were surveyed. SDLR(by Guglielmino), locus of control(by Rotter), self-esteem(by Coopersmith), interpersonal competence(by Buhrmester et al.), community service experience, and the time they decided to prepare the entrance of school of dentistry were surveyed. Correlation with pearson coefficients was testified and regression analysis was executed to find variables affecting students' SDLR.

Results: There were correlations between students' SDLR and Locus of control, self-esteem, and interpersonal competence, but only self-esteem and interpersonal competence were statistically significant variables(p<0.05). Community service experience and the time they decided to prepare the entrance of school of dentistry were not related with students' SDLR. According to the regression analysis, the significant factors affecting students' SDLR were interpersonal competence, self-esteem, and the time they decided to prepare the entrance, and the model was fit(R2=0.5417).

Conclusions: It is recommended for school of dentistry to select students with high self-esteem and high interpersonal competence among applicants, for self-esteem and interpersonal competence are predictable variables for SDLR. In addition, during the learning in school of dentistry educational support to care students' self-esteem and educational methods to build up students' interpersonal competence should be actively utilized in order to enhance students' SDLR.


0667 (119163)

An Interdisciplinary Approach to Case-Based Teaching in School of Dentistry. M.B.D.O. GARCIA, Univ. de Sao Francisco, Bragança Paulista, Brazil

Introduction: Case-based learning has been described in the dental literature as an important method of distilling the basic knowledge learned in texts and lectures and applying it to a patient. In Case-based learning instructors may use a clinical raise awareness about a specific issue, dramatize the importance of a particular health problem or treatment strategy, or introduce a topic. However, the ultimate goal of case-based learning is to educate students in a way that encourages them to consider the complete scope of patient's situation when planning and providing treatment. Objectives: The objective of this study was to determine if students who participated in a semester-long case-based seminar changed their ratings of the importance of patient-centered factors and interdisciplinary considerations. Methods: During two semesters dental students participated in a case-comprehensive care seminar. A total of 250 students gave written consent to have their data included in the research. At the end of each case-based seminar, the students submitted short essay responses to describe what they had learned in the class and identify any questions they wanted to have answered. Results: The results concerning the effect of teaching with a behavioral science instructor present showed the power of interdisciplinary instruction. These findings suggest that students who were taught in an interdisciplinary fashion developed a stronger appreciation of the complexity of factors that affect clinical decision making. Conclusion: The advantages of case-based method are the promotion of self-directed learning, clinical reasoning, clinical problem-solving, and decision marking by providing repeated experiences in class and by focusing the student on the complexity of clinical care.


0668 (119309)

Relationships of EBP Knowledge, Attitudes, Access, and Confidence in Skills. E.R. WALLMANN1, W.D. HENDRICSON2, D. STARK1, J.P. HATCH1, and J.D. RUGH2, 1University of Texas - San Antonio / Health Science Ctr, San Antonio, TX, 2University of Texas Health Science Ctr at San Antonio, San Antonio, TX

Objectives: The purpose of this study was to evaluate the relationships between dental school faculty knowledge of evidence-based practice (EBP), attitudes toward EBP, methods for accessing evidence, and confidence in their own critical appraisal skills using a modified version of the KACE questionnaire that we reported on last year. Our hypothesis was that increased knowledge would predict more positive attitudes, more frequent access of evidence, and greater confidence. Methods: Dental school faculty (n=55) completed the modified KACE questionnaire, comprised of items derived from the previously validated KACE instrument as well as original items. Scales were designed to measure knowledge (10 items), attitude (10 items), access (9 items), and confidence (6 items). The hypothesis was tested using Pearson's product moment correlation coefficient. Results: Consistent with our hypothesis, there was a statistically significant positive correlation between faculty members' knowledge of EBP and their attitudes toward EBP (r=0.27, p =0.047). There was also a significant correlation between knowledge and confidence (r=0.28, p =0.039). However, no significant correlation was found between knowledge and evidence access methods (r=0.16, p =0.257). Conclusions: Dental school faculty members possessing greater objective knowledge of EBP report more positive attitudes toward EBP and more confidence in their own critical appraisal skills; however, in this sample, increasing knowledge did not predict more frequent access of evidence. There is need for further validation of the instrument.

Supported by NIH/NIDCR R25 018663


0669 (117580)

Assessment of Effectiveness of Problem-Based Learning in Practical Oral Medicine. S. SEYEDZADEH SABOUNCHI1, Z. MALEKI2, F. HOSSEINI2, S. SEYEDZADEH SABOUNCHI2, M. ASNAASHARI2, and M. BAHARVAND3, 1Tehran University, Tehran, Iran, 2Shahid Beheshti university, Tehran, Iran, 3Shahid Beheshti University, Theran, Iran

Objectives:

The aim of this study was to determine the effectiveness of Problem-Based Learning in treatment and diagnosis of oral lesions for the eighth term students of Shahid-Beheshti dental school,Iran in the academic year of 2007-08.

Methods:

Thirty students who had selected module two clinical oral medicine were selected for this study and randomly divided into two groups of PBL and seminar (traditional). For each of the groups pretests and posttests were conducted and final exam was carried out for both groups simultaneously. Also questionnaires were handed out among PBL group to evaluate their opinions regarding PBL. The correlation between students' scores was evaluated by Pearson's correlation coefficient and score means were compared with t-test analysis.

Results:

Mean of posttest and final exam scores in PBL and seminar groups were 18.0± 0.6 , 89.88±15.56 and 16.9 ± 1.6, 83.39 ± 9.65 respectively. Posttest scores were significantly higher in PBL group compared to seminar group (P<0.05) but final exam scores in both groups were not significantly different. Posttest scores were higher in both groups compared to pretest scores (P<0.001). The only significant correlation coefficient was between score increase, pretest score and relation between mean scores of previous terms and final score.

Conclusion:

Both PBL and seminar teaching methods were effective and led to knowledge increase of students. According to the opinions of the students, the advantages of PBL were lifelong learning, team work enhancement and improvement in clinical thinking skills.


0670 (116067)

Development of a Preadolescent Oral Health Program: Pilot Study. S. NKASHAMA, N. VARMA, and N.K. CHILDERS, University of Alabama at Birmingham, Birmingham, AL

Objective: The preadolescent oral health educational program, “Sammy Shark's Smile Squad” (SS), presented a customized curriculum to initiate positive changes in health behavior and to increase knowledge of basic oral health in high-risk Alabama youth and their caregivers. Methods: Sites were selected by program directors' meetings. A caregivers' focus group provided feedback during implementation. Curriculum development was based on the ADA's “Smile Smarts” and Alabama Medicaid's “Smile Alabama!” programs. Parents gave informed consent for SS implementation following an IRB-approved protocol. Four weeks of 90-minute lessons were taught to five groups of children at four sites. Participants and their caregivers completed a pre-test and post-test to assess changes in oral health knowledge. Results: Consent was obtained for 61 students with an average age of 10.8 years. The male to female ratio was 57/43%. The children attended an average of 3.3 of 4 sessions. Thirty-one parents and 32 children returned pre-tests. Nine parents and 41 children returned post-tests. Of these, 8 parents and 28 children returned both tests. The parents scored an average of 16.6 and 17.9 of a possible 20 on the pre-test and post-test, while the children scored an average score of 16.0 and 16.2, respectively. Using a paired t-test, no significant difference between pre- and post-test scores were found (p=0.3). Conclusions: Development and implementation of a customized curriculum proved to be the most noteworthy part SS. Before SS can be proven beneficial, more stringent data collection and analysis is necessary. Although positive feedback was received, few returned tests may be due to shortcomings in participant compliance and data collection. Scores on returned tests could not be attributed exclusively to the curriculum.

Supported by NIDCR Grant 1T32DE017607-01 and NIH Grant R25TW007501.


0671 (114536)

Overnight Streptocccus Mutans inhibition with 0.2% Chlorhexidine Gel Tooth Brushing. S. HELAL, Riyadh College of Dentistry, Riyadh, Saudi Arabia

Objective: To examine the value of a CHX gel as  part of a home caries-preventive regimen.  Method: 31 patients between the ages of 17 and 43 years were randomly selected for 2 overnight experiments (night control + night test). Baseline salivary S. mutans levels were measured and categorized before nighttime toothbrushing and when the persons awoke in the morning. Counts were measured and categorized on the basis of risk level (OR = 1.0 x 105 CFU/mL). On the first night, patients used a fluoridated toothpaste  containing 1000 ppm sodium fluoride. On the second night, they used Cervitec® Gel (0.2% chlorhexidine digluconate and 900 ppm sodium fluoride). Brushing lasted for two minutes, and eating and drinking were prohibited afterward. Multiple regression analysis was used for analyzing the collected data, with the SPSS-PC program. Results: There were significant reductions on the second night for each patient in terms of S. mutans count and between the two nights collectively for all patients (p = 0.00001), while on the first night there was no S. mutans count change. Conclusion: More longitudinal studies are needed for evaluating the caries-preventive effect of the daily use of CHX gel combined with fluoride toothpaste.


0672 (118059)

S. mutans biofilm model and dose-response effect to chlorhexidine. J.A. CURY, Piracicaba Dental School - UNICAMP, Piracicaba, SP, Brazil, R.A. CCAHUANA-VÁSQUEZ, Piracicaba Dental School - UNICAMP, Piracicaba, Brazil, and H. KOO, Eastman Department of Dentistry,Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester, Rochester, NY

Objectives: Biofilm models should show dose-response effect to antibacterial substances and this study aimed to determine if a S. mutans biofilm model fits this condition. Methods: S. mutans UA159 biofilms were formed on saliva-coated bovine enamel slabs (7x4 mm) in batch culture at 37oC, 5% CO2, for 5 days. The biofilms were growth in ultrafiltered tryptone-yeast extract broth containing 0.10 mM glucose and they were additionally subjected for 1 min, 8x/day, to 20% sucrose solution containing 1.23 mM Ca, 0.74 mM Pi and 0.023 µg F/mL. The tryptone-yeast extract broth was changed at 24 h and sucrose every time. On the 3rd day of growth, the biofilms (n=4) were additionally treated for 1 min. twice daily, for more 2 days, with one of the following solutions: 1) 0.9% NaCL (Control), 2) 0.012% Chlorhexidine, 3) 0.024% Chlorhexidine, 4) 0.12% Chlorhexidine and 5) 0.05% NaF. The pH of the media (indicator of biofilm acidogenicity) was determined everyday before changing to fresh one. After the 5th day the biofilms were collected for: A) Biomass determination (bacterial viability, dry-weight and amount of protein), B) Extracellular soluble and insoluble polysaccharides and C) Intracellular polysaccharide determinations. Enamel demineralization was assessed by surface microhardness change and chemically by Ca released in the culture media. Results: Chlorhexidine showed dose-response effect reducing statistically biofilm biomass, its acidogenicity and the amount of polysaccharides accumulated compared with the control group (p<0.05, Kruskal-Wallis test). Also, this effect was significant for enamel demineralization when evaluated chemically. Fluoride treatment did not affect biofilm biomass (p>0.05) but it reduced enamel demineralization (p<0.05) compared with the control. Conclusions: The improved model may be suitable to evaluate the effect of antibacterial substances on biofilm and on enamel demineralization. Supported by FAPESP Proc. 2005/05143-8 and CNPq Proc. 305680/2007-2, 475800/2007-9.


0673 (115038)

Long-Term Effect of Xylitol Chewing Gum on Salivary MS Counts. Y. NAKAI, C. SHINGA, M. KAJI, K. MORIYA, M. TAKIMURA, K. MURAKAMI, and T. SHIMONO, Okayama University, Okayama, Japan

Objectives: As part of a caries prevention program in pregnant Japanese women, this study determined for 28 months the long-term effect of xylitol gum chewing on salivary MS counts during and after intervention.

Methods: After screening, 107 pregnant women with high levels of salivary MS (SM≥2) were randomly assigned into the xylitol (n=56) and control (n=51) groups. The participants in the xylitol group were instructed to chew one piece of gum containing 100% xylitol as a sweetener for 5 min at least 4 times a day. Gum chewing started at their 6th month of pregnancy and terminated 13 months later. The participants in both groups equally received oral hygiene instructions and professional tooth cleaning. Following the 13-month chewing period, all subjects were re-examined for 15 months after termination of such intervention (total follow-up period: 28 months). The counts of salivary MS were evaluated using Dentocult SM (Orion Diagnostica, Espoo, Finland). They were provided with a Xylitol Calendar on a 3 month-basis, on which were recorded the actual frequency of gum consumed daily.

Results: Mean frequency of xylitol consumption was 2.9 times/day (SD=1.5, range 0-10). Both median and mode of consumption was 3 times/day. The subjects in the xylitol group were significantly more likely to show low counts of salivary MS (SM≤1) than those in the control group for 7 months of intervention (p<0.01). Such differences of MS levels were observed between them from the 10th month of the intervention period (p=0.053) and until 15 months after termination (p=0.14), but non-significant.

Conclusions: The results suggest that xylitol gum chewing can have a long-term effect on MS since reduced bacterial growth was still observed 15 months following the termination of xylitol use.

Supported in part by Grant-in-Aid KAKENHI (15791208) from Japan Society for the Promotion of Science.


0674 (117001)

Effectiveness of Xylitol Wipes on Cariogenic Bacterial Transmission in Infants. L. ZHAN1, M. NGO2, C.I. HOOVER2, P. DEN BESTEN2, and J.D. FEATHERSTONE3, 1School of Dentistry, University of California - San Francisco, San Francisco, CA, 2University of California - San Francisco, San Francisco, CA, 3University of California San Francisco, San Francisco, CA

Objectives: To determine the efficacy of SpiffiesTM xylitol-containing wipes on transmission of mutans streptococci(MS) and lactobacilli(LB) to infants.

Methods: In a double-blind randomized controlled clinical trial, 44 mothers with active caries and their infants aged 6-24 months were recruited. DMFS/dmfs scores were recorded using WHO criteria. Saliva samples were collected from mothers and infants at baseline. The infants were randomized into xylitol-wipe or placebo-wipe groups(GrA and GrB, n=22/group). All subjects and investigators were blinded for group assignment except the PI(JDBF). Mothers were instructed to use the wipes 3 times daily for their infants. Saliva samples were taken from each infant at 3 and 6 months. MS and LB counts were enumerated using traditional culture.

Results: No statistically significant differences were found in caries status, age, gender, and cariogenic bacteria levels between groups at baseline(P>0.05, Student t test). All but one mother had MS infection with log10 mean±SD as 5.4±1.4(GrA) and 5.3±0.9(GrB). Six infants(GrA) and 7 infants(GrB) had MS and 1 infant in each group had LB at baseline. At 3 months, 0 in GrA and 3 in GrB had new MS infection, while 1 in GrA cleared MS infection. At 6 months, 3 in GrA and 1 in GrB had new MS infection, while 3 in GrA and 2 in GrB cleared MS infection. Two in GrA had new LB infection at 6 months and 2 in GrB had transient infection at 3 months. No significant differences were found between the groups for MS or LB changes at 3 or 6 months(P>0.05, Student t test). New MS or LB infection in each group was very low ranging from 0-15% of subjects at 6 months.

Conclusions: Tooth wipes may contribute to the low MS and LB infection rate in both groups. Supported by CSPD Research Grant and DR Products.


0675 (116033)

The effect of xylitol rinse on Streptococcus mutans in saliva. T. KAWAMORITA1, Y. YASUDA2, and T. SAITO2, 1Health Sciences University of Hokkaido, Tobetu, Japan, 2Health Sciences University of Hokkaido, Hokkaido, Japan

Objectives: Xylitol is being promoted as a preventive measure and cariostatic agent. The substitution of xylitol for sucrose has been shown to reduce dental caries and xylitol chewing gum inhibited the growth of Streptococcus mutans. The aim of the present study was to evaluate the effect of xylitol rinse on the number of S. mutans in saliva.

Methods: The effects of xylitol and sorbitol on the growth of S. mutans were investigated. The bacteria were grown in BHI medium in the presence of 0.01%, 0.1% and 1% xylitol or sorbitol. Growth was followed by measuring the absorbance at a wavelength of 600 nm. To examine the usefulness of xylitol rinse, the xylitol concentration in saliva was determined by D-Sorbitol/Xylitol assay kit after use of various xylitol products: chewing gum, candy tablet and rinse. The 40 participants were assigned to two groups balanced according to their S. mutans counts at baseline: the 5% xylitol rinse group and the control group (5% sorbitol rinse). The saliva samples were obtained after 2 and 4 weeks and were cultured on MSKB plates.

Results: While the xylitol dose-dependently inhibited the growth of S. mutans, the sorbitol had no effect. The mean xylitol concentration in saliva at baseline was 0.10 mg/ml. The xylitol concentration at 10 min after uses of chewing gum, candy tablet and rinse was 2.23, 1.74, and 2.43 mg/ml, respectively. However, no significant differences were observed between 3 groups. The sorbitol rinse reduced the level of S. mutans by only 10% even after 4 weeks. However, the xylitol rinse caused significant reduction the level of S. mutans by 35% and 67% after 2 and 4 weeks, respectively.

Conclusion: These results suggest that the use of xylitol rinse reduce the level of S. mutans in saliva and could be a method of caries prevention.


0676 (115869)

Effect of Antimicrobial Nanoemulsion on Oral Biofilm. V.A. LEE, Y.K. KUNG, and B.T. AMAECHI, University of Texas - San Antonio / Health Science Ctr, San Antonio, TX

The incidence of dental caries in the population is still high. The average adult in the U.S. has 10-17 decayed, missing or restored permanent teeth. Surfactant-containing antimicrobial nanoemulsions are non-toxic to animals, but very effective against bacteria, viruses, fungi and spores. Objectives: A pilot study was conducted to determine the ability of an oil-in-water nanoemulsion (soybean oil, Triton X-100, water, cetylpyridinium chloride, average droplet size 168nm) to inhibit the development of dental plaque biofilm and hence the formation of dental caries in human tooth enamel. Methods: This study was carried out using a continuous flow mixed-organism (Streptococcus mutans and Lactobacillus casei) biofilm model, which acts as an artificial mouth and simulates the biological and physiological activities within the oral environment. In this study 3 experimental groups, each with 15 enamel blocks (cut from extracted human teeth) were devised: A (emulsion), B (chlorhexidine) and C (no treatment). Groups A and B were treated with their respective solutions once daily for 30 seconds. All three groups were exposed to a sucrose solution 3x daily. At the conclusion of the experiment (5 days), enamel demineralization (early caries) was detected and quantified using Quantitative Light-Induced Fluorescence (QLF™). Results: Two statistical analyses were conducted, ANOVA with a Tukey post-test, and ANOVA of a log transformation of data with a Tukey post-test. These results indicate that nanoemulsion is as good or better than chlorhexidine and much better than no treatment (control)(P<0.05). No demineralization was detected in 71% of the enamel samples in group A. Conclusions: This pilot study highlights the antimicrobial potential of this nanoemulsion against oral biofilms and hence its potential to prevent dental caries. Supported by NIDCR T32 Grant #DE14318.


0677 (114779)

Reduction in Bacteria in Infected Dentine by Antimicrobial Bonding AGENT. A. BAYSAN, Barts and the London, School of Medicine and Dentistry, London, United Kingdom, F. YALCIN CAKIR, Hacettepe University, Ankara, Turkey, S. GURGAN, Hacettepe University, School of Dentistry, Ankara, Turkey, and R.A. WHILEY, Barts and The London School of Medicine and Dentistry, London, United Kingdom

Objectives: The aim of this in vitro study was to assess the effectiveness of a bonding agent (Clearfil Protect Bond, Kuraray, Japan), containing an antimicrobial agent, on the microflora in infected dentine of cavitated occlusal carious lesions.

Methods: Overlying plaque, surface stain and soft dentine were removed from cavitated occlusal surfaces of freshly extracted teeth (n=40). Subsequently, DIAGNOdent (KaVo Dental, Germany) was employed to identify leathery type carious sites on each occlusal surface for microbial samplings and analyses. The cavitated occlusal caries sites had a mean [±SE] Diagnodent score (Moment) of 12.3 ± 0.76 [range 6-29]. The clinical status of the infected dentine was recorded and a standardised sample of carious dentine was taken from each lesion for test (n: 20) and control (n: 20) groups before the application of bonding agents. Bonding agents (Clearfil Protect Bond and Clearfil SE Bond, Kuraray, Japan) were then applied according to the manufacturer's recommendations for the test and control groups, respectively. A second stardardised sample of infected dentine was then taken after removing the applied bonding agents.

Results: Microbial counts were transformed to log10[colony-forming units]. The mean total number of bacteria in the samples taken before and after application of test bonding agent were 5.25 ± 0.25 and 2.09 ± 0.49 whilst the control group had 4.54 ± 0.24 and 2.30 ± 0.46. Reductions in log10[colony-forming units] for test and control groups were 3.16 ± 0.42 and 2.24 ± 0.42 respectively (p<0.005). Conclusions: The data derived from this in vitro study indicated that both bonding agents significantly reduced the viable numbers of micro-organisms in infected dentine associated with cavitated occlusal caries. However Protect Bond, the bonding agent with antimicrobial agent was the more effective one in a laboratory setting.


0678 (115896)

Roentgen Microanalysis of Root Caries Lesions Treated with Chlorhexidine. A. BRODZIKOWSKA, Medical University of Warsaw, Warsaw, Poland

Objectives: The aim of the present study was to assess a chemical composition of active root caries lesions and arrested root caries lesions, treated with chlorhexidine varnish Cervitec, and chlorhexidine rinse Corsodyl. Methods: The samples were obtained from 40 tooth designated for extraction for various reasons (periodontal or prosthetic) with at least one primary root caries lesion diagnosed clinically. Patients were recruited from among those who were prepared, for prosthetic treatment. All of the patients agreed on application of preventive caries treatment to the tooth. Patients were then randomly divided into 3 groups, of 10 individuals each. Group 1 - the caries lesions were covered with Cervitec varnish once a week for 3 month. Group 2 - used Corsodyl rinse twice a day during 1 month, after that 1 month break, and next 1 month chlorhexidine rinse. Group 3 (control) received oral hygiene instruction and motivation once a month. Following a three month treatment with, the tooth was extracted, the lesion part were embedded into epoxy resin, polished and covered with thin layer (ca 20 nm.) of carbon. The samples were subjected to roentgen microanalysis procedure in the SU-30 Canmeca machine in order to establish chemical composition of the lesions. For calculation the software based on Pouchon and Pichoira correction program, was applied. Results: The roentgen microanalysis of the caries lesions revealed that the mean concentrations of elements in the control group was: Ca ~3,95%, P.~2,75%, F 0,0%, Cl ~2,64%, whereas in the group 1 (Cervitec treated lesions): Ca~31,36%, P.~16,55%, F~1,5%, Cl ~4,13%, and in the group 2 (Corsodyl rinse): Ca ~26,51%, P.~13,71%, F ~1,22%, Cl ~3.2%, respectively. Conclusion: The results of the study may indicate, that following the treatment of root caries lesions using chlorhexidine the process of remineralization has occurred.


0679 (116603)

Effects of Listerine and Paroex Mouthrinses on Plaque Acidogenicity. K. WIKÉN ALBERTSSON1, A. PERSSON2, P. LINGSTRÖM3, and J.W. VAN DIJKEN2, 1Dental Hygienist Education, Umeå, Sweden, 2Dental Hygienist education, Umeå, Sweden, 3Kristianstad University and Sahlgrenska Academy at Göteborg University, Gothenburg, Sweden

Objective: To evaluate in vivo the effect of two antimicrobial mouthrinses on dental plaque acidogenicity after a sucrose challenge.

Methods: 20 subjects (mean age 59 yrs) participated in the dubbelblind intraindividual randomised study. Three mouthrinses were used in 16 days rinsing periods in addition to their regular mechanical oral hygiene: a solution with essential oils (EO), a solution with alcohol-free chlorhexidine (CHX) and water (negative control). The three test periods were separated by 3-month washout periods. Changes in plaque acidogenicity were evaluated after a sucrose challenge at Day 0 (baseline) and at Day 17 of each mouthrinse period using the microtouch method.

Results: Both CHX and EO resulted Day 17 in statistically significant less attenuated pH falls compared to the water rinse. The CHX mouthrinse resulted in the least pronounced pH values compared with EO (ns) during the whole 30-min period. When calculated as area under the curve (AUC), significantly lower values (AUC6.2 ) were found for CHX and EO at Day 17 compared to Day 0. A significant difference for AUC6.2 between CHX and water was found at day 17. No statistically significant differences were found for any of the comparisons with AUC5.7.

Conclusions: CHX and EO may have a caries preventive potential against enamel caries, while CHX also showed this for dentin caries.


0680 (117522)

Plaque Acidogenicity Distribution and Response to Dentifrice. M. ZSISKA, M.A. KLUKOWSKA, B.W. PETERSON, and D.J. WHITE, The Procter and Gamble Company, Mason, OH

The exposure of dental plaque to dietary sugars results in generation of acids which cause dental caries.  The efficacy of topical treatments to reduce plaque acidogenicity may include acute or chronic effects on biofilm metabolism.  Objective:  In this study we examined the correlation between resting plaque acidogenicity and acute plaque response to dentifrice exposure ex vivo. Methods:  60 subjects were acclimated to a Crest Regular (CR) dentifrice for  two weeks.  Following this, subjects participated in a standard PGRM plaque acidogenicity protocol (White et al., J Clin Dent 6: 59-70, 1995). Subjects presented in the clinic on sampling mornings without carrying out hygiene and refraining from breakfast/food/drink.  A baseline plaque sample was collected from buccal surfaces of upper arch by swabbing. Subjects brushed lingual surfaces of teeth with 1.5 grams of CR dentifrice for 30 seconds and than swished with the generated slurry for another 30 seconds.  Plaque samples were collected again 15 and 45 minutes post brushing.  Collected plaque samples were dispersed in TSB buffer, adjusted to similar optical densities and then incubated with sucrose for 2 hours. Results:  Average incubation pH of plaque samples at baseline was 5.46±0.37.  Treatments with NaF dentifrice significantly increased pH at t = 15 (pH = 5.67±0.38; p < 0.0001) and 45 minutes (pH = 5.49±0.35; p < 0.0001).  t = 15 and 45 incubation final pH's were significantly correlated with baseline resting acidogenicity despite treatment effects:  pH15 = 0.98pHin + 0.49 r2=0.334 p<0.0001 while pH45 = 0.87pHin + 0.95 r2=0.284 p<0.0001.  Conclusion:   Plaques demonstrated almost 10 fold differences in acidogenicity at baseline – and yet responded to suppression effects of NaF dentifrice similarly across this range.  Acute and chronic changes in cariogenic plaque with variable acidogenicity acidogenicity may be modeled by biomass adjusted incubations.       


0681 (117975)

Anticariogenic Effect of Neem and Betel Leaf-AN Invitro Study. P. SUBRAMANIAM, and M. REDDY, The Oxford Dental College, Hospital and Research Centre, Bangalore, India

In developing countries chewing of neem and betel leaf is a common practice, especially among the rural population. The beneficial effects of neem are very well documented. Streptococcus mutans has been implicated as the primary causative agent of dental caries. OBJECTIVES: Hence this study was conducted to evaluate the effect of neem (Azadiracta indica) and betel (Piper betel) leaves on growth of Streptococcus mutans. METHODS: Pure extracts of neem and betel leaves were prepared using both distilled water and methanol. The extracts were analysed for their chemical composition. In order to study their effect on Streptococcus mutans growth, various concentrations of each extract were prepared. Streptococcus mutans was cultured on Mueller Hinton Agar (MHA) and transferred to Brain Heart Infusion (BHI) broth to prepare a suspension, which was spread evenly over the agar plate. Fifty micro-litres of each extract concentration were micropipetted into wells prepared on the plate. This was done in triplicate. Following incubation for 24hours at 37ºC, the inhibition zones were measured. RESULTS: Both neem and betel leaf extracts showed an inhibitory effect on Streptococcus mutans. CONCLUSION: The polyphenols present in these extracts make, neem and betel leaves an economical and easily available method of caries prevention.


0682 (119269)

Ultraconservative Caries Removal: Microbiological Evaluation, and Identification with PCR. M.A. LOZANO-CHOURIO1, O. ZAMBRANO1, L.E. RIVERA1, G. CHOURIO DE LOZANO1, N. ARRAIZ1, and L.A. AGUILERA2, 1Universidad del Zulia, Maracaibo, Venezuela, 2Universidad Autonoma de Zacatecas, Zacatecas, Mexico

Objectives: The purpose of this study was to compare changes in the cariogenic microbiota before and after procedures of ultraconservative removal and total removal of dentinal caries.Methods: Was done a clinical trial, randomized, double-blind in thirteen molars with occlusal caries and softened dentine, randomly assigned to an experimental group: ultraconservative removal with partial removal of softened dentine (n = 6) and a control group with total removal of softened dentine (n = 7). The removal procedure was performed with manual instruments. Samples of dentine before and after the removal procedure were cultivated in human blood agar, agar Mitis Salivarius and Rogosa agar. Species of S. mutans, S. sobrinus, L and L. rhamnosus casei were identified by PCR reactions. To compare the total CFU nonparametric tests were done, and U Mann Withney and Fisher test for the analysis of the type of species. Results: There were no significant differences in the number of CFU, or the type of species between the treatment groups; being S. mutans and L. rhamnosus the predominant species before and after the removal in both groups. Conclusions: This study found no evidence of differences in the cariogenic microbiota between ultraconservative treatment with partial removal of softened dentin and treatment with complete removal of dentin softened.


0683 (119913)

Antimicrobial effects of nanoemulsion against Streptococcus mutans. R. KARTHIKEYAN, B.T. AMAECHI, and V.A. LEE, University of Texas - San Antonio / Health Science Ctr, San Antonio, TX

Introduction: The most prevalent and costly bacterial disease afflicting human is undoubtedly dental caries. Streptococcus mutans is considered a prime cariogen in the induction of smooth surface decay in humans and in animal species. Nanoemulsions are a unique class of disinfectants produced by mixing a lipid-oil ‘discontinuous' phase with an aqueous ‘continuous' phase under high pressure. The result is an oil droplet that is able to fuse with and subsequently disrupt the membrane of a variety of different pathogens. Objective: The aim of the present study was to investigate the antimicrobial efficacy of nanoemulsion against Streptococcus mutans. Methods: In vitro antimicrobial susceptibility of nanoemulsion was determined as per National Committee for Clinical Laboratory Standards guidelines and agar diffusion, serial dilution technique for the determination of minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC). Efficacy was tested by kinetics of killing and biofilm assay. Results: Nanoemulsion concentrations ranging from 1:100 to 1:10,000 dilutions were effective against S. mutans through MIC/MBC assays. Nanoemulsion showed antimicrobial activity against planktonic cells at high dilutions, confirmed by time kill studies. 4-days-old S. mutans biofilms were treated with the nanoemulsion; subsequent reducing of bacterial cells was noticed with decreasing dilutions (1:1000 showed no growth). Conclusion: This preliminary study showed that nanoemulsion had effective antibacterial activity against S. mutans and it may be a useful medication in the prevention of caries. Supported by NIH/NIDCR K08DE018003.


0685 (121214)

Study of a Copper-Containing Sealant in a Microbial Caries Model. E.M. COLEMAN, M. FONTANA, C. GONZALEZ, and G. ECKERT, Indiana University School of Dentistry, Indianapolis, IN

Sealants protect the pit and fissure areas of teeth by isolating the sealed area from additional bacterial and nutrient sources derived from the oral environment, thereby preventing the development of caries lesions and/or arresting existing caries lesions. Copper salts have antimicrobial properties and have been used in the past to control microbial growth adjacent to copper-containing dental materials. Objective: To determine the anticariogenic potential of a copper-containing sealant (CI seal; Cooley & Cooley) by comparing it to a control non-copper sealant (Delton, Dentsply). Methods: Two groups of 12 human tooth specimens had a 1x1x2mm cavity preparation made. The small cavities were filled with either the copper-containing or the control sealant following the manufacturer's instructions, except that no acid etch was used to enhance the presence of a gap. After sterilization, specimens were inoculated with Streptococcus mutans and exposed for 4 days, at 37oC, to circulating trypticase soy broth supplemented with 5% sucrose (TSBS; 0.7 ml/min) for 1 h, 3 times a day, and to a mineral washing solution (MW; 0.7 ml/min during the day, and 0.15 ml/min at night) for the rest of the day. At the end of the experiment, specimens were sectioned in the middle of the sealant preparation and analyzed for caries development using confocal laser scanning microscopy. Two areas, 250 mm in length, adjacent to the sealant margins, were analyzed for caries lesion depth, area and total fluorescence. Results: The copper-containing sealant group developed significantly (p<0.05) larger caries lesions [total area= mean+SD=18601+6205, total fluorescence= 653981+320896, depth= 119+12] than did the control group [total area=7649+3803, total fluorescence=239428+150859, depth=48+20]. Conclusions: Under the conditions of this study the copper-containing sealant was not able to significantly reduce the development of caries adjacent to its margins. This study was supported by a grant from IUSD.


0686 (114726)

Antibiotic prophylaxis for routine implant placement by Oral Implantologists. T. FILARDI, S.F. ALVES, T. WASSALL, M.C. PEDRAZINI, A.M. MONTAGNER, and S.A. RAMALHO, Centro de Pesquisas Odontológicas São Leopoldo Mandic, Campinas, Brazil

Objectives: The aim of this study was to evaluate the administration or not of the antibiotic prophylaxis for routine implant placement by the Brazilian dentists who work in the implantology field. Methods: Data were collected through a questionnaire answered by 468 dentists of which 272 took part in the 4th São Paulo Dental Association International Meeting of Osseointegration (APCD), 119 participants of the 2nd International Congress of Minas Gerais, and 77 professors and post-graduated students of the São Leopoldo Mandic Dental Research Center. According to the questionnaire, the dentists were asked if they considered advisable or not the antibiotic prophylaxis, if they were implantology professors, and what was their origin. The answers were collected and statistically analysed. Results: (1) the information gathered were divided in the distribuition of the implantodontists according to the conglomerade (58.1% from APCD; 25.4% from the Congress of Minas Gerais; and 16.5% among professors and students from the São Leopoldo Mandic); (2) distribuition of the implantodontists between self-declared and not self-declared professors (26,5% self-declared professors); (3) distribuition of the implantodontists according to the regular use or not of the antibiotic prophylaxis and their origin (90.2% of the total dentists recommended the prophylaxis); (4) distribuition of the professors who were favorable to the antibiotic prophylaxis (91.12% were favorable ). Conclusion: Comparing the total number of dentists (90.2%) with the totality of professors (91.12%) who indicate the administration of antibiotic prophylaxis for routine implant placement, we found very similar results, indicating a parallel between what is taught in the implantology courses and what is done along the practice of this speacility.


0687 (116301)

Host Profile and Implant Aspects Associated with Implant Loss. F. ALVIM-PEREIRA, C.C. MONTES, and P.C. TREVILATTO, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil

Osseointegration failure is a complex, multifactorial trait, which may depend on host profile and implant individual aspects. Objectives: The aim of this study was to evaluate the association of host and implant features with dental implant loss. Methods: A sample of 280 patients from Latin American Dental Research Institute (ILAPEO) was divided into two groups: i) Multiple losses (ML), 36 individuals presenting more than one implant loss; ii) Non-Multiple Losses (NML), 244 individuals presenting none or one implant loss. In addition, placed implants installed in those subjects were classified as Healthy (H; n=1,232) or Lost (L; n=135). Patients socioeconomic profile, general medical condition, current medication, smoking, hygiene habits, dental appointment frequency, number of teeth, implants placed, and periodontal indexes were accessed. Also, the following clinical aspects were compared between H and L: implant position, primary stability, implant dimensions, design, type of platform, surgical technique, loading aspects, presence of graft, and bone quantity and quality. Results: Smoking was more frequent in NML group (p=0.01). Tooth mobility (p=0.03), medical treatment (p=0.05), and number of implants installed (p=0.01) were related with implant loss. With Logistic Regression Model, the number of implants (p=0.01) and smoking (p=0.03) remained statistically significant. Regarding implant clinical aspects, the following parameters were observed to influence implant failure in the univariate analysis: implant position (maxilla/mandible, p=0.01; anterior/posterior, p=0.04), implant length (p=0.01), and primary stability (p=0.01). Cox Regression model showed that primary stability (p=0.01), surgical technique (p=0.02), and bone quantity (p=0.05) associated with implant loss. Conclusion: It was observed that host profile and implant clinical features may influence implant loss.


0688 (116748)

Alveolar Ridge Preservation: Treatment Outcomes at Different Anatomical Locations. M. SALAS, D.N. TATAKIS, and B. LEBLEBICIOGLU, Ohio State University, Columbus, OH

Objectives: Alveolar ridge preservation (ARP) is a guided bone regeneration application at the time of tooth extraction to control bone resorption. The purpose of this study was to evaluate clinical healing following ARP at maxillary and mandibular posterior sextants.

Methods: Sixteen patients with a need for ARP at maxillary or mandibular posterior sites were included. Patient exclusion criteria were: systemic health conditions that could affect wound healing, smoking, localized acute infection, immediate implant placement indications. ARP was performed immediately after tooth extraction. Freeze dried bone allograft together with collagen membrane was placed. Baseline (pre-extraction) and post-treatment (at implant placement; average 4 months healing) impressions were taken to determine dimensional changes. Using a custom template, clinical measurements of soft tissue contours and alveolar ridge dimensions were obtained prior to tooth extraction and repeated prior to ARP, to determine the size of the bony defect. Dimensions of extracted tooth root(s) were recorded. Clinical measurements were repeated at time of implant placement. Repeated measures ANOVA followed by paired (time) and unpaired t-test (mandible vs maxilla) were performed. Pearson correlation analysis was completed for any association between the initial clinical parameters and final ridge dimensions.

Results: Following ARP, ridge height loss was negligible. However, average ridge width loss of 2.7±1.4 mm was observed in both maxilla and mandibule (P<0.05). In mandible, baseline attachment loss on the distal of extracted tooth correlated with post-treatment ridge height at the site (r=0.797, p=0.01). In maxilla, root diameter of extracted tooth was strongly associated with post-treatment ridge width (r=-0.782, p=0.038) and height (r=-0.943, p=0.001).

Conclusions: These results suggest that in different anatomical locations different factors may determine the clinical treatment outcome following ARP. Further studies are needed to better understand limitations of ARP.

Supported by the OSU Division of Periodontology


0689 (117271)

Clinical Evaluation of Osseointegration of Implants Placed in Grafted Bone. I. VOZZA, S. ROSSI, L. PICCOLI, and M. QUARANTA, Sapienza University of Rome, Rome, Italy

Objective: to evaluate osseointegration in early-loaded PBR (Primary Bone Regeneration) implants inserted, together with bone grafts, into atrophic alveolar ridges. Methods: We selected 24 patients (both sexes, mean age of 42 yrs, healthy, non-smokers) having maxillary and mandibular partial atrophic alveolar ridges and requesting implant-supported prostheses. We inserted 78 PBR implants (TMI®, Pressing Dental, San Marino, Italy) together with a bone graft material (Bio Oss, Geistlich, Wohlhusen, Switzerland). Minimum implant diameter was 3.75 mm, and minimum length was 10.5 mm. The primary implant stability was estimated by RFA. When the implant stability quotient (ISQ) resulted in a value ≥ 57, in the 2nd-stage surgery, the implants were loaded early (2.5 mos after surgery). The ISQ values were subsequently estimated every month until the 6th month, then at 9 and 12 months. The intra-oral x-rays were taken at 0, 2, 6, 9, and 12 months. Results: In the 2nd-stage surgery, a complete bone defect filling was observed in all the cases except one that was characterized by a partial bone defect filling (greater than 50% and without flap dehiscence). The most significant increase in ISQ values was observed in the first 2 months; a further ISQ value increase was observed at the 3rd-4th months, and successive ISQ values leveled off.  At the end of the second month, only 6 implants (7.7%) in five different patients failed to show the 57 ISQ value. Among these implants, 2 showed early clinical mobility (M) (third and fourth months); these were removed and recorded as failures. The intra-oral x-ray showed no change in the marginal bone level. Clinical and x-ray results, analyzed by Student's t test, were statistically significant (P < 0.005). Conclusions: These results showed that early loading of PBR implants, inserted together with bone grafts, seems to be a valid technique for the restoration of atrophic alveolar ridges.


0690 (117302)

Maxillary Ridge Augmentation with Fresh Frozen Bone Allografts. C. CONTAR1, J.R. SAROT2, J. BORDINI JÚNIOR2, G.V. NICOLAU2, G.H. GALVÃO2, and M.A.N. MACHADO1, 1Pontificia Un Católica do Paraná, Curitiba, Brazil, 2Universidade Federal do Paraná, Curitiba, Brazil

Introduction: Bone resorption in the maxillary ridge frequently results in a knife-edged deformity, which complicates implant placement and estabilization. Reconstruction of the severely atrophic maxilla is still a major challenge for oral and maxillofacial surgeons and autografting remains the gold standard for replacing bone loss. The use of bone allograft provides a reasonable alternative to meet the growing need for primary or supplementary graft material. Objectives: The present investigation clinically and histologically evaluated the use of fresh-frozen bone in the reconstruction of maxillary alveolar ridges to confirm the effective bone fill and support for the placement of dental implants. Methods: Fifteen patients who had atrophic maxillary ridge necessitating bone block grafts prior to implant placement, were submitted to maxillary reconstructions performed with human block grafts of tibia fresh-frozen chips. Nine months later the re-entry procedures were carried out and at this time a bone core was removed from the grafts for histological analysis. Results: Thirty four blocks were placed, and the number of blocks each patient received ranged from 1 to 4. During the re-entry procedures, all of the grafts were found to be firm in consistency, well incorporated and vascularized. A total of 51 implants were placed over the grafts with a minimum of 40-Newton torque in all cases. None of the implants were lost. The follow up period ranged from 24 to 35 months. The histological analysis of the bone specimens removed during the re-entry procedures revealed a living bone that showed features characteristic of mature and compact osseous tissue surrounded by marrow spaces. Conclusion: Bone allografts can be successful as graft material for the treatment of maxillary ridge defects. If adequate surgical techniques are adopted, this type of bone graft can be safely used in regions of implant placement as a suitable alternative to autogenous grafts.


0691 (117944)

Trabecular Volume of Mandible Using Micro-CT in Korean. S.-Y. WON1, S.-H. KIM2, S.T. KIM3, H.-J. KIM1, and K.-S. HU1, 1Division in Anatomy & Developmental Biology, Department of Oral Biology, Yonsei University College of Dentistry, Seoul, South Korea, 2Department of Prosthodontics, Yonsei University College of Dentistry, Seoul, South Korea, 3Advanced Education in General Dentistry, Yonsei University College of Dentistry, Seoul, South Korea

Objectives: The aim of this study was to investigate difference of the trabecular volume (TV) between dentulous and edentulous mandible.

Methods: In order to analyze trabecular structure of the mandible, 39 mandibles (72.3±12.6years) were scanned (micro-CT system), reconstructed three dimensionally, sectioned parallel to the axis of each tooth, calculated TV, analyzed (paired t-test, ANOVA, p<0.05).

Results: There was statistically significant difference of TV between dentulous and edentulous mandibles in molar region (p<0.05), but no difference in incisal and premolar region. In dentulous mandible, the central incisor region had the largest TV. The TV reduced gradually from the incisor region to the premolar region, and increased gradually reaching the molar region of the mandible. In edentulous mandible, the TV reduced gradually from central incisor region to molar region. In dentulous mandible, the greater value of TV was observed in male than female, but there was no statistically significant difference. In edentulous mandible, the greater value of TV was observed at the central incisor, first and second molar regions in male than female (p<0.05), but there was no statistically significant difference in other region.

Conclusions: The trabecular bone quality was different according to sex, region, and existence of teeth. It was most appropriate to place dental implant at anterior region of edentulous mandible in male.


0692 (118840)

Clinical Evaluation of Bone Graft and Implants Osteointegration. D. DELL'AQUILA, and M. CASSETTA, Sapienza University of Rome, Rome, Italy

Objectives: To study the clinical evolution of the osteointegration of implants inserted into grafted bone.

Methods: Sixteen patients received 36 implants and bone chip grafts stabilized with titanium mesh to correct atrophic alveolar ridges. After 2 months, second-stage surgery was performed to evaluate the incorporation of the graft and to evaluate implant stability with RFA during the overall observation period, in relation to graft healing and implant function.

Results: Two of the 36 implants were lost during the three-year follow-up. The bone defects were completely filled in 64.7% of the cases. The primary stability showed low implant stability quotient (ISQ) values (average value [AV], 52.2 ISQ). The biggest increase in ISQ values (AV 59.33 ISQ) was registered after the first 2 months, and a second one (AV 63.58 ISQ) when prosthetic loading was applied. When the graft was not fully incorporated, implant stability increased more slowly and was more influenced by function.

Conclusions: Two months seemed to be a sufficiently long healing period for bone chip graft incorporation. Bone graft incorporation seemed to improve implant stability significantly. Functional loading did not appear to jeopardize bone graft healing, but rather slightly augmented ISQ values.


0693 (115431)

Osseointegration of zirconia and titanium implants in different animal models. T. HEFTI1, H. SCHLIEPHAKE2, B. VON RECHENBERG3, and F. SCHLOTTIG1, 1Thommen Medical AG, Waldenburg, Switzerland, 2University Hospital Goettingen, Goettingen, Germany, 3University of Zuerich, Veterinary Clinic, Zuerich, Switzerland

Objectives: To compare the osseointegration of structured zirconia and titanium implants in two different animal models with biomechanics (torque-out) and histomorphometry.

Methods: The results of two studies where implants with identical shape were inserted in the pelvis of sheep and in the mandible of mini-pigs were compared. Implants were left in situ for 4, 8 and 12 weeks. Titanium implants with a sandblasted and acid etched surface were compared with zirconia implants with a sandblasted and alkaline etched surface. Surface roughness was measured using stereo-SEM and optical profilometry. In both studies implants were analyzed by torque-out measurements and histomorphometrically by bone to implant contact (BIC).

Results: Blasting resulted in a higher roughness on titanium than on the hard zirconia. Histomorphometry showed overall higher BIC values in the sheep, mainly for zirconia with BIC-values of 87.9 % after four weeks and 70.8% after eight weeks. However torque-out measurements showed higher values in the mini-pig mandible than in the pelvis of sheep. Comparing the two implant surfaces torque-out values were significantly higher for titanium at all timepoints and in both animal models.

Conclusions: Based on two different animal models osseointegration of structured titanium and zirconia implants was evaluated. Surface roughness in the range of the structure obtained by blasting seems to play a role in biomechanical testing. The biomechanical values in the pelvis of sheep were generally lower than in the mini-pig mandible whereas the BIC-values showed similar behavior in both animal models with a slight increase for the titanium over time and with a light decrease for zirconia. Both implant surfaces showed overall good osseointegration properties in both animal models.


0694 (116624)

Temperature Rise Associated with Grinding of One-piece Dental Implants. E.E. MACHTEI1, E. GABAY2, O. COHEN2, and E. ZUSSMAN3, 1School of Graduate Dentistry, Rambam Health Care Campus, Haifa, Israel, 2Rambam Health Care Campus, Haifa, Israel, 3Technion - Israeli Institute of Technology, Haifa, Israel

One-piece dental implants are re-emerging in recent years with the ever-growing popularity of immediate loading of implants. However, some concern has been raised regarding the possible heating of the implants during grinding, which is often required to prepare for the temporary crown.

Objective: to measure temperature changes in the cervical and apical aspects of one-piece dental implants during grinding of the implant's post.

Methods: Thirty one-piece Uno® dental implants (MIS - Implants Technologies Ltd., Shlomi, Israel) were inserted into an acrylic block by standard drilling procedures. Posts were ground in a circular motion for 90 sec or until temperature exceeded 47°C, by means of a high-speed turbine with air-water irrigation of 30 mL/min (W30 group) or no-water (W0 group). Temperature at the implant's cervical and apical aspects were sampled every 1 sec by means of a Pico TC-08® thermocouple input device (Pico Technology Ltd, St Neots, UK) and PicoLog® data-logging program. Temperature changes were compared between groups and within the same implant at different time points by the two-tailed Student's t test.

Results: Mean baseline cervical temperatures were 24.99 ± 1.1 and 25.18 ± 0.6°C (p = 0.5547) for W30 and W0, respectively. Likewise, baseline apical temperatures were 24.02 ± 1.2 (W30) and 24.42 ± 0.98°C (W0), p = 0.3464. Mean maximum cervical temperatures were 26.88 ± 0.8 (W30) and 57.51 ± 4.2°C (W0), p = 0.0001, while these same figures for the apical measurements were 25.13 ± 1.5 and 29.70 ± 3.7°C, p = 0.001. None of the implants in the W30 ever reached 47°C, while all implants in the W0 group reached this critical temperature within 11-22 sec (mean, 17.2 ± 3.6 sec). Maximal temperature at the apical aspect was significantly lower than that in the cervical part, 25.13 vs. 26.88°C (W30), p = 0.0003, and 29.70 vs. 57.51°C (W0), p = 0.0001.

Conclusion: In vitro crown preparation of one-piece dental implants with water spray irrigation of 30 mL/min resulted in minimal temperature rise; however, in the absence of water coolant, this temperature showed a dramatic increase within a few seconds.


0695 (116747)

Elastic Bone Properties of Maxillary Sinus Floor. W.-J. SEONG1, U.-K. KIM2, J.S. HODGES1, and C.-C. KO3, 1University of Minnesota, Minneapolis, MN, 2Pusan National University, College of Dentistry, Busan, South Korea, 3University of North Carolina, Chapel Hill, NC

Objectives: Primary implant stability is a good predictor of future implant success. Bicortical stabilization improves implant stability by engaging two layers of cortical bone at the top and bottom of the implant. Applying this concept in the maxilla requires engaging the maxillary sinus floor. It is not known whether bone in the maxillary sinus floor differs from alveolar crest and middle trabecular bone of maxillary sinus area in terms of elastic properties. This study measured Elastic modulus and Hardness of three vertical regions (alveolar crest, middle trabecular, sinus floor) of maxillary sinus area bone from fresh human cadavers, as well as thickness of alveolar crest and sinus floor cortical bones.

Methods: Twelve cross-sections of maxillary sinus area bones were retrieved from four fresh human edentulous male cadavers (mean age 83). Elastic modulus and Hardness were measured in three vertical regions per cross-section using nano-indentation. Each region received nine (3x3) indentations. Cortical bone thickness was recorded from histomorphometric slides. Repeated measures ANOVA was used.

Results: The Elastic moduli were significantly different (p=0.013): sinus floor (17.73±0.72GPa), alveolar crest (17.10±0.72GPa), and middle trabecular (14.59±0.72GPa). Hardness for the three regions were not different (p=0.95). Hardness for alveolar crest, middle trabecular, and sinus floor were 0.530±0.015GPa, 0.532±0.015GPa, and 0.536±0.015GPa, respectively. The average thickness of sinus floor bone was 0.26±0.12 mm ranging from 0.11mm to 0.49mm. Alveolar crest cortical bone thickness averaged 0.51±0.39mm ranging from 0.18mm to 1.09mm. Average sinus floor bone thickness was about half the average cortical bone thickness of the alveolar crest.

Conclusions: The Elastic modulus of the sinus floor cortical bone was similar to that of the alveolar crest and significantly higher than that of the middle trabecular bone. Thus, intentionally engaging the sinus floor to provide bicortical stabilization may improve implant stability in the posterior maxilla.

(Partially supported by NIH/NIDCR R21-DE015410)


0696 (119531)

Surface Condition of One-piece Type Titanium Implant after Cutting. M. TOYOTA, T. FUKUHARA, M. HOJO, and M. YAMAUCHI, Asahi University, Mizuho, Japan

Objectives:In one-piece type implant, after installation of the implant to a jawbone, the implant exposed in the mouth is cut to make a proper abutment form. The property of the cut surface is related to the adaptability and retention of a crown. This research examined the surface property of one-piece type titanium implant after cutting.

Methods:Commercially available one-piece type titanium implant (NobelDirect Groovy, USA) was used. The diamond point and carbide bur were used for cutting. The surface property of the implant before and after cutting was observed with the optical microscope and three dimension profile analyzer.

Results:ery small unique unevenness was found in the implant surface before cutting. After cutting with carbide bur, the margin was indistinct. A trace with an edge was observed in the cutting surface. There was no big change also after polishing with diamond point. By three dimension profile analyzer, surface roughness of polished surface was larger than that of intact surface (P>0.05 Tukey-Kramer method).

Conclusions:hese results suggested that the development of a polish system is desired.


0697 (120496)

Ostell`s Ability to Determine the Bone-Implant Contact in Vitro. M.P. LEÃO1, C.A.M. BENFATTI1, H.A. CUNHA1, A.F. SIQUEIRA1, P.C.R. ANDRADE1, N. LUCCHIARI JUNIOR1, J.G. SOUZA1, and M.J.F. BINDO2, 1Universidade Federal De Santa Catarina, Florianopolis, Brazil, 2Universidade Federal do Paraná, Curitiba, Brazil

Objectives: The purpose of this study was to evaluate the real capacity of the frequency of the resonance device (Resonance Frequency Pulses) (Ostell) in the implant-bone contact determination.

Methods: to appraise the ability to determine the contact of the implant with any material which is in contact with its surface, 13 mandibles of resin that simulate the characteristics of the jaw bone were used. In each mandible 5 perforations were done and 5 implants were then installed in such way so the first implant only with 1/3 apical set in resin (5mm), the second implant with 2/3 apical set in resin, the third one fully set in resin, the fourth implant 2/3 coronal set in resin and the 1/3 apical without contact with the resin and finally an implant with 1/3 coronal set in resin and the 2/3 apical without contact with the resin. After the installation of the implants, measurements of resin-implant contacts with the Ostell, in all the 13 jaw implants were taken, with a standardized position of the transducer shaft. Statistical analysis was performed by Anova and t-Tukey.

Results: There was a statistically significant difference between groups that have had their coronal portion outside the resin, on the other 3 groups, however, there was no difference between groups whose implants were entirely within the resin and those who showed their apical portion out the resin mandible.

Conclusion: The Ostell was effective in carrying out measures of bone-implant contact only in the coronal portion of implant and is not effective for the verification of that contact in the apical portions of the implants.


0698 (120980)

Pilot Evaluation of PRIMARY Implant STABILITY in GENERAL Dentistry Residents. E. SCHMIDT1, D. PAPADIMITRIOU1, C. FENG2, H. MALMSTROM3, J. CATON1, and G. ROMANOS4, 1Eastman Dental Center, Division of Periodontology, Rochester, NY, 2University of Rochester, Biostatistics, Rochester, NY, 3Eastman Dental Center, Divsion of General Dentistry, Rochester, NY, 4Eastman Dental Center, Division of Periodontology, Division of General Dentistry, Rochester, NY

Initial implant stability is necessary for a better implant integration and prerequisite for immediate loading. Objectives: The purpose of this experiment was to evaluate the primary stability of implants placed by a group of non-surgically trained dental residents in an ex-vivo model. Methods: 36 implants (Ankylos®, Dentsply), with a progressive thread design (11 mm length and 3.5 mm diameter) were placed by six students with similar clinical experience. The implants were placed in resin jaws that resemble type IV bone density. Measurements of stability were performed electromechanically using Periotest® and resonance frequency analysis (RFA) using the Osstell® device (ISQ values). The implants were classified in groups of stability based on the Periotest and ISQ values. Specifically, “stable” implants had Periotest values (-8 to +8); “non-stable” implants had higher than 8 values. The ISQ values were for “stable” implants more than 47 and less than 47, respectively according to Nedir et al. (2004). Statistical analysis (one-way analysis of variance, ANOVA) compared the implant stability among the residents and the McNemar's test was used for comparison of two methods of stability evaluation. Results: The mean Periotest value was 9.083 (min.: 1, max.: 29) and the mean ISQ value was 57.18 (min.: 28, max.: 78). Based on the Periotest values only 55.56% of the placed implants had high initial stability. Based on the ISQ 79.865% had high stability. The one-way ANOVA test showed significant differences were found among the residents for the Periotest® device (but not for the Osstell® device). The McNemar's test showed significant differences with a P-value of <0.0001 between the two stability tests. Conclusion: Variability in primary implant stability was found for residents with no surgical experience. Therefore, an intense training should be provided in the ex-vivo model before clinical application in compromised bone qualities.


0699 (115786)

Inter-Root Computed Tomography Measurements for Achieving Optimal Inter-Implant Gingival Esthetics. K. HUSTON, and A. FAKHRY, University of Iowa, Iowa City, IA

Objectives: Although dental implants have proven to be an effective treatment modality for replacing missing teeth, significant challenges still exist in providing a natural soft tissue appearance between two adjacent implants. The interproximal soft tissue is supported by the underlying bone and changes to the hard tissue level can result in loss of papillary height. Data has shown that a minimum inter-implant distance of 3 mm is necessary for optimal bone height retention and, as a product, the presence of an esthetic papilla. Methods: Fifty dry human skulls were scanned using a Siemens SOMATOM Sensation 64 slice scanner. Scans were processed with Vitrea 2 to provide axial slices at 2mm apical to the CEJ for teeth 3-14 and 19-30. Composite images of the axial slices were created for each arch using Photoshop CS3. Measurements of the smallest distance between roots along the arch curvature were performed in the axial plane using a custom grid. The mean, range, and standard deviations were calculated to summarize the data. Results: Of a total of 1,100 possible inter-root measurements, only 821 were made due to missing teeth, incomplete roots forms, or indistinguishable CEJs. The average inter-root distances ranged from 1.434mm (SD=0.456mm) in the mandibular incisor region to 3.142mm (SD=0.769) between the maxillary central incisors. Average inter-root distance of ≥3mm was only present between the maxillary central incisors. All other inter-root measurements were <3mm with the second largest measurement recorded in the molar/premolar areas (average 2.650mm). Conclusion: The minimal inter-implant distance of 3mm recommended for achieving optimal interproximal soft tissue esthetics can be only achieved between the maxillary central incisors. For all other sites, an inter-implant clearance of ≥3mm can be only achieved by selecting implants with a smaller diameter than the mesio-distal root dimension of the teeth they replace.


0700 (116085)

Radiographic Analysis of Bone Levels around Teeth that Oppose Implants. K. TAKAHASHI1, H. TSUGAYASU1, I. AOKI1, Y. KAMINO1, M. SAITOH1, T. MAIDA1, T. KAKU2, E. NAKAYAMA3, and Y. ABIKO1, 1Health Sciences University of Hokkaido, Sapporo, Japan, 2Health Sciences University of Hokkaido, Hokkaido, Japan, 3Health Sciences University of Hokkaido, Ishikari, Japan

Objectives: Although the bone levels around natural teeth that oppose an implant may be altered, little information has been reported. The aim of the present study was to evaluate the bone levels around natural teeth that oppose an implant using digitized conventional radiographs and subtraction images. Methods: Radiographs taken for 80 natural molars that oppose an implant were used. The radiographs were obtained at 6, 9 and 12 months after the implant crowns were fixed (HA coated implants of 4mm diameter, Spline, Zimmer Dental). Contralateral molars in the same jaw that did not oppose an implant were used as controls. The radiographs were digitized into a personal computer using a scanner. The images were manipulated by EMAGO/Advanced 5.x software (Oral Diagnostic system, Amsterdam, The Netherlands), and linear and logarithmic digital subtraction images were produced. The logarithmic subtraction was enhanced with the use of a filter. The bone levels around natural teeth that oppose an implant and around control teeth were assessed in the subtraction images. The subtraction image was analyzed using NIH image. The statistical difference between the bone levels was analyzed using F-test. Differences between the group of teeth that oppose implants and the control group were considered statistically significant at p<0.05 levels. Results: Significant bone loss or gain was often observed around the teeth that oppose implants at 6, 9 or 12 months after the implant crown was fixed. Little bone loss was observed around the control teeth. The variance of the data in the group of teeth that oppose an implant was significantly greater than that in the control group. Conclusions: Our results suggest that the bone levels around teeth that oppose implants may be altered when compared to bone levels around teeth that do not oppose an implant.


0701 (121047)

Nanoindentation Analysis of Cadaveric Specimen with Hydroxyapatite, Bone, and Implants. J. BLANKENSHIP, and J. LEMONS, UAB School of Dentistry, Birmingham, AL

Introduction: Materials of lower elastic modulus (bone) are known to microfracture when in contact with higher modulus materials such as cobalt (Co) alloy when a significant load is applied. Microcracks have been shown to alter bone adjacent to the implant bone interfaces due to constant modeling and remodeling of the bone. Many suggest that synthetic hydroxyapatite coating will minimize any microfraction of bone. Histological , histomorphometrical and nanohardness testing was done to evaluate long term in vivo interfaces between cobalt and hydroxyapatite versus bone from cadaver human implant specimens.

Materials and Methods: Three cadaveric samples with subperiosteal (Co alloy and HA coating) implants and hydroxyapatite (HA) particulate, each about 11 years in-vivo, were tested in vitro after being embedded in acrylic and polished using the Exact grinder. Keyence Digital Imaging was used to evaluate microtopography. Modulus and hardness values were determined using the MTS Nano G200. The method used was depth control for nanohardness measurements.

Results: The Co alloy implant had the highest modulus and hardness, followed by the HA coating and particulates, and lastly the bone. Comparing the bone sample there was no significant difference found in the hardness and modulus of the bone in relation to its proximity to the implant interface for Co alloy or hydroxyapatite.

Discussion: These results show that the alloy and HA to bone interfaces were of similar magnitudes for modulus and hardness supporting a minimal zone of bone alteration at the interface.

Conclusions: Nanodimension measures of modulus and hardness of alloy, HA and bone demonstrated minimal alterations of bone at the implant interfaces.

Support of NIH DART grant T32DE017607 is acknowledged


0702 (114197)

The Efficacy of Infiltration Anesthesia for Adult Mandibular Incisors. A. JABER, B. AL-BAQSHI, J. WHITWORTH, I.P. CORBETT, M. KANAA, and J.G. MEECHAN, Newcastle University, Newcastle upon Tyne, United Kingdom

Objectives: To compare the efficacy of 2% lidocaine and 4% articaine with 1:100,000 epinephrine in anesthetising mandibular incisors after buccal infiltration or a split buccal plus lingual dose.

Methods: Thirty one healthy volunteers received 1) buccal infiltration of 1.8mL lidocaine plus dummy lingual injection, 2) buccal plus lingual infiltrations of 0.9mL lidocaine, 3) buccal infiltration of 1.8mL articaine plus dummy lingual injection, 4) buccal plus lingual infiltrations of 0.9mL articaine, opposite a mandibular central incisor, in randomised order over 4 visits. Pulp sensitivities of the central incisor and contralateral lateral incisor were assessed electronically every 2min for 30min, then every 5min until 45min post-injection. The numbers of no responses to maximum stimulation from the pulp tester were recorded. Data were analysed by McNemar's test.

Results: For the central incisor, the number of episodes of no sensation on maximal stimulation was significantly greater after buccal infiltration with articaine (453) compared to lidocaine (244) (p< 0.001). Significant differences were also found between articaine and lidocaine buccal plus lingual infiltrations (499 versus 348 episodes respectively; p<0.001). Lidocaine buccal plus lingual infiltration was more successful than buccal infiltration alone (348 episodes versus 244; p<0.001). Articaine buccal plus lingual infiltration was more successful than buccal alone (499 versus 453 episodes; p<0.001).

For the contralateral lateral incisor, the episodes of no response after articaine and lidocaine buccal infiltrations were 234 versus 88 respectively (p<0.001). Articaine was more successful than lidocaine after buccal plus lingual infiltrations (319 versus 146 episodes respectively; p<0.001). Lidocaine buccal infiltration alone was less successful than lidocaine buccal plus lingual infiltrations (88 versus 146 episodes, p<0.001). Articaine buccal infiltration (234 episodes) was less successful than articaine buccal plus lingual infiltrations (319 episodes) (p<0.001)

Conclusions: 4% articaine provides better pulpal anesthesia than 2% lidocaine when used as an infiltration in the lower incisor region.


0703 (114522)

Effect of different articaine buccal injections on palatal pin-prick discomfort. A.A.S. GUERRA1, L.M.D.A. SOUZA1, J.C. RAMACCIATO2, R.H.L. MOTTA3, and J.G. MEECHAN4, 1Universidade Federal de Sergipe, Aracajú, Brazil, 2CPO Sao Leopoldo Mandic, Campinas, Brazil, 3São Leopoldo Mandic Dental School, Campinas, Brazil, 4Newcastle University, Newcastle, United Kingdom

Objectives: To compare the effect of maxillary buccal infiltration (BI) and posterior superior alveolar nerve block (PSANB) using 4% articaine with 1:100.000 epinephrine on pin-prick discomfort on palatal mucosa.

Methods: Following receipt of ethical approval 30 healthy subjects participated in this double-blind cross-over study. Each individual received two different maxillary buccal anesthetic techniques with 1.8ml of 4% articaine with 1:100.000 epinephrine; namely BI and PSANB. Injections were given by the same operator and separated by at least two weeks. Anesthesia of palatal soft tissue was assessed by pin-prick test with a 30g needle by an operator blinded to the type of injection. Discomfort of pin-prick was assessed before and 3, 5, and 10 minutes post-injection using a 100mm visual analogue scale (VAS). Data from the VAS were categorized as none to mild pain (0-30mm) and moderate to severe pain (>30mm). Data were analyzed by Chi-square test.

Results: Prior to injection all volunteers rated palatal pin-prick sensation in the moderate to severe category. Both techniques decreased VAS scores after injection. The effect was quicker following PSANB as 10% of volunteers rated pain in the none to mild category at 3 minutes compared to no subjects at this time after BI. At 5 minutes all volunteers rated pain in the none to mild range following PSANB compared to 70% of volunteers after BI (Chi Squared=10.5; p<0.001). At 10 minutes all volunteers rated discomfort in the none to mild range for both injections.

Conclusions: PSANB with 4% articaine and 1:100,000 epinephrine was more effective than BI in reducing pin-prick discomfort of palatal soft tissue at 5 minutes post-injection. Both techniques were equally effective at ten minutes.


0704 (115765)

Dexmedetomidine Suppresses Sympathetic Activities without Subjective Comfort during Intravenous Sedation. K. OKAWA, T. ICHINOHE, and Y. KANEKO, Tokyo Dental College, Chiba, Japan

Objectives: Dental treatments are frequently accompanied with anxiety, which cause systemic complications related with autonomic nervous disturbances. Intravenous (IV) sedation is useful to mitigate dental stresses. There was no study which compared the anxiolytic or stress mitigating effects during dexmedetomidine (Dex) and propofol (prop) sedation. This study was designed to examine whether Dex or Prop sedation affects autonomic nervous activities during psychological stress and whether these results are accompanied with the change in subjective feelings.

Methods: Twenty-five healthy volunteers were included in a randomized crossover manner. The subjects rested in a sitting position and heart rate (HR), HR variability (HRV), arterial oxygen saturation (SpO2) and bispectral index (BIS) value were continuously monitored. They were required to perform first mental arithmetic (MA) task for seven minutes as psychological stressor (Test-1). Second MA task was challenged under Dex or Prop sedation (Test-2). We aimed for OAA/S score 4 and BIS value of 75 – 85 as sedation level for both groups. HRV was assessed by means of the power spectral analysis (low-frequency (LF), high-frequency (HF) components and LF/HF ratio). Face Anxiety Scale (FAS) was used to grade their feelings as subjective index.

Results: During Test-2, there were no differences in BIS values between the two groups. HR, LF/HF and normalized unit LF (nuLF) increased, whereas normalized unit HF (nuHF) decreased in both groups. However, the changes in nuHF was larger in the Prop group and FAS score, SpO2, and the rate of the correct answers during Test-2 were also lower in the Prop group.

Conclusions: Although Dex more effectively suppresses sympathetic activities for psychological stresses than propofol, it is not followed by subjective comfort.


0705 (116393)

Effect of disinfection on integrity of dental local anesthetic cartridges. F.P. NOLASCO1, V.A.M. MONTALLI1, T. RICCI1, J.G. MEECHAN2, R.H.L. MOTTA1, and J.C. RAMACCIATO1, 1Sao Leopoldo Mandic Dental School, Campinas, Brazil, 2Newcastle University, Newcastle, United Kingdom

Objectives: To determine if disinfection affected the forces required to cause cartridge failure and the pH of dental anesthetic solutions.

Methods: Plastic and glass cartridges containing 3% prilocaine with 0,03UI/mL felypressin (Cristalia) and 2% mepivacaine with 1:100.000 epinephrine (Septodont) respectively were stored inside their boxes or soaked in 70% alcohol or 0.2% peracetic acid for 40 minutes or 24 hours (n=10 for each group). After each regimen the cartridges were placed in a dental syringe with no needle attached and placed in an EMIC testing machine. A force was applied to the cartridge plunger until failure occurred (fracture for glass; leakage for plastic). The force (in Newtons) required to produce failure was recorded. The pH of the cartridges was recorded after each storage regimen. Data were analysed by ANOVA and unpaired t test.

Results: Plastic cartridges failed at forces significantly less than those required to fracture glass cartridges (mean forces 289N and 418N respectively t=5.61; p<0.001). The force required for failure was not affected by the method of storage for plastic (F=1.05; p = 0.36) and glass cartridges (F=1.59; p=0.22). The pH of the solution in glass cartridges was unaffected by the method of storage. Storage in peracetic acid decreased the pH of the solution in plastic cartridges from a mean baseline reading of 4.55 to 4.18 at 40 minutes and 4.17 at 24 hours (F=5.48; p = 0.01). Similarly storage in alcohol decreased the pH of the solution in plastic cartridges to 4.10 at 40 minutes and 4.14 at 24 hours (F= 7.17; p = 0.03).

Conclusions: Disinfection in alcohol or peracetic acid for up to 24 hours did not affect the forces required to produce failure in dental anesthetic cartridges. The pH of the solution in plastic cartridges was significantly lowered after storage in peracetic acid or alcohol.


0706 (116911)

Experimental model of inferior alveolar nerve block in rats. R.A.P. SILVA1, L.A. BERTO1, M.C. VOLPATO2, J. RANALI2, E.D. PAULA3, and F.C. GROPPO2, 1State University of Campinas - Piracicaba Dental School, Piracicaba, Brazil, 2Universidade Estadual de Campinas- UNICAMP, Piracicaba, Brazil, 3State University of Campinas – Biological Institute, Campinas, Brazil

Objective: The aim of the present study was to evaluate a model to test dental local anesthetic solutions in inferior alveolar nerve block (IANB) in rats. Methods: An electrical wire (cooper, 0.3 mm, flexible and isolated) was fixed (dental composite) on the occlusal surface of both right and left inferior molars in 20 rats after general anesthesia induced by sodium thiopental (40mg/kg). After general anesthesia cessation, the animals were slightly sedated and 0.2 mL of 2% lidocaine with 1:100.000 epinephrine (LIDO) (Alphacaine, DFL Com. Ind. Ltda) or 0.2 mL of saline solution (SS) was randomly injected. The injection was performed by inserting a 13x3.5 needle extra orally in the inner part of the mandibular angle towards the mandible incisure. The control side was set as the SS injection side. The anesthesia parameters (pulpal anesthesia onset and duration – PO and PD) were evaluated by observing rat physical response after contacting an electrical pulp tester (EPT) with the extra orally exposed end of the wires previously fixed on molars surface. Results: The success (minimum of 10min of anesthesia) of the injection was 95% and 0% in the LIDO and SS sides, respectively. LIDO induced 55 (± 31.7) minutes of PA and 4.75 (±3.45) minutes of anesthesia onset. PD obtained in this study was not different (t test, p=0.8055) from those obtained in humans (58 ± 30.0 min). PO values were also similar (t test, p=0.6848) to the ones previously observed in humans (5.3 ± 5.6 min). The values of anesthesia parameters in humans were previously obtained by studies using EPT (Odor et al., 1994; Steinkruger et al., 2006). Conclusion: The model is practical and precise to estimate onset and duration of pulpal anesthesia after IANB, presenting similar variability to those obtained in humans. Supported by PIBIC-CNPq and FAPESP (#2006/00121-9).


0707 (118391)

Comparison of articaine and lidocaine for extractions of mandibular teeth. L.M.D.A. SOUZA1, C.E.S. SILVEIRA1, A.D.O. RIBEIRO1, G.A. CRUZ1, J.C. RAMACCIATO2, R.H.L. MOTTA3, and J.G. MEECHAN4, 1UNIVERSIDADE FEDERAL DE SERGIPE, Aracajú, Brazil, 2CPO Sao Leopoldo Mandic, Campinas, Brazil, 3São Leopoldo Mandic Dental School, Campinas, Brazil, 4Newcastle University, Newcastle, United Kingdom

Objectives: The aim of this study was to compare the efficacy 4% articaine with 1:100.000 epinephrine and 2% lidocaine with 1:100.000 epinephrine when injected as inferior alveolar nerve blocks (IANB) and long buccal nerve blocks (LBNB) for mandibular dental extractions.

Methods: 30 subjects with chronic periodontitis according to the classification of the American Association of Periodontology, who needed the extraction of at least 2 lower molars, one on each side of the mandible were selected. Each received an IANB and an LBNB with either 4% articaine with epinephrine 1:100.000 or 2% lidocaine with epinephrine 1:100.000 (the same solution was used for the IANB and the LBNB at each visit). At completion of the trial each patient had received both solutions over two visits at least one week apart. An analogical face scale assessed pain sensitivity in the range 0 (no pain) to 5 (worst possible pain) at three times at each visit: pre-anesthetic (for inclusion in the study patients had to have a minimum score of 5 at this time), during the luxation movements, when the need for supplementary intraligamentary injection was also assessed, and on removal of the tooth. The data were analysed by Mann-Whitney test.

Results: 4% articaine with epinephrine was significantly more successful than lidocaine with epinephrine in providing anesthesia (83% success versus 50% success respectively; p < 0.05). Only 16.7% of the patients anesthetised with the 4% articaine with epinephrine needed a supplementary anesthetic, compared to 46.7% with lidocaine with epinephrine (p<0.05).

Conclusion: 4% articaine with epinephrine 1:100.000 was more successful than 2% lidocaine with epinephrine 1:100.000 in providing combined IANB and LBNB anesthesia for the removal of teeth with chronic periodontitis.


0708 (118650)

High-dose remifentanil administration during orthognathic surgery caused postoperative hyperalgesia. H. AGATA, J. YUMURA, T. OUCHI, R. SERITA, and T. KOITABASHI, Tokyo Dental College, Ichikawa General Hospital, Anesthesilogy, Ichikawa-city, Chiba, Japan

Objectives: One of the major problems of remifentanil-based anesthesia is postoperative hyperalgesia. Although several studies have been conducted to evaluate the possibility of the hyperalgesia, this phenomenon is not confirmed in human. Therefore, we performed this study to investigate whether clinical relevant dose of remifentanil caused hyperalgesia during orthognathic surgery. Methods: Twenty adult patients who underwent orthognathic surgery were enrolled in this study. Patients were randomly assigned to one of two anesthetic regimens. In group-H, sevoflurane was kept constant at 1.0 % and a remifentanil infusion (minimal rates: 0.3 mcg/kg/min) was titrated according to the autonomic responses. In group-L, remifentanil was kept at 0.15 mcg/kg/min and sevoflurane was titrated according to autonomic responses. All patients were given a bolus of 4mcg/kg fentanyl 40 min before the end of surgery. Postoperative pain was managed with intravenous fentanyl administered by a patient-controlled-analgesia pump which was programmed to deliver 20 mcg of fentanyl with a lockout interval of 10 min. Blood pressure, heart rate, and visual analog scale (VAS) were evaluated at 1, 3, 6, 12, 24 hours following the operation. The cumulative fentanyl amount to be administered was also measured. Results: Sevoflurane concentrations during the operation were significantly different between two groups (0.9 ± 0.3% in the group-H vs. 1.6 ± 0.3% in the group-L), as well as, the mean cumulative remifentanil amounts (3.5 ± 0.9 mg in the group-H vs. 1.8 ± 0.3 mg in the group-L). Postoperative hemodynamic responses and VAS were similar in both groups. Group-H required significantly higher post-operative fentanyl (15 ± 0.3mcg/kg) than those in the group-L (7.3 ± 4.5mcg/kg). Conclusion: Although the VAS was similar between two groups, postoperative fentanyl consumption was increased in the group-H, suggesting the occurrence of hyperalgesia. This study demonstrates that the relatively high-dose remifentanil administration during orthognathic surgery possibly causes hyperalgesia.


0709 (119174)

Effect of posterior superior alveolar nerve block on anterior teeth. A.D.O. RIBEIRO1, C.E.S. SILVEIRA1, L.M.D.A. SOUZA1, L.A.P. PEREIRA2, R.H.L. MOTTA3, J.C. RAMACCIATO4, and J.G. MEECHAN5, 1UNIVERSIDADE FEDERAL DE SERGIPE, Aracajú, Brazil, 2FOP-Unicamp, Campinas, Brazil, 3São Leopoldo Mandic Dental School, Campinas, Brazil, 4CPO Sao Leopoldo Mandic, Campinas, Brazil, 5Newcastle University, Newcastle, United Kingdom

Objectives: The aim of the present work was to evaluate the effect of 4% articaine with 1:100.000 epinephrine administered as a posterior superior alveolar nerve block (PSANB) on pulpal responses of ipsilateral first premolar and lateral incisor teeth. Methods: Following receipt of ethical approval, thirty healthy subjects with a vital maxillary lateral incisor and first premolar were recruited. The pulp sensitivity was assessed with a refrigerating spray (Endo-ice©), which promotes refrigeration around -50°C. An analogical face scale was used to measure pain sensitivity in the range 0 (no pain) to 5 (worst possible pain) at three times: immediately before the injection (baseline), four minutes and eight minutes after a PSANB with 1.8mL 4% articaine with 1:100.000 epinephrine. A short (21 mm) 30G needle fitted to an aspirating syringe was used. Data were separated into 2 groups: scores of 2 or less on the face scale (G1) and scores of 3 or more on the face scale (G2) and they were analyzed by Chi-square test (p<0.05). Results: Pulpal pain sensitivity decreased significantly over the three time points for both the premolar (Chi Square = 55.0; p < 0.001) and the lateral incisor (Chi Square = 46.8; p < 0.001). At pre-injection only 5 patients reported discomfort as G1 for the premolar and incisor teeth compared to 26 patients for the premolar and 22 patients for the lateral incisor at 4 minutes. At 8 minutes post injection all patients reported a score of G1 for these teeth. Conclusions: A PSANB with 4% articaine with 1:100,000 epinephrine reduced pulp sensitivity in ipsilateral maxillary first premolar and lateral incisor teeth.


0710 (119203)

Adding ketamine to propofol anesthesia in dental treatment for handicapped. K.-I. FUKUDA, T. ICHINOHE, and Y. KANEKO, Tokyo Dental College, Tokyo, Japan

Objectives: Propofol anesthesia is recognized for its rapid emergence. We often apply non-intubated propofol anesthesia for behavior control in handicapped undergoing day-dental treatment. Ketamine has been reported as an analgesic agent even a small dose. Here we investigated the behavior control, hemodynamic, respiratory, emergence, and recovery effects and characteristics of adding a small dose of ketamine to non-intubated propofol anesthesia. Methods: After obtaining local institutional ethics committee and written parental consent, 20 handicapped patients for dental treatment were enrolled in a double-blind, placebo controlled, cross-over study. They randomly received two trials with 0.2mg/kg IV ketamine or saline in propofol anesthesia. Propofol was administered 1.2mg/kg initial dose followed by a continuous infusion of 8mg/kg/hour in both traial. We examined the incidence of patient's movement during treatments, mean arterial pressure, heart rate, peripheral oxygen saturation, recovery time, discharge time, and postoperative nausea and vomiting. Results: The incidence of patient's movement during treatments was 10% with ketamine significantly lower than 55% without ketamine. Other measurements in hemodynamic, respiratory, emergence, and recovery effects and characteristics were no difference between both trials. Conclusions: We concluded that the application of a combined small dose of ketamine in non-intubated propofol anesthesia would play an important role for behavior control in handicapped undergoing day-dental treatment safely and readily.


0711 (119295)

Evaluation of pain control during fixed orthodontic appliance therapy. V.A.M. MONTALLI1, C.J. PELISSON1, F.M. FLÓRIO1, J. RAMACCIATO1, R.H.L. MOTTA1, and F.C. GROPPO2, 1São Leopoldo Mandic Dental School, Campinas, Brazil, 2Piracicaba Dental School, University of Campinas, Piracicaba, Brazil

Objectives:The aim of this prospective, randomized, double-blind clinical trial was to compare the pain control effectiveness in fixed orthodontic treatment and evaluates comparatively the analgesic effects of different drugs for the control of this pain. Methods:The following agents were evaluated: sodium diclofenac 50mg (1), placebo (2), dexamethasone 4mg (3), nimesulide 100mg (4), ibuprofen 400 mg (5) and all of them were taken 1 hour before fixed orthodontic placement in patients. The patients recorded their discomfort on a 100-mm visual analog scale during several activities (biting, chewing, and touching back teeth and touching front teeth) at 5 time intervals: 2, 12, 24, 48 hours and 1 week after the placement. The patients (n = 150) were randomly assigned to the different groups. A repeated-measures Kruskal Wallis was performed as a function of time and treatment group (p=0.05). Results: The highest pain value occurred 24 hours after the placement (p<0.05). The most effective medication was formulation 3 (p<0.05). Conclusion: A single dose of Dexametasone 4mg 1 hour before of the fixed orthodontic placement can be a effective alternative for the pain control of the patients.


0712 (119768)

Environmental Tobacco Exposure and Airway Complications during General Anesthesia. B. CRAWFORD, S. THIKKURISSY, and M. SMILEY, Ohio State University, Columbus, OH

Objectives: The Purpose of this study was to examine the relationship between passive tobacco exposure and airway complications during dental rehabilitation under general anesthesia in pediatric patients.

Methods: Children ages 18months to 14 years were randomly selected in this double blind study. Children with a medical history significant for asthma, recent upper respiratory infection or other conditions affecting airway reactivity were excluded. After obtaining informed consent, the parents of the child were given a questionnaire evaluating the child's exposure level to passive smoke inhalation. The children were then evaluated throughout the course of the anesthetic for laryngospasm, hypersecretion, bronchospasm, breath holding, and coughing by a Dentist Anesthesiologist and PACU recovery nurse who were both be blinded as to the child's environmental tobacco exposure level.

Results: Data from 32 children (17 female and 15 male) were analyzed. The mean age was 61.7months (SD 28.2). The age of children where the primary caregiver was a non-smoker was significantly younger (p=.003). Overall, 50% of primary caregivers smoked, with 25% smoking 10-30 cigarettes per day. There was no difference in time spent at home between the two groups (p=.82). No significant differences were noted in breath holding, coughing, incidence of laryngospasm, or incidence of bronchospasm.

Conclusion: Results from this pilot study indicated no difference in airway complications during general anesthesia between children with passive smoke exposure and those without.


0714 (113077)

Clinical Study Evaluating Anti-Plaque Efficacy of Colgate® Total® Advanced Toothpaste. R. RICHTER, V. BARNES, T. XU, and W. DEVIZIO, Colgate-Palmolive Technology Center, Piscataway, NJ

While consumers understand a healthy mouth is critical to overall systemic health, consumers expect to experience the feeling of clean in their mouth. Consumers have indicated they want to maintain a smooth feeling on their teeth similar to a professional dental prophylaxis. Colgate® Total® is the only OTC dentifrice with both FDA and ADA approval for the treatment of plaque and gingivitis. A new enhanced silica based cleaning system has been identified that will continue to allow superior efficacy in addition to the enhanced feeling of smooth and clean of the teeth. Objective: To determine if the new silica cleaning system would have any impact on the anti-plaque efficacy of a triclosan/copolymer dentifrice. Methods: A double blind, randomized, cross over study was conducted utilizing 17 healthy volunteers. Subjects brushed with Colgate® Total® (CT), Colgate® Total® Advanced Toothpaste (CAC), and Colgate® Winterfresh Gel (WFG). A baseline plaque score was calculated immediately following a single brushing with the assigned dentifrice, in accordance with the published Modified Gingival Margin Plaque Index (MGMPI). Subjects refrained from oral hygiene for 24 hours at which point a final MGMPI plaque score was calculated. The final MGMPI plaque score was calculated as the difference between the baseline and final plaque scores representing the 24 hour level of plaque re-growth for each product. Results: CT produced an average 24 hr plaque score of 8.73 (±3.69), while CAC demonstrated 8.78 (±6.55). WFG, the negative control, produced an average 24 hr. plaque score of 18.71 (±9.11). The WFG plaque scores were significantly different from all CT and CAC scores (p < 0.05) while the CT and CAC scores were not significantly different.Conclusion: The enhanced cleaning system maintains the substantial anti-plaque efficacy of the triclosan/copolymer system in the new Colgate® Total® Advanced Toothpaste.


0715 (114913)

Clinical and Ayurveda efficacy of a Novel Ayurveda Dentifrice. A. KAKAR1, K. KAKAR2, W. DEVIZIO3, S. MANEK4, P.K. SREENIVASAN5, and P.D. DWIVEDI1, 1ADCRC,New Delhi, INDIA, New Delhi, India, 2ADCRC, New Delhi, India, 3Colgate-Palmolive Technology Center, Piscataway, NJ, 4Colgate Palmolive India Limited, Mumbai, India, 5Colgate-Palmolive Company, Piscataway, NJ

Objective: Ayurveda represents a health care system recognized in India with wide-spread utilization in this region. This 12-week clinical investigation compared the efficacy of a toothpaste formulated with Ayurveda recognized ingredients (Colgate Ayurveda Sampoorna) with a control dentifrice. Methods: 136 adult male and female subjects were screened and 120 enrolled following informed consent. Supragingival plaque and gingivitis were scored by the Quigley-Hein Plaque Index (Turskey Modification) and the Löe-Silness Gingival Index respectively. Ayurveda recognized clinical parameters i.e. plaque/debris on teeth and redness on gum margins were determined by a composite visual analog score (VAS). Subjects stratified for plaque scores and demographics were randomized to a treatment group. A dentist and an Ayurvedic physician conducted all study related clinical assessments at baseline and after 6 and 12 weeks of formulation use. 112 subjects completed all phases of the study for statistical analyses presented in this report. Results: The Ayurveda Sampoorna group demonstrated a statistically significant reduction in plaque score of 15% and 16% at the 6 and 12-week assessments respectively versus the control group (p<0.0005). Similarly, gingivitis scores demonstrated 20% and 21% reductions at the 6 and 12-week assessments respectively versus the control (p<0.0005). Results from the dental examinations were similar to the VAS based Ayurveda assessments. The Ayurveda Sampoorna group demonstrated 11% and 16% reductions in VAS scores of dental debris at the 6 and 12 week examinations versus the control and were statistically significant (p<0.0005). Gum redness observed by the Ayurveda physician also demonstrated significant reductions of 12% and 15% at the 6 week and 12-week exams (p<0.0005). No adverse events were reported during the study. Conclusion: Brushing with Colgate Ayurveda Sampoorna toothpaste demonstrated significant reductions in dental plaque and gingivitis versus the control paste at the 6 and 12 week assessments by both clinical and Ayurveda parameters.


0716 (118957)

Clinical Study Evaluating Anti-plaque Efficacy of Licochalcone A Containing Toothpaste. J. XU1, C. NIU2, and S. SHI2, 1Hawley & Hazel Chemical Co., (ZS) Ltd, Zhongshan, China, 2Hawley & Hazel Chemical Co. (ZS) Ltd, Zhongshan, China

Licorice, the root and rhizome of the Glycyrrhiza uralensis, Glycyrrhiza glabra, and Glycyrrhiza inflata, is known to be used in food and pharmaceutical industries. It is also historically used as natural medicine because of its broad therapeutic effect. G. inflata is a main botanical source of licorice and is chemically characterized by the presence of retrochalcones, e.g., licochalcone A, which is distinguished from ordinary chalcones by the absence of oxygen functionality at position 2. This structure difference is important for its broad biological activities, e.g., antiprotozoal, anti-inflammatory, anti-tumor promoting, antioxidative, and antimicrobial activities. However, there was little information reported for its antimicrobial activity against oral pathogens. Furthermore, no clinical report was published about licochalcone A containing extracted from G. inflata in the toothpaste on plaque control. Objective: This clinical investigation compared the anti-plaque effect of a G. inflata extract containing toothpaste (GCT) with a regular fluoride toothpaste (RFT). Method: An extraction process was developed to obtain a G. inflata extract, which contains more than 20% licochalcone A. 0.3% such extract was formulated into a toothpaste. A double blinded randomized crossover study was conducted utilizing 19 healthy volunteers. After washout, subjects brushed with an assigned toothpaste. A baseline plaque score was identified using the published Modified Gingival Margin Plaque Index (MGMPI). After 24 hrs post-brushing, a final plaque score was measured. The differences between the baseline and final MGMPI scores indicated the degree of anti-plaque effect of the toothpaste. Results: GCT showed a less plaque score of 15.60 vs. RFT with a score of 19.46. The difference was statistically significant (p < 0.05). Conclusion: The study suggested that GCT delivered anti-plaque efficacy. The data suggest that the use of licorice toothpaste may help control of dental plaque and keep a good gum health.


0717 (119593)

Evaluation of bioactive glass and sodium bicarbonate polishing powders. I. THOMPSON1, M. HAJATDOOSI-SANI1, A. BANERJEE2, and S. FARRELL1, 1King's College London, London, United Kingdom, 2King's College London Dental Institute, London, United Kingdom

Objective: To compare the clinical effectiveness of sodium bicarbonate and bioactive glass powders when used in prophylaxis treatments. Methods: Fifty Patients were recruited, twenty five patients were allocated to either a low or high oral hygiene subgroup determined by plaque scores and clinical examination. Using a double blinded, split mouth model, all patients underwent a full prophylaxis treatment on the lower jaw. The upper jaw was used as an untreated control. Bioactive glass (Sylc, OSspray ltd, UK) and sodium bicarbonate (Prophy Jet, Dentslpy, UK) were applied randomly to opposite sides of the mouth. Participants had three parameters measured, 1) sensitivity to cold air and ice, 2) shade change and 3) comfort of procedure. All parameters were recorded at pre and post treatment and at 10 day recall. Results: 1) The bioactive glass powder, in both sub groups, reported a 44% (0.80±0.10, p<0.05) decrease in sensitivity, against control, immediately post op, and 42% (0.85±0.05, p<0.05) at 10 day follow up when stimulated with cold air. Ice stimulation showed a 10% (3.05±0.17, p<0.05) and 22% (2.64±0.33, p<0.05) reduction in sensitivity immediately post op and at 10 day follow up. Application of sodium bicarbonate powders increase sensitivity, 17% (1.76±0.3, p<0.05), at 10 days when stimulated with cold air. 2) Both test powders showed variation between subgroups, bioactive glass powder 1 and 4 shades whiter, sodium bicarbonate 1 and 2 shades whiter in good and bad oral hygiene respectively. 3) Patients in both sub groups reported a 46% (7.9±1.4, p<0.05) increase in comfort of procedure with the bioactive glass over that of sodium bicarbonate. Conclusion: The bioactive glass powder was more effective at desensitising both good and poor oral hygiene groups, and removing stain in poor oral hygiene patients. The bioactive glass also provides better patient comfort. This research was sponsored by OSspray.


0718 (117805)

Study on the pH of dental plaque using pH-buffering toothpaste. K. MOON, J. KIM, B. KIM, W. HA, J. AHN, and S. KANG, LG Household & Healthcare Research Park, Deajeon, South Korea

Objectives: To control the pH of dental plaque using a toothpaste which contains pH-buffering system.

Methods: This was a parallel groups, examiner-blind, randomized and controlled in-vivo trial in which pH-buffering toothpaste(Perioe AlkaActionTM; PA) was compared with positive control(Arm & Hammer White SparkleTM; WS) and negative control(Perioe AlkaAction without buffering system; PC and Perioe BreathTM; PB). Total of 11 healthy adults, who weren't allow to any oral hygiene activity for a day, were enrolled into cross-over study. The pH values of saliva and dental plaque were measured by Thermo-Orion meter with Orion 9803BN electrode. Saliva and plaque samples were collected before treatment and subjects were rinsed 10wt% glucose solution followed by gargle with 33wt% toothpaste slurry. Saliva was collected in every two minutes. Interdental and subgingival plaques were picked up every ten minutes and diluted in 0.3 mililiters of 0.45wt% sodium chloride solution.

Results: 10 out of the 11 subjects completed the study. Initial pH of saliva was within the range of 6.0 to 7.0. The pH of saliva, right after rinsing with PA, WS, PC and PB was 7.6, 8.1, 7.1 and 7.1, respectively. After 15 minutes, the pH values of all subjects were restored to around 7.0 regardless of toothpaste. The pH of dental plaque initially was from 5.2 to 7.0 and dropped around 4.5 after rinsing with glucose solution. Right after gargling with PA, WS, PC and PB, pH of dental plaque increased to 7.4, 7.5, 6.5 and 6.5. After 30 minutes, pH of PA rinsed subjects maintained neutral, 7.1, but that of WS, PC and PB dropped again to 6.0, 6.2 and 5.6, respectively. PA toothpaste controlled the pH of dental plaque more effectively than any other toothpaste significantly.(P<0.05) Conclusion: Perioe AlkaActionTM toothpaste containing pH-buffering system was effective for controlling and maintaining neutral pH of dental plaque.


0719 (117645)

Caries Risk Assessment in Child Patients by Dental PBRN Dentists. J.L. RILEY, III1, C.T. AJMO2, V. QVIST3, J.L. FELLOWS4, D.B. RINDAL5, J.S. RICHMAN6, G.H. GILBERT6, V.V. GORDAN1, and F.T. DPBRN COLLABORATIVE GROUP6, 1University of Florida, Gainesville, FL, 2Private Practice in Dunedin, Dunedin, FL, 3University of Copenhagen, Copenhagen N, Denmark, 4Center for Health Research Kaiser Permanente Northwest, Portland, OR, 5Health Partners, Minneapolis, MN, 6The University of Alabama at Birmingham, Birmingham, AL

Purpose: The aims were to: (1) describe what dentists from a multi-region network consider as important factors when assessing caries risk in children, and (2) test for differences as a function of practice characteristics.

Methods: This study surveyed 509 Dental Practice-based Research Network (DPBRN; www.DentalPBRN.org) dentists who perform restorative dentistry on patients ages 6-18. DPBRN is a consortium of participating practices and dental organizations that comprises five regions: AL/MS: Alabama/Mississippi; FL/GA: Florida/Georgia; MN: dentists employed by HealthPartners and private practitioners in Minnesota; PDA: Permanente Dental Associates in cooperation with Kaiser Permanente Center for Health Research; and SK: Denmark, Norway, and Sweden.

Results: Sixty-nine percent of network dentists reported performing on a regular basis caries risk assessment of some variety, and 12% assess caries risk using a special risk assessment form. Some regional and practice model differences were evident. Regions where dentists most often were in a private practice model (FL/GA, AL/MS) were the least likely to perform caries risk assessment. Regions consisting mostly of large group practices (PDA, MN) were the most likely to use a special form for caries risk assessment. More-recent graduates from dental school were more likely to use caries risk assessment in their practice when compared to older graduates. Current oral hygiene, decreased salivary flow, and the presence of active caries were rated as the most important caries factors. We also observed considerable variability in dentists' views of the importance of specific caries risk factors in treatment planning, and only weak evidence that caries risk assessment is driving clinical practice when preventive treatment recommendations are being considered.

Conclusion: These data suggest significant differences in caries risk assessment routines as a function of practice characteristics. Not all private practice dentists assess caries risk. Support: DE 16746, DE 16747.


0720 (117668)

Plaque Removal Effectiveness of Normal Brushing on Overnight Accumulation. R.W. GERLACH1, M.L. BARKER1, M.E. RUBUSH1, B. THACKER2, K. KARPINIA2, and I. MAGNUSSON2, 1The Procter & Gamble Company, Mason, OH, 2University of Florida, Gainesville, FL

Objectives: Digital plaque image analysis was used to measure the effectiveness of normal oral hygiene to remove overnight plaque accumulation. Methods: Institutional review and informed consent were obtained from 39 healthy adults. After evening tooth brushing, these volunteers abstained from eating, drinking, and oral hygiene overnight prior to a morning (AM) evaluation. At the morning visit, subjects swished with 5 mL of a 1240 ppm fluorescein rinse and expectorated. Subjects were positioned, cheek retractors were inserted, and a digital image was collected under standardized lighting conditions. Subjects received a regular anticavity dentifrice (Crest® Cavity Protection) and standard manual toothbrush for routine whole mouth oral hygiene. Rinsing and imaging were repeated, and image analysis was used to objectively measure disclosed plaque on facial anterior tooth surfaces. A paired difference t-test was used to compare overnight prebrush and postbrush plaque areas. Results: Mean (SD) age was 34.7 (13.1) years. The population exhibited considerable variation in overnight plaque accumulation, ranging from 5.5-55.7% coverage. Mean (SD) prebush plaque area was 17.4% (9.77). While all subjects removed some plaque with brushing, none removed all plaque. Postbrush plaque area ranged from 3.9-37.3%. Mean (SD) postbrush area was 9.5 (6.21), and differed significantly (p<0.0001) from prebrush area. Conclusion: Digital plaque image analysis on facial anterior tooth surfaces demonstrated that normal morning brushing with a manual toothbrush and regular dentifrice removed on average 45% of overnight plaque accumulation.


0721 (117682)

Effectiveness of Timed Morning Brushing on Disclosed MQH Plaque. I. MAGNUSSON1, K. KARPINIA1, B. HALES1, A.A. WALANSKI2, M.L. BARKER2, and R.W. GERLACH2, 1University of Florida, Gainesville, FL, 2The Procter & Gamble Company, Mason, OH

Objectives: This research was conducted to assess the effectiveness of timed morning brushing on the overnight disclosed plaque in expanded and diverse population. Methods: The target population was approximately 200 generally healthy adults with disclosed overnight plaque. Volunteers were instructed to abstain from oral hygiene overnight. Overnight facial anterior disclosed plaque accumulation was assessed clinically using the Modified Quigley Hein (MQH) 6-point categorical scale (the prebrush score). Subjects were provided a regular anticavity dentifrice (Crest® Cavity Protection) and standard manual toothbrush for supervised 30-seconds. Subjects were again disclosed, and whole mouth MQH plaque was assessed (the postbrush score). Prebrush and postbrush plaque scores were compared using a paired difference t-test. Results: A total of 195 subjects were recruited in 3 cohorts. The study population exhibited considerable diversity. Age ranged from 18-73 years, with a mean (SD) age was 33.1 (14.2) years. Females predominated (71% of the sample). All subjects presented with some overnight plaque, with MQH scores ranging from 0.61 – 5.00. Postbrush mean (SD) scores ranged from 0.56 – 3.94. Comparing timepoints, mean (SD) MQH plaque was 2.3 (0.67) before brushing and 1.8 (0.62) after brushing. Prebrush and postbrush scores differed significantly (p<0.0001). Conclusion: A study involving a large, diverse population demonstrated that use of a regular toothbrush and dentifrice in timed, 30-second morning brushing resulted in a 22% reduction in mean overnight MQH plaque.


0722 (118258)

Anti-plaque effects of various dentifrices using a 4-day plaque model. T. HE, J. DUNAVENT, D. BOOKER, S. FIEDLER, and R. BAKER, Procter & Gamble Company, Mason, OH

Objectives: The present study evaluated the anti-plaque efficacy of various dentifrices using a 4-day plaque model. Methods: This was a controlled, double-blind, randomized, 4-treatment, 4-period, cross-over 4-day partial brushing plaque study. Test products included two stannous containing dentifrice prototypes, a triclosan containing marketed dentifrice (Crest Complete®), and a negative control (Colgate Cavity Protection®). Subjects received a dental prophylaxis prior to study initiation. Each study period took place over a span of 4 days. Treatment periods were separated by a washout period of 7 days. In each period, baseline visit involved a plaque examination using the Turesky modification of Quigley Hein plaque index (TMQHPI) followed by a polishing of the teeth. Subjects were then randomly assigned to a treatment sequence and used the products twice daily for 4 days over each study period. Subjects brushed their lingual surfaces for 30 seconds. After expectoration, each brushing was immediately followed by swishing with the dentifrice slurry for 60 seconds. Clinical examinations were conducted 4-day post treatment. Plaque scores were analyzed using analysis of variance (ANOVA) for crossover studies. Statistical comparisons were two-sided with a significance level of 0.05. Results: The stannous dentifrice prototypes and the triclosan containing dentifrice provided statistically significant plaque benefit when compared to the negative control (p<0.05). There was no significant difference between the two stannous prototypes and the triclosan dentifrice (p>0.6). Conclusions: The research demonstrated the effectiveness of the stannous and triclosan containing dentifrices in the control of dental plaque. The 4-day plaque model can be used as a fast and reproducible proof of concept tool to guide dentifrice formulation development.


0723 (115453)

Plaque Formation and inhibition measured by the MGMPI method. R. MOAZZEZ1, V. BOOTH1, V. BARNES2, R. RICHTER2, T. XU2, and W. DEVIZIO3, 1King's College London, London, United Kingdom, 2Colgate-Palmolive, Piscataway, NJ, 3Colgate-Palmolive Technology Center, Piscataway, NJ

Objectives:, Control of dental plaque is an important task for consumers and for dental professionals. Colgate Total is the only FDA approved Toothpaste (CTT) for its anti-plaque and anti-gingivitis benefit. Modified Gingival Margin Plaque Index (MGMPI) is a clinical method providing a time-efficient and subject convenient method to assess anti-plaque effect. The objectives of this study were to evaluate anti-plaque effect of a new variant of CTT known as Colgate Total Pharma (CTP) and to cross train new clinical examiners to use MGMPI. Methods:, Fifteen male/female subjects who met the inclusion/exclusion criteria were included into these double blind crossover studies. Ethical approval and written informed consent were obtained. After a 1 week washout with Colgate Regular fluoride toothpaste (CRT), subjects brushed with CRT before a 1 minute use of a test dentifrice. A baseline MGMPI plaque score was calculated. Subjects refrained from oral hygiene for 24 hrs and returned to the clinic for their 24 hr MGMPI score. Subjects entered the 2nd washout phase to repeat as per the crossover design. Delta MGMPI scores (final minus baseline) were calculated according to previous published equation (Xu and Barnes 2003). The above procedures were conducted three times by one experienced examiner and two new examiners. Results:, The results showed that CTP provided significant (P< 0.001) anti-plaque effect vs. CRT, 10.53 (+10.99) vs. 32.83 (+19.21), 11.51 (+8.78) vs. 34.89 (+17.71) and 14.07 (+/- 11.97) vs. 33.42 (+/- 19.08) for three examiners. The results are consistent with previously reported Colgate Total toothpaste anti-plaque effect as evaluated with MGMPI methodology. Conclusions:, This study confirmed that CTP provides significant anti-plaque effect. The study also accomplished a successful training for the use of MGMPI for two new examiners.


0724 (117365)

Determination of Fluoride in Human Saliva by Gas Chromatography. V. CHAUHAN, M. RAFTER, A. HAYHURST, and S. MAKIN, GlaxoSmithkline, Weybridge, United Kingdom

Objective: To develop and validate a new assay method capable of detecting fluoride in human saliva at a limit of quantification (LOQ) of 0.03ppm.

Methods: The most common technique reported in the literature for the analysis of fluoride in saliva is based on use of ion selective electrodes (ISE).  At sub ppm concentrations, ISE can suffer from instrument drift, poor measurement repeatability and hydroxide interference.  To overcome these problems, a gas chromatography with flame ionisation detection (GC-FID) was developed and validated.  The GC-FID method was chosen because it was highly selective and capable of achieving precise and accurate results. This method employed the silanisation of fluoride using trimethylchlorosilane (TMCS) to trimethylfluorosilane (TMFS) and the analysis of the headspace for TMFS which is directly proportional to the fluoride concentration. Method validation comprised of linearity, accuracy, precision, specificity and solution stability over the working range of 0.03ppm to 10ppm.

Results: Linearity, accuracy, precision, specificity and solution stability

 

Validation Test

Findings

Linearity (0.03ppm to 10ppm)

Coefficent of determination 0.999 1/x weighted

Accuracy (0.03ppm, 0.05ppm, 0.1ppm, 1ppm, 5ppm and 10ppm)

Mean recovery between 92% to 113%

Precision (0.03ppm, 0.05ppm, 0.1ppm, 1ppm, 5ppm and 10ppm)

Relative standard deviation (RSD) less than 15%.

Specificity

Less than 20% interferance with respect to 0.03ppm fluoride.

Solution stability (0.03ppm and 10ppm)

5 days freeze thaw cycling.

 

Conclusion: The assessment of the analytical techniques has shown that GC-FID would be the most suitable method for the determination of fluoride. The method demonstrated linearity, accuracy, precision, specificity and solution stability, and is suitable for the determination of fluoride in saliva for clinical studies.


0725 (117355)

HAP Dissolution Study II: SnF2 vs. NaF Dentifrice Study. A. BAIG, M. LAWLESS, and R. FALLER, The Procter & Gamble Company, Mason, OH

Superior protection against acid dissolution is key to deliver enamel protection benefits. Hydroxyapatite (HAP), the main mineral component of human enamel, provides an efficient means to determine the ability of compounds to attach to and protect apatite against acid dissolution. Objectives: To demonstrate the ability of SnF2 to protect HAP against acid dissolution. Methods: HAP powder was pretreated with dentifrice slurry supernatant (20g supernate/200mg HAP powder) followed by 3x washing with water, then freeze dried. 50mg of the pre-treated HAP was exposed to 25 ml of acid dissolution media (0.05M acetic acid, 0.05M sodium acetate and 0.109 M sodium chloride) adjusted to and maintained at pH 4.5. As exposure of HAP to the media results in dissolution and release of hydroxide ion, the increase in pH is compensated by automatic additions of dilute hydrochloric acid (0.1N) to maintain the pH (4.5) of the reaction cell (Brinkman Titrino). The total volume of titrant added after 30 minutes was used to calculate % reductions vs. control. In this study, results were compared between NaF (1100ppm F) and SnF2 (1100ppm F) dentifrice to determine their relative ability to protect enamel against acid challenge. Results: Reduction in dissolution for NaF was 63.1%, while the reduction in HAP dissolution for the SnF2 treated sample was 92.8%. Differences in % reduction were statistically significant (Paired-T Test). Conclusions: These results confirm the ability of SnF2 , as delivered from a SnF2 containing toothpaste, to: 1) bind to hydroxyapatite, the primary component of human enamel; and 2) inhibit dissolution of this key enamel component more efficiently than NaF. In terms of its relative ability to protect enamel against acid challenge, the 1100ppm F (SnF2) formulation included in this study provides a significant advantage over other fluoride actives in its ability to protect enamel against irreversible acid wear and dissolution.


0726 (117690)

Controlled Clinical Trial with 0.454% Stannous Fluoride in Induced Gingivitis. J.J. WITT1, A.R. BIESBROCK1, J.M. DUNAVENT1, R.W. GERLACH1, and L. ARCHILA2, 1The Procter & Gamble Company, Mason, OH, 2University of Texas - San Antonio / Health Science Ctr, San Antonio, TX

Objectives: This pilot clinical trial was conducted to evaluate whether use of 0.454% stannous fluoride dentifrice slurry affects gingivitis development in the absence of toothbrushing. Methods: A randomized, examiner-blind, 21-day induced gingivitis multi-group clinical study compared BID use of a therapeutic dentifrice slurry versus a regular dentifrice control slurry on induced gingivitis. After informed consent, healthy adults with gingivitis received two dental prophylaxes and thorough oral hygiene training/application over a 3-week period. Oral hygiene was then suspended, subjects were randomly assigned 0.454% stannous fluoride dentifrice (the experimental group) or regular anticavity dentifrice control slurries, and response was monitored over a 21-day period. Subjects rinsed under supervision BID during this period with their assigned slurry (1:3; 12 ml total) for 60 sec. After the 3 week non-brushing period, a prophylaxis was administered and oral hygiene was resumed. Whole mouth bleeding sites and gingivitis (GI) were measured using standard methods. Results: 57 subjects (mean 4.0 bleeding sites at baseline) completed the 21-day gingivitis induction phase for these treatments. After 21 days, adjusted mean (SE) whole mouth bleeding sites were 28 (2.4) with stannous fluoride group compared to 34 (2.4) with the control (p<0.04). For gingivitis, adjusted mean (SD) whole mouth scores were 1.33 (0.03) and 1.41 (0.03) for the experimental and control slurries (p=0.057), respectively. Treatment was well-tolerated, and post-induction recovery was unremarkable. Conclusion: In the absence of tooth brushing or other oral hygiene, use of a 0.454% stannous fluoride dentifrice slurry over 21-days significantly improved gingival health relative to a regular dentifrice control slurry.


0727 (120380)

Anti-plaque efficacy of 0.454% stannous fluoride dentifrices. T. HE, R. CHENG, R. BAKER, and A. BIESBROCK, Procter & Gamble Company, Mason, OH

Objectives: The four-day plaque model has been well established in the literature to assess the anti-plaque efficacy of oral hygiene products, including mouth rinses and dentifrices. The present study was conducted to evaluate the anti-plaque effect of 0.454% stannous fluoride dentifrices using a lingual brushing 4-day plaque model. Methods: This randomized, double-blind clinical trial was conducted to compare the plaque effect of a 0.454% stannous fluoride dentifrice (Oral-B Pro-Expert®) relative to two marketed controls: a positive control 0.454% stannous fluoride dentifrice (Crest Pro-Health®), and a negative control (Colgate Cavity Protection®). The study utilized a 3-treatment, 3-period, cross-over design. Subjects received a dental prophylaxis prior to study initiation. Clinical evaluation using the Turesky modification of Quigley Hein plaque index (TMQHPI) took place at baseline and Day 5. Subjects performed their assigned treatment regimen twice daily for four days under supervision. Subjects brushed their lingual surfaces for 30 seconds, followed by swishing with the dentifrice slurry for 60 seconds. Plaque scores were analyzed using analysis of variance (ANOVA) for crossover studies. Statistical comparisons were two-sided, with a significance level of 0.05. Results: Both 0.454% stannous fluoride dentifrices provided statistically significant plaque benefits when compared to the negative control (p<0.001). More specifically, Oral-B Pro-Expert resulted in 13.6% less plaque while Crest Pro-Health resulted in 15.0% less plaque relative to the negative control. There was no significant differences between the two stannous fluoride dentifrices (p=0.576). Conclusions: This research demonstrated the effectiveness of both 0.454% stannous fluoride dentifrices in the control of dental plaque. All test products were well tolerated in the study.


0728 (121463)

Altered Dental Phenotype in Hyperactivated TGFβ-1 Mouse CED Model. A. GULLARD1, X. WU2, O. MAMAEVA1, M. MACDOUGALL2, and X. CAO2, 1University of Alabama at Birmingham, Birmingham, AL, 2University of Alabama at Birmingham, Birmingham

Camurati-Engelmann disease (OMIM #131300) is an inherited skeletal disease that results from latent-associated peptide (LAP) domain-specific mutations in transforming growth factor-beta-1 (TGFβ-1). We have established a transgenic mouse pathogenetic model with a CED-derived TGFβ-1 mutation (H222D) driven by the 2.3 type I collagen promoter that results in excess active TGFβ-1 levels. Furthermore, TGFβ-1 is produced by the dentin matrix forming odontoblast cells and has been shown to regulate several dentin matrix proteins.  Objectives: Since the 2.3 type I collagen promoter is also active in odontoblasts, we investigated the possible dental phenotype of  the CED mice related to gross tooth morphology, DECM production and mineralization. Methods: The TGFβ-1 expression levels and ratio of active/total TGFβ-1 were determined in the CED mice by Western blot and ELISA assays. CED pups were collected at critical stages of dentinogenesis from newborn through 3-months and analyzed by gross morphology, x-ray analysis, histology, and micro-CT. Results: Preliminary analysis of the CED mice showed a diastema between the lower incisors causing a malocclusion of the incisors resulting in severe cases overgrowth of the mandibular incisor. X-ray analysis and micro-CT studies revealed CED mice incisors were longer with an altered curvature than the wild-type incisors. CED mice molars had more profound defects with decreased mineralized and higher matrix porosity than seen in the wild-type animals.  These defects were also found in the surrounding alveolar bone supporting the dentition. Conclusions: We have demonstrated a consistent altered dental phenotype in CED mice associated with higher active TGFβ-1 expression levels in the teeth. Studies are underway to investigate the altered regulation of dentin matrix proteins in this CED mice model. Support: UAB SOD DART  NIDCRT32-DE017607 and DK57501(X.C.)


0729 (120438)

Quantitative Mechanical/Chemical Imaging of Bone from Dmp1 Null Mice. X. YAO, J.L. ROSSER, L.F. BONEWALD, J.D. EICK, and Y. WANG, University of Missouri -Kansas City, kansas City, MO

Dentin matrix protein 1 (DMP1) is an acidic noncollagenous protein which plays an important role in mineralized tissue formation. Dmp1 null adult mice are ricketic and osteomalacic and are a model for hypophosphatemic rickets. Mutation in humans results is Autosomal Recessive Hypophosphatic Rickets (Feng et al, 2006). The degree of bone mineralization significantly contributes to bone tissue mechanical properties, but precise relationships and interactions between chemical and mechanical variables are unknown. Objective: To relate the changes of chemical properties to the mechanical properties in the Dmp1 wildtype (WT) and null (KO) mouse femoral cortical bone by using FTIR imaging and Scanning Acoustic Microscopy (SAM). Methods: Six femurs from 3 month old Dmp1 WT and KO mice (n=3) were fixed in 70% ethanol, and embedded in PMMA. The embedded blocks were cut longitudinally to 3-µm-thick sections which were then placed on BaF2 discs for FTIR chemical imaging. The chemical images were collected by using the Spectrum Spotlight 300 system, with 8 cm-1spectral resolution and 6.25 µm spatial resolution. The acoustic images were collected from the remaining blocks by using the KSI SAM with a 110 MHz transducer. Results: Interactive mechanical (elastic modulus) and chemical images (i.e., mineral/matrix ratios) were generated from the same region of bone at a lateral resolution of ~10 um. Mechanical analysis showed that bone in Dmp1KO had ~4 times lower elastic modulus (4.3±1.4 GPa) than that in WT (17.5±1.9 GPa). The mineral-to-matrix ratios in Dmp1KO (4.81±0.51) were ~2 times lower than that in Dmp1 WT (8.55±0.62). The mineral crystallinity and collagen crosslink ratios were not significantly different between KO and WT. Conclusions: The results relate the bone elastic modulus changes in Dmp1WT and KO mice with chemical changes by specific sites. These measurements provide a new tool for describing the variability of bone chemical and mechanical properties.


0730 (117035)

Periostin is required for postnatal amelogenesis and condyle formation. D. MA, Qilu Hospital, Shandong University, Jinan, China, R. ZHANG, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX, Y. XIE, Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX, and J.Q. FENG, Baylor College of Dentistry, TX A&M Health Science Center, Dallas, TX

Objectives: Great attentions have been focus on molecules that are critical for early organ development. Currently we do not know if mechanic loading has any effects on amelogenesis and whether there is a molecule which is linked to mechanical loading during amelogenesis and condyle formation. The goal of this study was to search for evidences to support a hypothesis that periostin, an adhesive molecule, is required for postnatal amelogenesis and condyle formation.

Methods: The in situ hybridization and immunohistochemistry assays were used to define periostin expression pattern during postnatal amelogenesis and condyle formation. Tooth trim was used to test the effect of unloading on amelogenesis and condyle formation. Histology, backscattered electronic microscopy, and radiograph were used to characterize periostin-null mice compared to the age-matched control.

Results: 1) the in situ hybridization assay shows that periostin mRNA is expressed in ameloblast and condyle; 2) periostin-null pups display no apparent enamel and condyle phenotype; 3) periostin-null develop defects in amelogenesis (including thin in enamel thickness and enamel wear out) and the condyle (reduction of the condyle size) started at age of 3-wks; and 3) tooth trim (unloading) led to a sharp reduction of mineralization in enamel of incisor.

Conclusion: Mechanical loading has a positive effect on amelogenesis, and periostin is required for postnatal condyle formation and amelogenesis in incisor. (This work is supported by DE018486).


0731 (119506)

Measuring Genotype-Phenotype Relationships in the Murine Dentition. T.L. COXON1, A. BROOK1, P. ANDERSON2, P. ADAMS3, and R. SMITH1, 1International Collaborating Centre in Oro-facial Genetics and Development, School of Dental Sciences, University of Liverpool, Liverpool, United Kingdom, 2Barts and the London School of Medicine and Dentistry, London, United Kingdom, 3Scantron Industrial Products Limited, Somerset, United Kingdom

Objectives: To advance the investigation of genotype-phenotype relationships in dental development by; (i) Developing and establishing the reliability of a novel 3D image analysis system (IAS) capable of producing ultra-structural surface maps of murine teeth; (ii) Validating this new surface profilometry technique by direct comparison with an existing 2D IAS; and (iii) Displaying previously unavailable 3D data and defining new morphometric variables.

Methods: Twenty left mandibular incisors were extracted from 20 CD-1 Wild-Type mice. Each incisor was imaged using a high resolution (0.1µm) non-contact measurement device (ProScan2000, ScantronLtd., Taunton, UK) modified with a novel 360º rotary stage development. The precisely engineered rotary stage moved the object at pre-defined intervals successfully adapting the instrumentation to acquire multiple view 3D surface maps. This rotary stage provides a central axis of rotation that simultaneously establishes a datum line indexing system used to assemble complete 360º topographical model reconstructions using SolidWorks Premium2008 software (DassaultSolidWorks, Massachusetts, USA).

Results: Intra-Operator Intra-Class Correlation Coefficients (ICCC) for repeatability's (≥ 0.874) represented excellent reliability for all variables (Table 1). Pearson's correlation (0.450-0.660) provides validation for this technique (Table 2.).

Conclusion: The study applies and validates a novel 3D IAS for the morphometric assessment of murine dentition. The system not only has a high systematic resolution but in using it for this application a high degree of operator reliability and method agreement was demonstrated. The quantitative 3D variables possible with this method will provide novel information to facilitate genotype-phenotype analysis in this model system and will be used to investigate further the aetiology of Amelogenesis imperfecta by directly comparing phenotypic variation in and between different groups of mutants, alongside previously described 2D techniques and methods for colour and whiteness assessment.  

Table 1. Intra-Operator Reliability

INTRA-OPERATOR RELIABILITY

Variable

2D

3D

overall length (mm)

angle of curvature (º)

width at mid-point (mm)

overall length* (mm)

labial length* (mm)

actual labial length  (mm)

width at mid-point* (mm)

actual width at mid-point (mm)

Circum-ference (mm)

Mean Dif. (mm)

0.036

0.849

0.003

0.043

0.065

0.039

0.014

0.011

0.046

SD of Dif. (mm)

0.065

1.465

0.013

0.078

0.088

0.147

0.030

0.022

0.133

SE (mm)

0.029

0.655

0.006

0.035

0.390

0.065

0.013

0.010

0.059

ICCC

0.997

0.874

0.936

0.996

0.993

0.991

0.999

0.999

0.999

RC

0.127

2.871

0.025

0.153

0.172

0.288

0.059

0.043

0.261

*projected measurement between two points

Table 2. 2D & 3D Method Agreement

 

METHOD AGREEMENT

Variable

2D & 3D

overall length (mm)

width at mid-point

Mean Dif. (mm)

0.023

0.092

SD of Dif. (mm)

0.158

0.052

SE (mm)

0.071

0.023

PEARSONS

0.660

0.405

RC

0.310

0.102

** significant at 0.05 level (2 tailed)

Sponsored by Wellcome Trust Grant#GRO75945MA


0732 (119214)

Fluoride Upregulates Amelogenin Expression in A/J Mice. Y. ZHANG1, S.O. KIM1, J. MENDOZA1, E.T. EVERETT2, and P.K. DENBESTEN3, 1University of California - San Francisco, San Francisco, CA, 2University of North Carolina at Chapel Hill, Chapel Hill, NC, 3University of California San Francisco, San Francisco, CA

OBJECTIVES: Dental fluorosis is characterized by the delayed removal of enamel matrix proteins, resulting in increased porosity and discoloration of enamel. The A/J mouse strain has been identified to highly susceptible to the formation of enamel fluorosis, and in this study, we used this mouse model to investigate the molecular mechanism of enamel fluorosis.

METHODS: Three-week old male and female A/J mice were given 50 ppm fluoride supplemented drinking water for 3 or 4 weeks, while the control mice were given deionized water. For morphological studies, the mice were perfused by PBS, followed by 4% paraformaldehyde. The mandibles were then dissected, post-fixed with paraformaldehyde and demineralized by 10% EDTA for one month. To analyse expression, mandibles were isolated, cut into small pieces, and total RNA was purified using a Qiagen RNeasy Micro kit. qPCR was done to compare expression of amelogenin, the enamel proteinases MMP-20 and KLK-4, and periostin, in control and fluoride treated mice.

RESULTS: After exposure to fluoride, incisors from both male and female mice developed severe dental fluorosis. H&E staining showed the ameloblasts in the fluoride treated mice were somewhat disorganized. qPCR results showed that amelogenin was significantly upregulated in fluoride treated mice as compared to controls, with females (9.02x control) significantly higher than males (2.54x control). In addition, MMP- 20 (2.6x control) and periostin (3.76x control) were significantly up-regulated in the female mice exposed to fluoride, as compared to controls.

CONCLUSIONS: Up-regulation of amelogenin expression by fluoride ingestion in female A/J mice could contribute to the formation of fluorosed enamel. In addition, increased periostin suggests an effect of fluoride on the eruption rate of the incisors of fluorosis susceptible mice.

Supported by grants #R01DE013508, R01DE014853 and R21DEO18633 from NIDCR


0733 (118494)

Characterization of Transgenic Mice Overexpressing Amelotin in the Enamel Organ. D. YAZDANSHENAS1, R. LACRUZ1, D.P. STOLF2, M. AL-RAYES3, S.N. WHITE4, M.L. SNEAD1, B. GANSS2, and M.L. PAINE1, 1University of Southern California, Los Angeles, CA, 2University of Toronto, Toronto, ON, Canada, 3University of Toronto, Toronto, Canada, 4University of California - Los Angeles, Los Angeles, CA

Objective: Amelotin is a recently identified protein with expression apparently limited to late-stage enamel formation. In mice, amelotin is secreted into the enamel matrix during maturation-stage amelogenesis. To date, the role of amelotin in amelogenesis remains unclear, but it may play a function in many diverse activities such as biomineralization, Ca++ transport, pH balance and/or cellular differentiation/dedifferentiation. Methods: In this investigation we set out to extend amelotin expression to the secretory stage of the developing enamel organ and to determine the effects on amelogenesis. The mouse amelogenin promoter was used to drive amelotin expression in a spatiotemporal pattern mirroring endogenous amelogenin. A FLAG epitope was engineered into the N-terminus of the transgene product to follow the expression profile of the transgenically expressed protein. Results: At this stage four amelotin-overexpressing animal lines have been generated, and their genotypes confirmed using Southern blot analysis and PCR techniques. Using a monoclonal anti-FLAG M2 antibody, the transgene expression profile has been investigated in the mandibles and teeth of 4-day old animals using immunohistochemistry and Western blot analysis. Polyclonal antibodies against amelotin as well as several enamel proteins (amelogenin, ameloblastin and enamelin) were also utilized to determine the expression pattern of endogenously and transgenically produced amelotin and to determine whether the expression pattern of other known enamel proteins was affected. Conclusion: We present an animal model in which amelotin gene expression is initiated at early-stage amelogenesis and extends to late-stage amelogenesis. Expression of the amelotin transgene has been confirmed by a number of methodologies. Additionally, the spatiotemporal distribution of other enamel proteins is not significantly affected, suggesting that the overexpression of amelotin does not exert any inhibitory effect on them. This work was supported by NIH/NIDCR grant # DE013404 and CIHR grant # MOP-79449.


0734 (118524)

Body Weight Assessment of Enamelin Null Mice. H.-L. CHAN, R. LERTLAM, Y.Y. HU, J.P. SIMMER, and J.C.-C. HU, University of Michigan, Ann Arbor, MI

Enamelin is a tooth-specific protein. However, the offspring of Enam null mice appear to have a smaller body size when compared to wild type mice. We hypothesized that the absence of enamel negatively influences food intake, which affects bodyweight gain (BWG), and that hard chow would show a more negative effect on BWG than soft chow. Objectives: To compare the BWG of Enam-/- and wild type mice maintained on either hard or soft chow from birth (D0) to day 42 (D42). Methods: C57BL/6 wild type (WT) and Enam-/- (KI) mice were given either hard chow (HC) or soft chow (SC). Four experimental groups were studied: WTHC (n=4), WTSC (n=4), KIHC (n=6), and KISC (n=5). Average litter bodyweights (ALBW) were obtained by weighing each litter as a group and then dividing the litter bodyweight by the number of pups in the litter from Day 0 (D0) to D21. In this interval the pups nutritional intake is mostly dependent upon the mother. The dam's bodyweight (DBW) was recorded daily. After D21, the pups were weaned and given the same type of food as their dam. ALBW was measured until D42. Data was analyzed using Mixed Model Analyses (SPSS v16.0). Results: The WT dam showed significantly higher bodyweight (DBW) regardless of the food type (p=0.000). ALBW significantly correlated with gene-food factor (p=0.001), with KIHC group starting to deviate below WT mice on D19. This trend was sustained to D42. ALBW in KISC is lower than WT groups; however, the difference was not significant statistically. ALBW did not correlate with DBW. Conclusions: Enamel defects may contribute to difficulties in nutritional intake, especially in eating hard food. These difficulties appear to decrease bodyweight gain, which contributes to a lower bodyweight among the Enam-/- mice. This study was supported by NIDCR grant DE011301.


0735 (120400)

Enamelin Transgene Expression by Ameloblasts. Y. LU, J.P. SIMMER, and J.C.-C. HU, University of Michigan, Ann Arbor, MI

Enamelin (Enam) is a critical constituent of the enamel matrix during the secretory stage of amelogenesis. Enamelin deficiency shows a dose effect. Enam+/- mice have fewer crystallites than wild type (Enam+/+) mice. Enamelin null (Enam-/-) mice do not produce enamel crystallites at all. Objectives: To generate an enamelin expression construct that specifically directs enamelin expression to secretory stage ameloblasts, to generate transgenic mice that express enamelin at levels similar to wild type mice, to mate Enam transgenics with Enam null mice to determine if the wild type enamel phenotype is recovered. Methods: An Enam recovery construct was fabricated that flanked the enamelin coding sequence with the amelogenin promoter and 3' amelogenin untranslated regions. We used this construct to generate enamelin transgenic mice. Founders were mated with wild-type C57BL6 mice. F1 offspring were sacrificed on day 5, first molars were collected, and real time RT-PCR was performed to quantify transgene expression levels in developing teeth. Enamelin transgenics (Enamtg/-) showing appropriate levels of enamelin gene expression were mated with Enam-/- mice so their enamel could be characterized. Results: Thirteen independent founders were positive for the Enam transgene; seven showed germline transmission. Real-time RT-PCR of RNA collected from day 5 (secretory stage) first molars showed a range of enamelin transgene expression levels including levels equivalent to normal wild type enamelin gene expression. Conclusion: An enamelin recovery construct has been fabricated that specifically directs the expression of enamelin by ameloblasts in transgenic mice. The enamelin transgene is expressed at different levels in different transgenics, but transgenic mice were identified that express the transgene at levels similar to endogenous enamelin expression. These mice are currently being mated to Enam-/- mice to analyze for phenotype recovery. This study was supported by NIDCR grant DE011301.


0736 (121204)

Pathological Basis for Enamel Malformation in Enamelin-Null Mice. J.C.-C. HU1, Y.Y. HU1, R. LERTLAM1, J.T. WRIGHT2, J.Q. FENG3, and J.P. SIMMER1, 1University of Michigan, Ann Arbor, MI, 2University of North Carolina at Chapel Hill, Chapel Hill, NC, 3Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX

Enamelin is a large (186-kDa) enamel matrix glycoprotein that is rapidly processed by Mmp-20 following its secretion. The intact protein specifically localizes to the mineralization front at the ameloblast distal membrane, suggesting that enamelin functions in enamel crystal elongation. The secretory stage mineralization front fails to support crystal elongation in the Enam null mice. Objectives: To characterize the pathological basis for enamel malformations in Enam-/- mice. Methods: Wild type, Enam+/-, and Enam-/- mice at E17, PN5, 7, and 14 were processed for LacZ staining and light microscopy. Amelogenin and enamelin expression was determined by real time RT-PCR and by immunohistochemistry. The enamel was characterized by scanning electron microscopy (SEM) and by radiography. Results: The polarized and differentiated ameloblast layer was observed on PN3, but small groups of ameloblasts exited the enamel surface and formed nodules within the stratum intermedium on PN5. These nodules became solid aggregates of cells, cell debris, and amorphous calcification by PN14, and typically were localized on the cusp slopes. Irregular aggregations of enamel matrix with pathological mineralization lacking organized crystals and prisms are consistent observations in the null mice. Amelogenin is the predominant protein in the developing matrix and is abundantly expressed by the null mice. The pathology was confined to the teeth. There was no evidence of any defects in bone. Conclusions: The extracellular matrix in Enam-/- mice lacks a critical framework that allows crystal initiation and elongation. The enamel does not mineralize or provide an adequate foundation for ameloblast attachment. The ameloblast layer loses continuity and ameloblasts exit the cell layer in contact with the matrix covering dentin. The dysfunctional ameloblasts lack a classic Tomes' process, and produce no crystals or true enamel. Enamelin function is tooth-specific and essential for crystal initiation and elongation. Supported by NIDCR grant DE011301.


0737 (120490)

Processing of Porcine Ameloblastin by Mmp-20 and Klk4. Y.-H.P. CHUN1, Y. YAMAKOSHI1, T. NAGANO1, J.D. BARTLETT2, and J.P. SIMMER1, 1University of Michigan, Ann Arbor, MI, 2The Forsyth Institute, Boston, MA

Mmp-20 and Klk4 are enzymes that cleave enamel proteins and are critical for proper dental enamel formation. Mmp-20 is expressed early, during the secretory stage. Its expression gradually diminishes and ceases early in the maturation stage. Klk4 is expressed late, starting in the transition stage and continuing throughout enamel maturation. We hypothesize that Mmp-20 cleaves ameloblastin (Ambn) to generate the full set of ameloblastin cleavage products that accumulate during the secretory stage. Objectives: To express and isolate recombinant ameloblastin, cleave it with Mmp-20 and Klk4, and characterize the sites cleaved by these enzymes. Also to determine where Mmp-20 and Klk4 cleave fluorescence resonance energy transfer (FRET) peptides corresponding to known Ambn cleavage sites. Methods: Porcine Ambn was cloned into pEF6/V5-His-TOPO and stably transfected into HEK293 cells. Secreted recombinant porcine ameloblastin (rpAmbn) was purified by ammonium sulfate precipitation, metal affinity chromatography, and RP-HPLC. The rpAmbn was incubated with rpMMP-20 or Klk4 isolated from in vivo. The digestions were evaluated by SDS-PAGE and Western blotting, using Ambn antibodies raised against five different regions of Ambn. Four FRET-Ambn peptides [Abz-SGVLGGLLANPK-nitro-Tyr; Abz-RGPAGRSRGPPG-nitro-Tyr; Abz-PGLADAYETYGA-nitro-Tyr; Abz-SLQGLNMLSQYS-Lys(Dnp)] were synthesized, incubated with Mmp-20 or Klk4, and the digestions were analyzed by RP-HPLC. Results: Recombinant Abmn migrated at 64-kDa on SDS-PAGE and Western blots, which showed the protein was intact and glycosylated. Mmp-20 and Klk4 readily cleaved rpAmbn, but generated different digestion patterns. The exact sites cleaved by Mmp-20 and Klk4 within the FRET-Ambn peptides were determined by LCMSMS. Conclusion: Mmp20 cleaves ameloblastin at the same sites that are cleaved in vivo to generate the Ambn cleavage products that accumulate during the secretory stage. Klk4 cleaves Ambn in vitro but at different sites than Mmp-20, which is consistent with its role as a late degradative enzyme. This study was supported by NIDCR grant DE015846.


0738 (120379)

AP3-B1 mouse mutants show increased thickness of Enamel. J.L. SHAPIRO, H.J. WANG, M.L. SNEAD, and M.L. PAINE, University of Southern California, Los Angeles, CA

Objective: Our previous work showed that endocytosis of amelogenin proteins occurs through LAMP-1 and CD63 coated vesicles. LAMP-1 and CD63 are sorted to the lysosome by AP3, which recognizes the lysosomal sorting sequence GYXXΦ present at the cytoplasmic tails of both LAMP1 and CD63. In this study we wished to examine the enamel microstructure when Adaptor Protein 3 (AP3) sorting of LAMP-1 and CD63 to lysosomes is disrupted in a mouse model.

Methods: AP3B1 mutant mice (B6.Cg-Ap3b1tm1.1Sms/J) were purchased from Jackson Laboratories. Also purchased as a control were C57/BL mice, which is the background strain for the AP3B1 mutant mice. At 6 weeks of age, both sets of mice were euthanized, the lower incisors extracted and fixed. All incisors from both strains of mice were fractured into 3 pieces at approximately the same region and viewed under scanning electron microscopy.

Results: The enamel prismatic architecture is unaltered in the mutant animals compared to wildtype, however, in the AP3B1 mutants, there is an increased thickness of enamel (~1.5x) as compared to the C57/BL controls.

Conclusion: Mutations in AP3 cause Hermansky Pudlak syndrome (HPS). The phenotypes seen in patients with HPS are occulocutaneous albinism, bleeding disorders, platelet deficits, and increased susceptibility to infection. These phenotypes are due to altered trafficking of proteins to lysosomes. In our study using a mouse model, we found that altered trafficking of LAMP-1 and CD63 due to a mutation in the beta subunit of AP3 resulted in increased thickness of enamel. Altered trafficking of enamel matrix proteins during amelogenesis may result in a prolonged maturation stage and increased enamel thickness.

This work was supported by Grants DE13404 and DE014867 from the National Institutes of Health, National Institute of Dental and Craniofacial Research.


0739 (121288)

Effects of indenters and load forces on enamel microhardness measurements. A. AMIN, University of Rochester School of Medicine and Dentistry, Rochester, NY, H. MALMSTROM, Eastman Dental Center, Rochester, NY, and Y.-F. REN, University of Rochester Eastman Dental Center, Rochester, NY

Objectives: to study the effects of load force and indenter selection on microhardness measurement of enamel. Both the micro-Vickers hardness (VHN) and micro-Knoop hardness (KHN) are evaluated under 10g, 25g, 50g, 100g, 200g and 300g of load for 10 seconds. Methods: Four enamel discs prepared from extracted human third molars and 5 indentations under each load were made using both the Vickers and Knoop indenters, resulting in 20 indentations for each load force and 120 indentations for each indenter. Indentation lengths, VHN and KHN were calculated for each load force and indenter and relative measurement errors were expressed as per cent deviation from the mean. Indentation depths were calculated from the geographic forms of the indentations and measured on 3D images obtained using a focus variation scanning microscopy. Results: Indentation diagonal lengths ranged from 20.8 to 120.1µm for KHN and from 7.8 to 39.0µm for VHN. The KHN and VHN are listed in Table 1. KHN was equivalent to VHN at 25g load, higher than VHN at load <25g and lower than VHN at loads >25g.

10g

25g

50g

100g

200g

300g

Mean   SD

Mean   SD

Mean   SD

Mean   SD

Mean   SD

Mean   SD

KHN

 334.7  50.7

349.7   32.0

348.6   29.7

319.8   27.4

303.7   20.4

297.0   26.9

VHN

307.3   45.7

347.2   41.6

368.1   39.4

350.0   20.0

334.8   27.5

332.6   34.6

KHN was consistent at load <50g but decreases significantly at loads >100g. Measurement errors were highest at 10g of load for both indenters (15.0%). Indentation depths of Vickers were significantly deeper than those of  Knoop under the same load. Conclusions: Taking indentation length, depth and measurement error into consideration, 25 to 50g load forces for Knoop indentation are suitable for studies of superficial enamel surface hardness. For studies that tolerate deeper indentations, 100g load for Vickers indentation can be selected.


0740 (121073)

AE2 as the cause of enamel defects and renal tubulopathy. P.M. YAMAGUTI1, G.B. BARRA2, G.C. FERREIRA1, L.M. PAULA1, F.A.R. NEVES2, and A.C. ACEVEDO1, 1Oral Care Center for Inherited Diseases, Health Sciences School, University Hospital of Brasilia, University of Brasilia, Brasilia, Brazil, 2Molecular Pharmacology Laboratory, Health Sciences School University of Brasilia, Brazil, Brasilia, Brazil

The anion exchanger AE2 is a protein, codified by SCL4A2 gene, expressed in several tissues including the corneal epithelium, thick ascending limb of Henle, and collecting renal duct, where it plays a chloride/base exchange activity. Recent in vitro and in vivo studies have also demonstrated that AE2 is expressed in the apical and basolateral membrane of ameloblasts at the maturation stage of development. During amelogenesis, it may be involved in the pH control in the microenvironment adjacent to ameloblasts. However this mechanism has not been completely elucidated. Knockout mice for the AE2 anion exchanger exhibit abnormal enamel, absence of the rod-inter-rod structure, a decreased mineral content and an increase of matrix proteins when compared with the wild-type enamel. At present, no human disease has been mapped to mutations in AE2 gene. Aim: The aim of this study was to perform AE2 mutational analysis in a 11 years-old-male-patient who presented enamel defects, ocular problems, and a renal tubulopathy in the region of the thick ascending limb of Henle. Methods: The patient was submitted to a complete questionnaire, physical and dental examination. DNA was extracted from venous blood sample. Specific primers were designed for the AE2 gene amplification and the PCR products were purified and sequenced. Results: He was the only affected member from non-consanguineous parents. At the moment of the renal pathology diagnosis the patient presented failure to thrive, bilateral nephrocalcinosis, low serum calcium, hypomagnesemia, polidpsia, poliuria, myopia, normal tooth eruption chronology, normal gingival tissue, enamel hypoplasias and linear enamel opacities. Sequence analysis revealed three known non disease causing alterations, but no mutations were detected. Conclusions: Further molecular analysis in other genes candidates is being performed. The molecular basis of the renal tubulopathy in this patient will contribute to a better understanding of the etiology of the dental defects observed.


0741 (121277)

The gene specifically expressed in Hertwig's epithelial root sheath. Y. DATE1, H. KONDO1, Y. YOKOYAMA1, T. DAMRONGRUNGRUANG2, K. OHYA1, S. ISEKI1, and S. KASUGAI1, 1Tokyo Medical & Dental University, Tokyo, Japan, 2Khon Kaen University, Khon Kaen, Thailand

Objectives: Although various experiments regarding tooth regeneration have been carried out, only tooth crown has been so far the target. There is no report about the regeneration of a complete tooth including the root. The tooth root is the most critical part that maintains the tooth function, however, the molecular mechanism of root development remains unknown. The aim of this study is to identify specific molecules involved in root morphogenesis.

Methods: Laser capture microdissection (LCM) was employed to isolate cementoblasts and PDL cells from undecalcified frozen sections of murine mandible and to obtain RNA in good quality for subsequent genetic analysis. After RNA extraction and amplification, the expression level of mRNA is compared between these tissues by MicroArray analysis. The primer sets of cementum-positive and PDL-negative genes were serially designed and expression of the cementum-positive and PDL-negative genes in RNA samples obtained from mandibles and femur were analyzed by quantitative RT-PCR. Then, expression pattern of those genes was examined by in situ hybridization.

Results: Bioanalyzer detected peaks of 18s and 28s rRNA both in the laser-dissected cementoblasts and in PDL cells, suggesting the sufficient quality of RNA. A comparative analysis of mRNA expression by GeneChip showed that about 2,000 genes were differentially expressed between cementoblasts and PDL cells. Several genes of cementum-positive and PDL-negative were exceedingly expressed in the mandible than in the femur. In situ hybridization analysis showed that one of those genes is specifically expressed in Hertwig's epithelial root sheath (HERS) during root formation.

Conclusion: We found a highly expressed gene in HERS. Although further functional analysis is required, it might contribute to the apical extension of tooth root and might be a specific factor for the initiation of cementogenesis.


0742 (115513)

Proteoglycans: Important Players in Tooth Development and Mineralization. H. PARK1, S. SUZUKI2, and A.B. KULKARNI2, 1Tufts School of Dental Medicine, Boston, MA, 2NIDCR, NIH, Bethesda, MD

During dentin mineralization, proteoglycans(PGs) such as biglycan and decorin rich in chondroitin-sulfate are secreted from odontoblasts into predentin and dentin. Proper degradation or removal of predentinal PGs seems to be necessary for predentin-to-dentin conversion, whereas dentinal PGs seem to facilitate mineralization by binding Ca++ ions through their glycosaminoglycan chains. Dentin-sialophosphoprotein(DSPP), most abundant noncollagenous protein in dentin, is implicated in dentinogenesis-imperfecta(DGI). DSPP mRNA is translated into single protein, DSPP, which is cleaved into three peptides, dentin-sialoprotein(DSP), dentin-glycoprotein(DGP), and dentin-phosphoprotein(DPP). Our recent observations using DSP TgKO mice that express only DSP in DSPP null background suggest that DSP also has positive role in dentin mineralization as does DPP. Moreover, porcine and bovine DSPs have been reported to form chondroitin sulfate-type PGs in dentin. OBJECTIVES: We examined different expression levels of decorin, biglycan, and chondroitin-sulfate in dentin of WT, DSP TgKO, and DSPP KO mice. METHODS: Molars and incisors were extracted from mice 20 or 30 days of age, and protein from dentin was isolated and purified. RESULTS: Using Western blots, we found that increased post-translational modification of DSP protein takes place in WT molars compared to WT incisors. We confirmed interaction between biglycan and chondroitin-sulfate. We also observed low expression levels of biglycan and decorin in 20-day-old TgKO and KO mice, while the expression levels were almost similar in TgKO, KO, and WT mice at day 30. CONCLUSION: Protein modification patterns of DSP are different in molars and incisors; most of molar DSP is of high molecular weight, while most of incisor DSP remains as core protein. Biglycan and decorin expression is inhibited at day 20, but rescued at day 30. These observations suggest that pattern of deposition varies in incisors and molars, and DSPP-mediated regulation of PGs deposition plays an important role in dentin mineralization. Supported by JNIDCR-DIR Grant 1-Z01-DE000698-10 LCDB.


0743 (120681)

Apatite decreases in-vitro proteolysis of amelogenin in a dose-dependent manner. W. CARPIAUX, Z. SUN, D. FAN, and J. MORADIAN-OLDAK, University of Southern California, Los Angeles, CA

Two enamel proteases, matrix metalloproteinase-20 (MMP-20) and kallikrein-4 (KLK-4), are known to cleave amelogenin and are necessary for proper enamel formation. However, the effect of hydroxyapatite (HAP) on the proteolytic activity of these enzymes remains unclear. Objectives: To determine whether HAP affects amelogenin proteolysis, and to accurately measure those induced changes in the proteolytic rate between the amelogenin substrate and corresponding enzymes. Methods: A recombinant full length pig amelogenin (rP172) and a recombinant homolog of its major cleavage product (rP148), were expressed in E-coli and purified. Working buffers were 25 mM Tris (pH 8) for rP172 and 25mM Bis-Tris (pH 6.5) for rP148. Solutions of 0.4mg/mL rP172 and 0.2mg/mL rP148 (200 μl each) were incubated with rpMMP20 and rhKLK4, using substrate/enzyme ratios of 400 and 800 respectively, at 37°C for 1-10 hours with addition of 0-2mg of HAP crystals. Reactions were stopped with addition of 2N HCl, simultaneously dissolving all HAP crystals. Proteolytic products were analyzed by utilizing reverse-phase high performance liquid chromatography (RP-HPLC) in conjunction with computer software that measures the area of all detected peaks, giving a quantitative comparison for calculation of remaining substrate. Results: The addition of HAP to both rP172 and rp148 showed dose-dependent reductions in the proteolytic rate as compared to controls. This was demonstrated to a greater extent in rP172 verses rP148. We suggest that the reduction in proteolysis may result from the binding of HAP to amelogenin, causing subsequent changes in enzyme affinity. The observed differences in the effect of HAP on the proteolysis of rP172 and rP148 are supported through the correlation of the individual substrates' binding affinity to HAP. Conclusions: HAP reduces the in-vitro proteolytic rates of amelogenin in a dose-dependent manner. Supported by NIH-NIDCR DE-015644 to JMO.


0744 (116255)

Etching Characteristics of Enamel From Amelogenin Null Mice. M.K. PUGACH, K. SHETH, R.G. LINDEMEYER, and C.W. GIBSON, University of Pennsylvania, Philadelphia, PA

The amelogenin proteins comprise 90% of the organic matrix of developing enamel, and are responsible for proper enamel thickness and structure. Patients with amelogenesis imperfecta caused by a mutation in the amelogenin gene have thin, pitted enamel. Enamel etching for restorative dental treatment depends on a predictable enamel surface to increase surface area for mechanical bonding.

Objectives: The objective was to identify etching characteristics of enamel from amelogenin null (KO) mice teeth, compared to wild-type (WT).

Methods: The facial surfaces of maxillary and mandibular incisors from 4 week old KO and WT mice were etched with 37% phosphoric acid for 45 seconds and analyzed by SEM. To examine the etching characteristics of enamel treated with fluoride, KO mice were given fluoride (0 ppm, 50 ppm and 100 ppm) in their drinking water for 2 weeks. These teeth were also etched with phosphoric acid and analyzed by SEM. Qualitative analysis of etching pattern organization was examined from SEM images, and surface topography assessed by Image J surface roughness plug-in to obtain relative surface roughness (Ra) measurements.

Results: Etched enamel surfaces from mandibular KO incisors appeared randomly organized and heterogeneous, compared to WT incisors, which had a regular, mostly homogeneous etching pattern. KO unetched enamel was significantly rougher (Ra) than WT unetched enamel, and had similar Ra values to both WT and KO etched enamel. The fluoride treatments seemed to result in a more uniform surface with improved organization of the etching patterns of KO enamel.

Conclusion: We concluded that unetched KO enamel had a naturally rougher surface than unetched WT enamel. Furthermore, etching of KO enamel generates a less organized etching pattern than WT and may remove much of the remaining enamel. These data may have important clinical implications for treatment of patients with amelogenesis imperfecta.

Supported by NIDCR grant DE010189.


0745 (117482)

Low pH Enhances Ameloblast Sensitivity to Fluoride-Mediated Cell Stress. R. SHARMA1, Z. SKOBE1, B. TANNOUS2, and J.D. BARTLETT1, 1Forsyth Institute, Boston, MA, 2Massachusetts General Hospital & Harvard Medical School, Charlestown, MA

Fluoride (F-) toxicity is initially manifested as dental fluorosis. Here, we ask why cells responsible for dental enamel formation (ameloblasts) are uniquely sensitive to F-. During enamel maturation, the mass precipitation of hydroxyapatite releases large quantities of hydrogen ions (H+), dropping the matrix pH below 6.0. These H+ ions combine with F- to form HF. Approximately 25-fold more HF is formed at pH 6.0 as compared to pH 7.4. Importantly, unlike F-, HF can easily diffuse in and out of cells. Therefore, we hypothesize that the low extracellular pH surrounding maturation stage ameloblasts will enable the conversion of F- to HF that will then enter the cell. The neutral pH of the cytoplasm will cause reversion of HF to F- that cannot diffuse out of the cell. The resulting increase in the concentration of intracellular F- will cause cell stress and impaired ameloblast function. Objective: We ask if exposure to low pH enhances F--mediated cell stress. Methods: We treated ameloblast-derived LS8 cells with F- at low pH and measured cell proliferation as well as expression of several stress-response genes. We generated LS8 cells stably transduced with the reporter Gaussia luciferase and measured secreted luciferase activity on exposure to F- at low pH, as an indicator of protein secretion. Finally, we compared the expression of several genes in secretory and maturation stage ameloblasts from rats fed 100 ppm F-. Results: We show that protein secretion decreases further when cells are exposed to F- at low pH. Low pH also enhances F--mediated activation of stress-response genes. Finally, we also demonstrate in vivo that maturation stage ameloblasts are more sensitive to F- than secretory stage ameloblasts. Conclusion: The acid environment surrounding maturation stage ameloblasts enhances their susceptibility to fluoride. This study was supported in part by NIDCR grant DE016276.


0746 (118374)

P120 Catenin is Essential for Amelogenesis: Enamel Organ Histology. Z. SKOBE1, J. DOBECK1, M. PEREZ-MORENO2, A. REYNOLDS3, and E. FUCHS4, 1The Forsyth Institute, Boston, MA, 2Centro Nacional de Investigaciones Oncologicas, Madrid, Spain, 3Vanderbilt University, Nashville, TN, 4Howard Hughes Medical Institute, New York, NY

We have shown that ablation of p-120 catenin results in severely malformed enamel. A principal function of p-120 is to stabilize E-cadherin at the cell membrane, but p-120 also has other functions. Objective: In order to better understand the role of p120 in the enamel organ, the histology and immunohistochemistry of amelogenesis was analyzed in p-120 cKO mice described in the previous abstract. Methods: Histological sections were prepared of control and cKO mice, ages 3, 7, and 9 days. Serial sections were stained with H&E, or using standard procedures for horseradish peroxidase visualization of antibodies (Ab) to: p-120 (1:250; BD Biosciences); E-cadherin (1:250; BD Biosciences); and amelogenin (1:10,000; Abcam). Results: Survey micrographs of 3day cKO molars revealed the absence of an organized enamel organ and the misplaced presence of large sinusoids, up to 100ƒÝm, mostly at the cervical loop region. Ameloblasts in the early secretory stage did not maintain polarity. Nevertheless, there was a thin layer of amelogenin-Ab positive material deposited at the DEJ, and in cyst-like spaces between the malformed enamel organs and the teeth. In contrast to control teeth, anti-p-120 Ab did not stain any cells of the enamel organ in cKO mice at any age. E-cadherin Ab stained control and cKO ameloblasts, including those cells lacking polarity and those with prematurely flattened morphology, though markedly less than controls, indicating partial downregulation of E-cadherin. Conclusions: As in salivary glands (Davis and Reynolds Dev Cell 10:21;2006), p-120 ablation resulted in ameloblast loss of polarity with subsequent degeneration and malformation of cells of the enamel organ. E-cadherin stability in functional and degenerated ameloblasts may be maintained by redundant function of closely related molecules. However, apparently the signaling and/or transcription factor activity of p-120 in ameloblasts is not duplicated by these molecules, thus p-120 is essential for normal amelogenesis.


0747 (119623)

Expression of ZBTB16 in dental follicle cells during osteogenic differentiation. C. MORSCZECK, G. SCHMALZ, S. VIALE-BOURONCLE, M. SAUGSPIER, T.E. REICHERT, and O. DRIEMEL, University of Regensburg, Regensburg, Germany

Objectives: Human dental follicle cells (DFCs) derived from wisdom teeth can differentiate into cementoblasts under in vitro conditions. However, less is known about osteogenic differentiation mechanisms of dental follicle cells. In previous studies, the transcription factor ZBTB16 and the growth factor BMP-2 were differentially expressed in DFCs during osteogenic differentiation. Nevertheless, the relation between BMP-2 and ZBTB16 in osteogenic differentiated DFCs is unknown. In this study, we investigated therefore the expression of ZBTB16 in DFCs in dependence on BMP-2.

Methods: DFCs were cultivated for osteogenic differentiation in different cell culture media comprising dexamethasone (standard differentiation protocol) or BMP-2. Total RNAs and proteins were isolated from DFCs at different points in time and gene expression of ZBTB16 was investigated by western-blot and real-time PCR analysis.

Results: DFCs did neither express the protein nor the mRNA of ZBTB16 before osteogenic differentiation. ZBTB16 could be detected after 3 days of osteogenic differentiation after applying the standard protocol, but was not expressed after treatment with BMP-2.

Conclusion: DFCs express ZBTB16 during differentiation with the standard protocol for osteogenic differentiation, but the expression does not dependent on the expression of BMP-2 during osteogenic differentiation in DFCs.


0748 (118549)

Establishment of Mature Ameloblast and Stratum Intermedium Immortalized Cell Lines. L. ZAHID1, O. MAMAEVA2, M.A. MACDOUGALL2, Y. WU1, and M. MACDOUGALL1, 1University of Alabama, Birmingham, AL, 2University of Alabama at Birmingham, Birmingham, AL

The enamel organ epithelium (EOE) gives rise to the major epithelial-derived tissues of tooth including the ameloblasts (Am), stratum intermedium (SI) and stellate reticulum (SR). These cells undergo a process of maturation ultimately leading to apoptosis/necrosis. Therefore, enamel tissue engineering studies have been limited due to the lack of available cell lines representative of these various epithelial-derived cell types. Objective: To establish and characterize epithelial-derived immortalized cell lines representative of Am, SI and SR. Methods: EOE was isolated from mouse 7 day postnatal (PN) molars, placed in primary culture, transfected with an E6/E7 onogene construct for 48 hours, cells were then dissociated and selected with G418 (250 μg/ml). Immortalized cell populations were initially screen by RT-PCR analysis for expression of informative markers: cytokeratin 14 (Ker 14), alkaline phosphatase (ALP), amelogenin (Amg), enamelin (Enam) and dentin sialophosphoprotein (DSPP). Two populations termed TG-B and TG-C were selected for establishment of clonal cell lines using colony selection or ALP FAC sorting. Cell lines were characterized by growth rates using a MTS assay, ALP in situ histochemistry, qRT-PCR analysis and immunohistochemistry. Markers used to distinguish cell types included matrix and membrane proteins and proteinases (Amg, Enam, DSPP, DMP-1, ameloblastin, amelotin, nestin, ALP, KLK-4, and MMP-20) and signaling molecules (Shh, Notch 1-3, Jagged-1, Patched and cp27). Results: Cells were initially separated by enriched ALP staining to establish clonal populations. Major cell lines established varied in their gene expression patterns and were representative of late secretory/maturation Am and SI. Levels of Amg expression varied dramatically between the cell populations while nestin was an informative marker to distinguish SI. Conclusions: We have established dental epithelia cell lines representative of maturation stage Am and SI for the first time. These cells will enhance tissue engineering studies designed to produce enamel and ultimately teeth. Funding: NIDCR T35-HL007473/UAB SOD IOHR.


0749 (118217)

Effect of HSP25 On Rat Dental Follicle Cells. J.-Q. LING, Y. DU, and H.-J. GU, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China

Objectives: Heat Shock Protein 25 (HSP25) has been reported to participate in the cell proliferation and differentiation during tissue development. The purpose of this study was to detect the expression of HSP25 in rat dental follicles both in vivo and vitro, and explore the underlying mechanism of the possible effect of HSP25 on the proliferation and differentiation of rat dental follicle cells.

Methods: Immunohistochemistry was performed to detect the expression of HSP25 in mandibles of postnatal rats on day 1, 3, 5, 7, 9 and 11 in vivo. In vitro, the expression of HSP25 in the dental follicle cells was detected by the indirect immunofluorescence assay. Recombinant rat HSP25 was diluted to 0, 1, 10, 50, 100 ng/ml. MTT assay, flowcytometry and alkaline phosphate (ALP) assay were introduced to identify the time-course effect mediated by different doses of HSP25 on rat dental follicle cells.

Results: Expression of HSP25 was not detected in dental follicle of the rats until day 5 after birth, and up-regulated in a time-dependent manner till day 11. HSP25 was revealed in the cytoplasm of cultured rat dental follicle cells. No significant difference could be observed on dental follicle cell proliferation after the stimulation of different concentrations of HSP25 on day 1, 2, 3 (P>0.05). HSP25 at a concentration of 50 ng/ml, 100 ng/ml could up-regulate the ALP activity of rat dental follicle cells on day 9 (P<0.05).

Conclusions: HSP25 has no significant effect on cell proliferation while may play a role in cementoblast/osteoblast differentiation of rat dental follicle cells.

This study was supported by National Natural Science Fund of China (No. 30672318)


0751 (117266)

Analysis of the effect of DSPP mutations on pre-mRNA splicing. S.-K. LEE, K.-E. LEE, H.-Y. KANG, J. JO, and J.-W. KIM, Seoul National University, Seoul, Korea, South Korea

Hereditary dentin defects, dentinogenesis imperfecta type II and dentin dysplasia type II, are caused by mutations in the DSPP gene. Majority of the mutations in the DSP portion are believed to affect pre-mRNA splicing, however the effect of the mutations on the splicing process was not verified yet. Objectives: To verify mutational effect on the pre-mRNA splicing and establish molecular pathologic basis of inherited dentin defects. Methods: Genomic DNA of a normal control without any dental and general health problems was amplified with pfu enzyme using PCR primers to include exon 2, 3, and 4 of DSPP gene. The amplification product was cloned into the pSPL3 splicing vector after double digesting with NotI and BamHI restriction endonucleases. PCR mutageneses were performed. Sequences of normal and mutant pSPL3 vectors were confirmed by direct plasmid sequencing. Normal and mutant pSPL3 vector were transfected into COS-7 cells, and total RNA was isolated after 36 h. RT-PCR products were excised from an agarose gel following electrophoresis, purified and characterized by direct DNA sequencing. Results: In vitro splicing assay revealed that most of known DSP mutations affected normal pre-mRNA splicing. However the splicing defects are not complete in most cases. So the RT-PCR results showed two bands (normally spliced and abnormally spliced bands). A c.52-3C>G mutation only resulted abnormally spliced band without normal band. Conclusions: Most mutations in the DSP portion of DSPP gene affect normal pre-mRNA splicing. We believe this result may provide us a better understanding of molecular pathophysiology of hereditary dentin defects. This work was supported by a grant from the Korea Science and Engineering Foundation (KOSEF) through the Biotechnology R&D program (M10646010003-08N4601-00310), and the Korea Science and Engineering Foundation (KOSEF) Science Research Center grant funded by the Korean Ministry of Education, Science and Technology (MEST) through Bone Metabolism Research Center (R11-2008-023-02003-0).


0752 (117922)

Molecular Analysis of Amelogenesis Imperfect in Chinese Population. Y. SONG, C. ZHANG, C. WANG, and Z. BIAN, Key Laboratory for Oral Biomedical Engineering of Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China

Objectives: Amelogenesis imperfectas (AI) are a group of disorders with obvious clinical and genetic heterogeneity, causing abnormalities in the amount, structure, and composition of enamel. The study aims to investigate diverse forms of AI in Chinese population, and to determine whether there are some involvements for mutations on the candidate ENAM and FAM83H gene in Chinese families with AI. Methods: A total of 10 Chinese families with isolated AI were investigated and enrolled in the study. Comprehensive oral examination was performed for available affected members. The hereditary mode and clinical phenotypes were determined in each family. Genomic DNA was analyzed in all investigated members and 50 unrelated normal individuals. Causative mutations were examined by amplifying all coding regions and splicing junctions of the candidate ENAM and FAM83H gene with PCR and sequencing the products. Results: Hypoplasia AI presented in all affected members in an autosomal dominant form in 5 families, and autosomal dominant hypocalcified AI was determined in other 5 families. The direct sequencing analysis revealed a heterozygous mutation IVS7+1G>A in the splice donor site of intron 7 in ENAM gene in one family with enamel hypoplasia, and identified 3 nonsense mutations (c.906T>G, p.Y302X; c.973C>T, p.R325X; c.2029C>T, p.Q677X) and 1 frameshift mutation (c.924insT, p.L308fsX324) in the C-terminal of FAM83H gene in 4 families with hypocalcified AI. The mutations cosegregated with the disease phenotype in the families and were not found in 100 control chromosomes. Conclusion: Our data provide the evidence that the genes ENAM and FAM83H are causative for a portion of autosomal dominant AI in Chinese population. Supported by grant no. 30771186 from the National Natural Science Foundation of China.


0753 (116063)

Immunohistochemical Localization of DMP1 in Human Dentin. G. ORSINI1, A.J. RUGGERI2, A. PUTIGNANO1, R. DI LENARDA3, A. NANCI4, and L. BRESCHI3, 1Polytechnic University of Marche, Ancona, Italy, 2University of Bologna, Bologna, Italy, 3University of Trieste, Trieste, Italy, 4University of Montreal, Montreal, Canada

Objective: Dentin matrix protein 1 (DMP1) is a non-collagenous matrix protein with a recognized role in the formation of mineralized tissues such as dentin. The aim of this study was to analyze the distribution of DMP1 in human dentin by means of immunofluorescence and high-resolution immunogold labeling.

Methods: Fully developed, sound human dentin specimens were submitted to fluorescence labeling and post-embedding immunolabeling techniques with a rabbit polyclonal anti- human DMP1 antibody followed by corresponding fluorochrome-conjugated or gold-conjugated secondary antibodies.

Results: Both immunofluorescence and immunogold labeling showed an intense labeling associated with the peritubular dentin. In addition, at the ultrastructural level, there was also a moderate and diffuse immunoreaction over intertubular dentin, and a weak labeling within predentin which increased in density towards the mineralization front.

Conclusion: This study suggests that in adult human teeth, like in rodents, DMP1 is prevalently concentrated at the level of peritubular dentin and this feature is preserved also in fully developed-teeth. These data are consistent with what has been observed in rodents and suggest that DMP1 plays a role in maintenance of the dentin tubular space.


0754 (119089)

Immunohistochemical analysis of proteoglycans in human sclerotic dentin. A. RUGGERI1, G. ORSINI2, A. MAZZONI1, F. NATO1, M. FALCONI1, and L. BRESCHI3, 1University of Bologna, Bologna, Italy, 2Polytechnic University of Marche, Ancona, Italy, 3University of Trieste, Trieste, Italy

Objective: Dental caries is a slowly progressive infectious disease. The carious process dissolves the mineral apatite contributing to expose the dentin organic matrix. In response to caries stimuli, sclerotic dentin can be formed by odontoblasts, greatly contributing to the preservation of the remaining tooth structure and protecting the dental pulp.

The objective of this study was to analyze the presence of a pool of proteoglycans (PGs) in sclerotic dentin, such as decorin (DCN), biglycan (BGN) and dentin matrix protein-1 (DMP-1), by an immunohistochemical approach, comparing their distribution vs the sound human dentin matrix.

Methods: Human dentin disks containing sclerotic dentin were submitted to either a pre-embedding immunolabelling procedure using monoclonal primary antibodies anti-DCN, BGN and DMP-1. Gold particles conjugated secondary antibodies anti-rabbit IgG were used to detect PGs by Field Emission in lens Scanning Electron Microscope (FEISEM), while fitch-conjugated secondary antibody were used to visualize sites of antigen-antibody reaction by Fluorescence Microscope (FM). Correlative labelling patterns were obtained and compared to sound dentin.

Results: The FEI-SEM analysis revealed structural modifications of the collagen network within the sclerotic dentin such as collapse, swelling, and branching of the fibrils. Labeling of DCN, BGN and DMP-1 was identified within the sclerotic dentin , but with lower intensity than sound dentin. On the contrary in sound dentin collagen network maintained its integrity and pattern labeling of proteoglycans was high and clearly identifiable. FM analysis confirm the data showing the positive reaction only in the front of predentin layer.

Conclusions: These data suggest that sclerotic dentin contains lower amount of PGs. This hypothesis will be confirmed in the future investigations.


0755 (120507)

TRIP-1 regulates odontoblast differentiation. A. RAMACHANDRAN, J. HAO, S. RAVINDRAN, A. EAPEN, and A. GEORGE, University of Illinois - Chicago, Chicago, IL

TGF-b receptor interacting protein (TRIP-1) is associated with TGF-b Type II receptor and plays a role in TGF-b signaling. It is a WD domain protein that also functions as an essential subunit of the eIF3, eukaryotic translation initiation factor 3 in animals, yeast and plants. To date there are no published studies on the role of TRIP-1 in tooth formation. The present study proposes that TRIP-1 is present in odontoblasts and plays an important role in dentin mineralization.

Objective:

To identify the presence of TRIP-1 in odontoblasts and to characterize the putative role it plays during dentin mineralization.

Methods:

Northern, in-situ hybridization and immunohistochemical analyses were performed to identify and localize TRIP-1 in the odontoblasts during odontogenesis. To characterize its function TRIP-1 was stably expressed in pluripotent embryonic mesenchymal C3H10T1/2 cells. Expression of genes involved in odontoblast differentiation and TGF-b signaling were analyzed by RT-PCR and immunoblotting. Mineralized nodule formation assay was performed and detected using von Kossa staining.

Results:

Expression of TRIP-1 was observed as a single transcript of 1.6 kb by Northern analysis. At postnatal day 20, in-situ hybridization analysis revealed the presence of TRIP-1 in developing rat teeth. Presence of TRIP-1 in tooth sections showed expression at all stages of odontoblast differentiation. Gene expression analysis showed up-regulation of ALP, matrix genes such as COL X, COL I, DPP, DMP4 and TGF-b pathway associated genes like TGF-b RI, TGF-b RII, Smad 2, 3 and 4. Interestingly, decreased expression of DMP1 was observed in TRIP-1 overexpressed cells. Von Kossa staining was significantly stronger in TRIP-1 overexpressing cells when compared with mock cells.

Conclusions:

TRIP-1 is expressed by odontoblasts and plays a regulatory role during odontoblast differentiation and tooth development.

This work was supported by NIH grant DE 11657


0756 (120662)

Cleavage Site Determination of Dentin Sialoprotein-Phosphophoryn Precursor Protein. R. YANG, and H.H. RITCHIE, University of Michigan, Ann Arbor, MI

Introduction: Dentin sialoprotein (DSP) and phosphophoryn (PP) are the two noncollagenous proteins classically linked to dentin, but more recently found in bone, kidney and salivary glands. These two proteins are derived from a single copy DSP-PP gene. Recently we identified DSP-PP240 precursor protein containing a 240 amino acid PP isoform, which was secreted into the extracellular space and self-processed into DSP430 and PP240 extracellularly. Because native PP has a DDPN N-terminal sequence, we hypothesized that SMQG447|D448DPN is the specific cleavage site for generating DSP430 and PP240. To test this hypothesis, our Objective was to generate DSP-PP240 containing mutated G447 and follow the expression and processing of this mutated precursor protein. Methods: To achieve this goal, we used site-mutagenesis to generate G447 and D448 mutations in DSP-PP240 cDNA in pGEM7Z(+) which were subsequently subcloned into pVL1392 baculovirus vector for protein expression. Results: Wild type and mutated DSP-PP240 precursor proteins are secreted into the extracellular space in the baculovirus expression system. Dynamic processing of wild type DSP-PP protein occurred extracellularly yielding both DSP and PP proteins. Using MS, MS/MS analysis on the chymotrypsin treated recombinant PP sample, the N-terminal sequence was determined to be DDPNSSDESNGSDGSDDANSESAIENGNHGDAS. DSP-PP240 cDNA containing G447 mutant yielded a DSP-PP240 precursor protein, which was not further processed into DSP430 and PP240. Conclusion: Using the baculovirus expression system to generate recombinant wild-type and G447|D448 mutated DSP-PP240 proteins, together with MS/MS analyses, we demonstrated that G447|D448 is the cleavage site for generating DSP430 and PP240 from the wild type precursor molecule. This work was supported by NIH DE11442-9 to HHR.


0757 (121232)

Proteomic Profiling Of Stem Cell Differentiation With BMP-2 And Phosphophoryn. N. ROBERTSON1, P.-N. TENG2, B. HOOD1, T. CONRADS1, and C. SFEIR1, 1University of Pittsburgh, Pittsburgh, PA, 2University Of Pittsburgh, Pittsburgh, PA

Title: Proteomic Profiling Of Stem Cell Differentiation With BM- 2 And Phosphophoryn

Authors: Neil Robertson, Bonnie PN Teng, Brian L. Hood, Thomas P. Conrads, Charles Sfeir

Objectives: System biology approaches were used to determine proteins and peptides involved in the signaling pathways of stem cells when treated with Phosphophoryn (PP) and Bone Morphogenetic Protein 2 (BMP-2). This was achieved by using Stable Isotope Labeling of Amino Acids in Cell Culture (SILAC).

Methods: Using SILAC, heavy and light isotopes of amino acids lysine and arginine can be added to depleted growth medium thus incorporating entirely into the cell's proteome.

C3H10T1/2 cells were grown in “heavy” or “light” medium. Cells grown in heavy medium were treated with PP or BMP-2 (250 ng/mL for 15 min) whereas those grown in light served as the control. Cells were pelleted, lysed, and protein quantified. Extracted proteins from light and heavy cells were mixed in a 1:1 ratio, digested with trypsin and analyzed by nanoflow RPLC-MS/MS. Peptides were identified and quantified using commercially available software.

Results: Mass spectrometry results showed full incorporation of labeling into the cells proteome, allowing further analysis. A total of 630 proteins were identified for BMP, another 652 for PP and 261 proteins were common to both. Further analysis showed that 217 were identified by greater than 2 peptides, 210 were found for PP and 157 were common to both pathways. Upon plotting the number of proteins identified per binned ratio, a Gaussian distribution was formed.

Conclusions: Using mass spectrometry and protein identification software, proteins and peptides involved in intracellular signaling during treatment have been quantified. By comparing proteins common and unique to both pathways, points of diversion in signaling and up and down regulation can be studied more efficiently.

This research was funded by:

NIH: 5K02DE016900

NIH: 5UL1RR024153


0758 (114772)

Images of Stem Cells Transplanted into Salivary Glands. C.Y. LIN, C.Y. DONG, W.L. CHEN, F.C. LI, and S.-S. JU, National Taiwan University, Taipei, Taiwan

In our previous study, transdifferentiation of bone marrow stem cells(BMSCs) was found after co-cultured with acinar cells. However, the in vivo dynamic changes of BMSCs transplanted into salivary glands had not been investigated.

Objectives: The purposes of this study were to investigate the in-vivo dynamic changes of BMSCs transplanted into the damaged salivary glands by using multiphoton microscope imaging system.

Methods: Male nod-scid mice, 6 weeks old, were locally received 15Gy irradiation to create hypofunctional salivary gland without compromising general health. After 10 days, BMSCs from enhanced GFP C57BL/6 male mice were injected into the submandibular glands of irradiated nod-scid mice. To visualize the submandibular gland, q titanium ring with a 5-mm round cover glass was adhered to the mice neck after exposure of the salivary gland, and the ring was fitted to a steel plate placed on the microscopic stage of an inverted multiphoton microscope at 1, 2, and 3 weeks after eGFP BMSCs-injection. The multiphoton microscope with a 780nm output titanium-sapphine laser was used for real-time observation of the glands. The detection bandwidths for the SHG, blue, green, and red fluroscence were collected. The flow rate of saliva from the mice with damaged salivary gland before and after transplantion of BMSCs were recorded and compared with the control group.

Results: The normal and atrophic submandibular glands could be easily distinguished from each other under the multiphoton microscope image investigation and eGFP BMSCs were survived at least 3 weeks in the atrophic glands. The effects of BMSCs in increasing the flow rate of saliva and repairing the damaged salivary gland were evident.

Conclusions: This is the novel study of using multiphoton microscope for in- vivo dynamic imaging of the transplanted BMSCs with the surrounding tissues. The multiphoton imaging is a useful tool for in vivo study of tissue engineering.


0759 (115355)

Cortisol and Chromogranin A in Patients with Dry Mouth. C. SHIGEYAMA1, T. ANSAI2, S. AWANO2, A. YOSHIDA2, T. HAMASAKI2, Y. KAKINOKI2, H. ANAN1, and T. TAKEHARA2, 1Fukuoka Dental College, Fukuoka, Japan, 2Kyushu Dental College, Kitakyushu, Japan

Objectives: To evaluate the salivary levels of cortisol and chromogranin A (CgA) in patients with dry mouth (perceived xerostomia and hyposalivation) compared to age-matched controls.

Methods: We studied 174 subjects, including dry mouth patients (n=116) and control subjects (n=58). The dry mouth group was further classified into 2 subgroups: subjects with perceived xerostomia and normosalivation (dry mouth 1, n=54), and subjects with perceived xerostomia and hyposalivation (dry mouth 2, n=62). The control subjects were patients at the same hospital (control 1, n=37) and healthy volunteers (control 2, n=21). Cortisol and CgA levels in stimulated whole saliva were measured using ELISA kits.

Results: All subjects with dry mouth had significantly higher cortisol and CgA levels than the controls. When we next compared between the two control subgroups and two dry mouth subgroups for the salivary levels of cortisol and CgA, the levels of cortisol were significantly higher in the two dry mouth subgroups than both control subgroups. On the other hand, the level of CgA was significantly higher in dry mouth 2 compared with both control sub groups. The statistical associations remained still significant when those were divided into the two subgroups, although somewhat weaker associations were observed. The influences of xerogenic drugs were found to be minimal on salivary flow rate and levels of cortisol and CgA.

Conclusion: We found significant associations between salivary cortisol and CgA levels and symptoms of oral dryness and reduced salivary flow.

This work was supported by Grants-Aid for Scientific Research (17592186) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.


0761 (116142)

Subjective and objective oral dryness in two study populations. C. DIOGO LÖFGREN, and C. CHRISTERSSON, Faculty of Odontology, Malmö University, Malmö, Sweden

Subjective and objective oral dryness in two study populations.

Objectives: This study aimed to assess the occurrence of reported subjective oral dryness in relation to objective sialometric values in one randomly selected group (RS) and one dental care seeking group (DCS). The RS-group comprised of 200 individuals (aged 20 to 80) in the Malmö region, southern part of Sweden and the DCS-group comprised of 200 individuals (aged 22 to 90 ) being admitted to the Faculty of Odontology, Malmö University.

Methods: Subjective oral dryness was assessed with a questionnaire (n=312) and a complementary clinical examination included measures of salivary flow rate (n=157). Results: The perceived oral dryness was 20% for the RS-group and 28.6% for the DCS-group. No statistically significant differences were found between the two study populations regarding percentage of reported subjective oral dryness and stimulated and unstimulated salivary flow rates and no statistically significant association between subjective oral dryness and unstimulated and stimulated salivary flow rates was found in either of the studied populations (Fisherxs exact test, p>0.05). Individuals reporting subjective oral dryness in the DCS-group presented “a small degree of abrasion in the dentine in the incisor region” to a greater extent (Fisherxs exact test, p<0.05). Individuals identified with subjective or objective oral dryness presented to a higher extent a history of oral rehabilitation than individuals that had no indication of oral dryness. Conclusions: Perceived oral dryness may be more dependent on qualitative parameters such as composition of saliva secretions and dynamic interactions of salivary components at oral interfaces, than only on the quantity of saliva secreted. The development of diagnostic criteria and functional tests are needed to discern individuals with subjective and objective oral dryness that will require oral treatment.


0762 (116706)

Effects of Benzodiazepines and Pilocarpine on Rat Parotid Glands. T.M.F. MATTIOLI, A.C. DAGULHAM, M.V. ZACLIKEVIS, S.D. SILVA, A.M.T. GRÉGIO, M.A.N. MACHADO, A.A.S.D. LIMA, S.A. IGNÁCIO, P.C. TREVILATTO, and L.R. AZEVEDO, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil

Objectives: The aim of this study was to evaluate the effects of benzodiazepines and pilocarpine on rat parotid glands and on the behavior of acinar and myoepithelial cells, Methods: Ninety male Wistar rats were allocated to nine groups. Control groups received saline during 30 (C30) and 60 days (C60), and topic pilocarpine (PILO) during 60 days. Experimental groups received Lorax® (L30) and Dormonid® (D30) during 30 days. Others experimental groups received Lorax® (LS60) and Dormonid® (DS60) associated with saline, and Lorax® (LP60) and Dormonid® (DP60) associated with pilocarpine during 60 days. The stimulated salivary flow rate (SSFR) was obtained by using the gravimetric method. After the animals were killed, parotid glands were removed and their mass (M) and size (S) were determined. The specimens were processed and stereological analysis revealed cell volume (CV). The immunohistochemical expression of calponin and PCNA on myoepithelial and acinar cells was evaluated. The normality and homogeneity of variances of the studied variables were tested by Kolmogorov-Smirnov and Levene tests, respectively. ANOVA, Multiple Comparisons Tukey HSD and Games-Howell tests were applied to detect differences among the groups. All the statistical tests were performed at a level of significance of 5% (p<0.05), Results: Benzodiazepines chronic use induced an increase in the S of the parotid glands and a decrease in the SSFR (p<0.05) in groups treated during 30 days. Group LP60 presented a significant increase (p=0.001) in SSFR when compared with LS60. Group LP60 presented a significant decrease (p=0.020) in CV when compared with LS60. Groups treated with Lorax® showed an increase in the number of positive staining cells for calponin when compared with controls (p<0.05), Conclusion: Pilocarpine showed significant secretagogue action in the treatment of hyposalivation induced by benzodiazepines chronic use.

This study was supported by CNPq (grant 474790/2004-5).


0763 (116798)

Gender and Sympathetic Vascular Responses in the Rat Submandibular Gland. L.C. ANDERSON, B. ULRICH, R. SHAH, and C. ANDRESEN, University of the Pacific, San Francisco, CA

INTRODUCTION: Estrogen increases endothelial production and bioavailability of NO, and this beneficial effect of estrogen is responsible, at least in part, for the lower risk of cardiovascular disease in premenopausal women compared with men of the same age. The purpose of this study was to determine whether gender affects sympathetic vascular responses in the rat submandibular gland.

METHODS: Male and female, Sprague-Dawley rats (total n=17) were anesthetized with pentobarbitone followed by chloralose. Blood flow responses to sympathetic stimulation (2 Hz and 4 Hz continuously or 20 Hz and 40 Hz in bursts of 1s for every 10 s) were measured using laser-Doppler flowmetry before and after inhibition of cyclooxygenase (indomethacin) and nitric oxide (NO) synthase (L-NAME).

RESULTS: The response to sympathetic stimulation was biphasic (vasoconstriction followed by vasodilatation), but depending on the experimental protocol employed the result was either an intense vasoconstriction (continuous impulses) or a net vasodilatation (burst stimulation). In female rats there was a large vasodilatory response to burst stimulation and there was a tendency to overcome the vasoconstriction induced by continuous stimulation. In contrast, the net vasodilatation observed in males during burst stimulation was significantly lower than that seen in females (p<0.02) and there was no recovery from the vasoconstriction seen under continuous stimulation. Indomethacin, either alone or in combination with L-NAME had no effect on blood flow response. However, L-NAME significantly reduced the vasodilatory responses in both males and females (p<0.01), and completely abolished all gender differences.

CONCLUSIONS: From these data we conclude 1) that NO is largely responsible for the vasodilatory response to sympathetic stimulation, and 2) that NO-mediated responses are greater in female than in male rats. Supported by a grant from NIDCR (R15 DE016586)


0764 (117049)

PDGF Regulates Salivary Gland Morphogenesis VIA Fgf Expression. S. YAMAMOTO1, E. FUKUMOTO2, K. YOSHIZAKI3, T. IWAMOTO3, A. YAMADA4, I. SAITO1, H. HAYASAKI1, Y. YAMASAKI1, and S. FUKUMOTO4, 1department of Pediatric Dentistry, Kagoshima University, Kagoshima, Japan, 2Nagasaki University, Nagasaki, Japan, 3Kyushu University, Fukuoka, Japan, 4Tohoku University, Sendai, Japan

Objectives: a coordinated reciprocal interaction between epithelium and mesenchyme is involved in salivary gland morphogenesis. The submandibular glands (SMGs) of Wnt1-Cre/R26R mice have been shown positive for mesenchyme, whereas the epithelium is â-galactosidase-negative, indicating that most mesenchymal cells are derived from cranial neural crest cells. Platelet-derived growth factor (PDGF) receptora is one of the markers of neural crest-derived cells. In this study, we analyzed the roles of PDGFs and their receptors in the morphogenesis of mouse SMGs.

Methods: (organ culture system) SMGs was dissected from embryonic day 13 ICR mice, placed on polyethylene terephthalate filters, and cultured in D-MEM / F12 medium supplemented with 150 ug/ml ascorbic acid, 50 ug/ml transferrin for 24-72 hours. Gene expressions were analyzed by semiquantitative and real-time PCR. Cell proliferation was examined by BrdU incorporation assay.

Results: PDGF-A was shown to be expressed in SMG epithelium, whereas PDGF-B, PDGFRa, and PDGFRb were expressed in mesenchyme. Exogenous PDGF-AA and -BB in SMG organ cultures demonstrated increased levels of branching and epithelial proliferation, although their receptors were found to be expressed in mesenchyme. In contrast, short interfering RNA for Pdgfa and -b showed decreased branching. PDGF-AA induced the expression of Fgf3 and -7, and PDGF-BB induced the expression of Fgf1, -3, -7, and -10, whereas short interfering RNA for Pdgfa and -b inhibited the expression of Fgf3, -7, and -10, indicating that PDGFs regulate Fgf gene expression in SMG mesenchyme. The PDGF receptor inhibitor AG-17 inhibited PDGF-induced branching, whereas exogenous FGF7 and -10 fully recovered.

Conclusions: these results indicate that fibroblast growth factors function downstream of PDGF signaling, which regulates Fgf expression in neural crest-derived mesenchymal cells and SMG branching morphogenesis. Thus, PDGF signaling is a possible mechanism involved in the interaction between epithelial and neural crest-derived mesenchyme.


0765 (117357)

Xerostomia and Salivary Hypofunction in West Virginia Elderly. R.C. WIENER1, B. WU1, R.J. CROUT1, M.A. WIENER1, E. KAO1, S. WEARDEN1, D. MCNEIL1, B.L. PLASSMAN2, J.M. CHALMERS3, M.L. BOONE3, and E. DINAPOLI1, 1West Virginia University, Morgantown, WV, 2Duke University, Durham, NC, 3University of Iowa, Iowa City, IA

Early detection and intervention in salivary hypofunction increases quality of life and decreases the incidence of caries and periodontal disease. Salivary diagnostics also show increased value for disease detection. However, often patients with hyposalivation only come to the attention of healthcare providers to seek treatment when they become aware of the symptoms. Therefore, inaccurate or blunted self-awareness may impede needed care. Objective: Little salivary research exists concerning rural Appalachia. The relationships among self-report of symptoms, salivary production, and oral tissue dryness were studied to determine the usefulness of self-report of symptoms for detection and treatment of salivary hypofunction, its underlying causes, and co-morbidities. Methods: As part of an ongoing study of oral health and cognition in later life, non-dental personnel administered a well-established 11-question xerostomia screening survey to 122 dentate WV participants age 70 and above. The dental team recorded oral findings that included measurement of unstimulated salivary flow rates and a visual evaluation of oral dryness. Based on previous studies, normal unstimulated salivary flow rate was defined as 0.3-0.4 ml/minute and hyposalivation as 0.1 ml/minute. Results: The average unstimulated flow rate was 0.43 (range 0.015-1.69)ml/minute. Sixteen subjects (13.11%) had hyposalivation, of which13 were women. Twenty-five (20.49%) subjects were visually identified with dry mouth; and 26 (21.31%) self-reported "My mouth feels dry" fairly often or very often. Nine (7.38%) subjects reported no xerostomia, but had hyposalivation; 22 (18.03%) reported xerostomia, but had normal flow rates. The dental team's visual observation corresponded with self-reports 81.1% of the time; and with low unstimulated salivary flow rates 31.2% of the time. Conclusion: Self-report was not effective for detection of hyposalivation and visual observations were of limited value in this elderly population. Obtaining routine unstimulated salivary flow rates may be a useful diagnostic aid in the elderly. This study is funded by NIH/NIDCR (1R21DE016970).


0766 (117991)

Submandibular gland recovery using b-FGF-impregnated gelatin hydrogel. J. KUROKI1, K. KIKUCHI1, R. IKEDA2, S. SATO1, and S. AIYAMA1, 1Nippon Dental University, Tokyo, Japan, 2Nippon Dental University College at Tokyo, Tokyo, Japan

Objectives:

It is known that the salivary gland parenchyma becomes atrophic and degenerates as a result of duct obstruction by a ptyalolith. Basic fibroblast growth factor (b-FGF) and gelatin hydrogel have attracted special interest recently, because the former has a cell growth and cytodifferentiation effect and the latter has excellent properties for drug release. This study was undertaken to examine the effect of a combination of b-FGF and gelatin hydrogel on salivary gland atrophy.

Methods:

The main excretory duct of the submandibular gland in 7-week-old male Wistar rats was ligated with 8-0 suture for 2 weeks. After ligature removal, the experimental group received implants of gelatin hydrogel impregnated with b-FGF (100µg) between the gland body and the capsule, on both the ventral and dorsal aspects. The control group received implants of saline-impregnated gelatin hydrogel. After 1 and 2 weeks, the glands were removed and examined histochemically and immunohistochemically.

Results:

The control group retained abundant duct-like structures in the lobules in addition to an increase of interlobular connective tissue even after 2 weeks. On the other hand, in the experimental group at 1 week some cells appeared to have changed the duct-like structure cells to acinar cells and there were also a few acinar cells with secretory granules. A large number of acinar cells were evident after 2 weeks. After 1 week, the proportions of PCNA-positive cells in the duct-like structures were 3.2±1.6% and 9.2±3.7% in the control and the experimental groups, respectively.

Conclusion:

These findings suggest that placement of gelatin hydrogel impregnated with b-FGF under the capsule is effective for regeneration of the submandibular gland parenchyma after injury due to duct obstruction, through controlled release of b-FGF from the hydrogel.


0767 (119464)

Mixed Actions of Clozapine on Salivary Secretion. J. EKSTROM1, T. GODOY1, and A. RIVA2, 1Section of Pharmacology, University of Gothenburg, Gothenburg, Sweden, 2University of Cagliari, Cagliari, Italy

Antipsychotics are usually associated with hyposalivation. Clozapine is an atypical antipsychotic drug for schizophrenia-treatment. Surprisingly, many clozapine-treated patients complain of drooling and hypersalivation particularly during night. The medication may be discontinued or anticholinergics may be used to reduce the secretion. Objective secretory studies in humans are few and inconclusive. In vivo animal experiments are lacking. OBJECTIVES: To test the effect of clozapine per se and on the secretion evoked by nerve stimulation or autonomic drugs. METHODS: The parotid and submandibular gland ducts were cannulated in pentobarbitone-anaesthetized rats. Saliva was collected in pre-weighed tubes. Drugs were given I.V. Values are means. RESULTS: 1) Clozapine (a gift from Novartis) evoked secretion over 1-2 hours from both glands. Submandibular glands were more sensitive than parotid glands. All submandibular glands secreted (0.7 µl/5 min, n=11) to clozapine 3 mg/kg, while only 2 out of 21 parotids responded to 10 mg/kg. The secretion was unaffected by propranolol and phentolamine but abolished by atropine or pirenzepine. 2) Parotid saliva (49 µl, n=8) secreted to parasympathetic stimulation (10 Hz, 1 min) was almost abolished by clozapine 10 mg/kg. 3) Submandibular saliva (19 µl, n=17) secreted to sympathetic stimulation (20 Hz, 1 s every 10th second, 2 min) was reduced, at the most, to 25% by clozapine (3-10 mg/kg); the persisting response was unaffected by phentolamine but abolished by propranolol. 4) Methacholine (5µg/kg)-evoked submandibular (15 µl, n=33) and parotid secretion (8 µl, n=25) was (almost) abolished by clozapine 10 mg/kg. 4) Though clozapine (1 mg/kg) evoked no submandibular secretion it almost doubled the isoprenaline-evoked secretion. CONCLUSIONS: Mixed agonistic (muscarinic 1-receptors)/antagonistic (muscarinic 3-receptors and alpha-adrenoceptors) actions combined with synergistic interactions (beta-adrenoceptors) suggest that in humans, clozapine may enhance salivation during rest and reduce salivation during meals.

The Swedish Science Council (05927), The LUA/ALF agreement (ALFGBG-11907) and The “INTERLINK”-agreement (II04C00H8M).


0768 (119470)

Cevimeline induced salivation from perfused mouse submandibular glands. Y. KONDO, T. NAKAMOTO, M. KIDOKORO, T. MUKAIBO, C. MASAKI, and R. HOSOKAWA, Kyushu Dental College, Kitakyushu City, Japan

Objectives: Cevimeline, a muscarinic agonist used clinically to rescue dry mouth, was explored to identify the mechanisms of its direct effects on salivary gland fluid secretion. Methods: Submandibular glands from C57/Bl6J mice were perfused with physiological saline solution, and then stimulated with parasympathetic agonists carbachol (CCh: 0.1-30mM), an experimentally used muscarinic agonist, or cevimeline (1mM-1mM), a clinically used muscrinic agonist, at 37 degree. Stimulation was applied for 10 minutes and the flow rate and total amount was compared. Results: CCh induced salivation was detectable from 0.1mM which showed maximum effect at 1mM (183.2+/-13.2 mL/ 10 min.), and then the amount of saliva decreased as the concentration became higher. However, cevimeline acted very differently, producing little salivation at 1mM (9.5+/-3.3 mL/10 min.), then the effect gradually increased up to 30mM (122.3+/-4.7 mL/ 10 min.) and the flow was preserved when the gland was stimulated with 1mM (124.1+/-6.0 mL/ 10 min.). Surprisingly, even at maximum response, cevimeline showed only 66% of maximum CCh response. Conclusion: Even though its maximum secretion was significantly less than CCh, cevimeline has a very broad effective range for fluid secretion. These data suggest that salivary cells might not become sensitized to cevimeline during prolonged stimulation in vivo.


0769 (119757)

The Signalling Network in Regenerating Submandibular Glands: a Microarray Study. E. COTRONEO, E. ALDECOA-OTALORA ASTARLOA, M. ARNO, G.B. PROCTOR, and G.H. CARPENTER, King's College London, London, United Kingdom

Understanding the molecular mechanism of submandibular gland regeneration following ligation-induced atrophy could help to elucidate the starting signals of regeneration. Our previous results showed embryonic/perinatal features occurring during early rat submandibular gland regeneration. However, our data also suggested that embryonic Wnt pathway is not involved at that stage. Objective: to investigate signalling pathways involved in the progression of early submandibular gland regeneration using microarray and bioinformatic approach. Methods: 6 rats were used in this study. Atrophy was induced by ligating the main submandibular gland duct for 2 weeks. The duct was than deligated for 3 or 5 days, then glands were collected and RNA was extracted for microarray analysis. Rats were killed by anaesthetic overdose. Microarray data from the time points were compared using 3 days as the baseline. Resulting data were analysed using Pathway-Express (Wayne State University, USA). Results: In the 5 days regenerating gland Pathway-Express identified 36 genes involved in the MAPKinase pathway, important for cellular proliferation, differentiation, also involved in Calcium signalling. Several positive modulators (e.g. Fgf9, Fgfr2/3, Jund, Map2k2/3, Myc and Pdgfa) were up-regulated (p<0.05), suggesting activation of this pathway. We also found 20 genes involved in the Wnt pathway; positive modulators (e.g. Csnk1e) were down-regulated (p<0.05) whereas inhibitors (e.g. Ppp2ca/b and Ctbp1) were up-regulated (p<0.05), confirming that the Wnt is probably not activated at this time point. The Notch pathway was also found to be involved (14 genes), however activators (e.g. Jag1, Maml1 and Pcaf) as well as inhibitors (Numb and Hdac2) were up-regulated (p<0.05); this may reflect the complexity of the tissue, meaning that the activation/inactivation of this pathway may be cell-type specific. Conclusion: Our data showed novel information on the signalling network operating in regenerating gland with particular emphasis on embryonic and cell proliferation pathways.

We acknowledge Wellcome Trust for funding this study.


0770 (120767)

Homeopathy and phytotherapy on salivary function of irradiated rats. L.R. NERY1, F.C. GROPPO2, J.C.L. SILVA1, P.C. VENÂNCIO1, F.N. BÓSCOLO1, and S.M. ALMEIDA1, 1Piracicaba Dental School, Piracicaba, Brazil, 2Piracicaba Dental School, Piracicaba-SP - Sao Paulo, Brazil

The deleterious effect of radiotherapy on salivary glands is well known. Objective: The aim of the present study was to compare the radioprotective effect on salivary glands of two formulations - a homeopathic solution (X rays 15 CH) and a phytotherapy solution (copaiba, Copaifera langsdorffii Desf.) – with E vitamin (a well know radioprotective). Methods: Forty rats were divided into the following groups: G1 - NaCl 0.9% (control); G2 – suspension of dl-alpha-tocopherol acetate (E vitamin) 40mg/kg/vo/day; G3 – 15 CH X rays homeopathic solution 1mL/kg/vo/day and G4 – copaiba oil 2g/kg/vo/day. The treatments were kept during 7 days. After this period, the animals were anesthetized (ketamine/xilasine), positioned on a linear accelerator and all animals received 15 Gy of X radiation. The treatments were kept for additional 7 days and after 12 hours and 24 days of irradiation, the animals were sedated (pentobarbital 30mg/kg/ip) and saliva was collected after stimulating salivary secretion with 2.5 mg/kg pilocarpine. Salivary samples were immediately weighed right after collection. Results: Saliva weight (mean±SEM) was 0.42 (±0.07) g, 0.27 (±0.09) g, 0.51 (±0.12) g and 0.34 (±0.15) g, respectively for G1, G2, G3 and G4, considering the 12-hours period. Considering the 24-days period, the saliva weight was 0.89 (±0.16) g, 0.87 (±0.19) g, 1.04 (±0.18) g and 1.12 (±0.23) g, respectively for G1, G2, G3 and G4. A statistically significant (ANOVA, LSD t test, p<0.05) increase was observed between the 12-hours and 24-days periods considering G2, G3 and G4. G1 did not exhibit statistically significant differences (p>0.05) between the periods. None statistically significant differences (p>0.05) were observed among the solutions considering each period (12-hours or 24-days). Conclusion: Both copaiba oil and X-rays homeopathic solutions presented similar radioprotective properties when compared to E vitamin. Financial support FAPESP #2007/08024-5, CAPES.


0771 (121072)

Salivary Damage Caused by Xerostomia in Rat Salivary Gland. K. UCHIHASHI, and Y. NISHIKAWA, Osaka Dental University, Osaka, Japan

Objective: The aim of this study was to examine the functional disorders caused by water secretion in the salivary gland acini of xerostomic rats, and whether the muscarinic receptor subtypes exert exocrine functional roles in the rat salivary gland. Methods: Male Wistar rats, weighing 280-320 g each, were used. Experimental animals were divided into two groups, normal and xerostomic rats. Glycopyrrolate was administered to induce xerostomia, and we raised both anti-AQP5 antibody and anti-ZO-1 (tight junctional protein) antibody, and examined the distribution of these proteins in rat salivary gland acini. Results: Glycopyrrolate markedly inhibited the acetylcholine-evoked fluid responses in about 25% of the normal rats. Pirenzepine, 4-DAMP, and glycopyrrolate significantly inhibited acetylcholine-evoked amylase activity, whether the reduction of the amylase activity caused by pirenzepine, 4-DAMP, and glycopyrrolate was inhibited by L-NAME. In the normal rats, AQP5 was intense along the luminal membrane and was less intense at the lateral membrane, and ZO-1 was detected on the basolateral membrane. In xerostomic rats, distribution of AQP5 was translocated along the lateral membrane. ZO-1 disappeared in the essential region. Tight junctional permeability to the FITC-labeled dextran was enhanced in the xerostomia gland. Conclusion: The water-rich fluid was secreted in the lumen of the acinar cells where both AQP5 and ZO-1 were abundantly present. It is reasonable to speculate that both intracellular and paracellular transport plays an important role in concomitant water secretion.


0772 (121203)

Clinical Evaluation of Erosion Prevalence in a Xerostomic Population. M.L. SINGH1, A. PAPAS1, E. TZAVARAS1, A.A. WALANSKI2, M.L. BARKER2, and R.W. GERLACH2, 1Tufts University, Boston, MA, 2The Procter & Gamble Company, Mason, OH

Objective: The purpose of this study was to evaluate erosion prevalence and its associated risk factors in a group of subjects taking xerogenic medications. Methods: Volunteers from the Boston area who were taking a known xerogenic medication were enrolled. Unstimulated saliva was collected over a 5 minute period and measured using the Colin-Dawes method to determine salivary hypofunction. A single calibrated examiner measured erosion using the Erosion/Tooth Wear Index and measured sensitivity using the Air Blast Index. Results: 95 subjects that completed the study were analyzed. Mean (SD) age was 56.6 (13.4) years. By type, cardiac drugs (38%) were the most common xerogenic medications. Mean (SD) unstimulated saliva was 0.062 (0.058) ml/min, while healthy individuals typically have a salivary flow rate of 0.3 ml/min or above. A total of 44 subjects had at least one tooth with evident erosion/wear with an occurrence rate of 46.3% and a 95% CI of (36.0, 56.9). Among subjects with erosion/wear, 30.9% of measured teeth were affected with a 95% CI of (24.6, 38.0) using a generalized linear model. Air blast sensitivity in 1 or more quadrants of the mouth occurred in 31.58% of the subjects with a 95% CI of (22.42, 41.92). No statistically significant (p>0.96) relationship was observed between the occurrence of air blast sensitivity and erosion. Conclusion: This survey of adults with hyposalivation associated with xerogenic medications found both erosion/wear and sensitivity to be common, with occurrence greater than 30%. Larger clinical and longitudinal research studies are necessary to determine possible causal relationship between erosion, medical conditions and medications.


0773 (117685)

Effect of Periowave on Root Canals Infected with Enterococcus faecalis. Y. LI, and R.M. APRECIO, Loma Linda University, Loma Linda, CA

Objective: To evaluate the antimicrobial effect of Periowave Photodynamic Disinfection (PDD) System (Ondine Biopharma Corporation, Vancouver, BC, Canada) on root canals infected with Enterococcus faecalis (ATCC 4082). Methods: Extracted single rooted human teeth were instrumented and irrigated with 1.3% NaOCl and 0.5 M EDTA. Tips of the teeth were sealed with nail polish before autoclaving. The teeth were then placed in microcentrifuge tubes and the canals were inoculated for four weeks with E. faecalis. Root canal inoculum was collected prior to the PDD treatment for viability determination. Periowave Methylene Blue formulation (20 µL) was added to the canal and left for 5 minutes before the PDD treatment. The canals were dried with paper points and placed with 1 mL PBS for cfu/mL. Gate #4 (Miltex, York, PA) was applied into the canal with 20 µL PBS. A paper point was used to collect shavings for cfu/mL. The cfu/mL of both positive (untreated) and negative controls (untreated but autoclaved) were collected in the same manner as the test samples. Results: The root canal inoculum collected before PDD treatment showed 108 cfu/mL. The PDD treatment produced 99.7% killing in root canals and 99.998% killing in the root canal shavings. The positive control showed 99.9% survival rate whereas the negative control showed no growth. Overnight culture of E. faecalis when exposed to the PDD treatment for 3 minutes and 5 minutes showed 100% killing whereas the untreated showed 100% survival to 108 cfu/mL. Conclusions: The treatment of PDD is highly effective in killing E. faecalis in root canals and in root canal shavings. A direct exposure of an overnight culture of E. faecalis to the PDD for 3 and 5 minutes eradicates the organism. Partially supported by a grant from Ondine Biopharma Corporation.


0774 (118441)

Molecular Microbiological Analysis of Severe Caries in Primary Teeth. E.L. GROSS1, E.J. LEYS1, B. VRIESENDORP1, N.D. FIRESTONE1, D.A. JANIES1, J.S. MARTIN1, B.J. PASTER2, and A.L. GRIFFEN1, 1Ohio State University, Columbus, OH, 2The Forsyth Institute, Boston, MA

Dental caries is the most common chronic disease of childhood, but we do not have a complete understanding of its complex microbial etiology. Dental plaque contains several hundred different organisms and many are poorly studied. In addition, comparatively little attention has been paid to identifying health-associated bacteria. Objectives: Our purpose was to identify bacterial species present in health and established severe caries of the primary dentition using an open-ended molecular approach. Methods: Plaque samples were collected from 30 subjects with severe caries, age 2 to 6, and 30 healthy controls matched by age, race, and sex. A plaque sample was taken from each of four sites in each caries subject: intact enamel, whitespots, the surface of cavitated lesions, and dentin. Quantitative clonal analysis of bacterial 16S ribosomal genes isolated from the plaque samples was used to identify bacterial taxa. Phylogenetic trees based on likelihood models using bootstrap cutoffs were used to define taxa. Clinical data were analyzed by repeated measures ANOVA. Results: Resulting taxonomic designations were not always in agreement with traditional species designations. Streptococcus mutans and several other streptococci were found at high levels and increased as caries progressed. Multiple Lactobacillus species were associated with more advanced caries, and several were found at high levels. Propionibacterium australiense was also associated with advanced caries. Health-associated species found at high levels included Streptococcus mitis, Streptococcus oralis, and Streptococcus sanguinis, as well as Streptococcus gordonii, Streptococcus cristatus, and the Streptococcus intermedius/anginosus/constellatus group. Multiple additional taxa found at lower levels were more common in health than in caries. Conclusions: Many Streptococcus and Lactobacillus species are consistently found at high levels in subjects with established severe caries of the primary dentition. There are many health-related species that appear to be lost as caries progresses. Supported by NIH DE16125, F30DE019339.


0775 (118853)

Source evaluation of microbiologic contamination on a phopshor plate system. S. KALATHINGAL, A. YOUNGPETER, J. MINTON, M. SHROUT, D. DICKINSON, and K. PLUMMER, Medical College of Georgia, Augusta, GA, Georgia

Objective: The advantages of digital radiography have encouraged many clinicians to switch from film to this modality for imaging. Digital sensors are reusable so it is imperative that they are not contaminated when reused on multiple patients. The objectives for this study were to determine: (a) the rate and source of microbiologic contamination of photostimulable phosphor plates in a dental school predoctoral clinic environment, and (b) if a combination of weekly gas sterilization and barrier protocols can prevent contamination of photostimulable phosphor (PSP) plates .

Methods: Fifty of the 300 PSP plates in clinical use and 25 gas sterilized control plates were selected for examination. The PSP plates were pressed onto blood agar plates, which were then incubated at 37°C. The number, size, distribution, and variety of resulting colonies were noted. As a preliminary test to examine whether these bacteria could have come from oral sources, 17 colonies were selected for culture on Mitis-Salivarius (M-S) agar, commonly used for the detection of oral streptococci, and colonies that grew on the M-S agar were Gram stained.

Results: Twenty-eight of the 50 test plates (56%) exhibited growth of bacterial colonies on blood agar. The rate of contamination of PSP plates were on the rise after each day of clinical use. Of the seventeen bacterial colonies selected for growth on M-S agar, 13 (76.47%) showed growth. Of these 13, 9/13 (69%) were gram positive. The control PSP plates gave no colonies.

Conclusion: Our results indicate the manufacturer's infection control procedures alone do not insure uncontaminated PSP plates in clinical uses. Reinforcing standard precautions of infection control for intra oral radiography as well as gas sterilization of plates after each day's clinical use is a potential solution.


0778 (119662)

In-vitro investigation of pH-lowering potential of probiotic and cariogenic lactobacilli. R. SCHILKE, M. REICHELT, F.B. FELGENHAUER, G. LEYHAUSEN, J. VOLK, and W. GEURTSEN, Medical University of Hannover, Hannover, Germany

Objective: Various strains of lactobacilli are used as probiotic additives in food and drugs. Objective of this in-vitro study was to determine the pH-decrease in a liquid medium with different lactobacilli and carbohydrates. Results of well-known cariogenic species were compared to the probiotic strains. Methods: The type strains Lactobacillus casei (DSMZ 20011) and Lactobacillus fermentum (DSMZ 20052) as well as the probiotic strains Lactobacillus paracasei subsp. paracasei (DSMZ 20312) and Lactobacillus rhamnosus GG (isolated from InfectoDiarrstop®LGG, Infectopharm, Heppenheim/Germany) were incubated in a modified de Man-Rogosa-Sharpe broth (1x107 vital bacteria/ml, 37 °C, 5% CO2). Equimolar amounts of the monosaccharides fructose or glucose (20 g·l-1) and semi-equimolar amounts of the disaccharides lactose or saccharose were added to the media. Inital pH was adjusted at 5.7. Optical density the correlate for growth rate and the pH-decrease was read continuously over 24 and 36 h, respectively. Each experiment was reproduced twice. Results were analysed using ANOVA. Results: Except of L. fermentum, which metabolised all carbohydrates nearly to the same pH, monosaccharides led to higher growth rates than disaccharides. The pH dropped markedly below 5.2 in both monosaccharide solutions with each strain of lactobacillus at least after 8 h. After 24 h pH-values varied as follows: 4.30 - 3.34 in fructose, 3.84 - 3.34 in glucose, 5.63 - 3.80 in lactose, and 5.51 - 3.91 in saccharose solutions. The lowest pH was observed with the combination L. rhamnosus GG – lactose (DpH=0.07), the highest with L. rhamosus GG – fructose and L. paracasei subsp. paracasei – glucose (DpH=2.36). Conclusions: The investigated probiotic strains were able to decrease the pH significantly in the presence of monosaccharides, whereas disaccharides resulted only in slight pH-changes. In case of retention of these lactobacilli in the oral cavity, not only the interaction with other cells but also their cariogenic potential must be considered.


0779 (119717)

Chemical analysis of black stain on deciduous teeth. P. PUTZER1, F.B. FELGENHAUER1, W. GEURTSEN1, K. BECHSTEIN2, C. VOGT2, and R. SCHILKE1, 1Medical University of Hannover, Hannover, Germany, 2Leibniz University Hannover, Hannover, Germany

Objectives: Dental literature indicates that the dark discoloration (black stain = bs) of deciduous teeth is caused by ferric sulfide or chromogen bacteria in a paramarginal biofilm. The hypothesis to be tested was that iron content is not sufficient to stain the deposit black.

Methods: Specimens (n=8) of human bs deposits were scraped off tooth surfaces and analyzed with an energy dispersive X-ray/scanning electron microscope (EDX/SEM) to characterize its composition. Exfoliated deciduous teeth with bs (n=6) were examined by X-ray microfluorescence (µ-XRF) to get more detailed data of the iron content and various other elements. Furthermore, two samples (n=2) were studied by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to determine the exact content of iron. These served as controls. In addition mixtures of FeS/FeSx (0.16%; 1.6%; 16% (w/w)) with synthetic hydroxyapatite/bovine serum albumin, and human calculus/bovine serum albumin were prepared to analyze the beginning of a dark coloration of the material.

Results: The iron content found with EDX/SEM was lower than 0.2% (w/w), whereas the cumulative mean (±SD) of C and N was 60.3% (w/w) (±7.3%). The largest mineral fraction consisted of Ca, P, and K with 13.4% (w/w) (±4.8%). The µ-XRF bs deposits revealed no increased Fe, Zn or Cu concentration, contrary to C, N, S, K, Ca, Na and Mg. LA-ICP-MS analysis revealed an iron concentration below 100 ppm in both samples. Mixtures of FeS/FeSx with inorganic and organic substances showed a barely visible discoloration up to a concentration of 16% (w/w) which resulted in a light grey color in both mixtures.

Conclusions: The iron content in bs is to low to darken the deposit. Therefore iron is not responsible for the dark color of bs. It may be speculated that bs deposits are associated to the metabolism of microorganisms after the formation of a biofilm.

 


0780 (119798)

Bacterial diversity of primary endodontic infections by 16SrRNA analysis. A.C. RIBEIRO, Institute of Biomedical Sciences - University of São Paulo, São Paulo, Brazil, M. FAVERI, Guarulhos University, Guarulhos - SP, Brazil, D.M. ZEZELL, Center for Lasers and Applications IPEN - CNEN / SP, Sao Paulo, Brazil, and M.P.A. MAYER, Institute of Biomedical Sciences - University of São Paulo, Sao Paulo, Brazil

Objectives: The purpose of this study was to investigate the bacterial diversity of root canal infections by using culture-independent molecular methods based on 16S ribosomal RNA cloning. Methods:Samples were collected from asymptomatic root canals of twelve teeth with primary endodontic infection. Genomic DNA was isolated and 16SrRNA amplified by PCR with universal primers. Amplicons were cloned using TOPO TA Cloning Kit and transformed into electrocompetent E.coli cells. The insert DNA was sequenced using ABI Prism BigDye terminator cycle sequencing. The 500 base-pair sequences were aligned and used for a BLAST sequence homology search against the GenBank database. The percentage similarity cut-off for species identification was set at 98%. Results: All samples were positive for Bacteria. 543 clones were sequenced (45.6±4.4 clones/sample). Three to 15 phylotypes were found per root canal sample. Sixty-one distinct bacterial taxa were identified, of which 31 (51%) are considered as-yet-uncultivated phylotypes. Most of the species belonged to the Firmicutes phyla. The most prevalent species were Eubacterium infirmum and Prevotella oris, which were identified in six and four of the twelve samples, respectively. Dialister invisus, Dialister pneumosintes, Pseudoramibacter alactolyticus were found each in four samples. The majority of the taxa were present in only one sample, such as Enterococcus faecalis, Streptococcus mutans, Lachnospiraceae oral clone BP1-14, Eubacterium oral clone A53MT and Parvimonas micra. Conclusion: The present study suggested a wide diversity of oral species associated with primary endodontic infections. Support FAPESP 2007/52492-3, 2006/59856-8.


0781 (119802)

Archaea In Aggressive Periodontitis And Healthy Subjects. F. MATARAZZO1, M. FAVERI2, A.C. RIBEIRO1, and M.P.A. MAYER1, 11. Institute of Biomedical Sciences , University of Sao Paulo, Sao Paulo, Brazil, 2Guarulhos University, Guarulhos - SP, Brazil

OBJECTIVE: To evaluate the prevalence and diversity of Archaea in subgingival samples of aggressive periodontitis and periodontally healthy subjects by clonal analysis of the archaeal 16S rRNA gene. METHODS: Twenty-tree aggressive periodontitis (AP) and 21 periodontally healthy (PH) subjects were selected. Detection of Archaea was performed by PCR in 9 subgingival biofilm samples per subject using domain-specific primers. Samples were collected in AP subjects from shallow, intermediate and deep probing depths sites. Diversity was evaluated in a single positive sample per subject, randomly selected from 9 diseased and 7 periodontally healthy subjects. PCR products were cloned, 25-50 clones/sample were sequenced and the phylotype was determined by comparing the data against the 16S rRNA sequence database. RESULTS: 396 samples were analyzed, 207 of AP group and 189 of PH group. Archaea was detected in 16 of 23 subjects with AP (69.5%) and in 20 of 21 healthy subjects (95.2%) (p<0.05). In AP subjects positive for Archaea, the domain was detected in forty-eight sites (29.8%), and there was no association between detection of Archaea and probing depth. The domain was detected in 116 sites (64.4%) of healthy subjects harboring Archaea. One to three phylotypes of Archaea were identified in samples from both groups. Methanobrevibacter oralis was identified in all positive samples, and was the only detected Archaea in 6 of 9 AP subjects, and in 3 of 7 PH samples. Methanobacterium congolense/curvum and Methanosarcina mazeii were identified in 8 and 7 of the 16 studied subjects, respectively.

CONCLUSION: The high prevalence in healthy subjects suggested the lack of association between detection of Archaea and disease. The domain exhibited very little diversity in subgingival sites, and Methanobrevibacter oralis was the most prevalent species of the Archaea domain both in healthy and aggressive periodontitis subjects. Grants FAPESP 2006/52890-6; 2007/56509-8.


0782 (119885)

In Vitro Inhibition of Oral Bacteria Growth by Novel Product. A.K. BURWELL1, A. GIBSON2, and G. LATORRE1, 1NovaMin Technology, Inc, Alachua, FL, 2Biofilm Limited, Blantyre, Scotland

OBJECTIVES:  The antibacterial activity of calcium sodium phosphosilicate (NovaMin®) has been repeatedly demonstrated in vitro and in vivo.  A novel resorbable polymer system has been designed to deliver NovaMin® directly onto tooth surfaces and adjacent gingival tissues.  The objective of this work was to assess the ability of this novel product to inhibit growth of oral bacteria associated with caries development and periodontal disease.

METHODS:  Aqueous solutions of 1.0% and 0.5% NovaMin® were prepared from hydroxypropyl methylcellulose polymer strips that contained 15% NovaMin®.  Six sets of 100%, 50%, and 25% serial dilutions were prepared from each solution.  5mL aliquots of each dilution were inoculated with 1 drop (approximately 0.02mL) of overnight cultures of Streptococcus mutans ATCC 25175, Streptococcus sanguinus ATCC 10556, and Staphylococcus aureus NCTC 10418Positive and negative controls were also prepared.  All test dilutions and controls were incubated overnight at 35°C and then streaked to tryptone soy agar plates.  The agar plates were then incubated at 35°C overnight and examined for growth.  Growth was classified as No Growth (-), Sparse Growth (+), Growth (++/+++), or Profuse Growth (++++) using the positive controls as a Profuse Growth benchmark for comparison.

 

RESULTS:    

 

  Organism

  100%

  Dilution

  50%

  Dilution

  25%

  Dilution

    1.0%

    Solution

  Streptococcus mutans

     -

     -

    +

  Streptococcus sanguinus

     -

     -

    +

  Staphylococcus aureus

     -

     -

    -

    0.5%

    Solution

  Streptococcus mutans

     -

    +

    +

  Streptococcus sanguinus

     -

     -

    +

  Staphylococcus aureus

     -

     -

    +

At full (100%) strength the 1.0% and 0.5% solutions completely inhibited growth of all three bacteria.  Dilution of the solutions slightly diminished the inhibitory effect but no growth higher than Sparse (+) was observed.

 

CONCLUSIONS:  A novel resorbable polymer product containing NovaMin® has the potential to inhibit the growth of cariogenic and periodontal bacteria on tooth surfaces and adjacent gingival tissues.  The clinical implications of these results will need to be evaluated.

This research was financially supported by BioFilm Limited, UK


0784 (120474)

Effect of nicotine, cotinine and caffeine on biofilm in brackets. S.C. MOHAMED1, M.D.S. CARVALHAES1, A.D. FIGUEIREDO1, F.M. FLÓRIO1, J. RAMACCIATO1, R.H.L. MOTTA1, and F.C. GROPPO2, 1São Leopoldo Mandic Dental School, Campinas, Brazil, 2Piracicaba Dental School, University of Campinas, Piracicaba, Brazil

Objectives: The aim of this study was to analyze the influence of nicotine, caffeine and cotinine on the adherence of biofilm formed on orthodontic brackets.Methods: Bovine teeth were used to make the test specimens, to which the orthodontic brackets were fixed onto the tooth enamel. The test specimens were fixed in sterilized polystyrene tubes, and only the vestibular face of the tooth enamel with the bracket came into contact with the culture medium (BHI + 1% sucrose). The inoculum of 1.0 x 108 ufc/mL was placed in the tubes, which were incubated in triplicate for 18h at 37° C and 10% CO2. After this period, the culture mediums were exchanged for new mediums containing final concentrations of nicotine, cotinine and caffeine at the following concentrations:400ìg\ml, 100ìg\ml, 25ìg ml, 6.25ìg\ ml, 1.5ìg\ml and 0.325ìg\ml. In each battery of tests new solutions of both drugs were used: 7.5 ml culture medium, 0.5 ml substance and 80 uL in 8 mL. After 18 h of incubation under the same conditions, the brackets were sonicated in serum, submitted to spectrophotometric reading at 660nm and compared with the growth in the positive control tubes (serum+bacteria). Results: As with nicotine, the evaluated concentrations of cotinine and caffeine inhibited bacterial growth on the test specimens, even at the lower concentrations. However, the three evaluated solutions stimulated the growth of S. Salivarius. Conclusion: nicotine, cotinine and caffeine could have an influence on the biofilm induced on orthodontic brackets.


0785 (114993)

Methylene blue-loaded polymeric nanoparticles: Effect of serum on bacterial photodestruction. D.A. PAPAMANOU1, X. SONG1, H. YOUM2, C.B. PATEL1, L.K. YU1, N. PATEL3, M.M. AMIJI4, and N.S. SOUKOS1, 1Forsyth Institute, Boston, MA, 2Harvard School of Dental Medicine, Boston, MA, 3School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, 4Northeastern University, Boston, MA

Objectives: To investigate the effect of serum proteins on the photodynamic activity of biodegradable and biocompatible polymeric nanoparticles loaded with the photosensitizer methylene blue (MB) against Enterococcus faecalis. Methods: (MB)-encapsulated nanoparticles of poly(lactic-co-glycolic acid) (PLGA) with negative and positive surface charge were prepared and characterized. E. faecalis species were sensitized in planktonic phase with MB-loaded PLGA nanoparticles (final concentration: 12.5 ìg/ml equivalent to MB) for 15 minutes followed by exposure to red light at 665 nm with an irradiance of 100 mW/cm2 and energy fluence of 30 J/cm2 in the presence of brain heart infusion (BHI) broth or phosphate buffered saline (PBS). After photodynamic therapy, all samples were serially diluted, cultured on blood agar plates and survival fractions were calculated by counting colony-forming units (CFU). Results: In the presence of light, the cationic MB-loaded nanoparticles produced 80% and 90% bacterial killing when dissolved in BHI broth and PBS, respectively. The anionic MB-loaded nanoparticles eliminated microorganisms by 13% in BHI broth and 72% in PBS. Conclusions: The photodynamic effects of MB-loaded PLGA nanoparticles on E. faecalic species were probably reduced by the presence of serum proteins in BHI broth. Supported by NIDCR grant RO1-DE-16922.


0787 (117509)

Rapid Method for Detecting/Estimating Dissolved Oral Thiols. A. BURGESS-CASSLER, QuantRx Biomedical Corporation, Portland, OR, and M. LEESMAN, ALT BioScience, Lexington, KY

Objectives: Oral halitosis and periodontal diseases very often involve the microbial production of Volatile Sulfur Compounds (VSCs), primarily hydrogen sulfide and methyl mercaptan. Historically, efforts have focused on detecting their presence in exhaled breath, rather than within microbial biofilms. Our objective was to develop test strips targeting dissolved thiols, which provide rapid, visual results, are easy to use, and are non-irritating to oral tissues.

Methods: We screened various materials for their ability to provide visually discernable responses to dissolved thiols, after pretreatment with a thiol detector compound. The propensity of the dried detection reagent to leach from the pad was estimated spectrophotometrically, by challenging rinse-fluid with added thiol. Prototype test strips were placed into a stability study in order to estimate shelf life. Irritancy testing was performed by an independent lab. Finally, we varied the [detection reagent], to determine if different ‘cut-off' result colorations could be achieved.

Results: A porous pad material was identified, which had good physical characteristics and was compatible with the thiol detection reagent and its chromogenic product. Once dried onto the pad, the reagent showed a low propensity to leach upon rehydration, maintained good spectral responses, and showed reasonable stability over time. Pad treatment reagent was found to be non-irritating to cultured gingival tissue cells, when compared to standard oral care products. Finally, by raising or lowering the reagent concentration (amount of detector in the pad), we found we could manipulate the plateau coloration of the test.

Conclusions: Our results suggest test strips employing this technology might be useful as aids in detecting causative agents of halitosis and periodontal diseases.


0788 (118039)

Use of HealOzone for Additional Disinfection of the Root Canals. B. JANKOVIC, V. NEGOVETIC MANDIC, D. MATOSEVIC, A. KNEZEVIC, V. PANDURIC, Z. TARLE, and K. PRSKALO, School of Dental Medicine, University of Zagreb, Zagreb, Croatia

Objective: This in vivo study tried to determine whether additional disinfection of the root canal with ozone after classic chemomechanic treatment produces further decrease in the number of root canal colonies.

Methods: The study encompassed 44 randomly chosen patients with visible chronical periapical lesion determined by Rtg. For each sample, three swabs were taken for microbiological analysis. Sterilized paper points were used for swab taking and then placed in WMGA transport media for anaerobs. The first swab was taken before root canal instrumentation, and then standard hand instrumentation was performed up to a number 30 file with 2,5% sodium hypochlorite irrigation. After completed instrumentation, the second swab was taken and root canal was additionally treated with HealOzone for 40 sec. Finally, the third swab was taken and microbiological analysis of obtained samples was performed. Information was statistically processed with SPSS computer program.

Results: Distributions of all original variables were statisticaly significantly different from the normal distribution. Monte Carlo statistical significance of Kolmogorov-Smirnov one sample test varied from <0.001 up to 0.023. Therefore non parametric Friedman and Wilcoxon tests were used for the assessment of differences in median number of bacteria remained after the therapy and after the additional treatment with ozone.

Decrease in number of bacteria after the additional treatment with ozone were highly statistically significant: Z=-4.6, p<0.001 for aerobic, and Z=-4.5, p<0.001 for anaerobic bacteria. Median number of aerobic bacteria was decreased from 11.5 to 1.5 (median decrease of 87%) after the additional treatment with ozone. Median number of anaerobic bacteria was decreased from 5.0 to 0.5 (median decrease of 82%).

Conclusion: Since after standard hand instrumentation certain number of bacterial colonies always remain, HealOzone can be used for additional root canals disinfection.

The study was supported by grant 065-0352851-0410 of MZOS, Croatia


0791 (115220)

Methicillin Resistant Staphylococcus aureus Present on Dental Student Laptop Computers. R. DUNLOP, University of Indiana - Indianapolis, Indianapolis, IN, C. PALENIK, Indiana University School of Dentistry, Indianapolis, IN, and M. KOWOLIK, University of Indiana Indianapolis, Indianapolis, IN

Objective: This study evaluated the number of multiple drug resistant Staphylococcus aureus (MRSA) isolates present on dental student laptops before and after disinfection.

Methods: Fourth Year Dental Students participated voluntarily. All information collected remained confidential (IRB 07-9-64). There were two microbial samplings – prior to disinfection and then after disinfection. Three cotton swabs moistened with PBS (0.85 M, pH 7.2) sampled the entire top surface of each laptop. The swabs went into 2.0 mL of PBS and then vortexed. Spiral plating of specimens onto two enriched trypticase soy agar (ETSA) plates and a mannitol salt agar (MSA) plate followed. Incubation was at 37˚C for 48 hours. One ETSA and the MSA plate were incubated aerobically, the other ETSA plate underwent anaerobic incubation. Then, all colony types underwent sub-culturing in trypticase soy broth with 0.25% (w/v) glucose. Aerobic incubation was at 37˚C for 48 hours. Spread plating of 0.1 mL specimens involved four types of media – MSA, cefotamine screening test (ETSA with antibiotic discs), oxacillin resistance screening agar and BBL CHROMagar (selective and differentiating for MRSA). Aerobic incubation was at 35˚C for 48 hours. After the initial sampling, three weekly disinfection processes occurred. Sampling of the laptops was the same as just described.

Results: Forty-two laptops completed all phases of the study. Specimens from pre-cleaned laptops produced 148 isolates of which 41 were S. aureus. Seven laptops yielded eleven MRSA isolates of which eight were also cefotamine resistant. Sampling after disinfection produced 114 isolates of which 49 were S. aureus. Six laptops produced eight MRSA isolates of which five were also cefotamine resistant.

Conclusion: Overall, 14.3% of all laptops evaluated produced drug resistant S. aureus isolates. Three weekly disinfection procedures did not reduce the number of drug resistant isolates present.

Partial funding of this study was from the ICR-Student Research Fellowship.


0792 (116004)

Monitoring microbial contamination on namecard-holders to prevent nosocomial infections. A. WATANABE, N. SATOH, N. TAMAKI, I. TANIMOTO, H. MAEDA, S. TAKASHIBA, and S. KOKEGUCHI, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan

Objectives: Aerosols and splatters contaminated with bacteria are produced during dental treatments and may spread microbial infections to patients and dental staff in the dental clinic. This study monitored the level and type of microbial contamination present on namecard-holders (NCHs) usually attached at the breast on dentist's white coats, in order to assess the risk of transmitting nosocomial microorganisms during dental treatments.

Methods: Sterile swab samples were obtained from plastic NCHs used for one year (n=50; polycarbonate, 7x9cm) and from new NCHs (n=3). Bacterial contaminations on NCHs were analyzed by molecular biological techniques. Bacterial 16S rDNAs isolated from NCHs were amplified by PCR and cloned into Escherichia coli and after each 16S rDNA was sequenced. Selected antibiotic-resistant genes, mecA, blaIMP,blaVIM, vanA and vanB in nosocomial pathogens were identified by PCR. The nucA specific for Staphylococcus aureus was also determined by PCR.

Results: Bacterial contamination and accumulation of potentially pathogenic microorganisms on NCHs were approximately 10-fold greater than those on new NCHs based on the patterns of PCR-amplified bands. However, blaIMP, blaVIM, vanA and vanB were not detected on any NCH tested. There were 3 nucA-positive and 4 mecA-positive findings on different NCHs. These resistant forms suggested the presence of S. aureus and methicillin-resistant coagulase-negative Staphylococci causing nosocomial infections. On 16S rDNA sequence analysis, oral Streptococci, Prevotella, Atopobium and Veillonella species of apparently human origin were identified as the most dominant bacteria contaminating NCHs. Soil and environmental bacteria, Geobacillus, Delftia, Agrobacterium, Xanthobacter, Mesorhizobium species were identified as contaminants of new NHCs.

Conclusions: NCHs of dentists may also serve as reservoirs for the transmission of microorganisms, similar to doctor's neckties and pens. Conventional PCR for the specific bacterial gene and antibiotic-resistant genes on NCHs may be available for rapid monitoring of nosocomial infection in dental clinics.


0793 (115202)

DUWLs Treated with Sterisil Silver Ion Based Products. W. ZHANG, R.N. KHOIE, O.A. MOHAMED, T.J. WILKENS, E.K.W. TSENG, and Y. LI, Loma Linda University, Loma Linda, CA

Objective:  To investigate the efficacy of Sterisil silver ion based products in controlling heterotrophic bacteria of dental unit waterlines (DUWLs) in multiple dental offices over four-year period.  Material and Methods:  The four silver ion based products tested were manufactured by Sterisil Inc. (Palmer Lake, CO) for controlling microbial contamination of DUWLs: PureTube and Citrisil tablets were designed for bottle systems; PureTube Plus for municipal water; and PureLine for multiple dental units.  A total of 264 samples of DUWLs were collected from 28 dental offices.  The standard method 9215D of the American Public Health Association was used for determining the heterotrophic plate count (HPC) by using the membrane filtration technique, R2A agar and incubation for seven days at 22oC.  Results:  Among the 54 samples treated with PureTube, 98.1% met the CDC guidelines of ≤500 CFU/mL.  For the samples treated with PureTube Plus, 52 of 53 had ≤100 CFU/mL; only one exceeded 500 CFU/mL and required an additional shock treatment.  The PureLine and Citrisil tablet group contained 117 and 40 samples, respectively; both products eradicated 100% of HPC.

Treatment

N

Heterotrophic Plate Counts (CFU/mL)

% Pass Rates (<500)

≤10

10 - ≤100

100 - ≤500

>500

PureTube

54

45

8

2

1

98.1%

PureTube Plus

53

46

6

0

1

98.1%

PureLine

117

115

2

0

0

100.0%

Citrisil tablet

40

36

4

0

0

100.0%

Total samples

264

242

20

2

2

99.2%

% of Total

 

91.7%

7.6%

0.8%

0.8%

 

Conclusions:  The data demonstrate that all four Sterisil's products perform equally well, exceeding the standards established by the CDC and ADA for dental water quality.  To maximize the benefits of silver based products, adequate shock treatment is essential to control existing biofilm in DUWLs. Partially supported by Sterisil Inc.


0794 (115466)

Low Electric Current Enhancement of a Dental Unit Waterline Cleaner. M.R. WIRTHLIN1, N. LIU1, A. GUNSTREAM2, and C.I. HOOVER1, 1School of Dentistry, University of California - San Francisco, San Francisco, CA, 2School of Dentistry, University of California - San Francisco, San Francisco

Objective: Evaluate, by bacterial culture, the effect of low amperage current on ClO2 control of planktonic effluent and biofilm in a simulated dental unit waterline (DUWL). Methods: The 15' reservoir-to-air-water-syringe distance of a DUWL was simulated by three 5' sections of 1/8" polyurethane tubing joined by barb fittings. One length containing 0.2mm diameter platinum wire and a parallel length without wire (control) were connected via Y-fitting to a peristaltic pump and a 10L carboy of sterilized water. During experiments the pump was run 5min every half-hour, 9AM-5PM, 5 days-a-week. The water was inoculated with Pseudomonas aeruginosa (104CFU/ml) and the system run until there was a steady state of effluent bacterial counts. The system was then supplied with sterile water or a 1/10 dilution of 0.1% stabilized ClO2 (MicroClear, Rowpar Pharmaceuticals Inc.). An electric potential (15V DC, 10mA) was applied to the wire as cathode or anode with opposite polarity at barb fittings. Effluent was sampled every other day, serially diluted, spread in triplicate on Pseudomonas-selective agar, and incubated aerobically (22°C, 48h). Colony counts were converted to colony-forming units (CFU)/ml. After trials, biofilm formation was determined by culture of 2.1cm sections of tubing, as described above, and expressed as CFU/cm2. Mean±S.D. counts were compared by t tests. Results: Effluent counts of water with or without current did not significantly differ, however biofilm counts near barb anode were 3.7x101±0.03x101 CFU/cm2 with current and 2.0x104±9.5x103 CFU/cm2 without (P≤0.02). Over 4 weeks, with ClO2 and wire as cathode or anode, effluent counts were usually zero, whereas counts from samples without current were statistically greater. Biofilm counts near barb cathode or anode were zero, whereas without current counts ranged from 5.3x101± 3.2x101 to 5.8x102±2.0x102 (P≤0.05). Conclusion: A 10mA current significantly enhanced efficacy of a buffer stabilized ClO2 waterline cleaner against planktonic bacteria and biofilm.


0795 (115828)

Respiratory pathogens in the oral cavity of hospitalized patients. D. ZUANAZZI1, M.B.A. MATTOS1, R. SOUTO1, M.R. ZUANAZZI1, B.R. TURA2, C. SANSONE1, and A.P.V. COLOMBO1, 1Federal University of Rio de Janeiro, Rio de Janeiro, Brazil, 2National Institute of Cardiology, Rio de Janeiro, Brazil

Objective: The purpose of this investigation was to determine the prevalence of specific nosocomial respiratory pathogens including Acinetobacter ssp., Dialister pneumosintes, Pseudomonas spp., and Staphylococcus spp. with or without the mecA resistance gene in the oral cavity of hospitalized patients. Methods: The target population included 30 hospitalized patients (mean age 63.5±1.7 years; 77% males; 13 edentulous and 17 dentate) undergoing myocardial revasculation. Periodontal clinical assessment was performed at 6 sites per tooth in the dentate subjects. Saliva was collected from all subjects, whereas supra- and subgingival biofilm samples were obtained from 4-6 periodontal sites of each dentate subject, before orotracheal intubation and after extubation. DNA was extracted from samples, and the bacterial species and mecA gene were detected by PCR. Additionally, samples were cultivated in selective media for identification of Staphylococcus spp. Statistical differences between or within groups pre- and post-surgery were sought by Mann-Whitney and Fisher's Exact, or Wilcoxon sign tests, respectively. Results: The prevalence of the bacterial species in saliva in both groups was: Pseudomonas spp. (83.3%), Staphylococcus spp. (81.5%), Acinetobacter spp. (63.6%), D. pneumosintes (33.3%), and Pseudomonas aeruginosa (16.7%). A higher frequency of D. pneumosintes was observed in dentate (41.2%) than edentulous (23.1%) patients (p<0.05). In plaque samples, dentate subjects with >14 teeth showed a higher mean prevalence of Pseudomonas spp. (100%) compared to individuals with ≤14 teeth (69.1±12%; p=0.048). Approximately 13% of all staphylococci isolates were positive for mecA. After extubation, P. aeruginosa tended to decrease in prevalence in all samples; however, no significant changes were observed for this or the other bacteria. Conclusion: The oral cavity of edentulous or dentate individuals demonstrated to be a reservoir for pathogens associated with nosocomial respiratory infections, particularly Pseudomonas spp. Supported in part by FAPERJ, UFRJ, CNPq, Brazil. FAPERJ, UFRJ, CNPq, Brazil.


0796 (116378)

Sampling Methods for Evaluating Microbial Contamination of Oral Devices. R.S. CONRAD1, R.T. GLASS1, J.W. BULLARD1, and J.A. VON FRAUNHOFER2, 1Oklahoma State University - Center for Health Sciences, Tulsa, OK, 2University of Maryland, Baltimore, MD

Objectives: Due to the absence of existing protocols, the purpose of this study was to develop laboratory procedures for the isolation and identification of the microorganisms found on the surfaces and in the depths of oral devices such as dentures and protective athletic mouth-guards (PAM). Methods: Sterile end-cutting nippers were used to section dentures and PAM. Surfaces and depths of the sectioned material were touched three times to blood agar plates (BAP), chocolate agar (CA), and Sabaroud dextrose agar (Sab). All media were incubated at 37°C for 24 hours. Colony forming units (CFU) were enumerated by serial dilution of previously weighed oral device material, minced by either sterile nippers (dentures) or sterile razor blades (PAM) and vortexed in known volumes of sterile water. Media demonstrating microbial growth were scored by three independent investigators using a previously validated microbial intensity scale (0 to 4). Results: Microorganisms were isolated and identified by using pure culture techniques, selective and deferential media, physiological tests, and molecular biochemical techniques. Standard laboratory procedures and sterile techniques were observed for all procedures throughout these studies. The potential danger of fracturing oral devices required strict observation of safety precautions for all procedures. Conclusion: These techniques have been used successfully to isolate and quantify a wide spectrum of aerobic and facultative bacteria, yeasts, molds, mycoplasma, and amoebae from a variety of oral devices and can be used in a glove box for the isolation of strict anaerobes. Companion studies of the surfaces, porosities, and biofilms of these oral devices by electron microscopy were consistent with the biological findings.


0797 (118205)

Clinical effectiveness of photodynamic therapy on the disinfection of dentures. D.G. RIBEIRO1, A.C. PAVARINA1, L.N. DOVIGO1, E.G.O. MIMA1, C.E. VERGANI1, and V.S. BAGNATO2, 1Araraquara Dental School, Sao Paulo State University-UNESP, Araraquara, Brazil, 2São Paulo University - USP/IFSC, São Carlos, Brazil

Objectives: This study evaluated the effectiveness of photodynamic therapy (PDT) on the disinfection of complete dentures. Methods: Biofilm samples were collected from dentures of 30 patients, which were divided into two experimental groups (n=15/gp): Group 1- patients had their maxillary denture sprayed with 50mg/L of Photogem®; Group 2- patients had their maxillary denture sprayed with 100mg/L of Photogem®. After 30min of pre-irradiation, all dentures were exposure to blue LED light at 37.5J/cm2 (26min). Denture samples were taken with sterile cotton swab, before (left side surfaces) and after (right side surfaces) PDT. All microbial material was diluted (10-1 to 10-3) and plated (25μL) on selective media for Candida spp. (CHROMagar), Staphylococcus spp. (Manitol Salt Agar), mutans streptococci (SB20) and a non-selective media (Mueller Hinton). After incubation (48h/37ºC), the number of colony-forming units (cfu/mL) was counted. Microorganisms which grew on selective media were identified using biochemical methods before and after PDT. The data were submitted to Kruskal-Wallis and Dunn tests (p<.05). Results: PDT with 100mg/L (Group 2) sterilized 60% of dentures. In addition, the disinfected dentures showed reduced cfu/mL values of Candida spp. (p=0.0035), Staphylococcus spp. (p=0.0214), mutans streptococci (p=0.0003) and non-identified species (p<0.0001) compared to cfu/mL observed before PDT. For Group 2, the identified species were Candida albicans, Candida glabrata, Candida tropicalis, Staphylococcus aureus and Streptococcus mutans. In Group 1, the results showed that 40% of dentures were sterilized with 50mg/L. PDT also promoted significant reduction in cfu/mL of Candida spp. (p=0.0003), Staphylococcus spp. (p=0.0075), mutans streptococci (p=0.0012) and non-identified species (p<0.0001) compared to cfu/mL obtained before PDT. For Group 1, the colonies grown after PDT were identified as Candida albicans, Staphylococcus aureus and Streptococcus mutans. Conclusions: PDT demonstrated to be an alternative procedure to disinfect dentures from patients. The use of 100mg/L was more effective in sterilizing dentures.

Grant: FAPESP2005/02192-8


0798 (118226)

The Effect of Delmopinol on Acid Adaptation by Dental Plaque. T. SJÖDIN1, U. TROEDSSON2, and G. SVENSÄTER2, 1Sinclair Pharma AB, Askim, Sweden, 2Malmö University, Faculty of Odontology, Dep. of Oral Biology, Malmö, Sweden

Introduction:

Under acidic conditions some bacterial species, e.g. S. mutans, can alter their physiology and induce an acid tolerance response (ATR) in order to survive the low pH that arises in dental plaque biofilms when carbohydrates are metabolised. It has been reported that this induction can be prevented by the presence of fluoride during the adaptation phase, and this study was performed to evaluate if similar effects will be obtained with delmopinol and combinations of delmopinol and fluoride.

Methods:

Monocultures (S. mutans) and pooled human plaque samples were tested in two flow cell models. Studies on the effect of delmopinol on ATR development were performed in flow cells consisting of two parallel glass slides separated by rubber spaces. In studies aimed to evaluate the combined effect of delmopinol and fluoride the Ibidi micro-flow cell system was used. The samples were subjected to different acid adaptive tests and bacterial viability was assessed by fluorescence microscopy using the LIVE/DEAD BacLight viability kit.

Results:

It was found that delmopinol at sublethal concentrations inhibits development of ATR in biofilms of S. mutans and that delmopinol and fluoride do not interfere with respect to their inhibition of ATR development. Instead their action seems to be additive and the inhibitory effect was obtained at very low concentrations of the compounds. This was true for both the mutans as well as the plaque sample biofilms.

Conclusions:

·Delmopinol strongly affects the ability of Streptococcus mutans and plaque bacteria to adapt to acidic conditions.

·The action of delmopinol and fluoride is additive and the ATR-inhibitory effect is obtained at low doses of the compounds.

·This study suggests that a combination of delmopinol and fluoride should be valuable for caries prevention.


0799 (120111)

Fomite Potential of Toys in Pediatric Dental Office Waiting Areas. L.A. TROTTER, K.R. VOLKMANN, G.S. SCHUSTER, T. SCHAFER, F. RUEGGEBERG, R. MESSER, J. LEWIS, and A. PATEL, Medical College of Georgia, Augusta, GA

OBJECTIVE: The goal of this study was to evaluate the microbial growth on hard and soft toys in pediatric dental office waiting areas to better assess the potential role of fomites in the transmission of disease.

METHODS: Over a period of 14 months, 63 fomites were tested from two different pediatric dental offices. Forty-nine fomites from the MCG pediatric dental clinic and fourteen fomites from a private practice pediatric dental office were evaluated. The toys were tested initially as found in the offices, then disinfected with 10% sodium hypochlorite and retested. Finally the toys were replaced into the offices for 7 days of child contact and retested once again. Bacterial and fungal colonies were quantified on blood and nutrient agar plates.

RESULTS: The initial swabbed samples resulted in the most numerous bacterial and fungal colonies in both offices. There was a significant decrease (97.2%) in the number of colonies after disinfection of the toys and in some cases, no colonies were noted. After retesting, there was a return of bacterial and fungal colonies (69.4 % of baseline); however, there were not as many as observed initially. Overall, toys tested from the MCG clinic yielded more microbial colonies than those from the private practice dental office. In all cases, soft toys yielded more colonies than hard toys, especially fungal colonies. There were some α- and β-hemolytic colonies noted, primarily from soft toys.

CONCLUSIONS: These results support our hypothesis that soft toys serve a more significant role as fomites than hard toys, and disinfection of the toys is effective in decreasing microbial load.


0800 (120982)

Occupational Accidents: Experiences of Brazilian Dental Students. W.W. NASCIMENTO PADILHA, and A.A. LIMA, Universidade Federal Da Paraiba, João Pessoa, Brazil

Objectives: This study aimed to verify the occurrence of work accidents in graduation students of the Federal University of Paraiba (UFPB) and to analyze their knowledge about how to proceed in these cases. Methods: An inductive approach was used, with statistical-descriptive procedure and extensive direct observation technique, by means of a questionnaire. A sample of 168 (83.58%) dentistry students of the UFPB, 5º to 10º period, was obtained. Results: It can be observed: 100 (59.52%) students referred to already have suffered occupational accident (OC), most of them was male gender (62.07%) and of the last three semesters (72,13%). The superficial accidents were cited by 84 students and the percutaneous by 33; the main causes of accidents were distraction (24.23%) and rush (18.94%). The anesthesia needle (19.39%), the nº5 exploratory probe (16.35%), the operative dentistry (28.49%) and surgery (25.14%) were the most cited instruments and clinics, respectively. Of the accidents before the treatment 60% were during the washing. The incomplete use of the Individual Protection Equipment was observed in 80 (80.23%) that suffered accidents, and the complete use in 73.53% of the ones that never suffered accidents. Thirteen (13.12%) visited a specialized center in occupational accidents. Of the students that obtained previous knowledge about how to proceed in accidents 90 (56.57%), 38 (22.62%) answered correctly. Only 110 (65.48%) and 37 (22.02%) students possess complete immunization for hepatitis B and tetanus, respectively. Conclusions: It can be concluded that the experience with occupational accidents increases as the semesters evolve. The critical points found were: negligence in the post-accident conducts, washing of the instrumentals, absence of rubber gloves and complete immunization.


0801 (121150)

2.5% NaOCl- 2% CHX-gel x LPS/ Bacteria in root canals. F. MARTINHO, M. VIANNA, E. PINHEIRO, and B.P.F.A. GOMES, Piracicaba Dental School- State University of Campinas, Piracicaba, Brazil

Endotoxins liberated by Gram-negative bacteria represent one of the main etiologic agents involved in the pathogenesis and perpetuation of periapical inflammation. Because of their high toxicity, their removal/ neutralization during endodontic treatment is important for the healing process of the periapical lesion. Objective: The aim of this work was to evaluate the efficacy of the chemomechanical preparation (CMP) with 2.5% sodium hypochlorite (NaOCl) and 2% chlorhexidine gel (CHX-gel) in reducing bacterial load and LPS from infected root canals. Methods: Thirty-eight root canals from single root teeth, asymptomatic, with pulp necrosis and periapical lesions were selected. A total of 76 samples were recovered from the infected root canals at different sampling times: before (s1) (n=38) and after CMP (s2) (n=38) with 2.5% NaOCl (n=19) and 2% CHX-gel (n=19). Strict anaerobe techniques were used to cultivate as many microorganisms as possible. A quantitative chromogenic Limulus Amebocyte Lysate assay (QLC-1000) was used to determine the amount of LPS. Results: At s1, bacteria (mean: 2.8 x 105 CFU/mL) and LPS (mean: 239.81 EU/mL) were recovered from 100% of the root canals sampled. The CMP with 2.5% NaOCl and 2% CHX-gel were effective in reducing the initial amount of bacteria in 99.78% (mean: 3.6 x 102 CFU/mL) and 99.97% (1.0 x 102 CFU/mL) respectively (p<0.05). At s2, LPS were detected in 100% of the root canals samples. CMP with 2.5% NaOCl and 2% CHX-gel were able to reduce a mean percentual value of 68% (from 228 to 67 EU/mL) and 73% (154 – 47 EU/mL) of the total initial amount of LPS found in root canals at s1 (p<0.05). Conclusion: Our findings indicated that CMP with either 2.5% NaOCl or 2% CHX-gel was moderately effective against bacteria but less effective against LPS in root canal infection.(Supported by FAPESP (05/55695-7, 07/58518-4, 08/06162-4) & CNPq (304282/2003-0, 305437/2006-2)


0802 (116297)

Simulated Microbe Removal around Finger Rings Using Four Sanitation Methods. A.A. ALUR1, M.J. RANE2, T.G. MAYFIELD3, J.P. SCHEETZ3, and L. GETTLEMAN3, 1Ballard High School, Louisville, KY, 2University of Louisville, School of Medicine, Louisville, KY, 3University of Louisville, School of Dentistry, Louisville, KY

Objective: Cross-contamination under examination gloves while wearing jewelry, such as finger rings, has been underestimated by the CDC and the WHO, who only "recommend" removing jewelry, and only washing hands for fifteen seconds with soap and warm water. A fluorescent powder like GloGerm™ glows in UV light and can simulate where germs accumulate, especially in areas difficult to clean. This study examined finger rings and several washing procedures with simulated microbes.

Methods: A gloved rubber hand was made and four fingers fitted with rings (loose, snug, tight, and with stone setting) or no ring, dusted with simulated microbes, and washed with a scrub brush for 5, 15, and 25 seconds under 20°C and 40°C water alone, or with liquid hand soap. Light levels (in lux) of fluorescent powder before and after washing were measured. An alcohol-based hand sanitizer alone was used as a control. Univariate 2-way ANOVAR with Tukey's HSD of before-and-after differences was done of 3 replicates of both sides of the hand (n=72).

Results: Longer rinses were more effective than shorter rinses (p=0.001), 40°C water was more effective than 20°C (p=0.001), and soap was more effective than water alone except at 5 seconds. All methods were equally effective by 25 seconds. Loose and perforated rings accumulated more simulated microbes which were easily rinsed away. Alcohol-based hand sanitizer showed no change because simulated microbes were only redistributed.

Conclusions: The most effective treatment was washing with warm water and liquid soap, except cold water alone at 5 seconds. Longer times were more effective. The palm was easier to clean than the back of the hand because of loose or perforated rings facing the back of the hand.


0803 (116664)

Bacterial Adhesion and Growth on Different Composite Materials. M. VIZZARDI, K. BERTELLI, L. MADINI, N. BARABANTI, C. BONFANTI, and A. CERUTTI, University of Brescia, Brescia, Italy

Objectives: The aim of this in vitro study is to assess and compare the bacterial adhesion on methacrylate-based and silorane-based filling materials, by means of a very sensitive and specific microbiological system based on Real-Time PCR.

Methods: One hundred disc-shaped specimens (6 mm in diameter, 2 mm in thickness) were made using five different dental restorative composite materials (Filtek Silorane and Filtek SupremeXT, 3M ESPE; CeramX Duo, Dentsply; Venus, Heraeus; Tetric EvoCeram, Ivoclar Vivadent). The samples were light cured with a halogen lamp (1000 mW/cm2 ) for 40 seconds in oxygen-free conditions below a glass slide device to prevent roughness, then sterilized by means of a UV-lamp.

Specimens for each material were divided in 5 groups, then incubated for 2, 4, 6, 24 and 48 h at 37 °C with Streptococcus mutans NCTC 10449 and processed to extract DNA from the bacteria adhered to the surfaces. Real-time PCR amplification was performed. Using a standard quantitative curve based on serial dilutions of a specific recombinant plasmid, the S. mutans concentration on each sample surface was calculated, considering a latency phase (2 to 4 h) and a growth phase (6 to 48 h).

The inter and intra group results were analysed with ANOVA statistic method.

Results: No significant difference was found in the overall performance of the tested materials after 48 h (p>0,05), with remarkable bacterial concentration on all samples. In the bacterial adhesion phase (2 to 4 h), Filtek Silorane showed the lowest grade of adhesivity (64,04%). In the 6 to 48 h time frame, Tetric EvoCeram showed the lowest S. Mutans percentual growth.

Conclusion: S. mutans may grow on all composite material surfaces. At the same time we observed that Filtek Silorane seems to prevent the initial bacterial adhesion compared to other composite materials.


0804 (116937)

Management of dental consulting rooms residues – self-evaluation of working conditions. G. VICTORELLI1, A.D.S. FONSECA SILVA1, F.L. CUNHA2, P.L.F.F. RONCAGLIA3, and F.M. FLÓRIO1, 1São Leopoldo Mandic Dentistry School, Campinas, Brazil, 2São Leopoldo Mandic Denstistry School, Campinas, Brazil, 3Municipality of Valinhos (São Paulo - Brazil), Campinas, Brazil

In Brazil, the management of health service residues is regulated by state and federal legislation that must establish adequate handling, with a view to preserving the environment and the health of workers and population in general. OBJECTIVE: The aim of this study was to analyze the procedures related to the management of dental resides in the municipality of Valinhos (São Paulo), which has a population of 94,124 inhabitants and 126 dentists. METHOD: The questionnaires were delivered by hand, in which information was sought about the type of professional occupation and about the strategies for managing residues generated by the health services. RESULTS: Of the professionals in the municipality, 30.7% participated in the study. After analyzing the data, it was verified that the sample was composed of dentists that were involved exclusively in private practice (42.5%), exclusively public service (30 %) or mixed (27.5%). It was verified that the use of garbage cans exclusively for infectant residues was equal to 91.7% (public service), 88.2% (private practice) and 81.8% (mixed activities), with the majority of the responses mentioning the ideal characteristic of the garbage cans (pedal operated) in 83.3; 70.6% and 72.7% respectively. Perforating/cutting materials were also shown to be correctly accommodated in boxes with rigid walls in 75.0%; 76.5% and 72.7% of the replies, and the remainder of the professionals discarded them inside plastic bottles. The majority of professionals discarded chemical products in the public sewerage system (50%; 70.6% and 63.6%). CONCLUSION: The majority of dentists correctly separate and accommodate their infectant residues, however, approximately 20% of these professions do not discard the residues correctly, by not separating infectant from common residues. Furthermore, the majority of professionals handle chemical residues inadequately (sewerage).


0805 (120511)

Novel chemotherapeutic-approach using natural molecules on biofilm and caries development. J.-G. JEON1, M.I. KLEIN2, J. XIAO2, S. GREGOIRE2, K. SCOTT-ANNE2, P.L. ROSALEN3, and H. KOO4, 1Chonbuk National University and Natural Product Research in Oral Biology group (NatPROB), Jeonju, Jeonbuk, South Korea, 2University of Rochester School of Medicine and Dentistry, Rochester, NY, 3FOP/UNICAMP and Natural Product Research in Oral Biology group (NatPROB), Piracicaba, Brazil, 4University of Rochester School of Medicine and Dentistry and Natural Product Research in Oral Biology group (NatPROB), Rochester, NY

The development of novel chemotherapeutic agents that disrupt the formation and virulence of dental biofilms is a promising route to prevent or reduce oral infectious diseases such as dental caries. Aims: The aim of the present study was to examine whether the association of bioactive natural molecules (myricetin and tt-farnesol) enhance the cariostatic properties of fluoride by acting cooperatively on the expression of virulence of Streptococcus mutans. Methods: The effects of topical application of combinations of 1 mM myricetin, 2.5 mM tt-farnesol and fluoride (125 or 250 ppm F) on S. mutans UA159 biofilm formation in vitro and development of caries in vivo were examined. The biofilms were subjected to biochemical, structural (laser scanning confocal fluorescence microscopy) and molecular (real-time PCR) analyses. Sprague-Dawley rats were infected with S. mutans UA159 and treated twice daily with the combinations of agents using our rat dental caries model. Results: The biofilms treated with combinations of agents displayed less biomass and acidogenicity, and fewer insoluble extracellular polysaccharides (EPS) than did those treated with fluoride alone or vehicle control (P<0.05). The spatial distribution and biovolume measurements of EPS-matrix and bacteria were also markedly affected by the combination of agents; the biovolume of EPS was significantly reduced when compared to fluoride alone or vehicle control (P<0.05). Furthermore, the agent combinations disrupted the pattern of gtfBCD, aguD and atpD expression by S. mutans biofilms. The development of dental caries was significantly reduced by the combination therapies in vivo (P<0.05). The combination of natural molecules with 125 ppm F was particularly effective, and the cariostatic properties were comparable with those observed with 250 ppm F (positive control). Conclusion: Results from these studies showed that combination of myricetin, tt-farnesol and fluoride is an alternative and effective anti-caries chemotherapeutic approach. (NIH/NIDCR DE016139, DE18023 and Chonbuk National University Overseas-Research Funds)


0806 (115507)

Validation of Questionnaire Assessing Stress and Social Support in Periodontitis. J. LEVINE, and M. GLOGAUER, University of Toronto, Toronto, ON, Canada

Chronic periodontal disease is an infectious inflammatory process which involves progressive attachment and bone loss. It is initiated and sustained by bacterial plaque, but host defense mechanisms play a role in its pathogenesis. There is growing evidence to suggest that stress and depression are risks of chronic periodontal disease and social support acts as a modifying factor. In a clinical setting, these factors can be best determined through the use of questionnaire data. Objectives: To validate a newly designed shortened questionnaire in measuring stress and social support in adult patients with chronic periodontal disease. A secondary objective was to perform a case-control analysis to investigate whether there is a difference in stress, depression, and social support in patients with chronic periodontitis compared to periodontally healthy patients. Methods: 101 patients with chronic periodontitis and 50 controls completed a questionnaire package and results were analyzed. The questionnaire package consisted of a newly designed shortened questionnaire as well as stress, social support, and depression questionnaires that have been validated and used in the literature. Results: The revised questionnaire provided a valid and reliable measure of stress and social support in adult patients with chronic periodontal disease. There was a trend for cases and patients with more severe disease to have increased total stress and increased depression compared to healthy controls. There was also a significant inverse association between social support and both chronic and total stress. Conclusion: A newly designed shortened questionnaire provides both a valid and reliable measure of stress and social support in adult patients with chronic periodontal disease.


0807 (116052)

Stress Hormones in Saliva and Periodontitis in Older Japanese Adults. A. ISHISAKA, T. ANSAI, A. YOSHIDA, S. AWANO, T. HAMASAKI, and T. TAKEHARA, Kyushu Dental College, Kitakyushu, Japan

Objective: The relationship between periodontitis and psychoneuroimmunologic variables, such as stress-related hormones, is poorly understood. In the present cross-sectional study, we analyzed the association between levels of the stress-related hormones, cortisol and dehydroepiandrosterone (DHEA) and periodontitis in elderly subjects.

Methods: A total of 171 subjects (85 males and 86 females) participated in this study. The subjects were independently living elderly people with a mean age of 68.4 (± 4.46) years. Stimulated whole saliva samples were were collected, and the levels of dehydroepiandrosterone (DHEA) and cortisol in saliva were determined. A medical questionnaire regarding medical conditions, lifestyle, and psychosocial stress also was administered. The clinical examinations included probing depth (PD), bleeding on probing (BOP), and clinical attachment loss (CAL).

Results: The subjects were divided into three groups based on periodontitis severity, hormone levels were significantly higher in subjects with severe PD or CAL who had never smoked. Multiple regression analysis showed that higher cortisol and DHEA levels were associated significantly with greater numbers of teeth with severe PD or CAL in those who had never smoked, after adjusting for confounding variables.

Conclusion: Our results suggest a close relationship between the periodontitis severity and salivary levels of cortisol and DHEA in healthy elderly subjects who had never smoked. Further, levels of cortisol and DHEA are useful candidate biomarkers for evaluating a part of the etiopathogenesis of periodontitis.

This work was supported by a Grant-in-Aid for Scientific Reseach (17592186) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.


0808 (118179)

Are Postmenopausal Women Aware of their Periodontal Health?. D. SANTOS, B. ATKINS, J. SHAH, N. ALMUDALLAL, and L. BAHL-PALOMO, Case Western Reserve University, Cleveland, OH

Objective: Are postmenopausal women aware of their periodontal health status? Methods: 94 postmenopausal women who reported receiving “regular” dental and medical care participated in this IRB approved observational study. Participants responded to questionnaire and received a periodontal exam from a calibrated examiner. Plaque score percentage (PS) for each participant, and periodontal probe depth (PD), and clinical attachment level (CAL) in mm on 6 sites per tooth were measured. Based on clinical attachment levels participants were classified as mild (1-2mm CAL), moderate (3-4mmCAL ), severe (>5mmCAL on greater than 30% of sites) periodontitis. Perception of periodontal health status was compared to actual diagnosis from clinical exam outcome. Results: 97.8% of participants reported having “healthy gums”, 2.1% reported having had “history of gum disease, but currently healthy gums”, and 0% reported having gum disease. Based on clinical exam findings, 36.2% had severe, 26.6%had moderate, and 34.0%had mild periodontitis. 3.2% did not have periodontitis. When asked about frequency of dental visits to maintain current periodontal conditions, 86.2% reported “every 6 months ”, 3.2% reported “every 3 month”, and 10.6% did not know. Average Plaque score was 67.5%. When asked if they could be at risk for tooth loss, 98.9% answered “no”, when asked why the most common answer given was “good dental coverage”. Conclusions: Postmenopausal women who visit dentists and physicians regularly are not aware of their periodontal health. Patient education must be a priority to prevent progression of periodontitis and tooth loss.


0809 (116832)

Periodontal Clinical Examination: Calibration of First-Year Residents. N. BEAINI, B. LEBLEBICIOGLU, D.N. TATAKIS, A. MARIOTTI, and L. CLAMAN, Ohio State University, Columbus, OH

Objectives: The purpose of this study was to assess the outcomes of a protocol used to train and calibrate first-year residents in a graduate periodontics program.

Methods: Following focused and detailed didactic instruction, a clinical calibration exercise was performed. Patient selection criteria were: periodontitis (2 quadrants), each quadrant with ≥ 5 teeth (at least 1 molar), 2 sites with gingival recession, 4 pockets > 5 mm (at 2 interproximal sites and at 3 different teeth). Exclusion criteria were systemic diseases, antibiotic prophylaxis needs, and local factors impeding probing. Each resident measured probing depths (PD) and gingival margin location (GM), using a UNC probe on six sites per tooth. All measurements were taken twice (repeated by the examiner to assess intra-examiner differences, or by examiner and gold standard trainer to assess inter-examiner differences). Results from 24 first-year residents (last 6 consecutive years) were statistically analyzed for intra- and inter-examiner differences.

Results: Mean intra-examiner difference in PD and GM was 0.39±0.23 mm and 0.34±0.17 mm, respectively. For PD, intra-examiner duplicate measurements were 97±3% and 99±1% within 1 and 2 mm, respectively. The corresponding GM results were 98±2% and 99±1%. The PD and GM mean inter-examiner differences were 0.64±0.18 mm and 0.78±0.2 mm, respectively. For PD, inter-examiner duplicate measurements were 92±6% and 98±3% within 1 and 2 mm, respectively. The corresponding GM results were 88±9% and 98±2%. The PD and GM inter-examiner differences were significantly greater than the respective intra-examiner differences (P<0.001).

Conclusions: Intra-examiner differences in PD and GM are smaller than inter-examiner differences. Intra- and inter-examiner differences compare favorably with values previously reported for examiner calibration. These results suggest that the instituted calibration protocol is effective in training residents.

Supported by OSU College of Dentistry Pre-doctoral Research Program and the Division of Periodontology.


0811 (115967)

Incidence of tacrolimus-induced gingival overgrowth in the absence of calcium-channel-blockers. R.T. SEKIGUCHI1, C.G. PAIXÃO1, C.M. PANNUTI2, L. SARAIVA2, H.T. SILVA JUNIOR3, G.A. ROMITO2, and R.F.M. LOTUFO2, 1University of Sao Paulo, Sao Paulo, Brazil, 2University of Sao Paulo, São Paulo, Brazil, 3Universidade Federal de São Paulo, São Paulo, Brazil

OBJECTIVE: The aim of this study was to determine the incidence and severity of gingival overgrowth (GO) induced by tacrolimus (Tcr) compared with ciclosporin-A (CsA) in the absence of calcium channel blockers in renal transplant recipients. METHODS: Forty nine subjects (24 Tcr/25 CsA) were evaluated before, 30, 90 and 180 days after kidney transplantation. Demographic, periodontal parameters and GO score were recorded for all subjects. Clinical assessment was performed by a single trained and calibrated examiner (ICC=0.967) who was blinded to the patient's drug regime. GO was analyzed by visual examination of the buccal and lingual papillae of the six most anterior teeth of the upper and lower arch. A score ranging from 0 to 5 was attributed to each papilla according to the quantity of GO both in the horizontal and vertical axes. Patients showing a score ≥30 were classified as presenting clinically significant GO. Included in the study were subjects of both sexes older than 18 years, who presented no clinical or radiographic signs of periodontitis. Smokers, diabetics, patients presenting some type of gingival overgrowth during the pre-transplant period and taking any of the following drugs were excluded: nifedipine, diltiazem, verapamil, phenytoin, sodium valproate, azithromycin. RESULTS: The mean GO score was significantly lower in the Tcr group compared with the CsA group after 30 days (p=0.03), 90 days (p=0.004) and 180 days (p=0.01) of immunosuppressive therapy. At 180 days post-transplant, clinically significant GO was observed in 18% of the CsA group and in 9% of the Tcr group. This difference was not statistically significant (p=0.66). CONCLUSION: Despite of the incidence of GO in Tcr group was lower than CsA group, no significant difference in the incidence of clinically GO was observed between both groups up to 180 days of immunosuppressive therapy. (Funded by FAPESP 04/13167-1)


0812 (115792)

Periodontal Status and Risk Indicators of Brazilian Subjects. C.M. SILVA-BOGHOSSIAN, R.R. LUIZ, and A.P.V. COLOMBO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

Objectives: The purpose of the present study was to assess the prevalence, extent and severity of clinical attachment loss (CAL) and probing depth (PD), and investigate the associations between socio-demographic and behavioral parameters with CAL and PD in subjects attending a Public Dental School in Brazil. Methods: 521 consenting participants (14-77 years of age) were submitted to full-mouth periodontal clinical examination at six sites per tooth, assessment of missing teeth, and anamnesis-questionnaires. The data were analyzed by multivariable models using logistic regression analyses. Results: The prevalence of individuals with at least one site with CAL ≥5mm or ≥7mm, and PD ≥5mm or ≥7mm was 69.5%, 58.9%, 66.6%, and 51.8%, respectively. Mean CAL and PD ranged from 2.3 to 4mm, and 2.3 to 3.1mm, respectively, according to age. Likewise, the mean frequency of sites with moderate (5-6mm) and severe (≥7mm) CAL and PD ranged from 5.9-22.5%, 5.2-16.2%, 2.6-13.5%, and 1.9-5.6%, respectively. Multivariate analyses identified bleeding on probing (BOP) (odds ratio [OR]= 13.9 to 37.7), and age ≥36 years (OR= 6 to 11.1) as risk indicators for CAL ≥5mm in ≥10% of sites; age of 36-45 years (OR= 5.9), ≥56 years (OR= 9.6), smoking (OR= 4.8), BOP (OR= 17.7 to 66.7) as risk indicators for CAL ≥7mm; smoking (OR= 5.2), and BOP (OR= 24) as risk indicators for PD ≥5mm in ≥10% of sites; and age ≥36 years (OR= 5.9 to 9.6), smoking (OR= 4.8), and BOP (OR= 17.8 to 66.7) as risk indicators for PD ≥7mm. Conclusions: This particular Brazilian population presented high prevalence and extent of severe periodontal disease. Age, smoking and BOP were risk indicators associated with moderate and severe attachment loss and probing depth in these individuals. Supported by CAPES, CNPq, FAPERJ, Brazil.


0813 (119138)

Aggressive Periodontitis in High School Attendees in Khartoum, Sudan. A. ELAMIN, Sr., The Gades Institute, Department of oral microbiology, University of Bergen, Bergen, Norway, J.M. ALBANDAR, Temple University, Philadelphia, PA, R.W. ALI, University of Science and Technology Umdurman, Khartoum, Sudan, and N. SKAUG, University of Bergen, Ulset, Norway

Objectives: To assess the prevalence and clinical features of aggressive periodontitis among high school attendees in Khartoum, Sudan, and to study the effect of socioeconomic and demographic factors on disease occurrence.

Methods: The study sample consisted of 1,200 students (600 females and 600 males) aged 14-18 years who were selected using a multi-stage, probability sampling design from 38 high schools representative of private and public schools in Khartoum, Sudan. The subjects were examined clinically by a single calibrated examiner, and the measurement of gingival recession, probing depth, and bleeding on probing was performed at 6 sites per tooth, with subsequent calculation of clinical periodontal attachment loss for each site. Aggressive periodontitis was defined as presence of at least 2 first molars and/or 2 incisors with interproximal sites showing ≥4 mm attachment loss. Assessment of demographics, socioeconomic status, and other health-related variables was performed by an interview and using a written questionnaire. Differences in frequencies between groups were evaluated using the Mantel-Haenszel Chi-Square test.

Results: In this population 28 subjects (2.3%) had aggressive periodontitis. The prevalence of the disease was higher in females (1.6%) than in males (0.8%) (p<0.05), and in the low (1.9%) than in the high (0.5%) socioeconomic status groups (p< 0.05). Molars and mandibular incisors demonstrated the most severe attachment loss. Gingival recession was most prevalent at mandibular anterior teeth. Ethnicity did not seem to play a significant effect on disease prevalence.

Conclusion: This population has a relatively high prevalence of aggressive periodontitis. Low socioeconomic status and a female gender may predispose to a higher prevalence of aggressive periodontitis.


0814 (119139)

Early Childhood Malnutrition and Periodontal Disease in Young Haitians. G. JEAN-CHARLES, State University of New York - Buffalo, Buffalo, NY, S.L. RUSSELL, NYU College of Dentistry, New York, NY, W. PSOTER, New York University, New York, NY, S.E. PROPHETE, State University of Haiti, Port-au-Prince, Haiti, and B.J. GEBRIAN, Haitian Health Foundation, Jeremie, Haiti

Objectives: This retrospective cohort study investigated whether exposure to protein-energy malnutrition during the first five years of life (early childhood protein-energy malnutrition, ECPEM) is related to the subsequent development of periodontal disease in adolescents and young adults aged 12-19.

Methods: We examined 96 persons aged 12-19 living in rural Haiti for clinical signs of periodontal disease using modified WHO diagnostic criteria (Community Periodontal Index). Malnutrition data of the study participants had been collected during the years 1988-1993 by a non-governmental organization. We compared those who were regularly or intermittently malnourished, based on anthropomorphic data collected during the first five years of life, with those who were not malnourished, regarding mean CPI score, and used linear regression to control for differences in age, sex, socioeconomic status and smoking distributions between groups.

Results: Overall, 50.5% of the participants had been exposed to ECPEM, and 57.3% of the participants demonstrated a CPI score of 3 or greater in at least one sextant. Socioeconomic status measured at birth was related to ECPEM – those in the lowest SES category (“poorest”) were more likely than those classified as “poor” to have ECPEM (Chi-Square = 7.4, df=2, p=0.02) ECPEM was independently and positively related to mean CPI score, when controlling for sex and smoking: adolescents who were malnourished during the first five years of life had higher mean CPI scores compared to those who were not malnourished (p=0.02). Conclusions: Periodontal pocketing, as measured by CPI  3, was detected in more than half of these young Haitians. ECPEM (measured in childhood) was related to the subsequent development of periodontal disease associated with permanent teeth in Haitian adolescents aged 12-19.

Supported by NIDCR grant: R01 DE14708


0815 (116622)

Periodontal Status and Treatment Needs of Epileptics in Lagos. M.E. SORUNKE, Dept of Preventive Dentistry, LASUTH, Lagos, Nigeria, G.A. AGBELUSI, Dept of Preventive Dentistry, College of medicine, University of Lagos, Lagos, Nigeria, and K.O. SAVAGE, Dept of Preventive Dentistry, College of Medicine, University of Lagos, Lagos, Nigeria

OBJECTIVES:

Knowledge of Periodontal Status and Treatment Needs of a group of people is important for the appropriate planning of Dental Health Services for such a group. This study aims to determine the periodontal status and treatment needs of a group of epileptic patients receiving treatment at the Lagos University Teaching Hospital with a view of planning an adequate preventive dental service for them.

METHODS:

One hundred and fifty consecutive epileptic patients attending the Neurology out-patient Clinic of the Lagos University Teaching Hospital within a 6-month period were selected. An equal number of patients forming the control group were included in the study. Both groups were made to fill questionnaires and were examined to determine their oral and periodontal status. Oral hygiene status was determined using the Gingival Index Simplified Oral Hygiene Index of Greene and Vermillion. The Community Periodontal Index of Treatment Needs (CPITN) was used to assess the periodontal status and treatment needs.

RESULTS:

The mean Oral Hygiene Index Scores (OHIS) for epileptic and control groups were 1.89 + 0.758 and 1.55 + 0.864 respectively. The differences in OHI-S and Oral Hygiene Status between the epileptics and control group were statistically significant (p<0.05). Percentage of persons with healthy periodontium was lower in the epileptics (7.3%) than in the control group (18.0%). The difference in the prevalence of periodontal disease between the two groups was highly significant. (p=0.006).Most subjects in both groups needed scaling and polishing and oral hygiene instructions (OHI) (epileptics 86.7%, control 77.3%). None of the subjects in both groups needed complex periodontal treatment.

CONCLUSIONS:

The periodontal status of epileptic patients seen in this study was poorer than that of controls. Improving their oral health awareness through active oral health education may be a means of solving this problem.


0816 (116909)

Dental Care and Oral Disease in Alcohol Dependent Persons. A. KHOCHT1, S. SCHLEIFER2, M. JANAL2, and S. KELLER2, 1Temple University, Philadelphia, PA, 2UMDNJ, Newark, NJ

Objective: Dental/oral health of alcoholics and substance abusers is often neglected. It is not clear that alcohol dependence has effects on oral health beyond those expected in non-alcoholic persons of similar socioeconomic status (SES). Study objectives were to examine the personal dental care habits, ability to access professional dental care and the types of services received, and examine their effect on the oral health of alcoholics and substance abusers. Methods: Forty DSM-III-R diagnosed alcoholics and a comparison group of 25 non-alcoholic subjects matched for race, age, sex and SES were recruited. Subjects were medically healthy. Each subject received a comprehensive oral/dental examination and an interview was conducted to record personal dental hygiene habits, ability to access professional dental care and types of dental services provided. Results: No statistical differences were found between the oral care habits of the groups. Forty-four percent of all subjects had access to charity professional dental care. Tooth extraction was the main dental service they received. Seventy-five percent of subjects brushed their teeth once or more per day. In the non-alcoholic group, brushing frequency was inversely associated with plaque levels (p = 0.05); in the alcoholic group brushing frequency showed no statistical effect on plaque levels. Access to professional dental care was inversely associated with periodontitis in the alcoholic group (p = 0.002). Conclusions: Alcohol dependence may increase plaque levels above that seen in race, sex, age and SES-matched controls, but professional dental care can limit the subsequent development of periodontal disease in these people.

NIDR #DE10592, NIAAA #AA08195


0817 (119246)

Smokeless Tobacco and Periodontal Health in Rural Male Population. Y.H. CHU1, D.N. TATAKIS2, M.-E. WEWERS2, J. SHULTZ3, and A.G. WEE4, 1University of South Carolina, Columbia, SC, 2Ohio State University, Columbus, OH, 3Worcester County Health Department, Snow Hill, MD, 4University of Nebraska Medical Center, Omaha, NE

Objectives: Despite the reported effects of smokeless tobacco (ST) on the periodontium and the high prevalence of ST use in rural populations and in males, there are very few studies on this specific topic. The purpose of this cross-sectional investigation was to evaluate the periodontal health status of male ST users from a rural population.

Methods: Adult males, daily ST-users, with a clearly identifiable unilateral mandibular oral ST keratosis lesion, and residents of two rural Appalachian Ohio counties, were recruited. Participants completed a questionnaire and received an oral examination. Teeth present, ST keratosis lesion, Plaque and Gingival Index, probing depth, recession depth and attachment level were recorded. Statistical analysis compared ST-site mandibular teeth (teeth adjacent to the subject's unilateral ST keratosis lesion) and NST-site teeth (contralateral corresponding teeth).

Results: The study included 73 ST users, 55% having mandibular ST lesion on the right side and 45% on the left, with no difference on the number of teeth corresponding to the ST lesion (p=0.403, unpaired t-test). Recession prevalence was much greater in ST-site quadrants, when compared to NST-site quadrants (36% of ST quadrants vs. 18% of NST quadrants, p=0.0002, McNemar's test). Twice as many teeth had recession on the ST-site (~20%) than the NST-site (~10%) (p=0.0032, paired t-test), while the average buccal recession depth on the ST-site teeth was greater than on the NST-site teeth (p=0.0074, paired t-test).

Conclusions: The results indicate that greater gingival recession prevalence, extent and severity are associated with ST in rural male ST users.

Supported in part by NIH R01 DE13926 (MEW), NIH K23 DE016890 (AGW) and the OSU Division of Periodontology.


0818 (117581)

Effect of smoking on gingival responses to plaque accumulation. C.R. MATTHEWS1, V. JOSHI1, M. DE JAGER2, M. ASPIRAS2, and P.S. KUMAR1, 1Section of Periodontology, The Ohio State University, Columbus, OH, 2Philips Oral Healthcare, Snoqualmie, WA

Introduction: The effect of smoking on plaque-induced gingivitis has been previously reported. Although it is known that the severity of gingivitis is lower in smokers, it is not known if smoking affects the onset of clinical response to plaque accumulation.

Objective: The purpose of this study was to compare clinical response to plaque accumulation between periodontally healthy current and never smokers during experimental gingivitis.

Methods: 15 current and 15 non-smokers over age 18 without history of systemic disease, pregnancy, and recent or prophylactic antibiotic use were recruited. All subjects received a baseline examination and prophylaxis. Stents were fabricated to protect 3 adjacent teeth in 2 posterior sextants during brushing. Instructions were given to avoid mouthwash, flossing, or other hygiene aides in the area. Turesky's plaque index and Loe & Silness's gingival index were recorded at baseline, 1, 2, 3, 4, 7, 14, and 21 days. Supragingival and subgingival plaque, and gingival crevicular fluid was also collected. At the conclusion of each visit, patients were scaled, polished, and flossed to ensure undisturbed plaque development for the following visit.

Results: Smokers had a significant exposure to tobacco as compared to non-smokers (p<0.05). Plaque index was not significantly different between groups (p>0.05). The gingival index in both non-smokers and smokers showed a significant change from days 7 to 14 (p=0.0001, repeated measures ANOVA). Gingival crevicular fluid levels significantly increased in non-smokers from days 14 to 21 (p=0.01), while smokers showed no significant change. Smokers demonstrated moderate gingivitis (mean gingival index >1) at 4 days, while non-smokers reached this threshold at 14 days.

Conclusions: Smokers demonstrated an earlier onset of moderate gingivitis as compared to non-smokers in response to similar amounts of plaque accumulation.

Supported by a research grant from Philips Oral Healthcare.


0819 (118952)

Smoking strongly affects salivary MMP-8 in adolescents. A.M. HEIKKINEN1, T. SORSA1, T. TERVAHARTIALA1, J. PITKÄNIEMI1, M. KOSKENVUO1, and J. MEURMAN2, 1University of Helsinki, Helsinki, Finland, 2University of Helsinki, Helsinki University Central Hospital, Helsinki, Finland

Background: Matrix metalloproteinase-8 (MMP-8), released from neutrophils and gingival fibroblasts, is involved in inflammation and remodelling and degradation of periodontal tissue. MMP-8 in saliva has been shown to reflect periodontitis (Mancini et al. J. Periodontol 1999;70:1292). The effect of smoking on the salivary levels of MMP-8 is not well known, however.

Objective: To investigate salivary MMP-8 as a periodontal inflammatory biomarker in smoking and non-smoking adolescents.

Methods: Oral health of 501 15-16-year-old adolescents was examined and bone loss assessed from radiographs. Health habits were asked. Paraffin-wax stimulated saliva samples were taken and analyzed with immunofluorometric (IFMA) assay for MMP-8. The results were analyzed between smokers and non-smokers with respect to the salivary MMP-8 concentrations and clinical parameters.

Results: Of boys 61 and of girls 66 were smokers while 197 boys and 177 girls did not smoke. The MMP-8 median value in total material was 166.1µg/ml. Statistical significant differences in MMP-8 values linked with mean bleeding on probing (BOP) only in non-smoking boys. Among them 59.2% of the MMP-8 values were below the median and BOP mean (51%), while 38.5% were above BOP mean. Of the MMP-8 values of non-smoking boys 40.8% were over the median and below BOP mean, while 61.5% were above BOP mean (p=0.004). Periodontal pockets ≥4 mm were observed in 42.4% of the non-smoking boys having the MMP-8 concentration <166.1µg/ml while of these 61.9% had no pockets. Percentages for those having periodontal pockets ≥4mm and MMP-8 >166.1µg/ml was 57.6% vs. 38.1% of the boys with no pockets (p=0.01).

Conclusion: Salivary MMP-8 concentration associated with gingivitis and also with initial periodontal tissue breakdown only in the non-smoking boys in the present study. Hence smoking apparently affects the MMP-8 and it needs to be taken into account as a strong confounder when evaluating oral fluid MMP-8 diagnostics.


0820 (119479)

Elastase in Saliva of Smoking and Non-smoking Adolescents. K. KARI1, A.M. HEIKKINEN1, T. SORSA1, J. PITKÄNIEMI1, M. KOSKENVUO1, and J. MEURMAN2, 1University of Helsinki, Helsinki, Finland, 2University of Helsinki, Helsinki University Central Hospital, Helsinki, Finland

Background: Neutrophil elastase proteinase increases in inflammation, including gingivitis. This enzyme inhibits the proliferation and/or function of lymphocytes. According to Pauletto et al. (J Periodontol 71:58, 2000), adult smokers showed salivary elastase levels lower than those in former or non-smoking periodontitis patients. This has not been investigated in an adolescent population whose smoking history is shorter.

Objective: Data on the effect of teenage smoking on the salivary levels of neutrophil elastase are unknown. We investigated this inflammatory biomarker in smoking and non-smoking adolescents.

Methods: The oral health status of 501 15- and 16-year-old adolescents was recorded according to the WHO criteria. Health habits were ascertained by structured questionnaire. Bite-wing x-rays were taken for the assessment of bone loss. Paraffin-wax-stimulated saliva samples were taken and analyzed by immunofluorescence assay for elastases. The results were analyzed statistically by cross-tabulation with the SPSS program.

Results: Sixty-one boys and 66 girls were smokers, while 197 boys and 177 girls did not smoke. The total elastase median value was 0.0099ΔOD405/h. Of those who smoked daily, 57.5% had elastase values below the median, while for the non-smokers, the respective percent was 47.4% (p = 0.051). Elastase values below the median were observed in 63.9% of boys who smoked vs. 48.5% in non-smokers (p = 0.035). No difference was observed in girls. Bleeding on probing (BOP) was linked with elastase values only in boys who did not smoke. Of the elastase values for these boys, 63.5% were over the median, while 36.5% were below the median, with a mean BOP value over 51.0%. The corresponding percentages for those having mean BOP values below 51.0% were 39.2% and 60.8%, respectively (p = 0.001).

Conclusion: Elastase values reflected gingival inflammation, as we had expected, but only in non-smoking boys. Consequently, smoking needs to be taken into account when this biomarker is analyzed.


0821 (118425)

Metabolomic Profiling of Gingival Crevicular Fluid. V.M. BARNES1, H. TRIVEDI1, R.P. TELES2, T. XU1, W. DEVIZIO1, and L. GUO3, 1Colgate-Palmolive Technology Center, Piscataway, NJ, 2Forsyth Institute, Boston, MA, 3Metabolon, Durham, NC

Background: An unbiased metabolic profiling has rapidly enhanced disease characterization and drug development. Periodontal disease, until recently, has been studied primarily from clinical outcomes in lengthy human studies. Efforts are underway to identify reliable biomarkers in an effort to better understand the disease, improve the clinical study of periodontal disease and enhance the development of products to combat the disease. Metabolomic profiling may greatly assist in these efforts.

Objective: To determine if metabolomic profiling of GCF could deliver potential biomarkers for the further study and understanding of periodontal disease.

Methods: 21 “healthy” subjects presenting with only select gingivitis sites and 22 “diseased” subjects presenting with healthy, gingivitis and periodontitis sites were identified. The volunteer subjects met all inclusion/exclusion criteria and signed the IRB approved consent. A total of 108 GCF samples were collected. Healthy subjects donated GCF from healthy and gingivitis sites, while diseased subjects donated GCF from healthy, gingivitis and periodontitis site. GCF was analyzed by Metabolon via mass spectrometry technology as described in Lawton et al., 2008. Anova and t-tests were performed to compare data from healthy, gingivitis, and periodontitis sites.

Results: Changes in key metabolites for oxidative stress, inflammation, protein degradation, urea cycle, lipid degradation and glycolisis were measured. Interestingly, the increase or decrease of the metabolite was commensurate with the level of periodontal disease present from the sampling site.

Conclusion: Metabolic profiling may be a powerful tool to study periodontal disease. This technology may identify unique biomarkers useful in the clinical study of the disease as well as the development of oral care products targeted to fight periodontal disease.


0823 (120477)

Salivary Chemokines in Patients with Chronic Periodontal Disease. G.L. TREVISAN, P.P. COSTA, V.K.D.S. KAWATA, F.R. DE MORAES, D.B. PALIOTO, S.L.S. DE SOUZA, M. GRISI, A. NOMIZO, and M. TABA, Jr., University of Sao Paulo, Ribeirao Preto, Brazil

Objectives: Chemokines are crucial in the activation and recruitment of inflammatory and immune cells to the periodontal sites. The aim of the study was to examine the salivary levels of a panel of chemokines in patients with chronic periodontitis.

Methods: A total of 32 subjects were divided in healthy (Control, n=11) and periodontal patients (PD, n=21). Clinical data were recorded and non-stimulated saliva samples were analyzed for Interleukin-8 (IL-8), Regulated on Activation Normal T cell Expressed and Secreted (RANTES), monokine induced by INF gamma (MIG), interferon inducible protein (IP-10), and macrophage chemoattractant protein-1( MCP-1) by using a simultaneous multiplex assays CBA-Cytometric Bead Array, BD Bioscience, San Jose, CA).

Results: The clinical parameters evaluated PPD, CAL and BOP, were statistically different between groups (p<0.05). All chemokines levels were higher in PD patients in comparison to healthy controls: IL-8 (Control=378.56±119.85; PD=2457.7±523.44, p<0.01); IP-10 (Control=193.85±64.21; PD=423.78±85.67, p=0.08); MCP-1 (Control=362.42±87.07; PD=1269.30±260.51, p<0.01); MIG (Control=173.33±79.28; PD=341.26±77.23, p=0.05); RANTES (Control=1.88±1.04; PD=6.18±2.14, p=0.03).

Conclusion: The results suggest chemokines could play key roles in both activation and recruitment of inflammatory and immune cells in the local periodontal environment. The examined chemokines are subject to be monitored in saliva samples and they may be correlated to diseased condition.

FAPESP: 2007/00866-7

CNPq 477428/2006-1


0824 (119696)

Cytokine Levels in Gingival Crevicular Fluid during Menstrual Cycle. U. BASER, and F. YALCIN, University of Istanbul, Istanbul, Turkey

Objectives: The purpose of this longitudinal, prospective study was to compare gingival changes of cyclic women at different phases during their menstrual cycle.

Methods: Twenty-seven female dental students were included in this study. They all had clinically healthy gingiva in most sites and mild gingival inflammation in some sites. Pregnant women, smokers, and those who were receiving fertilization treatment or had irregular periods were excluded from the study. The students completed demographic forms to assess oral and systemic complaints and the frequency of aphthous lesion occurrence during the different phases of the menstrual cycle. Subjects were given oral hygiene instructions before the study began, and their plaque index (PI) scores were recorded once a week for two months. Menstrual cycle duration and regularity were also checked at the same time. PI and gingival index (GI) and sites with bleeding on probing (BOP) were recorded, and gingival crevicular fluid (GCF) was collected for laboratory examinations on the first day of menstruation (MD), on the estimated ovulation day (OD), and on the estimated day of predominant progesterone secretion (PgD), when premenstrual syndrome began. These exact menstrual cycle days were determined according to serum progesterone and estradiol levels. For laboratory examinations, we collected GCF to analyze interleukin-1 beta and tumor necrosis factor-alpha levels. We performed probing depths (PD) only once to assess the periodontal condition of the subjects.

Results: Even though PI did not show any significant change, BOP, GCF volume, and IL-1alpha levels were significantly higher on the PgD. There were no statistically significant differences between GI scores of the different phases of the menstrual cycle.

Conclusion: We observed in this study that even with optimal oral hygiene, fluctuations in sex steroid hormones, especially progesterone, affect gingival physiology in women of reproductive age.


0825 (117162)

Association of TNF-á-308/LT-á+252 Gene Polymorphisms and Periodontitis. Y.-P. HO, C.C. TSAI, and K.Y. HO, Kaohsiung Medical University and Hospital, Kaohsiung, Taiwan

Objective: Tumor necrosis factor (TNF) is a proinflammatory cytokine that stimulates a number of events related to the pathogenesis of periodontal disease. Evidences suggest genetic polymorphisms in TNF-á-308 and LT-á+252 might increase the production of TNF and consequently modify the risk of periodontitis. The aim of this study was to investigate the association of TNF-á-308 /LT-á+252 genetic polymorphisms and susceptibility to periodontitis in a Taiwanese population. Materials and methods: The study population consisted of aggressive periodontitis patients (AgP, n=90), chronic periodontitis patients (CP, n=369) and healthy controls (HC, n=161). Genotypes of TNF-á-308 and LT-á+252 were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The distribution of genotypes among groups was compared by chi-square test. The risk for periodontitis associated with genotypes was calculated by logistic regression and was expressed as the odds ratio and 95% confidence interval. Results: The distribution of genotypes of the two genes investigated was not deviated from the Hardy-Weinberg equilibrium. The TNF-á-308 GG genotype was found at 78.9%, 78.8% and 82.6% in AgP, CP, and HC, respectively. In LT-á+252 gene polymorphism, the frequency of AA, AG, and GG genotypes was found at 18.9%, 60.0% and 21.1% in AgP patients; 29.8%, 39.0% and 31.2% in CP patients; 24.2%, 50.9% and 24.8% in HC, respectively. The genotype distribution and allelic frequency of these two loci were not significantly different between periodontitis patients and healthy controls. No difference in the distribution of combined genotypes (TNF-á-308 and LT-á+252) among groups was observed. There was no association between the carriage of either the polymorphic TNF-á-308 or LT-á+252 variant and the susceptibility to periodontitis. Conclusion: The results of this study revealed no association between the TNF-á-308 /LT-á+252 genetic polymorphisms and susceptibility to periodontitis in Taiwanese.


0826 (116663)

Association of inflammatory biomarkers with periodontitis in diabetic patients. M. TANAKA1, K. TORII2, Y. FUKUZATO2, T. MAKINO2, M. OTSUKI3, S. KASAYAMA4, and S. SHIZUKUISHI1, 1Osaka University Graduate School of Dentistry, Suita, Japan, 2Sunstar Inc, Takatsuki, Japan, 3Osaka University Graduate School of Medicine, Suita, Japan, 4Nissay Hospital, Osaka, Japan

Objectives: The relationship between periodontitis and other diabetic complications remains unclear. The purpose of this investigation was to examine association of various diabetic complications with periodontitis and to search inflammatory biomarkers related to periodontitis and the other diabetic complications.

Methods: The study group consisted of 98 type 2 diabetic patients (62.2 year-olds, 65 males and 33 females). For all subjects, general health and oral examinations were performed. In addition, the samples including blood, GCF and saliva were collected. Inflammatory biomarker levels were determined by ELISA. Periodontitis group was defined as upper 25th percentile based on percentage of teeth with ≥ 4mm of CAL.

Results: By bivariate analysis, the diabetic patients with periodontitis showed significantly lower BMI and higher prevalence of macrovascular disease(s) in comparison to the diabetic patients without periodontitis. In addition, a multiple logistic model, which included diabetic complications as independent variables, revealed that macrovascular disease(s) and BMI were independently associated with periodontitis (odds ratios; 4.02 and 0.77, respectively). Diabetic microangiopathies of retinopathy, nephropathy and neuropathy were not associated. Furthermore, diabetic patients with both macrovascular disease(s) and periodontitis had significantly higher levels of serum ICAM, serum lipid peroxide and GCF CRP than those of diabetic patients with macrovascular disease(s) but not periodontitis.

Conclusion: Macrovascular disease(s) are associated with periodontitis in diabetic patients. Levels of the inflammatory biomarkers including ICAM, lipid peroxide and CRP may increase in diabetic patients with both macrovascular disease(s) and periodontitis.


0827 (114926)

Maxillary Labial Frenum Attachment in Children. E.A. BOUTSI, Lavrion Health Center, NHS, Athens, Greece, and D.N. TATAKIS, Ohio State University, Columbus, OH

Objectives: The attachment position of the maxillary labial frenum may contribute to several conditions manifesting in adults and children. Studies on the distribution of maxillary labial frenum attachment in children are limited. The purpose of this cross-sectional study was to examine the prevalence of the various types of maxillary labial frenum attachment in children.

Methods: Children (age 3-18) attending a public health clinic in Lavrion, East Attica, Greece, were clinically examined for maxillary frenum attachment location. Frenal attachment was classified according to the Placek (1974) classification into: mucosal, gingival, papillary and papillary penetrating. Demographic information was recorded. Parents provided written informed consent.

Results: 94 children, mean (± sd) age of 8.6 ± 3.0 years, were examined. 50 were male (8.7 ± 2.7 years old) and 44 were female (8.6 ± 3.3 years old), while all children were Caucasian. Greek descent (47%) was most common, while Turkish (24%), Afghani (14%), and Albanian (13%) descent were also prevalent. The prevalence of the various forms of maxillary labial frenum attachment was as follows: mucosal 10%, gingival 47%, papillary 24%, and papillary penetrating 18%. Frenum attachment differed significantly between genders (p<0.05), with males twice as likely to have gingival attachment and females twice as likely to have mucosal attachment. Frenum classification differed significantly by age (p<0.01).

Conclusions: This distribution of maxillary labial frenum types differs significantly from one reported in a predominantly adult population (Placek 1974). The results of this study suggest that, in children, maxillary labial frenum attachment may vary by gender and age.


0828 (116029)

Elevated Plasmatic 25-hydroxyvitamin D3 is Associated with Aggressive Periodontitis. K. LIU, H. MENG, X. TANG, L. XU, L. ZHANG, Z. CHEN, D. SHI, X. FENG, and R. LU, Department of Periodontology, Peking University School and Hospital of Stomatology, Beijing, China

Objectives: Vitamin D is associated with quantities of inflammatory diseases and plays a significant role in regulating bone metabolism. Serous 25-hydroxyvitamin D3 (25OHD3) had been demonstrated to be potentially associated with periodontal disease. The purpose of this study was to evaluate: ¢Å whether an association existed between plasmatic 25OHD3 and periodontitis; ¢Æ whether plasmatic levels of bone related biomarkers regulated by vitamin D were related with periodontitis.

Methods: 66 aggressive periodontitis (AgP) patients, 52 chronic periodontitis (CP) patients and 60 healthy controls were included. Periodontal examination consisted of probing depth, attachment loss, Bleeding Index, BOP% measurements. Hematic 25OHD3 and bone related biomarkers (osteocalcin, alkaline phosphatase, calcium and inorganic phosphorus) levels were detected using RIA kits or a standard hospital analytical technique.

Results: Plasmatic 25OHD3 levels were higher in AgP patients than those in healthy controls (11.71 ng/mL vs 8.64 ng/mL; P=0.011) and statistically significantly correlated with Bleeding Index in AgP patients (r=0.321, P=0.001). Plasmatic osteocalcin values were higher in AgP patients than those in healthy controls (0.90 ng/mL vs 0.70 ng/mL; P=0.013). Serous inorganic phosphorus values in both AgP and CP group were lower than those of the healthy controls (1.06 mmol/L vs 1.10 mmol/L vs 1.26 mmol/L; P<0.01).

Conclusions: Plasmatic 25OHD3 might be a useful marker for monitoring AgP.

This research was supported by National Natural Science Foundations of China (30471882); National Key Project of Scientific and Technical Supporting Programs of China (2007BAZ18B02); National Natural Science Foundations of China(30772420).


0829 (116059)

Enhanced adipokine levels in gingival crevicular fluid in obese adolescents. C. BLOMBERG1, B. WONDIMU1, T. YUCEL-LINDBERG1, C. MARCUS2, and T. MODÉER1, 1Karolinska Institutet, Institute of Odontology, Stockholm, Sweden, 2Karolinska Institutet, Paediatric Department, Stockholm, Sweden

Objectives: This study was designed to investigate whether the levels of adipokines in gingival crevicular fluid (GCF) in obese adolescents are enhanced compared to age and gender matched normal-weight control patients.

Methods: The study was conducted on 104 subjects, 52 obese subjects and 52 controls. All subjects answered a questioner regarding oral hygiene, smoking habits and parent's background. The two groups were equal in age (mean 14,4 years) and socioeconomic background in term of parents education level and parents country of birth. Body Mass Index (BMI) was calculated and adjusted for age and gender (BMI-sds). The clinical examination included recording of Visible Plaque Index (VPI%), Gingival inflammation (BoP %), pathological pocket depths (>4mm), and the occurrence incipient alveolar bone loss diagnosed on radiographs were recorded. The samples of GCF were collected from two sites (16 and 41) per subject. The levels of adiponectin, interleukin- 1beta (IL-1beta), interleukin-8 (IL-8), plasminogen activator inhibitor (PAI-1) and tumor necrosis factor alpha (TNF-alpha) in GCF was determined by using commercially available luminex kits.

Results: There was a significant enhanced mean level of adiponectin (P<0.01), IL-1beta (P<0.001) and IL-8 (P<0.01) in the GCF from the obese group compared to the controls, on the contrary PAI-1 and TNF-alpha did not differ between the groups. Obese adolescents had a higher occurrence of pathologic periodontal pockets (> 4mm) (P<0.001) compared with the controls. Two of the obese and one of the controls exhibited incipient bone loss.

Conclusion: The results indicate that the levels of adipokines in GCF are enhanced in obese adolescents, which may alter the local immune response in periodontal tissue.


0830 (116286)

TNF-alpha (G-308A) polymorphism and periodontitis in a Brazilian population. P.C. TREVILATTO1, R.B. BRITO JR2, R.M. SCAREL-CAMINAGA3, A.P.D.S. PARDO4, A.A.S.D. LIMA1, M.A.N. MACHADO1, L.R.A. ALANIS1, A.M.T. GREGIO1, A.W. SALLUM4, and S.R.P. LINE4, 1Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil, 2Sao Leopoldo Mandic Dentistry School, Campinas, Brazil, 3Sao Paulo State University, Araraquara, Brazil, 4Faculdade de Odontologia de Piracicaba Unicamp, Piracicaba, Brazil

Tumor necrosis factor-alpha (TNF-alpha) is a major mediator of the immune-inflammatory response and may play an important role in the pathogenesis and progression of chronic periodontal disease (PD). Polymorphisms in the promoter of the TNF-alpha gene have been associated with some types of inflammatory diseases, such as asthma and rheumatoid arthritis. Objectives: The aim of the present study was to investigate the association between a functional single-nucleotide polymorphism (SNP) of the TNF-alpha (G-308A) gene and severity of chronic PD in Brazilians. Methods: One hundred and thirteen (113) non-smoking subjects over 25 years (mean age 41.2) were divided according to the severity level of periodontal disease: 44 healthy individuals (control group), 31 subjects with moderate and 38 with severe periodontitis. Genomic DNA was obtained from epithelial cells through a mouthwash with 3% glucose and scraping of oral mucosa. The samples were analyzed for TNF-alpha (-308) polymorphism using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques. The significance of the differences in the allele and genotype frequencies of the polymorphism between the control and PD groups was assessed by Chi-square test (p<0.05). Results: No significant differences in the genotype distribution and allele frequency were found between control and groups with PD. Conclusions: It was concluded that TNF-alpha (-308) polymorphism was not associated either with the susceptibility to or with the severity of chronic PD. Other polymorphisms in this or/and other genes of the host inflammatory response might be involved in determining susceptibility to PD in the study population.

This study was supported by FAPESP grants 99/05610-2 and 99/06094-8.


0832 (120095)

Formylpeptide Receptor SNP 348T>C and Chemotaxis in Aggressive Periodontitis. P. MANEY, and J.D. WALTERS, Ohio State University, Columbus, OH

Objectives: Formylpeptide receptors (FPRs) play an important role in guiding the migration of polymorphonuclear leukocytes (PMNs) to infection sites. Defects in FPR expression and PMN chemotaxis are common in patients with aggressive periodontitis (AP). The gene that encodes FPRs is highly polymorphic. Our previous work has shown that African Americans who are homozygous for the 348T variant of SNP 348T>C have an increased risk of developing AP. We hypothesize that the 348T FPR variant is associated with FPR expression defects, chemotaxis defects and increased susceptibility to AP. To test this hypothesis, we assayed chemotactic activity with PMNs obtained from African-Americans with AP and from healthy ethnically matched controls to determine whether 348T is associated with reduced neutrophil chemotaxis;

Methods: Peripheral blood was drawn from 25 subjects with AP and from 32 controls. PMNs were isolated by Ficoll centrifugation and dextran sedimentation. Chemotaxis to N-formyl-Met-Leu-Phe was assayed in a modified Boyden chamber. FPR genotype was determined by direct sequencing of a PCR-amplified segment of the coding region;

Results: PMN chemotactic activity was 22% lower in AP cases than in controls (P<0.001, Mann-Whitney test), whereas random migration was similar. In AP cases, all three 348 genotypes exhibited a significantly lower chemotactic response compared to the mean response from controls, but individuals who were homozygous for 348T exhibited the weakest response. Moreover, PMNs from 348T homozygotes (who were all AP cases) exhibited a significantly lower response than PMNs obtained from cases and controls who were 348 heterozygotes or 348C homozygotes (P<0.03 for both, Holm-Sidak test);

Conclusions: The results support the hypothesis that 348T may be associated with PMN chemotaxis defects and increased susceptibility to AP. Further investigation is warranted to determine whether 348T contributes to decreased FPR expression and define the mechanism by which this may potentially occur. Supported by DE017178.


0833 (120733)

Methylation Status of IL-1B Promoter Region In Chronic Periondontitis Patients. S. ZHANG, S. BARROS, and S. OFFENBACHER, University of North Carolina at Chapel Hill, School of Dentistry, Durham, NC

Objectives: Chronic periodontitis has been associated with persistent elevated levels of PGE2 and IL-1b. In previous studies we have found altered COX-2 promoter methylation levels in disease suggesting the biofilm induces local epigenetic changes in inflammatory pathways. This pilot study sought to determine the DNA methylation status of the promoter region of interleukin-1 beta (IL-1B) genes in human gingival tissue biopsies from patients with periodontitis in comparison to those subjects free of periodontitis.

Methods: Genomic DNA was isolated from 23 surgically removed gingival tissues: 12 with chronic periodontitis and 11 free of periodontitis. After bisulfite conversion, a promoter region of IL-1B promoter region (-3757 to -2508bp) was amplified by PCR with the primers that are specific to modified DNA template. Methylation level of 6 potential methylation sites (CpG sites) within the promoter region in the PCR products was then analyzed by Pyrosequencing technology (Biotage). Differences between CpG site specific methylation levels at all 6 CpG sites between health and disease were tested using Student's T-test.

Results: Of the 6 potential methylation sites studied there was no significant difference in methylation levels comparing health to disease (62.5+4.2% vs 67.6+5.9%), respectively. Thus, in contrast to the epigenetic modifications of the COX-2 promoter, the increases in tissue levels of IL-1b may not be attributable to differential methylation of the IL1B promoter.

Conclusions: These findings suggest that chronic periodontal disease is not associated with alteration in the DNA methylation of the IL1B promoter. This suggests that epigenetic changes are not uniformly associated with regulating inflammatory molecules, but rather suggests a selective process targeting specific genes.


0834 (120825)

Invasion-Associated P. gingivalis Polymorphisms. E. KOZAROV, and S. DOLGILEVITCH, Columbia University, New York, NY

Objectives: Genomic differences among subspecies account for many important pathogenicity traits. P. gingivalis strains invade human cells in vitro with different invasion abilities, varying by up to three orders of magnitude therefore genetic heterogeneity exists between genomes of different strains. Since the most comprehensive way to study P. gingivalis interstrain genomic polymorphisms is using microarrays, we used them in strain-to-strain comparison to reveal the molecular basis of this polymorphism and consequently, the host cell invasion determinants. Such whole-genome approach is a practical method to reveal the genetic determinants “missing” from the non-invasive P. gingivalis strain.

Methods: Comparative genomic hybridization (CGH), utilizing P. gingivalis DNA microarrays, can facilitate bacterial genome-wide assessment. We used CGH and P. gingivalis microarrays (from PFGRC – JCVI/TIGR) to compare the genomes of a non-invader to the database W83 strain (invader). For hybridization and scanning, the JCVI/TIGR protocols were used.

Results: Using the JCVI/TIGR online resources (http://cmr.jcvi.org/tigr-scripts/CMR/CmrHomePage.cgi?db=gpg) we were able to identify 82 annotated and 126 hypothetical ORFs that are missing in the non-invasive strain. Among these are cell surface proteins (such as fimbrilin and the rag locus), transcriptional regulators, capsular polysaccharide biosynthesis enzymes and immunoreactive proteins. Many ORFs encoding integrases and transposases are also missing from the non-invader's genome.

Conclusion: Although relatively few in number, such data using microbial DNA microarrays establish the quality and usefulness of the arrays for genomic studies of bacterial phenotypes. Some of the CGH-identified ORFs have been previously reported to have a role in P. gingivalis virulence. Therefore, bacterial microarrays can be used to provide a set of host cell invasion-associated P. gingivalis genes using the CGH approach.

This study is supported by NIH DE18006.


0835 (114531)

Polymorphisms of the Interleukin-18 and -4 Genes in Periodontitis Patients. C.C. TSAI1, K.Y. HO1, Y.-P. HO1, Y.M. WU2, Y.-H. YANG2, and W.-C. HUANG2, 1Kaohsiung Medical University and Hospital, Kaohsiung, Taiwan, 2Kaohsiung Medical University, Kaohsiung, Taiwan

Objectives: Few studies provided the association between IL-18 and IL-4 gene polymorphisms (SNPs) and periodontitis. Since the frequencies of the gene genotypes are different among ethnics, our aim was to evaluate whether the IL-4 and IL-18 SNPs are associated with peridontitis in a Taiwanese population.

Material and Methods: DNA was extracted from peripheral blood of 100 health controls (HC) and 100 patients with chronic periodontitis (CP). IL-4 and IL-18 SNPs were genotyped by polymerase chain reaction and restriction fragment length polymorphism analysis. The JMP statistical software was used to determine the association by c2-test, ANOVA and logistic regression analysis.

Results: No differences in demographic data, frequency distributions of habitual drinker, betel quid chewing, and in IL-4 -590C„³T(c2 =0.005, p=0.9462) and IL-18 -137G„³C (c2 = 1.014, p=0.3140) polymorphisms were found between CP and HC groups. However, the smokers (vs. non-smokers) with IL-4 -590C/C or IL-18 -137C/C had higher susceptibility to CP (OR= 2.87 or 2.90 respectively, p<0.05). The OR of developing CP in smokers with IL-4 -590(C/T+T/T) or IL-18 -137(G/C+G/G) was 3.31 or 5.47 respectively (p<0.05) . The smokers with the composed IL-4 -590C/C and IL-18-137C/C still had higher susceptibility (OR=2.50) to CP. The OR for developing CP of smokers with composed IL-4 -590(C/T+T/T) and IL-18 -137(G/C+G/G) was 5.14. These data suggested that individuals with IL-4 -590C/C and IL-18 -137C/C could be less susceptible to CP, particularly in smokers.

Conclusions: This study demonstrated no association between IL-4 -590C„³T and IL-18 -137G„³C and the risk of susceptibility for CP in Taiwanese. Smokers might have a trend to increase OR for developing CP in individuals of IL-4 -590(C/T+T/T) (vs. C/C) or in individuals of IL-18 -137(G/C+G/G) (vs. C/C). Further study in larger numbers of subjects is necessary to prove the definitive association of these polymorphisms with CP.


0836 (115728)

Gene Polymorphisms of Cyclooxygenae-2 and risk for Periodontitis with Diabetes. J. ZHANG, C. XIE, L. XIAO, W. FAN, and D. XUAN, Guangdong Provincial Stomatological Hospital, South Medical University, Guangzhou, China

Objective: The common genetic background is likely one of the mechanisms for the relationship between diabetes and periodontitis. The specific function of cyclooxygenase-2 (COX-2) makes it a candidate gene. This study is aimed to assess the association between three polymorphisms (rs689466, rs20417 and rs5275) of COX-2 and the risk of chronic periodontitis (CP) with type 2 diabetes (T2DM). Methods: A total of 392 subjects were enrolled and divided into four groups: T2DM (G1, n=46), T2DM+CP (G2, n=76), CP (G3, n=158), and healthy controls ( G4, n=112). Periodontal condition, onset age and duration of diabetes, smoking status, body mass index (BMI), and other demographic data were recorded. Genotypes were determined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The distribution of gneotypes among the groups were compared by x2 test. The odds ratios (ORs) were calculated by logistic regression analysis.Results: After adjustment of confounding variables, it was found that there were statistical significant differences (p < 0.05) in genotype distributions of rs689466 and rs20417 between G3 and G4, and that the A allele frequency of rs689466 was significantly higher (p=0.017) in G2 compared with in G4. The difference for the A allele in G2 remained marginal significant after p value corrected for multiple testing (p=0.051), and the OR was 2.949 (AA+GA vs GG, 95%CI 1.321-6.587, P=0.008) after adjusted. There were no significant differences for the genotype distributions between G1 and G2, and no differences for the genotype distributions of rs5275 among the groups. Conclusions: The results suggested that diabetic subjects carring the variant A allele of rs689466 may have an increased risk for periodontitis, further studies in larger size of samples on more putative genes are needed. (Funded by the grant from National Science & Technology Pillar Program in the Eleventh Five-year Plan Period of China, No. 2007BAI18B02)


0837 (115824)

Toll Receptor Gene Polymorphisms in African-Americans with Periodontitis. M. CHOU, W. MAUGHAN, J. GUNSOLLEY, H.A. SCHENKEIN, and S.E. SAHINGUR, Virginia Commonwealth University - VCU/MCV, Richmond, VA

OBJECTIVE: Toll like receptors (TLRs) play an important role in innate immunity and evidence indicates that the host immune responses to TLR ligands may be associated with single nucleotide polymorphisms (SNPs) within TLR genes, resulting in an altered susceptibility to various diseases. The aim of this study was to determine the frequency of SNPs in TLR genes in chronic periodontitis (CP), localized aggressive periodontitis (LAP), generalized aggressive periodontitis (GAP) and periodontally healthy African-American subjects.

METHODS: 71 CP, 25 LAP, 50 GAP, and 59 periodontally healthy subjects were enrolled. Genotyping was performed for TLR2 (+2408 G>A), TLR4 (+896 A>G), and TLR9 (-1486 T>C) polymorphisms by TaqMan® allelic discrimination assays (Applied Biosystems). Accuracy of genotyping was confirmed by known DNA samples of each genotype and also by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analyses. Fisher's exact test and chi-squared analyses were performed to compare genotype and allele frequencies.

RESULTS: The distribution of TLR9 (-1486 T>C) genotypes was significantly different between the periodontally-healthy –subjects and the diseased groups. The frequency of individuals expressing the C allele of TLR9 gene polymorphism (CC and CT) was significantly higher in control group (81.36%) compared to all the diseased groups (45.07% CP, 48.00% LAP, 52.00% GAP) (p=0.0001). There were no statistically significant differences in the distribution of TLR9 genotypes between chronic periodontitis and aggressive periodontitis patients and we could not detect any significant differences for TLR2 and TLR4 gene polymorphisms between diseased and control groups in this population.

CONCLUSION: Based on the findings of this study, C allele of TLR9 (-1486 T>C) polymorphism may confer protection against periodontal disease in African -Americans. These results are in contrast with our previous reports in Caucasians that did not find any effect of TLR9 polymorphisms in disease susceptibility for chronic periodontitis.(Supported by Alexander Fellowship Funds)


0838 (114949)

β-TCP and FGF-2 combination enhances periodontal regeneration in dog. Y. OI, M. OTA, S. YAMAMOTO, Y. SHIBUKAWA, and S. YAMADA, Tokyo Dental College, Chiba, Japan

Objectives: The aim of periodontal tissue regeneration is to restore supporting periodontal tissue destroyed by periodontal disease. Basic fibroblast growth factor (FGF-2) induces angiogenesis, chemotaxis, and the proliferation of periodontal ligament cells. Previous study reported that FGF-2 clearly induced periodontal tissue regeneration, even when a solution containing no scaffold was applied, in a series of their experiments. Because of their biocompatibility and osteoconductivity, a number of calcium phosphate biomaterials have been developed as bone substitutes. One of these materials, β-tricalcium phosphate (β-TCP) has been shown to exhibit good biocompatibility and osteoconductivity in both animal and clinical studies. The objective of this study was to determine the effect of β-TCP on the regeneration of periodontal tissue with a combination of β-TCP particles and FGF-2.

Methods: Either β-TCP and FGF-2 (β-TCP/FGF-2 group) or FGF-2 alone (FGF-2 group) was applied in intrabony defects. The control group was received neither β-TCP nor FGF-2 The tissues were histologically examined at 2, 4, or 8 wk following treatment.

Results: The control group was characterized by an appearance long junctional epithelium and little bone formation. In β-TCP/FGF-2 group, a time-lag was evident between the peak value of the TRAP-positive cell population and that of new bone formation, indicating that a coupling-like phenomenon was occurred in the β-TCP-filled bone defects. The β-TCP/FGF-2 group showed a statistically significant increase in both new bone and cementum formation compared to the FGF-2 alone group (76.3% vs. 65.3%, p< 0.01, and 81.0% vs. 68.35, p< 0.01, respectively).

Conclusion: These findings suggest that β-TCP may be a suitable scaffold for FGF-2 and the combination of β-TCP and FGF-2 can enhance bone and cementum formation.


0839 (115014)

Cervical Restoration May Not Prevent Root Coverage. Randomized Clinical Trial. M. SANTAMARIA1, F. SUAID1, M. CASATI2, F.H. NOCITI, Jr.3, A.W. SALLUM4, and E. SALLUM2, 1Piracicaba Dental School, Piracicaba - SP, Brazil, 2Piracicaba Dental School - UNICAMP, Piracicaba, Brazil, 3University of Campinas, Piracicaba-SP, Brazil, 4FACULDADE DE ODONTOLOGIA DE PIRACICABA - UNICAMP, Piracicaba, Brazil

Objective: Gingival recession is frequently associated with non-carious cervical lesion, complicating its treatment. The aim of this study was to evaluate the success of the treatment of gingival recession associated with non-carious cervical lesions by a connective tissue graft alone (CTG – control group), or in combination with a resin-modified glass ionomer restoration (CTG+R – test group).

Methods: Forty patients presenting Miller Class I buccal gingival recessions, associated with non-carious cervical lesions were selected. The defects were randomly assigned to receive either CTG or CTG+R. Bleeding on probing (BOP), probing depth (PD), relative gingival recession (RGR), clinical attachment level (CAL), and cervical lesion height (CLH) coverage were measured at the baseline and 45 days, 2, 3, and 6 months after the treatment.

Results: Both groups showed statistically significant gains in clinical attachment level and soft tissue coverage. The differences between groups were not statistically significant in BOP, PD, RGR and CAL, after 6 months. The percentages of CLH covered were 74.88±8.66% for CTG and 70.76±9.81% for CTG+R (P>0.05). The estimated root coverage was 91.91± 17.76% for CTG and 88.64±11.9% for CTG+R (P>0.05).

Conclusion: Within the limits of the present study, it can be concluded that both procedures provide similar soft tissue coverage after 6 months and the presence of glass ionomer restoration may not prevent the root coverage achieved by connective tissue graft.


0840 (116751)

Coronally Advanced Flap to Treat Gingival Recession and Cervical Lesion. E. SALLUM1, M. SANTAMARIA2, D. FEITOSA2, F. SUAID2, M. CASATI1, F.H. NOCITI, Jr.3, and A.W. SALLUM4, 1Piracicaba Dental School - UNICAMP, Piracicaba, Brazil, 2Piracicaba Dental School, Piracicaba - SP, Brazil, 3University of Campinas, Piracicaba-SP, Brazil, 4Piracicaba Dental School, Piracicaba, Brazil

Objective: The aim of this study was to evaluate the long-term success of the treatment of gingival recession associated with non-carious cervical lesions by a coronally advanced flap alone (CAF), or in combination with a resin-modified glass ionomer restoration (CAF+R).

Methods: Sixteen patients with bilateral Miller Class I buccal gingival recessions, associated with non-carious cervical lesions were selected. The defects received either CAF or CAF+R. Bleeding on probing (BOP), probing depth (PD), relative gingival recession (RGR), clinical attachment level (CAL), cervical lesion height (CLH) coverage were measured at the baseline and 6, 12 and 24 months after the treatment.

Results: Both groups showed statistically significant gains in clinical attachment level and soft tissue coverage. The differences between groups were not statistically significant in BOP, PD, RGR and CAL, after 2 years. The percentages of CLH covered were 51.57±17.2% for CAF+R and 53.87±12.6% for CAF (P>0.05). The estimated root coverage was 80.37±25.44% for CAF+R and 83.46±20.79% for CAF (P>0.05).

Conclusion: Within the limits of the present study, it can be concluded that both procedures provide similar soft tissue coverage after 2 years and the glass ionomer restoration may not prevent the root coverage achieved by coronally advanced flap.


0841 (118854)

Particulate Ovine Bone in the Treatment of Periodontal Defects. J.C. ZIELAK, T.M. DELIBERADOR, U. ALMEIDA, A.F. GIOVANINI, C.C. GONZAGA, G.M. CORRER, F. RYCHUV SANTOS, and A. WACHESKI, Positivo University, Curitiba, Brazil

Objectives: The neoformation of bone can be aided by bone substitutes (bone inductive and/or conductive) with well-known histological and clinical activities. The present study evaluated the effect of particulate ovine bone sterilized by autoclave and ethylene oxide in periodontal defects of wistar rats under light microscopy.

Methods: The particulate ovine bone was sterilized in autoclave (Sa) and by immersion in ethylene oxide (Se). A periodontal defect was created using a low-speed carbide bur under irrigation in 18 animals, which were divided in 6 groups: Group 1Sa and 1Se received biomaterial graft and had the euthanasia in 1 week. Group 3Sa and 3Se also received the biomaterial and had the euthanasia in 3 weeks. In the control group a blood clot was maintained for 1 (1C) and 3 (3C) weeks.

Results: Histological analysis revealed a more intense inflammatory infiltrate in 1Sa and 1Se than 1C, with the occurrence of macrophages and the presence of multinucleated giant cells (MGC), also more evident than in 1C. 1Se demonstrated a more intense angiogenesis. 3Se presented a similar inflammatory degree to 1C. 3Sa presented more intense occurrence of macrophage, MGC and angiogenesis than 3C, although the bone formation was similar. Regarding the repair of median region diameter defect, 3Se presented an average of 1.3mm, while 3C presented a 0.6mm and 3Sa presented a 0.4mm defect diameter.

Conclusions: It was concluded that the particulate ovine bone sterilized by autoclave has a potential as bone grafting biomaterial.


0842 (117627)

Root coverage procedures for the treatment of localized recession-type defects. L. CHAMBRONE1, F. SUKEKAVA2, M. ARAUJO3, F.E. PUSTIGLIONI4, L. CHAMBRONE5, and L.A. LIMA2, 1University of São Paulo, Cidade Universitária - São Paulo, Brazil, 2University of São Paulo, São Paulo, Brazil, 3Universidade Estadual de Maringá, Maringá, Brazil, 4University of Sao Paulo, São Paulo, Brazil, 5Methodist University of São Paulo, Sçao Bernardo do Campo, Brazil

Objectives: The aim of this systematic review was to evaluate the effectiveness of different root coverage procedures in the treatment of recession-type defects.

Methods: The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched up December 2007. There were no restrictions with regard to publication status or language of publication. Only randomized controlled clinical trials (RCTs) of at least 6 months' duration evaluating recession areas (Miller's Class I or II > 3 mm), and that were treated by means of PPS procedures were included. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios for dichotomous outcomes.

Results: Twenty three RCT provided data. Only one trial was considered to be at low risk of bias. The results indicated a significant greater reduction in gingival recession and gain in keratinized tissue for subepithelial connective tissue grafts (SCTG) compared with guided tissue regeneration with resorbable membranes. There was a significant gain in the clinical attachment level for acellular dermal matrix grafts compared with coronally advanced flaps (CAF) with mean difference of 0.62 mm. A significant greater gain in the keratinized tissue was found for enamel matrix protein when compared to CAF (0.40 mm) and for STCG when compared to GTR rm. Limited data exist on aesthetic condition change related to patient's opinion and patients' preference to a specific procedure.

Conclusions: Subepithelial connective tissue grafts, CAF alone or associated to other biomaterial and GTR may be used as root coverage procedures for the treatment of localized recession-type defects. In cases where both root coverage and gain in the keratinized tissue are expected, the use of SCTG seems to be more adequate. More RCTs are necessary to identify possible factors associated to the prognostic of each PPS procedure.


0843 (114074)

GEM 21S in the management of localized aggressive periodontitis patients. M. TAALAB, W.A.E.A. AMER, F.R. ABU EL ENIN, and M.M. MAHMOUD, University of Alexandria, Alexandria, Egypt

Growth factors are potent bioactive proteins known by being mitogenic and chemotactic agents. Objectives: of this study were to evaluate the effect of using platelet derived growth factor( PDGF) in conjunction to Beta Tricalcium Phosphate (GEM 21Smaterial) in the management of localized aggressive periodontitis (LAP) in comparison to Decalcified freeze dried bone allograft(DFDBA).Methods:14 intraosseous defects in 6 patients were divided into2groups,Group1(n=7)was treated with GEM 21S material,Group2(n=7)treated with DFDBA. Clinical measurements included clinical attachment loss (CAL), probing depth (PD), plaque & Gingival indices. While the radiographic measurements included bone density and bone height as assessed by using Image J program. Results: The CAL,PD(using paired t test analysis P<0.05),gingival and plaque indices(using WSR test analysis P<0.05) showed statistically significant reduction by the two groups. While the radiographic results (using paired t test analysis) proved that the increase in percent change in bone density was greater for group 1 than group 2(40.58±22.65versus13.73±5.74 respectively P < 0.05) and the same for percent change in bone height (42.15±10.86versus20.54 ± 6.98 respectively P < 0.05). Conclusion: GEM 21S material proved to be effective in the management of intraosseous defects in LAP patients as compared to DFDBA.


0844 (117457)

Bovine Pericardium in Gingival Recessions: A Controlled Clinical Study. M. SCHLEE, Private Praxis, Forchheim, Germany, D. NIKOLIDAKIS, Radboud University Nijmegen, Medical Centre, Nijmegen, Netherlands, and A. SCULEAN, Semmelweis University of Medicine, Budapest, Hungary

Objectives: Connective tissue grafts (CTG) and cellular human dermis (ADM) have been demonstrated to result in predictable coverage of gingival recessions and increase in soft tissue when used in plastic periodontal surgery. Recently, a collagen membrane made of acellular deproteinised bovine pericardium (BP) (Tutoplast®, Tutodent, Neunkirchen am Brand, Germany) has been used in general surgery for closing ventricular septae and hernia. However, at the time being there are no data from clinical studies evaluating recession coverage using BP.

Aim: To compare clinically the treatment of gingival recessions with BP or CTG.

Methods: Two groups of 14 healthy non-smoker patients presenting either Miller Class I or II recessions, were treated with a coronally advanced split flap technique. 62 recessions were treated with BP (test) and 64 with CTG (control). Gingival recession (GR), Probing Depth (PD), Clinical Attachment Level (CAL), as well as width and thickness of keratinized gingiva (KG) where assessed at baseline (i.e. before surgery) and at 6 months after.

Results: In the test group, the early wound healing appeared to be more delayed as indicated by a more pronounced inflammatory reaction. However, at 6 months 39 out of 62 recessions (62.9%) where completely covered. GR changed from 2.4 ± 1.0 mm to 0.3 ± 0.3 mm (p< 0.0001). The width of KG improved from 1.6 ± 0.7 mm to 2.5 ± 0.8 mm (p< 0.0001). In the control group GR where statistically significantly reduced from 2.8 ± 1.2 mm to 0.2 ± 0.3mm (p< 0.001). Both treatment modalities demonstrated a significant coverage of recessions (p< 0.0001). Neither the initial values (p =0.3001) nor the results differed (p = 0.2382) statistically significantly between the 2 groups.

Conclusions: The use of BP for recession coverage resulted in comparable clinical outcomes to those obtained with CT.


0845 (116428)

Free Gingival Graft Healing: Effects of Smoking. C. SILVA, Faculdade Ingá - Uningá, Maringá - PR, Brazil, É. RIBEIRO, Universidade Federal Da Bahia, Salvador - BA, Brazil, A.W. SALLUM, FACULDADE DE ODONTOLOGIA DE PIRACICABA - UNICAMP, Piracicaba, Brazil, and D.N. TATAKIS, Ohio State University, Columbus, OH

Objectives: This clinical study aimed to evaluate the influence of tobacco smoking on free gingival graft (FGG) healing, by assessing FGG dimensional changes and donor site wound healing.

Methods: Twelve non-smokers and ten smokers treatment planed for FGG to augment keratinized tissue dimensions, due to lack of attached gingiva associated with oral hygiene deficiency, high frenulum attachment or gingival recession, completed the study. Probing depth (PD), gingival margin position (GM), clinical attachment level (CAL), keratinized tissue width (KT), gingival thickness (GT), and FGG dimensions (height, length, and area) were assessed and recorded before surgery, and 7, 15, 30, 60, and 90 days postoperatively (PO). The palatal donor area was evaluated for immediate bleeding (IB) and complete wound epithelialization (CE). Differences between the 2 groups (smokers and non-smokers) were statistically analyzed.

Results: Postoperatively, FGG dimensions changed significantly. At 90 days PO, FGG height, length, and area were respectively reduced by 31%, 22%, and 44% in non-smokers and by 44%, 25%, and 58% in smokers, with no significant differences between the 2 groups (p>0.05). KT increases were observed in both groups (5.5 mm and 4.1 mm in non-smokers and smokers, respectively). IB was significantly more prevalent in non-smokers (75%) compared to smokers (30%) (p=0.04). At 15 days PO, donor site complete epithelialization was much more prevalent in non-smokers (92%) than in smokers (20%) (p<0.002).

Conclusions: Smoking alters FGG donor site wound healing, by reducing bleeding incidence and by delaying epithelialization, without discernible effects on the graft itself.


0847 (116388)

A Diode Laser as An Adjunct to Periodontal Surgery. J. SANZ MOLINER, State University of New York - Buffalo, Barcelona, Spain, and S. CIANCIO, State University of New York SUNY Buffalo, Buffalo, NY

Objective: The purpose of this study was to clinically compare the use of the Odyssey diode laser (DL) during periodontal surgery (PS) to conventional periodontal surgery (CPS). Methods: Thirteen patients with periodontal pockets in two different quadrants with at least one tooth exhibiting a probing depth (PD) of >7 millimeters (mm) and clinical attachment levels (CAL) of >7mm were selected. One side was randomly selected to receive CPS and the other CPS in conjunction with DL. The DL was used to de-epithelialize the inner aspect of the periodontal flap and photo-biostimulate the surgical area. PD, CAL, plaque index (PI), gingival index (GI) were evaluated at baseline, 6-weeks and 5-months. Pain scale assessment (PS), quantity of pain medication (QPM) used, tissue edema (TE), tissue color (TC) were evaluated one week following PS. Results: Treatment differences were analyzed using McNemar's test, paired t-tests or Wilcoxon Signed Rank Test. No statistical differences of CAL gain, PD, GI, PI reduction between test group (TG) and control groups (CG) were seen. No statistical differences for TC and PS values between TG and CG were seen. Statistically greater TE reduction was demonstrated in TG compared to CG (p≤0.05). Borderline significance (p=0.10) was seen for QPM post surgically, with a lesser quantity required in the diode laser group (TG). The PS and QPM values were statistically different the 7th postoperative day in the laser group (TG) compared to CG (p<0.05). The first surgical treatment performed in both groups was rated as more painful than the second (p<0.05). When data was analyzed from the first surgical procedure, it was found that TG was less painful than CG (p<0.001). Conclusion: The use of the diode laser as an adjunct to periodontal surgery provided less post operative pain and tissue edema and was safe to oral tissues.


0849 (118108)

Diode Laser or Photodynamic Therapy for Residual Periodontal Pockets?. I. CAPPUYNS, N. CIONCA, C. GIANNOPOULOU, and A. MOMBELLI, School of Dental Medicine, University of Geneva, Geneva, Switzerland

Objectives: To compare the clinical effect of antimicrobial diode soft laser therapy (DSL) or photodynamic therapy (PDT) with conventional deep scaling and root planing (SRP) in the treatment of residual pockets of patients with chronic periodontitis.

Methods: Single center, three arm randomized longitudinal study including 22 patients with residual pockets after completion of non-surgical treatment. One site with a probing pocket depth (PPD) ≥5 mm, clinical attachment loss ≥2 mm and bleeding upon probing (BOP) was selected in each of three quadrants. Residual pockets were first debrided with an ultrasonic device. Next, one quadrant was subjected to SRP with Gracey curettes, one quadrant was treated with DSL (wavelength 810 nm, output power 1W, Elexxion Dental Academy), and one quadrant was treated with PDT (690 nm, 1W, phenothiazine chloride as photosensitizer, Helbo Photodynamic Systems). PPD, BOP and gingival recession (REC) were evaluated at baseline, and again 2 and 6 months after treatment (M2, M6).

Results: PPD significantly decreased for all three treatments, on average from 5.5±0.7 to 3.8±1.3 (M2) and 3.8±1.2 (M6) (p<0.001). The BOP also significantly decreased from 100% to 65% (M2) and 55% (M6) p<0.01). No significant differences were observed between the groups at any time point. REC significantly increased from baseline to M6 in sites treated by DSL and PDT (p<0.05). 25 of the 66 study sites still presented a PPD ≥4 mm and bled on probing at M6. 12 of these sites clustered in 4 subjects, where the response was unsatisfactory in all three study sites and could not be associated with a specific form of therapy.

Conclusion: All three treatments resulted in a significant clinical improvement. Where results were unsatisfactory, patient specific factors, rather than the treatment allocation, seemed to influence the clinical outcome.


0850 (118653)

A Retrospective Study on The Survival of Root-resected Molars. H.Y. WANG1, Y.-P. HO2, K.-Y. HO2, Y.M. WU3, and C.C. TSAI2, 1Kaohsiung Medical University and Hospital, Kaohsiung City, Taiwan, 2Kaohsiung Medical University and Hospital, Kaohsiung, Taiwan, 3Kaohsiung Medical University, Kaohsiung, Taiwan

Objective: Treatment of furcation ¨Cinvolved multirooted teeth is a great challenge for periodontists. Root resection to remove the most severely destructed root(s) is one of the treatment modalities to simplify the tooth topography and to improve the maintenance. The aim of this investigation was to analyze factors associated with the clinical outcome of root resection by a retrospective study. Material and Method:

This investigation consisted of 82 subjects (34 males, 48 females). The mean age of the patients was 51years (ranged from 35 to77years). Data including the reasons for root resection, and the type of restoration, occlusion, the reason and time for root extraction, frequency of re-call visits, personal habits (smoking, alcohol drinking, betel quid chewing), systemic diseases and root survival time after root resection were collected. Results: In a total of 91 resected teeth included in the present study, 46 were maxillary first molars (50%), 28 were mandibular first molars (34%) and 17 were second molars (16%). The majority (80%) of root resections were done due to severe periodontal disease followed by root/crown fractures (15%) and others (5%). The time of follow-up was ranging from 7 years to one month. The mean survival time was 3 years with 49/91 (52%) longer than 3 years. Twenty-nine of the root-resected molars (32%) were extracted, among them, 20 roots (69%) were due to continuing periodontal destruction, 5 roots (17%) were due to fracture, 4 roots were due to others (including endodontic failure). Conclusion: The major reason for the extraction of resected-roots was due to the continuing periodontal destruction, therefore, the pre-surgical evaluation and post-surgical oral hygiene education and maintenance and regular re-call visits were important for the long-term survival of resected-roots.


0851 (116601)

Masticatory muscle activity and arousal levels in sleeping guinea pigs. T. KATO1, A. YOSHIDA2, Y. MASUDA3, and T. MORIMOTO3, 1Osaka University Graduate School of Dentistry, Suita, Osaka, Japan, 2Osaka University, Suita, Osaka, Japan, 3Matsumoto Dental University, Shiojiri, Nagano, Japan

Objectives: In patients with sleep bruxism, increased masseter muscle activities occur in association with micro-arousals mostly in light NREM sleep. Physiological correlates between muscle activity and arousal levels may underlie the exaggerated motor activity in sleep bruxism. The aim of this study was to assess cortical activity and heart rate in association with masticatory muscle activities in NREM sleep of the guinea pig.

Methods: Young adult guinea pigs were prepared for chronic experiments. Electroencephalogram (EEG), electro-occulogram, electrocardiogram and electromyograms from the dorsal neck, masseter and digastric muscles were recorded for 3 hours under audio-video surveillance. Sleep stages were scored for every 10-second epoch. Delta power of EEG activity, mean heart rate and integrated muscle activities were calculated for each epoch during wakefulness and NREM sleep. Muscle activities during sleep epochs were normalized by mean activity during wakefulness. Standard deviations of normalized muscle activity were used for estimating the variability of muscle activity. Muscle activities for all epochs were classified into four levels using the cut-off points of 1st, 2nd and 3rd quartile values for each muscle.

Results: Mean muscle activity was significantly higher for masseter (24.1 %) than for digastric muscle (9.5 %) during NREM sleep (p<0.01). The variability of muscle activity was larger for masseter (37.2 %) than for digastric muscle (25.7 %) (p<0.05). Mean delta power was higher and mean heart rate was lower during NREM sleep than wakefulness (p<0.01). Mean delta power significantly decreased as muscle activity levels increased for two muscles (p<0.01). Mean heart rate was significantly increased as masseter activity level increased (p<0.01), while no difference was noted for digastric muscle.

Conclusion: Although the magnitude and variability of muscle activity differ between masseter and digastric muscles, the graded arousal levels involve a degree of motor activation for individual masticatory muscles during sleep.


0852 (114756)

Sleep Disordered Breathing Symptoms and Craniofacial Morphology in Children. H. TSUDA, S. FASTLICHT, F.R. ALMEIDA, and A.A. LOWE, University of British Columbia, Vancouver, BC, Canada

Objective:

The aim of this study was to assess children enrolled in orthodontic teaching clinic as to the relationship between sleep disordered breathing(SDB) symptoms and craniofacial morphology with a standardized questionnaire, cephalograms and study models.

Methods:

All parents were asked to complete a SDB questionnaire at the commencement of orthodontic therapy. Higher scores indicate a greater probability of disease and/or a reduced quality of life. The UBC cephalometric analysis included upper, lower and total face height, hyoid position, soft palate length, mandibular length, vertical airway length, overjet and overbite. The measurements of the study models included upper and lower dental width, depth and palatal height. The subjects were divided into two two groups according to their dentition.Statistical analysis were performed with SPSS 10.0 software and Spearman rank correlations.

Results:

A total of 173 children (male 50.3%, mean age 10.1±1.7years) completed the OSA18questionnaire, the cephalometric (CA) and model (MA) analysis. The questionnaire suggested that only two children in the UBC orthodontic pool (1.2%) had an increased chance of exhibiting SDB. However, loud snoring, mouth breathing and difficulty awakening were reported in more than 20% of the children. In total, a higher total score correlated with retroclined upper incisors (CA) and high palatal height (MA) (p<0.05). Although there was no significant score differences between the groups, a higher total score correlated with a long soft palate (CA)(p<0.05) in the deciduous dentition group and a high palatal height (MA) in the mixed dentition group (p<0.05).

Conclusion:

The incidence of SDB in an undergraduate orthodontic teaching clinic appears to be relatively low at 1.2%. SDB symptoms were related to many cephalometric variables and study model measurements that differentiated between the decidous and mixed dentition groups. It appears that attributes of SDB in growing children may be in part related to specific craniofacial variables.


0853 (121355)

Relationships between personality traits and sleep bruxism. H. ITOH1, T. HAKETA2, T. SUGANUMA1, and K. BABA1, 1Showa University School of Dentistry, Tokyo, Japan, 2Tokyo Medical & Dental University, Tokyo, Japan

Objective: This study investigated the relationship between personality traits as evaluated by Temperament and Character Inventory (TCI) and sleep bruxism levels as measured by nightly masseter EMG recordings.

Methods: Forty-six dental students (average age 24.0 +/- 2.3, ranges 22-32, 54% female) participated in the study. They recorded EMG activity from the right masseter muscle by means of a portable EMG devise at home for 6 consecutive nights. The first night EMG data were excluded from the analysis in order to avoid the first night effect. Using remaining 5 night data, all EMG elevations above 20% of each subject's maximum voluntary contraction level were quantified with regard to duration per hour of sleep. The variable, which was total duration of bruxism per hour, was established for each night and then averaged across the 5 nights for each subject. Personality traits were assessed using the TCI, a self-report questionnaire based on Cloninger's 7 factor model. The Japanese version of TCI includes 240 items that discriminate 4 temperament and 3 character scales. The temperament dimensions assessed novelty seeking, harm avoidance, reward dependence, and persistence, while the character dimensions assessed self-directedness, cooperativeness, and self-transcendence. The EMG data were considered as a dependent variable, while the questionnaire data were considered as independent variables. A multiple stepwise regression (MSR) analysis was conducted between the independent and dependent variables.

Results: The MSR analysis revealed that the harm avoidance score was significantly associated with the sleep bruxism variable, where the lower harm avoidance score was associated with the longer sleep bruxism durations (Regression coefficient : -1.15, 95% confidence interval: -1.88 to -0.41, p=0.003).

Conclusion: The study results suggest that individuals with a lower harm avoidance score, who are relaxed and optimistic; bold and confident; outgoing; and vigorous, are more likely to exhibit longer sleep bruxism.


0854 (119311)

Bruxism: Relationship with Quality-of-Life, Occlusion and Parafunctional Habits in Children. P.M. CASTELO, M.B.D. GAVIÃO, and T.S. BARBOSA, State University of Campinas, Piracicaba, Brazil

Objectives: Bruxism is one of a number of parasomnias, with multifactorial etiology that includes central neurological factors, peripheral stimulus, and medicines. However, there is no consensus in the literature about the importance of each factor, and there is a need for further investigations on the etiology of bruxism. This study evaluated the quality-of-life (QL) of 65 children, aged 6-8 years, with (30.8%) and without (69.2%) signs and symptoms of nocturnal bruxism, and its relationship with divorce or death of their parents, occlusion, and presence of parafunctional habits. Methods: Data were collected in caries-free children from public schools, by applying a translated and validated version of the Autoquestionnaire Qualite de Vie Enfant Image (AUQEI), clinical examination and interview with the parents. AUQEI is a generic instrument which explores the sub domains family, autonomy, function, and leisure. The diagnostic criteria for bruxism was the presence of both wear facets on permanent teeth and parent's report (at least three nights a week). Logistic regression stepwise-backward evaluated the association of AUQEI's scores, early parent's loss or divorce, presence of sucking habit, nail biting, enuresis nocturna, malocclusion, occlusal interference, and crossbite with bruxism, as the dependent variable, controlling for gender and age. Results: AUQEI's and sub domains's scores (Cronbach's alpha coefficient= 0.7) did not differ significantly between bruxers and non-bruxers (p>0.05; t-test). Only the independent variable "presence of crossbite" was significantly associated with bruxism (p≤0.05; odds ratio: 4.68; CI: 0.99-22.23). Conclusion: Although several research articles have emphasized the importance of emotional disturbances on the etiopathogenesis of bruxism, in the sample studied bruxers presented similar scores of QL than non-bruxers, and children with crossbite were significantly more likely to present such parafunction. Thus, peripheral factors may not be refuted in the etiology of bruxism. (Financial support: FAPESP 07/05760-2).


0855 (119443)

Correlation between morphological characteristic of mouth and awareness of bruxism. M. YAMAUCHI1, M. MIO1, and M. TOYOTA2, 1Asahi University, MIzuho, Japan, 2Asahi University, Mizuho, Japan

Objectives:When there is bruxism, it is reported that tooth attrition, wedge shaped defect, etc. exist. The relation of the above-mentioned morphological characteristic of mouth relevant to awareness of bruxisim was investigated

Methods:455 men (53.6 years old) and 45 women (53.3 years old) were investigated. 26 items such as awareness of bruxism, cheek bite marks, a palatine torus, a mandibular torus, a tooth attrition, a wedge shaped defect,, temporomandibular joint noise, and pain, were investigated. Questionnaire survey of 28 items such as temporomandibular joint noise, pain, and a lifestyle, were performed. The multivariate analysis (qualification theory ± and II theory) was conducted about the diagnosis item and the questionnaire item, and the relation for 54 items was considered.

Results:Pain existed in seven examples. Temporomandibular joint noise existed in 75 examples.

Cheek bite marks existed in 179 examples. The palatine torus existed in 25 examples.

The mandibular torus existed in 88 examples. The wedge shaped defect existed in 79 examples. Correlation was accepted in existence of a palatine torus and existence of temporomandibular joint noise as a result of the multivariate analysis(P>0.05).

Conclusions:Although many views which make existence of bruxism suspect were observed, there was no correlation with awareness of bruxism and other items.

Existence of bruxsim is checked from the muscle activity during sleep, and relation with the morphological characteristic should be examined.


0856 (115626)

Use of Prescribed Sleeping Pills is Associated with Self-Reported Bruxism. K. AHLBERG1, A. SAVOLAINEN2, M. PARTINEN3, C. HUBLIN4, A. ALAKUIJALA1, J. SINISALO5, M. KÖNÖNEN1, and J. AHLBERG1, 1University of Helsinki, Helsinki, Finland, 2Finnish Broadcasting Company, Helsinki, Finland, 3Rinnekoti Research Centre, Espoo, Finland, 4Institute of Occupational Health, Helsinki, Finland, 5Helsinki University Central Hospital, Helsinki, Finland

Background: Previous studies among multiprofessional media personnel with or without irregular shift work revealed that frequent bruxers had more often visited a physician within the preceding 12 months (p<0.01), and that bruxism was significantly more prevalent in those subjects that suffered from disrupted sleep (p<0.05) (Ahlberg et al: Acta Odontol Scand 2003; 61: 315-18, Head Face Med 2008; 4: 4). The aim of the present study was to investigate whether the use of prescribed sleeping medicine was associated with reported bruxism while controlling the possible effects of shift work, age, gender, and disrupted sleep.

Objectives: 874 media workers of the Finnish Broadcasting Company. Mean age was 45.6 (SD 10.4) years in males (53 %) and 42.7 years (SD 10.6) in females (47 %).

Methods: The participants completed a questionnaire that covered demographic items, the use of sleeping pills within the past three months (prescribed by a physician), insomnia (International Classification of Sleep Disorders, Diagnostic and Statistical Manual of Mental Disorders IV), and frequency of self-assessed bruxism (never, seldom, sometimes, often, continually).

Results: Altogether 18.3 % of subjects had used prescribed sleeping pills within the past 3 months, 9.4 % had done so at least once a week, and 2.4 % daily. Of all subjects, 10.1 % reported frequent bruxism (present ‘often' or ‘continually'). According to logistic regression, the probability of frequent bruxism was significantly positively associated with younger age (p<0.01), disrupted sleep (p<0.05), and with more frequent use of sleeping pills (p<0.05).

Conclusions: Self-reported disrupted sleep and frequent bruxism seem to be related in healthy subjects. In addition, many of those who seek help for their sleep problem may also brux their teeth which could be useful knowledge for all health care professionals. The complex interactions of sleep and bruxism, and perhaps pain, need further investigation.


0857 (115753)

Current Orofacial Pain Experience and Self-Reported Bruxism in Healthy Subjects. J. AHLBERG1, K. AHLBERG1, A. SAVOLAINEN2, C. HUBLIN3, M. PARTINEN4, A. ALAKUIJALA1, J. SINISALO5, and M. KÖNÖNEN1, 1University of Helsinki, Helsinki, Finland, 2Finnish Broadcasting Company, Helsinki, Finland, 3Institute of Occupational Health, Helsinki, Finland, 4Rinnekoti Research Centre, Espoo, Finland, 5Helsinki University Central Hospital, Helsinki, Finland

Background: A previous study among healthy adults revealed that the presence of orofacial pain (OP) was over six times more likely in those reporting frequent bruxism (p<0.001), and also that disrupted sleep was an independent significant factor associated with OP (p<0.001) (Ahlberg et al: Acta Odontol Scand 2005; 63: 213-7). However, the relationship of bruxism and orofacial pain has remained unclear. The aim of the present study was to investigate whether perceived OP and self-reported bruxism were associated when the effects of somatization, alexithymia, perceived insomnia, gender, and age were simultaneously controlled.

Objectives: Altogether 874 media workers of the Finnish Broadcasting Company. Mean age was 45.6 (SD 10.4) years in males (53 %) and 42.7 years (SD 10.6) in females (47 %).

Methods: The participants completed a questionnaire that covered demographic items, current orofacial pain experience (Research Diagnostic Criteria for Temporomandibular Disorders), insomnia (International Classification of Sleep Disorders, Diagnostic and Statistical Manual of Mental Disorders IV), somatization (Symptom Check List -90-R), alexithymia (Toronto Alexithymia Scale -20), and frequency of self-assessed bruxism (never, seldom, sometimes, often, continually).

Results: Current OP (present within the last month) was found overall in 19.6 % of the subjects. Those reporting insomnia that had lasted at least a month also reported significantly more often current OP (p<0.01). Logistic regression revealed that frequent bruxers (10.6 %) were 3.8-10.8 times (p<0.001) more likely to have OP. Female gender (p<0.01), younger age (p<0.05), somatization (p<0.001), and disrupted sleep (p<0.05) were also independently associated with current OP.

Conclusions: Somatization is a central factor to be controlled for when studying OP. Similarly, the relationship between insomnia and the presence of pain should be borne in mind. Nevertheless, self-reported bruxism and orofacial pain experience seem to be independently associated in healthy adults.


0859 (114963)

Effect of serotonergic drugs on the attrition rate in rats. F.M. GÓMEZ1, J.E. ORTEGA2, A. ARRUE1, and M.T. GIRALT1, 1Faculty of Medicine and Odontology, University of the Basque Country, Bilbao, Spain, 2Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM and University of the Basque Country, Bilbao, Spain

Central catecholaminergic neurotransmitters, especially dopamine and serotonine, have been involved in the etiopathogenesis of bruxism. In this context, the treatment with selective serotonine reuptake inhibitors (SSRI) induces the occasional appearance of bruxism as an adverse effect which is generally attenuated by adding buspirone, an anxiolytic drug, to the antidepressant treatment. Jaw clenching, accompanied by exaggerated tooth wear, is also frequently observed in up to 70% of ecstasy users.

Objectives: The aim of this study was to test the ability of diverse serotonergic drugs to modulate tooth wear in an animal model, in which the measurement of the attrition rate of the lower incisors is considered as an index of bruxism in the rat.

Methods: Male Sprague-Dawley rats were treated daily i.p. with either sertraline (10 mg/kg), fluoxetine (10 mg/kg), amitriptyline (10 mg/kg), ecstasy (10 mg/kg) or buspirone (3 mg/kg) for 7 days. A group of rats (n=14) was treated with saline and used as a control. All animals were fed with a soft powder diet.

Results: After finishing the treatment, only the group treated with ecstasy (n=12) showed a significant increase in incisal attrition (4.81 ± 0.4 mm; p=0,001) in relation to the control group (3.44 ± 0.1 mm). This increase was prevented by a buspirone injection 15 min before the administration of ecstasy.

Conclusions: Globally, our experimental data are in accordance with those of previous clinical reports in which ecstasy was seen to induce secondary bruxism more frequently than SSRI. The results also support that the measurement of the incisal attrition rate is, indeed, a reliable index of experimental bruxism.

Supported in part by the University of the Basque Country (P.I. 00095.327-E-13954/01) and the Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM.


0860 (121267)

Upper airway effects with intra-oral appliance for obstructive sleep apnea. A.L.P. RANIERI, and J.T.T. SIQUEIRA, Faculdade de Medicina do Hospital das Clinicas da Universidade de São Paulo, Sao Paulo, Brazil

The main action mechanism of intra-oral appliances (IOA) for mandibular advancement is the increase in upper airway (UA). This increase is reached after the correct titration of the IOA, and with it in the mouth. Objective: Thus, the aim was to assess the increase of the upper airways through cephalometry before and after treatment in patients responsive to IOA. Methods: We evaluated 6 patients (4 men and 2 women), with an average age of 45.6 years, in use of IOA. All patients underwent the cephalometry with and without the IOA, and then the analysis with the same references points and lines were made. Results: The reduction of apnea and hypopnea index (AHI) was statistically significant decreasing from 23.4 to 10.2 (p = 0001) after 6 months of use in all patients. There was an increase of the regions of the anterior wall of velopharynx (p = 0.04) and posterior wall of the hypopharynx (p = 0.03). Conclusion: With these results we concluded that the patients respond to treatment with AIO have increased the assessment of UA through cephalometry.


0861 (120439)

Heart Murmur and MVP in a TMJ Surgical Population. S.L. MYERS, S. KAIMAL, S. BEIRAGHI, W. KANG, and J.R. FRICTON, University of Minnesota, Minneapolis, MN

Overlap of common signs and symptoms, such as generalized hyperlaxity, flexibility and/or extensibility, has led investigators to hypothesize that mitral valve prolapse (MVP) and some temporomandibular joint (TMJ) disorders (TMD) share common underlying collagen defects. In our previous 2008 IADR abstract, we found the incidence of MVP and/or heart murmur (HM) in a population of subjects with TMD was comparable to the general population. Objectives: Investigate the subset of TMJ surgical subjects, in the National Institute of Dental and Craniofacial Research's TMJ Implant Registry and Repository (NIDCR's TIRR), with a history of HM, MVP or both. Methods: TMJ surgical subjects, recruited to NIDCR's TIRR over the past six years, were evaluated for HM and MVP through the Registry database. Results: Current NIDCR's TIRR population consists of 985 subjects (866 F, 119 M) with a history of TMD. 95 subjects (89 F, 6 M) reported a history of HM and/or MVP; 51 (54%) of these had a history of TMJ surgery and 36 (38%) had a history of TMJ implants. 32 subjects reported MVP (31 F, 1 M); 21 (66%) of these had a history of TMJ surgery and 15 (47%) had a history of TMJ implants. Subjects reporting either MVP or heart murmur ranged from 21 to 76 years of age. Conclusions: Subjects identified with MVP and HM, in the TMD surgical population studied, were more likely to have had TMJ surgery with or without implants. Further evaluation of this subset by molecular methods is underway.

This project is supported in part by NIDCR/N01-DE-22635.


0862 (117010)

Analysis of Criteria for MRI Diagnosis of TMJ Disc Displacement. C. RILEY, Harvard University, Boston, MA, and J. SHAEFER, Harvard University, Hingham, MA

Objectives: The most common TMJ arthropathy is disc displacement (DD), with 1/3 of patients who seek treatment for TMD experiencing disc derangement. DD, however, does not always correlate with TMJ dysfunction—at least in the way displacement is currently determined. The gold-standard for diagnosis is via MRI, comparing the location of the posterior band of the disc to the 12 o'clock position on the condyle. Using this method, DD is poorly associated with two common measures of dysfunction: TMJ arthralgia and MRI effusions (suggesting inflammation). Perhaps more advanced DD is best predictive of dysfunction, while more mild displacement can be considered a variant of normal. We contend that the criteria for determining DD should be related to a functional position to better delineate the association between DD, MRI effusions, and arthralgia.

Methods: The study compares the standard protocol for diagnosis of DD to an alternative protocol. The latter is based on the functional relationship between the condyle, disc, and articular eminence, using the point on the condyle that intersects with a line perpendicular to the posterior slope of the eminence as a reference for disc position. The disc position is measured using both protocols, and the diagnoses are compared in terms of how they correlate with TMJ arthralgia and/or MRI effusions. The proposition is that these alternative criteria will offer a better understanding of the role of DD in the pathophysiology of TMJ dysfunction.

Results: Preliminary research demonstrates a trend of increased correlation between DD and symptoms using the alternative versus standard protocol for diagnosis (0.58 kappa agreement between protocols; the alternative protocol showed a 15% increase in specificity to predict arthralgia).

Conclusions: The use of the standard criteria in former studies may explain the discrepancy between DD and TMJ dysfunction reported previously. Further data collection/analysis is underway.


0863 (120354)

Validation of Dental Pain/Anxiety Assessment Using EMA System. R. KUROI1, H. MINAKUCHI1, C. SAKAGUCHI1, A. KAWAKAMI1, Y. MATSUKA1, H. OKADA2, and T. KUBOKI1, 1Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan, 2Okayama University Hospital, Okayama, Japan

Objectives: Ecological Momentary Assessment (EMA) has been utilized to assess real-time physical and/or mental conditions in psychiatry. Recently, a cellular-phone based EMA (c-EMA) system has been introduced to improve the real time accessibility to the patients. In this study, validity of this c-EMA system was investigated in comparison to the paper-based self-administered questionnaire assessment.

Methods: Twenty one residency program dentists (male/female: 12/9, average age=25.5+/-1.1 yrs) were recruited exhaustively from our prosthodontic clinic. The c-EMA system was administered by an exclusive PC server and sent questions to their cellular phones at pre-set timing automatically. The newly-developed 2 questions of the c-EMA asked their levels of current oral pain and anxiety with 11-grade (0-10), drop-down rating scales (DRS). The subjects were also asked to answer paper-based questionnaires containing 11-grade (0-10) Visual Rating Scales (VRS) as well as 10 cm Visual Analogue Scales (VAS) of oral pain and anxiety as golden standards. We compared the answer obtained from the DRS of the c-EMA system to the identical answer from the VRS and VAS of the paper-based questionnaire assessment in terms of current oral pain and anxiety, respectively. The statistical analysis was done to test the correlation by Spearman's correlation coefficient by rank.

Results: Significant correlation were observed between the DRS of c-EMA and the paper-based VAS (pain: p<0.001, r=0.983, anxiety: p<0.001, r=0.983), between the DRS of c-EMA and the paper-based VRS (pain, p<0.001, r=0.981; anxiety, p<0.001, r=0.981).

Conclusions: These results suggested the results obtained from the c-EMA system developed in this study showed highly consistent and valid to the results from the paper-based VRS/VAS of oral pain and anxiety.


0864 (116584)

Risk factors for Temporomandibular Disorders: A 3-year Prospective Cohort Study. R. AKHTER1, M. ESAKI2, N. KIMIYA2, and M. MORITA3, 1Okayama University, Okayama, Japan, 2Hokkaido University, Sapporo, Japan, 3Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan

“Objectives:” To examine the 3-year period incidence of temporomandibular disorders and to evaluate the risk of self-reported temporomandibular disorders (TMD) among university students.

“Methods:” The study population comprised 2, 374 university students examined at the start of their undergraduate course and completely re-examined (n = 492) after 3 years with the aid of a questionnaire regarding symptoms of TMD, jaw injury, stress and parafunctional habits. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated to determine the degree of risks of these variables for temporomandibular disorders using logistic regression.

“Results:” Results of logistic regression analysis showed that male and female subjects with presence of the history of jaw injury had a 3.5 (CI=1.40-8.61, p<0.01) and 4.7 (CI=1.36-16.49, p<0.05) fold higher risk of incidence of TMJ pain than those who did not. A significant relationship was found between male subjects who had the history of biting hard objects and TMJ pain risk (OR= 3.1, CI= 1.10-8.54, p<0.05).Female subjects who reported presence of stress and the history of bruxism had a 5.1 and 5.7 (CI= 1.02-25.84, p<0.05 and CI= 1.40-22.96, p<0.05, respectively) fold higher risk of TMJ sound than those who did not. Male subjects who reported the history of tongue biting were at higher risk of TMJ sound than non tongue biters (OR=2.1, CI=1.05-4.19, p<0.05).

“Conclusion:” The results indicated history of jaw injury, stress, bruxism, tongue biting and biting hard objects, were significantly associated with increased risks of incidence of temporomandibular joint disorders.


0866 (116450)

Masticatory Muscle Activity and Pain-Pressure Threshold of Myofascial Pain Patients. P.C.R. CONTI1, L.M.N. ROSSETTI1, P.D.S. CALDERON2, C.D.R.P. DE ARAUJO1, and P.H.O. ROSSETTI3, 1Univerisade de São Paulo - Faculdade de Odontologia de Bauru, Bauru, Brazil, 2Universidade de São Paulo - Faculdade de Odontologia de Bauru, Bauru, Brazil, 3Universidade do Sagrado Coracao, Bauru, Brazil

Aims: To test the correlation between rhythmic masticatory muscle activity (RMMA) and pressure-pain threshold (PPT) at morning, on myofascial pain (MFP) patients with and without sleep bruxism Materials and Methods: Thirty MFP patients (RDC/TMD criteria) underwent polysomnographic recording (PSG) for two consecutive nights. PPT values were verified bilaterally for masseter (origin, body, insertion, and deep portion), as well as for temporalis (anterior, medium, and posterior portion) muscles on the morning following PSG (second night). After bruxism diagnosis (PSG criteria), the 16 women and 3 men composed the bruxers MFP group and 8 women and 3 men composed the non-bruxers MFP group. The groups were age-matched. Results: All MFP patients reported pain complaints on masseter and/or temporal muscles. Most of MFP patients reported mild or moderate pain (46.67%, and 43.33%, respectively), and only 3 (10%) reported severe pain. Pain duration ranged from 2 to 120 months (mean of 34.67 ± 36.96 months). There were no significant differences in clinical symptoms between groups (VAS, maximal mouth opening, worst pain period, joint sounds, number of tender muscular points, muscle tenderness score and PPT values. Among bruxers, two negative and moderate correlations between RMMA and morning PPT were found. Among non-bruxers, five negative and high correlations between RMMA and morning PPT were seen. Conclusions: These findings suggest that non-bruxers with MFP seem to show more tenderness on palpation due to more intense RMMA than do MFP bruxers. It could be speculated that bruxers could present more trained and exercised muscles, being less susceptible to increases in RMMA. (Supported by FAPESP – 02/03469-5, and CAPES – BRAZIL).


0867 (118067)

Psychological Factors of Adult Orthodontic Patients with TMD. M. NOMURA, E. MOTEGI, Y. FUJITA, D. YAMAGUCHI, and K. SUEISHI, Tokyo Dental College, Chiba, Japan

Objectives: It is important to monitor psychological factors in orthodontic patients with TMD ,which is a multi-factorial disorder. The purpose of this prospective study was to clarify the difference of psychological factors of orthodontic patients with TMD between before and after orthodontic treatment.

Methods: The subjects were 13 patients, their averages were 22 years 6 months at the beginning of the treatment and 27 years 5 months at the end of the active treatment. They answered the questionnaire before and after their treatment using a psychological test called TMJ ScaleTM (Pain Resource Center Inc., Durham ,U.S.A.). The TMJ ScaleTM was comprised 97 multiple-choice questions with 5 possible answers per question.

Results: Results were compared between the two stages. These scores are PR (pain report), PP(Palpation Pain), JD(joint dysfunction), MO(perceived malocclusion), NT(non-TMDisorder) and RL(range of motion limitation) as physical parameters, PF (psychological factors), ST (stress) and CN(Chronicity) as psychosocial parameters, and GS (global) as a global parameter. The score of after treatment showed lower in almost parameters than that of before treatment except NT. Significant difference between the two stages was observed in PR, MO, RL and GS at the 5% level. No significant difference was found in other parameters.

Conclusions: These results indicated the improvement of dysfunction before treatment. The TMD symptom might be effected by orthodontic treatment. It is necessary that we have to consider these psychological differences when we treat adult orthodontic patients with TMD.


0868 (115811)

Effectiveness of a Prefabricated Occlusal Appliance, Relax, in the Long-Term. E. EKBERG1, M. DOEPEL2, Y. LE BELL2, and M. NILNER1, 1Malmö University, Malmö, Sweden, 2University of Turku, Turku, Finland

Objectives: To compare the long-term effectiveness of a prefabricated occlusal appliance with a stabilization appliance in myofascial pain patients.

Methods: Sixty-five patients with the diagnosis myofascial pain at two centres for Stomatognathic Physiology in Sweden and Finland were included in a randomized controlled trial. Patients were randomly assigned to a prefabricated appliance (R-group, 27 women, 5 men, mean age 38 years) or a stabilization group (S-group, 31 women 2 men, mean age 37 years). General practitioners performed the treatment. History and clinical examination was performed according to RDC/TMD. At the 6 months- and 1 year follow-up the treatment outcome regarding pain according to the visual analogue scale and overall rating of pain according to the verbal scale was evaluated.

Results: At baseline there were no differences between the groups regarding frequency of myofascial pain, number of years suffering from the pain, worst or mean pain during the last six months. At the 12-months follow-up 30% and 50% pain relief in the R- and S-groups were reported in 24 and 21 patients and 23 and 17 patients respectively. According to a verbal scale 26 and 21 patients in the two groups reported themselves to be better, much better or symptom-free. All calculations were done per protocol. An increased open bite was registered in one patient.

Conclusions: In a long-term perspective both appliances seemed to have an equal effectiveness in the treatment of patients suffering from myofascial pain. The prefabricated appliance, Relax, can be recommended as a long-term treatment modality when used night time only. Frontal open bite should be regarded as a contraindication.


0869 (119493)

Effects of Intraoral Splints on Electromyographic Activities. E. MUMCU, F. UNALAN, and T. SULUN, University of Istanbul, Istanbul, Turkey

Objectives:

Appliance therapy which is also called stabilization splints (SS) and anterior repositioning splints (ARS) is commonly used in the management of anterior disc displacement with reduction. The purpose of this study is to compare  the effectiveness of SS and ARS on ‘disc displacement with reduction' patients, by using computerized electromyography (EMG).

Methods:

A total of 120 patients were involved in the study, where 30 patients for each treatment group were randomly assigned. For each patient, a SS or an ARS was constructed for the maxillary arch using 2-mm Biocryl and clear self curing acrylic resin as described by Okeson. After 6 months, 96 patients continued to control and recall sessions. 24 patients using SS only at night-time, 24 patients using SS all-day, 27 patients using ARS only at night-time, 21 patients using ARS all-day were diagnosed according to Research Diagnostic Criteria for Temporomandibular Disorders. EMG recordings from masseter and anterior temporalis muscles were analyzed during the maximal biting situation. Bipolar surface electrodes of silver amalgam 8-mm diameter with an inter-electrode distance of 20 mm were used. The average value of EMG recordings was evaluated by a two-tailed Student's t-test. The level of significance was set at p<0.05.

Results:

The results of the investigation revealed the following: Before and after appliance therapy, the EMG activity from the masseter muscle was less than from the temporal muscle (p <0.05) by the use of the splints, the EMG activity of the masticatory muscles showed a significant reduction (p<0.05) after a period of 6 months.

Conclusion:

EMG activity of the patients using SS and ARS all-day, reduced after 3-6 months. Splint therapy has shown to be effective in reducing pain (80%) and clicking (85%) in patients having disk displacements with reduction.

                


0870 (117759)

Survival Protein Expression in Vascular Endothelial Cells Predicts Tumor Progression. J. STIEBER, P.J. POLVERINI, T.M. BOTERO, and P. KUMAR, University of Michigan, Ann Arbor, MI

Objectives: The Bcl-2 family of proteins plays a key role in enhancing the survival of tumor-associated endothelial cells and tumor progression. We have shown that tumor associated endothelial cells expressing Bcl-2 exhibit a heightened growth response to proangiogenic mediators and have a survival advantage over normal endothelial cells where they acquire resistance to a number of anti-tumor and anti-angiogenic agents. We propose that as tumors or their precursor lesions progress toward malignancy, survival protein expression becomes more readily detectable in tumor endothelial cells. As a consequence, there is increased neovascularization and endothelial cells become more resistant thus driving tumor progression. Methods: Benign mucosal hyperplasia, dysplasia, carcinoma in situ and invasive squamous carcinoma were obtained from archived biopsy specimens. Endothelial cells lining vessels were quantitated in 5-10 randomly selected high powered (400X) fields per sample following immunostaining for Bcl-2, Bcl-xL and the inhibitor of apoptosis XIAP. Negative controls consisted of adjacent non-dysplastic or neoplastic regions of epithelium. The results following immunostaining of invasive squamous carcinomas are reported here. Results: Bcl-2 and XIAP staining was restricted primarily to the growing tips of new capillaries whereas Bcl-xL was widely distributed in both small and large blood vessel endothelial cells. Of the survival proteins examined, XIAP appeared to be the most abundantly expressed in capillary endothelial cells where 5.9 ± 1.4 endothelial cells per HPF stained positive for this protein. Bcl-2 was also expressed predominantly in capillaries (3.0 ± 0.5 per HPF) but less so than XIAP. Bcl-xL positive vessels (3.8 ± 0.5) were present in both tumor-associated and non-tumor endothelium. Conclusions: Our results indicated that survival proteins are differentially expressed in tumor-associated endothelial cells populating squamous carcinomas. XIAP is abundantly expressed in tumor-associated endothelial cells, Bcl-2 is expressed moderately in comparable samples, and Bcl-xL is expressed in tumor- and non-tumor associated endothelial cells.


0871 (118644)

G-CSF/Bcl-2 signaling in head and neck tumor angiogenesis. W. LOVE, V, and J. NOR, University of Michigan, Ann Arbor, MI

Granulocyte-Colony Stimulating Factor (G-CSF) is used clinically for the prevention of neutropenia in cancer patients undergoing chemotherapy. However, the effects of G-CSF on angiogenesis and tumor cell invasion are unknown. Objectives: To test the hypothesis that G-CSF functions as a pro-angiogenic signaling molecule. Methods: Expression of G-CSF receptor (G-CSFR) in human dermal microvascular endothelial cells (HDMEC) and secretion of G-CSF by head and neck squamous cell carcinomas (HNSCC) (UM-SCC-11A, UM-SCC-17B, UM-SCC-74A, OSCC3) were evaluated by Western blots and ELISA, respectively. The effect of G-CSF on endothelial cell proliferation was evaluated by Sulforhodamine B (SRB) assay, and in angiogenesis was evaluated by a capillary sprouting assay. Western blots were used to evaluate if G-CSF, or conditioned medium from HNSCC, induced Bcl-2 in endothelial cells. Co-cultures of HDMEC (bottom chamber) and HNSCC (Transwell coated with Matrigel) were used to evaluate the effect of G-CSF on tumor cell invasion. Results: HNSCC cells secrete G-CSF while endothelial cells express G-CSFR. G-CSF induces endothelial cell proliferation and capillary sprouting in vitro (P<0.05). Recombinant G-CSF, or HNSCC conditioned media, induces Bcl-2 in endothelial cells via G-CSFR signaling. Blockade of G-CSF with neutralizing antibodies inhibited invasion of HNSCC. Conclusion: These results reveal that G-CSF is a potent angiogenic factor that induces Bcl-2 expression in endothelial cells. Notably, our laboratory has previously shown that Bcl-2 is upregulated in tumor blood vessels of head and neck cancer patients. Given that G-CSF is a common adjuvant therapy for cancer, and that tumor recurrence and metastasis depend on the angiogenic switch, it is possible that the G-CSF-Bcl-2 signaling axis is involved in the poor outcome of patients with advanced head and neck cancer.

Supported by AADR fellowship and School of Dentistry Student Research Program Award (WJL); grant P50-CA97248 from the NIH/NCI, and grants R01-DE14601, R01-DE15948, R01-DE16586, R21-DE19279 from the NIH/NIDCR (JN).


0872 (118646)

The role of Sprouty 2 in wound angiogenesis. M.S. WIETECHA, L. CHEN, M.J. RANZER, and L.A. DIPIETRO, University of Illinois - Chicago, Chicago, IL

Objectives: Angiogenesis, a crucial component of wound healing, follows a branched tubular development and is regulated by signals received by receptor tyrosine kinases (RTKs). Mammalian Sprouty (Spry) proteins are known to function by specifically antagonizing the activation of the mitogen-activated protein kinase (MAPK) signaling pathway by RTKs, especially vascular endothelial growth factor (VEGF) receptors. The purpose of this research is to determine the role of Sprouty 2 in the regulation of wound angiogenesis.

Methods: To examine Spry2 levels during wound healing in vivo, excisional dermal wounds were made on the dorsum of 6-to-8 week-old female FVB-strain mice using 3-mm punch-biopsy instruments; wound samples were harvested and analyzed for mRNA expression of Spry2 at 0, 1, 3, 5, 7, 10, 14, 21, 28 days post-injury using Real-Time PCR and GAPDH as endogenous control (n=5). In another study, gel containing Spry2, negative dominant Y55F mutant of Spry2, or green fluorescent protein (GFP) control was applied topically to healing wounds 5 days post-injury; wound samples were harvested 10 days post-injury and analyzed for vascularity using PECAM-1 staining (n=3).

Results: mRNA expression quantification experiments showed that Spry2 mRNA levels increase after day 5 and peak at day 14 post-injury, a time when vascular regression occurs (p<0.05). Western blot protein analyses confirmed the general pattern of Spry2 expression. Quantification of positive PECAM-1 staining showed a decrease in blood vessel formation in Spry2 treated mice compared to the GFP control group, whereas mice treated with the Y55F mutant exhibited a relative increase in vascularity.

Conclusion: Spry2 production follows a defined pattern that parallels the pattern of wound angiogenesis, with peak Spry2 levels occurring during active vascular regression. Application of exogenous Spry2 to wounds inhibits angiogenesis. Taken together, the results suggest that Spry2 down-regulates vascularity and/or vascular branching during wound angiogenesis.

R01 GM50875 (LAD); T32 DE018381 (LAD,MW)


0873 (118816)

Anti-tumor and anti-angiogenic effect of TW37 and Cisplatin combination therapy. N. ASHIMORI, B. ZEITLIN, K. WARNER, and J. NOR, University of Michigan, Ann Arbor, MI

We have recently shown that Bcl-2, an anti-apoptotic and pro-angiogenic protein, is highly expressed in the blood vessels of head and neck cancer patients. Objectives: To evaluate the anti-angiogenic and anti-tumor effect of a novel small molecule inhibitor of Bcl-2 (TW37) used by itself, or in combination with Cisplatin. Methods: Sulforhodamine B (SRB) assay and propidium iodide staining followed by flow cytometry were used to characterize the cytotoxicity of TW37 and/or Cisplatin in human dermal microvascular endothelial cells (HDMEC) and in a panel of head and neck squamous cell carcinomas (HNSCC) (OSCC3, UM-SCC-11A, UM-SCC-74A). Drug effects on HDMEC and HNSCC cell cycle were evaluated by flow cytometry. Human xenografted tumors vascularized with functional human blood vessels were generated with the SCID Mouse Model of Human Tumor Angiogenesis to evaluate the effects of single drug, or TW37 and Cisplatin combination therapy, in vivo. Results: Combination therapy with TW37 and Cisplatin was more cytotoxic (P<0.05) than single drug treatment in HDMEC and the HNSCC lines evaluated here. Indeed, some of the concentrations tested showed synergistic effects of the combination of TW37 and Cisplatin. Interestingly, TW37 induced “S” phase cell cycle arrest in HDMEC and HNSCC. In vivo, combination therapy with TW37 and Cisplatin inhibited tumor progression and enhanced animal survival more effectively than single drug treatment. This was accompanied by a decrease in microvessel density and increase in tumor cell apoptosis. Conclusion: Blockade of Bcl-2 function with TW37 potentiates the effect of Cisplatin and inhibits xenografted head and neck tumor progression. These results suggest that patients with head and neck cancer might benefit from a treatment strategy that includes therapeutic inhibition of Bcl-2.

Supported by grant P50-CA97248 (University of Michigan Head and Neck SPORE) from the NIH/NCI, and grants R01-DE14601, R01-DE15948, R01-DE16586, R21-DE19279 from the NIH/NIDCR (JEN).


0874 (119349)

Endothelial cell Bcl-2 and HNSCC lymph node metastasis. S.B.C. TARQUINIO, Angiogenesis Research Laboratory - University of Michigan, Ann Arbor, USA; Federal University of Pelotas, Pelotas, Brazil, Z. ZHANG, Angiogenesis Research Laboratory - University of Michigan, Ann Arbor, MI, and J.E. NOR, Angiogenesis Research Laboratory, Department of Cariology, Restorative Sciences and Endodontics - University of Michigan, Ann Arbor, MI

Head and neck squamous cell carcinomas (HNSCC) show lymph node metastasis. However, the mechanisms involved in HNSCC metastatic spread through the lymphatics are unknown. Objective: To evaluate the effect of vascular endothelial growth factor-C (VEGF-C) on the expression of the pro-survival protein Bcl-2 in human lymphatic endothelial cells (HMVEC). Methods: HMVEC were exposed to rhVEGF-C and Bcl-2 expression was evaluated by Western blotting. The role of VEGFR3 and PI3k-Akt in VEGF-C-induced Bcl-2 expression was evaluated with neutralizing antibodies and LY294002, respectively. Alternatively, HMVEC were treated with HNSCC (UM-SCC-11A, UM-SCC-11B, UM-SCC-17A, UM-SCC-17B, UM-SCC-74A, UM-SCC-74B) conditioned media. Laser capture microscopy (LCM) was used to retrieve endothelial cells from tumors of HNSCC patients with or without metastasis, and RT-PCR was used to evaluate Bcl-2 expression. As controls, we retrieved the endothelial cells of normal oral mucosa. Results: VEGF-C induces Bcl-2 expression in lymphatic endothelial cells via the VEGFR3/PI3k-Akt signaling axis. Bcl-2 gene expression was upregulated in the endothelial cells of HNSCC with metastasis as compared to endothelial cells from HNSCC without metastasis. Notably, Bcl-2 was poorly expressed by the endothelial cells of normal oral mucosa. Conclusion: VEGF-C signals through the VEGFR3/PI3k-Akt axis to induce Bcl-2 expression in lymphatic endothelial cells. Notably, Bcl-2 was upregulated in the endothelial cells of tumors that showed the ability to metastasize to lymph nodes. These data raises the hypothesis that the VEGF-C/Bcl-2 pathway is involved in the process of metastatic spread of HNSCC. Supported by CAPES (ST) and by grant P50-CA97248 (University of Michigan Head and Neck SPORE) from the NIH/NCI, and grants R01-DE14601, R01-DE15948, R01-DE16586, R21-DE19279 from the NIH/NIDCR (JEN).


0875 (114493)

Altered expression of tumor suppression genes following rat tongue carcinogenesis. D.A. RIBEIRO, Sr.1, A.C. FRACALOSSI1, C. OSHIMA1, and D.M.F. SALVADORI2, 1Federal University of Sao Paulo - UNIFESP, Santos, Brazil, 2Universidade Est. Paulista Julio Mesquita, Botucatu, Brazil

Objectives: This study was undertaken to investigate, by immunohistochemistry, the expression of some tumor suppressor genes such as p53, p16, p21 and Rb during 4-nitroquinoline 1-oxide induced rat tongue carcinogenesis. Methods: Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12, and 20 weeks. Ten animals were used as negative control. Results: Neither histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure, nor significant statistically differences (p>0.05) in expression of all tumor suppressor genes were found when compared to negative control. However, the levels of p53 and Rb were increased (p<0.05) in pre-neoplastic lesions at 12 weeks following carcinogen exposure. In well-differentiated squamous cell carcinomas induced after 20 weeks of treatment with 4NQO, p53, p16 and Rb were expressed in some tumor cells. Conclusions: Taken together, our results support the belief that expression of p53, and Rb are closely events related to malignant transformation and conversion of the oral mucosa, being reliable biomarkers linked to oral cancer pathogenesis.


0878 (115363)

Glucose transporter-1 and Carbonic Anhydrase IX Expression in Oral Cancers. K. SHEVCHENKO1, S. CHOKSHI2, S. NARENDRAN3, N. VIGNESWARAN1, and M. WILLIAMS4, 1University of Texas - Houston/Health Science Center, Houston, TX, 2University of Texas at Austin, Austin, TX, 3Case Western Reserve University, Cleveland, OH, 4UT-MDACC, Houston, TX

Oral cancers (OC) contain hypoxic areas that are not found in normal tissue,which arestrongly associated with resistance to chemo/radiation therapies and metastatic progression.Carbonic Anhydrase-IX (CA-IX)is an endogenous marker of hypoxia and Glucose transporter-1 (GLUT-1) mediates cellular glucose uptakeand thus promotes the survival of hypoxic tumor cells. Objective: To examine the expression patterns CA-IX and GLUT-1 in HNSCC and correlate their expression levels with different clinicopathological features. Methods: Expression of CA-IX and GLUT-1 were examined immunohistochemically in OC (n=51). Clinical data wereobtained from the medical records and histopathological features were graded according to published methods. Expression levels of CA-IX and GLUT-1 were scored semiquantitatively based on the intensity of the positive stating and the fraction of tumor cells that are positive. Results: CA-IX and GLUT-1 were mostly expressed on the surface of OC cells. CA-IX staining was noted focally in tumor islandsthat were away from the blood vessels and in close proximity to the necrotic areas. CA-IX expression was not observed in superficial areas of the tumors or dysplastic epithelium. GLUT-1 expression was noted in large areas of tumors involving both superficial and deeper portions. GLUT-1 expression was up-regulated in the dysplastic epithelium adjacent to the invasive tumors. CA-IX expression was high in 18%, moderate in 21%, and low in 61% of OC cases. GLUT-1 was high in 67%, moderate in 25% and low in 8% of cases. Conclusion: There was no significant association between CA-IX and GLUT-1 expression patterns. GLUT-1 overexpression was significantly more frequent than CA-IX in OC. Clinicopathologic features of OC with their CA-IX and GLUT-1 expression levels were also investigated. Our data suggest that GLUT-1 overexpression in OC is an early event and its overexpression is not hypoxia dependent. CA-IX over-expression in OC, however, is primarily related to hypoxia. NIH grant RO3 DE15723 (NV)


0879 (116009)

Beta-catenin's Role in The Carcinogenesis of Oral Squamous Cell Carcinoma. M. FAN, Y. DUAN, and Q. XU, Key Laboratory for Oral Biomedical Engineering Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China

Objectives: beta-catenin, depending on subcellular localization, plays a dual role: as a member of WNT signaling pathway (in the cytoplasm/nucleus) and as an adhesion molecule (in cell membrane). Furthermore, it can be regarded as a kind of transcriptional factor, which can promote expression of downstream genes, such as cyclin D1, c-myc. In this study, we sought to determine the role of beta-catenin in the carcinogenesis of oral squamous cell carcinoma.

Methods: based on an immunohistochemical study, the expression of beta-catenin, E-cadherin which mediate cell-cell adhesion together with beta-catenin, axin relevant to beta-catenin phosphorylation and vascular endothelial growth factor (VEGF) which is one downstream target gene of beta-catenin were investigated in 120 paraffin-embedded specimens including 20 normal oral mucosa, 24 oral pre-malignant lesions (OPLs), 76 oral squamous cell carcinoma (OSCC). Moreover, we statistically evaluated their correlations with clinicopathologic variables.

Results: In the analysis based on membranous expression of beta-catenin, there was nearly a trend of decrease from normal mucosa, OPLs to OSCC. The positive rates were 100%, 79.2% and , 53.9% respectively. The similar results were seen in the expression of E-cadherin. In the analysis of another category of beta-catenin expression, a cytoplasmic/nuclear pattern was observed in 23(30.3%) of the 76 OSCC, most (19/23, 82.6%) of which had a concomitant reduction of membranous expression of beta-catenin. Axin staining showed a reduced expression in OSCC and OPLs compared with in normal mucosa. VEGF was over expressed in OSCC while less expressed in normal epithelial and OPLs. The cytoplasmic/nuclear pattern of beta-catenin was significantly associated with metastasis, axin expression, but not with VEGF expression.

Conclusions: The present study suggests that altered expression of beta-catenin may play an important role in the progression and metastasis of oral squamous cell carcinoma through loss of differentiation and WNT signaling pathway activation.


0880 (116495)

Mitogenic effects of FGF7 in Head and Neck Cancer. B. BICHON, M. MARSHALL, L. MAREK, and L. HEASLEY, University of Health Sciences, Denver, CO

Objectives: Currently, Fibroblast Growth Factor-FGF7 (palifermin) is approved to reduce the severity and duration of oral mucositis in hematological cancer patients undergoing radiation and/or chemotherapy. Clinical trials are underway to investigate the use of FGF7 in solid tumors including Head and Neck Cancer. Few published studies have been conducted to determine if FGF7 may be implicated in proliferation of human head and neck squamous cell carcinoma (HNSCC), a cancer that is frequently treated with combinations of radiation and chemotherapy. Our current study was designed to examine the mitogenic effect of FGF7 on a panel of 10 human HNSCC cell lines. Methods: To initially characterize the HNSCC cells lines, real-time quantitative PCR (RT-QPCR) was employed to measure transcript expression levels of FGF's and their FGF receptors (FGFR), including receptor splice variants. In addition, HNSCC cell lines were analyzed for their ability to stimulate signal transduction (pERK) when stimulated with FGF7. Cell proliferation from exogenous FGF7 was also evaluated. Results: The results revealed frequent expression of FGF's and FGFR's in HNSCC cell lines. Moreover, specific FGFR splice variants known to respond to FGF7 (FGFr2b) were detected in 6 of 10 HNSCC cell lines. Treatment of the different HNSCC cell lines with exogenous FGF7 activated the ERK MAP kinase pathway in all but one cell line that expressed FGFr2b. Cell proliferation results demonstrated marginal increases in some HNSCC cells lines. Conclusions: Based on these results, treatment of oral mucositis with FGF7 in HNSCC patients that have undergone radiation and/or chemotherapy may induce undesired squamous cell carcinoma cell proliferation. Treatment of radiation/chemotherapy induced oral mucositis with FGF7 may be contraindicated in those patient populations expressing FGFr2b receptors in HNSCC.


0881 (117034)

The Integrin αvß6 Influences EMT in Oral Cancer. S. SADLER, D. DANG, and D.M. RAMOS, University of California - San Francisco, San Francisco, CA

34,000 Americans are diagnosed with oral or pharyngeal cancer annually and over 8,000 deaths per year can be attributed to this disease. Squamous cell carcinoma (SCC) accounts for over 96% of these tumors. Treatment success has not improved over the last 50 years and 50% of patients do not survive 5 years post diagnosis.  Epithelial tumors including head and neck squamous cell carcinoma are a heterogeneous group of cells, some of which is accounted for by ongoing mutations that occur because of genetic instability and environmental factors.

Objective: In this study we evaluated whether the forced expression of the β6 integrin would modulate epithelial to mesenchymal transition (EMT). 

Methods: SCC9β6 cells were established through retroviral transduction with the full length β6 cDNA.  The SCC9β6D1 cells were established by expression with a β6 construct in which the terminal 11 AA were removed from the C-terminus. SCC9SN cells were also established in our laboratory by expressing the blank vector. 

Results: When the full length β6 integrin was expressed in the poorly invasive SCC9 cells, the resulting SCC9β6 cells acquired a fibroblast like morphology, increased expression of the mesenchymal marker vimentin and decreased the expression of the epithelial markers keratin and E-cadherin.  The SCC9β6D1 cells retained their epithelial morphology and did not alter vimentin or E-cadherin expression.  This suggests that the full length β6 subunit can induce EMT in oral SCC cells.  We previously showed that expression of β6 increases both MMP3 activation and TN-C expression and we now show that both molecules are MEK dependent.

Conclusion: These results demonstrate that the terminal 11 AA of β6 contains information important for establishing an epithelial to mesenchymal transition. 

Support: This work was supported by the National Institute of Craniofacial Dental Research R01DE11930, PO1DE13904 and an Individual Investigator Award from UCSF Academic Senate to DMR.


0882 (117145)

Promoter Activity in Decreased Expression of Beta-defensin-1 in Oral Carcinoma. H. SATO1, R. TAKAI1, K. MURATA1, M. URAKI1, Y. OBARA1, Y. SASAMOTO1, S. MIYATA1, M. YAMAZAKI2, M. NISHIMURA3, M. SAITOH1, T. ARAKAWA3, T. KAKU3, T. TAKUMA3, and Y. ABIKO1, 1Health Sciences University of Hokkaido, Sapporo, Japan, 2Health Sciences University of Hokkaido, Ishikari, Japan, 3Health Sciences University of Hokkaido, Hokkaido, Japan

Objective: Previously, we described the decreased expression of human beta-defensins (hBD), a family of antimicrobial peptides, in oral squamous cell carcinoma (SCC) cell lines (Abiko,Y. et al. Cancer Lett., 1999). hBD-1 has been identified as a tumor suppressor gene in renal and prostate cancers. In addition, decreased gene expression of hBD-1 in the development of oral SCC was demonstrated. In the present study, we investigated the decrease of hBD-1 transcription in oral SCC. Methods: Eight oral SCC-established cell lines (SAS, HSC-2,-3,-4, SCC-9, OSC-19, BSC-OF, HAC) and normal keratinocytes were used. The expression level of hBD-1 mRNA was estimated by quantitative RT-PCR. Total DNA was extracted and the promoter region of hBD-1 up to -900 was directly sequenced using an ABI PRISM 310 Genetic Analyzer (Applied Biosystems, CA). In order to examine whether hypermethylation is involved in the change in transcriptional levels, cells were treated with the DNA methyltransferase inhibitor, 5-aza-dCyd (Sigma), and the promoter activities were analyzed by luciferase reporter assay after transfection of the constructs into HaCaT cells. Several experiments were performed, each in triplicate. The data was analyzed using one-way ANOVA. Results: The RT-PCR assay revealed that the expression level of hBD-1 mRNA in SAS and OSC-19 cell lines was less than one-fifth the level observed in normal keratinocytes. Neither SAS nor OSC-19 showed changes in the expression level of hBD-1 mRNA after 5-aza-dCyd treatment. By direct sequencing, polymorphisms were revealed at -688(C/G) in SAS, and at -20(C/T) and -52(T/C) in OSC-19. The luciferase activity in SAS with -688(G) was one-fifth of that in the wild-type. The activity in OSC-19 with both -20(T) and -52(C) was one-third of that in the wild-type. Conclusion: These results indicate that genetic polymorphism sites at -20,-52,and -688 may be crucial for the decreased expression of hBD-1 mRNA in oral SCC.


0883 (117392)

SDF-1 and CXCR4 polymorphisms and the risk of oral cancer. S.-F. YANG1, J.-S. YANG1, and Y.-C. CHANG2, 1Chung Shan Medical University, Taichung, Taiwan, 2Chung Shan Medical University, Taichung R.O.C, Taiwan

Objectives:The aim of this study was to estimate the relations of Stromal cell-Derived Factor-1 (SDF-1) and its receptor, CXCR4, gene variants on oral cancer risk and clinicopathological status. Methods:Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was used to measure SDF-1-3'A (rs1801157) and CXCR4 (rs2228014) gene polymorphisms in 284 healthy controls and 113 oral cancer patients. Results:The individuals with A/G heterozygotes of SDF-1 had 1.86 fold risks to develop oral cancer compared to G/G wild type homozygotes after adjusting for age. Furthermore, oral cancer patients with at least one mutated T allele of CXCR4 gene had 2.66 fold risk to develop stage III or stage IV and 2.62 fold risk to induce lymph-node metastasis compared to patients with C/C homozygotes after adjusting for age, alcohol, tobacco consumption, and betel nut chewing. Conclusions:SDF-1-3'A gene polymorphism may be considered as a factor increasing the susceptibility in oral cancer disease in Taiwanese.


0884 (117808)

STAT3 signal transduction in squamous cell carcinoma stimulated by IL-22. L. NAHER, T. KIYOSHIMA, H. FUJIHARA, I. KOBAYASHI, K. NAGATA, K. FUKIWAKE, Y. OOKUMA, S. NAKAMURA, and H. SAKAI, Kyushu University, Fukuoka, Japan

Objectives: Cytokines or cytokine-related mediators influence the cellular behavior of malignant tumors. Interleukin (IL)-22 is recently discovered as a member of the IL-10 family that binds to a class II cytokine heterodimeric receptor composed of IL-22R1 and IL-10R2. While IL-10R2 is a ubiquitous protein, IL-22R1 expression is restricted to non-leukocytic cells. Therefore, IL-22 appears to be unique among a huge number of cytokines in that this protein is not functional between leukocytes but rather between leukocytes and the non-leukocytic cell compartment. In the present study, we have studied IL-22 signal transduction in squamous cell carcinoma of the head and neck (HNSCC), compared with IL-6, major activator of the STAT3 signaling system.

Methods: & Results: Human HNSCC, MISK81-5 and HSC-3, expressed IL-10R2 and IL-22R1 receptor chains as indicated by RT-PCR and immunoblotting. The immunoblotting showed that IL-22 induced a transient tyrosine phosphorylation of STAT3 (pTyr705) 5, 15, and 30 min after stimulation of MISK81-5 cells with rIL-22, compared with basal levels in unstimulated controls. After 60 min the signal returned to pre-stimulation level. This tendency was also seen in STAT3 (pTyr705) activation after stimulation of MISK81-5 cells with rIL-6. Little change in STAT3 protein was observed during the examination periods. Whereas STAT3 (pTyr705) activation was noted in HSC-3 cells stimulated by rIL-6, the activation was undetectable after stimulation of HSC-3 cells with rIL-22. The immunocytochemistry demonstrated that stimulation of rIL-22 induced translocation of pSTAT3 into the nucleus of MISK81-5 cells. However, pSTAT3 translocation was not apparent in the HSC-3 cells with rIL-22 stimulation. MISK81-5 cells were responsive to IL-22.

Conclusions: IL-22 can activate the STAT3 signaling system depending on the type of HNSCC, and may play a role in the tumor growth and progression through the STAT3 activation.


0885 (118357)

The Tumor Microenvironment Modulates DNA Methylation Through DNMT1 and Histones. T. DESROCHERS1, C. ZHAO1, Y. KUDO2, T. TAKATA2, and J. GARLICK1, 1Tufts University, Boston, MA, 2Hiroshima University, Hiroshima, Japan

Objective: We have shown that E-cadherin expression during oral-squamous-cell-carcinoma (OSCC) progression can be regulated by the tumor-microenvironment through direct modulation of DNA-methylation of the E-cadherin promoter. Here we analyze possible mechanisms through which the microenvironment may control the epigenetic regulation of E-cadherin expression by examining DNA-methyltransferases (DNMTs) and histone modifications in an OSCC cell line.

Methods: An OSCC cell line that was E-cadherin-deficient due to promoter hypermethylation was analyzed for DNMT expression in both 2D cell cultures and engineered, 3D-human-tissue-equivalents to determine if the 3D-microenvironment could induce alterations in DNMT and histones. We used immunofluorescence staining, Western blot analysis, RT-PCR, and ChIP assay to compare gene expression in monolayer culture vs. 3D-tissues. In addition, histone modifications related to methylation-mediated silencing were analyzed through ChIP and the inhibition of histone deacetylases (HDACs).

Results: We found an increase in DNMT1 protein expression in OSCC cells in 2D as well as localization to those cells that were negative for E-cadherin expression and found along the basement membrane in 3D-tissue-equivalents. In contrast, cells in 3D-tissues that were in complete contact with other tumor cells were found to re-express E-cadherin and not express DNMT1. Treatment of E-cadherin-deficient cells with HDAC inhibitors renewed expression of E-cadherin, suggesting a role for histone modifications in DNA methylation-mediated suppression of E-cadherin.

Conclusions: The tumor-microenvironment can modulate the expression of DNMT1, resulting in the methylation-mediated silencing of E-cadherin. However, loss of cell contact with extracellular-matrix (ECM) resulted in the loss of DNMT1 expression, concomitant promoter de-methylation and re-expression of E-cadherin, and establishment of homotypic cell-cell interactions. Our findings indicate that regulation of E-cadherin methylation-mediated silencing by the tumor-microenvironment involves regulation of DNMT expression and histone modifications by the ECM and cellular milleu.

Supported by NIH grant no. 2RO1DE011250-06 and RO1DE017413-01 (JAG) and a grant to CITE at Tufts Dental


0886 (119401)

GSTM1/GSTT1 Null Polymorphisms and Risk of Salivary Gland Carcinomas. S. KONDO1, E. STURGIS2, C. ZHAO2, Q. WEI2, and G. LI2, 1University of Texas - Houston/Health Science Center, Houston, TX, 2University of Texas M.D. Anderson Cancer Center, Houton, TX

OBJECTIVES: Glutathione S-transferase (GST) genes detoxify and metabolize carcinogens, including oxygen free radicals which may contribute to salivary gland carcinogenesis. This study was performed to determine the relationship between GSTM1 and GSTT1 null genotypes and the risk for salivary gland carcinoma.

METHODS: This cancer center-based case-control association study included 166 patients with incident salivary gland carcinoma (SGC) and 511 cancer-free controls. We performed multiplex polymerase chain reaction genotyping assays for GSTM1 and GSTT1 null genotypes. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with multivariate logistic regression analyses adjusted for age, sex, ethnicity, smoking, family history of cancer, alcohol use and radiation exposure.

RESULTS: 53.0% of SGC cases and 50.9% of controls were null for GSTM1 (P = 0.633), and 27.7% of SGC cases and 20.6% of controls were null for GSTT1 (P = 0.054). The GSTT1 null genotype was associated with an increased risk for SGC (adjusted OR 1.5, 95% CI 1.0-2.3). Additionally, 13.9% of SGC cases but only 8.4% of controls were null for both genes (P = 0.176; adjusted OR 1.9, 95% CI 1.0-3.5).

CONCLUSIONS: The presence of GSTT1 null genotype and the simultaneous presence of GSTM1 and GSTT1 null genotypes appear associated with SGC risk. These findings warrant further study with larger sample sizes.


0888 (119614)

The OSCC risk of CCND1 polymorphisms in a Taiwan population. C.-W. LEE1, L.-H. WANG2, C.-H. CHEN3, C.C. TSAI4, and Y.-C. LIN1, 1Kaohsiung Medical University/Faculty of Dentistry, Kaohsiung, Taiwan, 2Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, 3Kaohsiung Medical University and Hospital/Faculty of Dentistry, Kaohsiung, Taiwan, 4Kaohsiung Medical University and Hospital, Kaohsiung, Taiwan

Objectives: The dysfunction in the control of cell cycle accelerates the tumor development. The cyclin D1 (CCND1) gene was involved in the G1-S checkpoint of cycle. However, the association between CCND1 polymorphisms and OSCC remains unclear. Our aims were to determine the association between CCND1 +870A>G polymorphisms and OSCC.

Methods: Patients with oral lesion were recruited from Kaohsiung Medical University Hospital. Healthy controls were recruited from a community survey for oral cancer and a company health examination in Southern Taiwan. After inform consent, 10 ml peripheral blood was collected for DNA extraction and a standardized questionnaire was interviewed to collect demographic data and potential confounding factors. Genetic polymorphisms were determined using PCR-RFLP. JMP statistical software was used to analyze the association.

Results: A total of 324 OSCC, 64 oral submucosal fibrosis (OSF), 83 oral leukoplakia patients (OL), and 331 healthy controls were recruited into the present study. By simple logistic regression, no association was found between OSCC and CCND1 +870A>G polymorphisms. After adjusting possible confounding factors, the CCND1 +870(AA+AG) was a risk factor for OSCC development (OR=1.90, 95%CI=1.00-3.64) and malignant potential of OSF (OR=3.66, 95%CI=1.19-12.62). We stratified the participants by the habits of drinking, betel quid chewing, and smoking. The risks of CCND1 polymorphisms to OSCC could be differentiated by different substance usage.

Conclusion: We suggest that CCND1 +870A>G polymorphisms associate with OSCC development and malignant potential of OSF. An effect of interaction between CCND1 polymorphisms and substance usage on the OSCC was found in the present study.


0889 (119979)

A Human Case Study: Circadian Gene Changes in Oral Cancer. K.B. JONES1, B.L. SCHMIDT1, and R.C.K. JORDAN2, 1University of California - San Francisco, San Francisco, CA, 2University of California, San Francisco, San Francisco, CA

Background: Biological rhythms, like the 24-hour circadian rhythm (CR), are present in almost all cells and organisms. CR genes may be important in regulating the cell cycle as well as initiation/progression of cancer. Studying the relationship of CR genes and cell proliferation genes over time in normal oral mucosa (NOM) and oral squamous cell carcinoma (SCC) could be important in determining the best time(s) to administer anti-cancer therapeutics.

Objectives: To compare the RNA levels of the cell proliferation markers Ki-67 and Histone 3j (H3/j) along with the CR genes Per-1, Per-2, Bmal-1, and Clock in NOM and SCC tissue samples from the same patient.

Methods: A patient with SCC who required selective, modified radical neck dissection was recruited (n=1). 3mm punch biopsies of tumor and NOM were taken every two hours during surgery and flash frozen in liquid nitrogen (n=5 for NOM and SCC). DNA and RNA were isolated from each sample and gene expression levels measured using a novel, modified semi-quantitative real-time PCR technique.

Results: Per-1, Bmal-1, Clock, Ki-67, and H3/j genes in NOM compared to SCC showed considerable differences in expression peaks/levels over time; Per-2 may be synchronous. Expression levels/peaks of Ki-67 and H3/j in NOM appear similar; their levels/peaks in SCC also appear similar.

Conclusions: We report for the first time the in vivo expression patterns of Ki-67, H3/j, Per-1, Per-2, Bmal-1, and Clock from an SCC tumor in situ using a novel modification of the URG method for QRT-PCR. Expression patterns and levels for almost every gene varied between NOM and SCC; thus NOM and SCC may be sensitive to anti-cancer therapeutics at different times during the day. Further study of a larger patient cohort will be important in confirming these differing gene expression levels and their therapeutic potential.

Support: AADR Student Research Fellowship, T32-DE017249, RO1-CA095231


0890 (120112)

Overexpression of Dicer in Oral Squamous Cell Carcinomas. A. JAKYMIW, R. PATEL, N. DEMING, I. BHATTACHARYYA, C. STEWART, D. COHEN, and E. CHAN, University of Florida, Gainesville, FL

Recently, several reports have demonstrated that Dicer, an RNase III endonuclease involved in microRNA (miRNA) maturation, is up-regulated in prostate and precursor lesions of lung adenocarcinomas. Furthermore, Dicer protein levels have been reported to be regulated by let-7, a miRNA whose expression level has been reported to be reduced in lung cancer. Objectives: To determine whether Dicer is aberrantly expressed in oral squamous cell carcinomas (OSCCs) due to altered expressions of let-7. Methods: Dicer protein and mRNA levels were examined by Western blot analysis and real-time-PCR, respectively, in a panel of head and neck squamous cell carcinoma (HNSCC) cell lines, including OSCC cell lines, and compared to normal primary gingival epithelial cells (pGECs). The let-7 expression levels were analyzed by real-time-PCR. In addition, Dicer protein levels were examined in paraffin embedded OSCC tissues by indirect immunofluorescence studies. Lastly, an OSCC cell line was transiently transfected with either chemically synthesized let-7 or small interfering RNA (siRNA) targeting Dicer to evaluate the effect on Dicer levels and cell proliferation, respectively. Results: Dicer protein was found to be overexpressed in a panel of HNSCC cell lines compared to pGECs. Moreover, Dicer expression was found to be high in poorly differentiated OSCCs. Interestingly, the levels of Dicer mRNA were not significantly up-regulated in the HNSCC cell lines indicating a post-transcriptional form of gene regulation. Let-7 levels were reduced in HNSCC cell lines in comparison to pGECs and transfection of let-7 resulted in the downregulation of Dicer expression. Lastly, silencing of Dicer inhibited cell proliferation. Conclusion: Dicer is up-regulated in OSCCs due to the aberrant expression of let-7 miRNA and appears to be important for cell proliferation.

This work was supported in part by the Andrew J. Semesco Foundation, the NIDCR grant K99DE018191, and the Bankhead-Coley Cancer Research Program grant 08BN-02.


0891 (120890)

Calprotectin Negatively Regulates Head and Neck Squamous Cell Carcinoma. A. KHAMMANIVONG, C. CHAMPAIBOON, K.J. SAPPINGTON, K.F. ROSS, and M.C. HERZBERG, University of Minnesota, Minneapolis, MN

Calprotectin is a heterodimer of S100A8 (MRP8) and S100A9 (MRP14) calcium-binding proteins normally expressed in the cytoplasm of squamous epithelial cells, but is down-regulated in head and neck squamous cell carcinoma (HNSCC).  Generally functioning as an innate immune response molecule, calprotectin was recently found to control tumor growth at the G2/M cell cycle checkpoint.  When in complex with S100A8, the C-terminal region of the S100A9 subunit binds to arachidonic acid (AA), a precursor of prostaglandin E2 (PGE2) biosynthesis implicated in malignant transformation.  Objectives: We sought to determine whether calprotectin regulates malignant transformation-associated genes and if the C-terminal AA binding domain of S100A9 in calprotectin affects suppression of tumor growth and invasion in HNSCC.  Methods: Calprotectin-negative and calprotectin-transfected oral epithelial carcinoma cell lines were compared for gene expression profiles using Affymetrix human genome array chip HU133A.  Levels of expression of genes of interest were confirmed by quantitative real-time RT-PCR.  The S100A9 subunit was truncated at the C-terminal tail by in vitro deletion mutagenesis.  Proliferation and invasion studies were done by soft agar anchorage-independent growth and transwell cell invasion assays, respectively.  Results: Carcinoma cell line transfected to over-express calprotectin down-regulates the expression of the malignancy-associated genes AKT3, RET, JUN, PLA2, COX, and PGE2 receptor and the tumor self-renewal genes BMI1 and PIWIL1.  Calprotectin up-regulates the cellular differentiation marker CD24 and anti-tumor factor EPB41L3.  Calprotectin expression reduces anchorage-independent growth and invasion of carcinoma cells, whereas deletion of C-terminal tail of S100A9 subunit increases both tumorigenic activities.  Conclusion: Calprotectin negatively regulates malignancy-associated genes and tumorigenic activities in vitro.  In cases of HNSCC, down-regulation of calprotectin may contribute to the progression of the malignancy. Supported by NIH/NIDCR grant R01DE11831.


0893 (114778)

Finite Element Analysis of Traumatic Fractures in Maxillary Central Incisors. K. NICHOLSON, L. KOROLUK, and C.-C. KO, University of North Carolina, Chapel Hill, NC

Traumatic fractures of maxillary incisors are common but diverse in their presentation.  The distribution of forces during traumatic maxillary incisor fractures has not been well studied. Objectives:  This study investigated potential facture patterns on a central incisor with external forces of various directions and points of application.  Methods:  A mathematical model of a central incisor and its supporting structures was constructed in SolidWorks® from a microtomograph template.  ANSYS Workbench 10.0 was used to conduct a 3-D finite element analysis (FEA) of the model using 21 static load forces of 200N.  The forces simulated traumatic blows to the labial surface of the crown at 3 different angulations (0º,45º,90º) with 7 different points of application.  The von-Mises stress as well as the maximum and minimum principal stresses were calculated to identify fracture-prone areas.  ANSYS output characterized the magnitude and location of generated stresses in the crown and root of the incisor.

  Results:  TABLE 1 - Mean Value for the Peak Stress of Each Force Direction

FORCE DIRECTION

 

VON-MISES

STRESS (MPa)

MAXIMUM PRINCIPAL STRESS

(MPa)

MINIMUM PRINCIPAL STRESS

(MPa)

Horizontal (0º)

494.0±6.3

389.4±10.0

-527.3±12.8

Oblique (45º)

467.0±20.8

331.0±25.2

-501.0±27.4

Vertical (90º)

246.9±17.7

192.8±11.1

-211.8±20.6

Loads yielded different stress patterns on the incisor.  Horizontal forces produced the highest magnitude stresses.  Force direction had more influence on stress trajectory than point of application.  All forces generated stresses along the crown and root surfaces; however, stresses were more prevalent on coronal surfacesConclusion:  FEA can map the distribution of stress patterns in a maxillary central incisor model to characterize crown fractures. Force direction rather than point of application has more influence on fracture patterns.  Horizontal forces produce stresses confined to coronal surfaces while vertical forces disperse more stresses along the root surfaces.


0894 (116389)

Histomorphometric Analysis of Corticotomy-Facilitated Tooth Movement. S. CHIARI, S.S. BALOUL, C.A. AKCAN, E. GOGUET-SURMENIAN, R.S. CARVALHO, T.E. VAN DYKE, and A. KANTARCI, Boston University, Boston, MA

Objective: The aim of this study was to evaluate the bone turnover rate induced by corticotomy combined with tooth movement as a function of time in a rat model.

Methods: Eighty-one healthy adult male rats were divided into three groups of corticotomy (CORT), tooth movement (TM), or the combination (CTM). Selective alveolar decortication was performed on the buccal and palatal cortices adjacent to the upper left first molar while the tooth movement was accomplished by moving the upper left first molar mesially with a Sentalloy® coilspring. After 6 weeks of “active phase”, the appliances were removed and the stability was tested for an additional 6 weeks. Histomorphometric analysis was performed to study the bone turnover rate and the linear distance as a result of the tooth movement.

Results: After the initial resorption, the trabecular bone in the CTM group was restored to baseline levels at the end of the active phase (1.1±0.6mm2). The newly formed bone was stable in the CTM group (1.3±0.3mm2). A higher rate of tooth movement was achieved in the CTM group within the first two weeks compared to the TM group (p<0.05); by 21 days the CTM and the TM groups showed no significant differences with the rate of tooth movement consistent during the rest of the active phase. During the stability phase, no significant reversal of TM was observed in the CTM group while the distance between the first and second molar showed a decrease after week 7 in TM group.

Conclusion: Corticotomy enhances the rate of the tooth movement during the initial period following surgery. Bone turnover rate is enhanced and the newly formed trabecular bone shows high stability after the active treatment phase suggesting that the tooth movement accomplished represents a faster and stable response to corticotomy. Supported by USPHS Grant DE16191.


0895 (116714)

Carpal and Vertebral Maturation in Girls with Different Malocclusion Types. P.H. CORAZZA1, V. GUARIENTI1, L. PALUDO1, F.E. WOITCHUNAS1, and M.F. DAMIAN2, 1Universidade de Passo Fundo, Passo Fundo, Brazil, 2Universidade Federal de Pelotas, Pelotas, Brazil

OBJECTIVE: Comparing the carpal maturation index (CMI) and the vertebral maturation index (VMI) in female patients with Angle Class I, II and III malocclusion, investigating the relation between these indexes in different malocclusion types. METHODS: The samples were lateral cephalometric and hand-wrist radiographs obtained through radiographic files of 142 girls, aged between 82 and 191 months. The radiographs could not be taken with more than 3 months of interval between them to be selected. The method proposed by Baccetti et al. (2002) was used to determine the VMI, in lateral cefalometric radiographs, and the method of Martins and Sakima (1977), to determine the CMI in hand-wrist radiographs. The correlation between the methods, for each one Angle's malocclusion, was obtained by the Spearman rank-order correlation coefficient, at a significance level of 1%. RESULTS: The highest expressive number of girls had Class II malocclusion (82 patients). The correlations between the indexes were positive and statistically significant in all the types of malocclusion. The correlation values (r) were 0,768, 0,706 and 0,613 to girls Class I, II and III, respectively. Among all the correlations, the strongest one was in Class I people. CONCLUSION: It was concluded that both methods can be applied in girls whit Class I, II or III malocclusion, demonstrating to be more efficient when used in girls Class I.


0896 (121211)

Oxidative stress drives disulfide bond formation of bHLH transcription factors. T. DANCIU, University of Michigan, Ann Arbor, MI, and M. WHITMAN, Harvard University, Boston, MA

Twist proteins are basic helix-loop-helix (bHLH) transcription factors that play essential roles during development. Mutations in TWIST1 cause Saethre-Chotzen syndrome characterized by craniosynostosis, a narrow or cleft palate, and limb defects. The C-terminus domain of Twist named the “Twist box” interacts with and inhibits the function of transcription factors such as NF-kB and Runx2 which are essential regulators of inflammation and osteoblast differentiation, respectively. Twist proteins form functional heterodimers with E2a proteins; the dimerization partner of Twist then determines the functional output of Twist1 expression.

Objective: The aim of this study was to determine if the redox state of the bHLH factors Twist and E2a proteins can alter their dimerization status and thus affects gene regulation.

Methods: Cells transfected with epitope-tagged Twist1 or E2a proteins were stimulated with hydrogen peroxide at concentrations that did not affect cell viability. Whole cell lysates were analyzed by immunoblotting in the presence or absence of reducing agents. Site-directed mutagenesis was performed in order to identify the cysteine residues implicated in disulfide bond formation between Twist1 homodimers and Twist1-E2a heterodimers.

Results: Reactive oxygen species modulate disulfide bond formation between Twist1 homodimers and Twist1-E2a heterodimers with heterodimers being favored over homodimers. Hydrogen peroxide treatment leads to oxidation of the cysteine residue located C-terminally to the bHLH domain of Twist1 which then rapidly forms a disulfide bond with the identical cysteine of Twist1 in a homodimeric complex or a corresponding cysteine in a heterodimeric complex with E2a proteins.

Conclusion: Reactive oxygen species change the dimerization partner preference of bHLH proteins; further studies need to be performed to identify the functional implication of such a response.

K22DE016614 (TD)


0897 (115126)

Early Androgen Exposure, Hand Digit Ratios, and Odontometric Sexual Dimorphism. C.L. FOSTER, and E.F. HARRIS, University of Tennessee, Memphis, TN

Tooth crown dimensions are sexually dimorphic—males tend to have larger teeth than females. However, while both the primary and permanent teeth are dimorphic, they all form many years prior to the onset of steroid-mediated adolescence. Considerable recent work has used the digit ratio of the hand (D2-to-D4 length ratio) as a proxy for the extent of early exposure to testosterone. Objective: The purpose of this study was to test for a statistical association, within sex, between digit ratios and tooth crown sizes, which would suggest a common etiology. Methods: Records of 228 American white adolescents were studied. Digit lengths (D2, D3, D4) were measured from standardized hand-wrist radiographs, and maximum buccolingual crown widths of 3 tooth types (U1, U3, U6) were measured in each arch from dental casts. Technical error of measurement was quite low. Results: Digit lengths, digit ratios, and tooth dimensions all exhibited significant sexual dimorphism, though more so for tooth dimensions. By correlation analysis within sex, there was no association between amount of sexual dimorphism between digit ratios and crown sizes. In contrast, digit lengths (perhaps as a proxy for linear body size) had low but significant positive associations with crown size in females. Highest correlations were between L3 tooth and D3 digit dimensions (r = 0.20). Data for males uniformly failed to exhibit a significant association. Conclusion: Our speculation that the extent of sexual dimorphism in digit ratios would parallel that occurring in tooth crown sizes was not supported. Within sexes, the D2:D4 ratio was not predictive of the extent of crown size, so the processes generating dimorphism in these two tissue systems appear to be independent. Supported by the University of Tennessee Alumni Endowment for Research.


0898 (115737)

Association Analyses on 1p36 Identify Candidate Gene for Mandibular Prognathism. F. XUE, and A.B.M. RABIE, University of Hong Kong, Hong Kong, Hong Kong

Heredity plays an important role in the etiology of mandibular prognathism (MP). Following a genome-wide scan in a sample of Korean and Japanese families comprised of sibling-pairs with MP, a region on 1p36 near the microsatellite marker D1S234 was detected as the best evidence of linkage (maximum Zlr = 2.51, p<0.0012). Objectives: To determine if there are genetic factors for MP located within this genomic region. Methods: We genotyped 111 single nucleotide polymorphisms (SNPs) across 9Mb including the marker D1S234 and four candidate genes on 1p36 in 158 cases with skeletal mandibular prognathism and 147 controls. Genotypes and linkage disequilibrium (LD) analyses were performed using Haploview software. Results: A significant genetic association between rs2249138, rs2254241, rs2788890 and MP was observed respectively; all three SNPs pointed to the same gene EPB41. Haplotype association analysis revealed the consistent result with individual SNPs study; rs2254241 was in strong LD with rs2249138 and rs2788890 (D>0.95) and their combination showed significant association with MP (P=0.018 and P=0.0221). Both single SNPs and haplotype analysis showed significant association between MP and the markers on 1p36. Multivariate logistic regression analysis showed that rs2254241-TT genotype (OR, 2.38; 95% CI, 1.11- 5.00) was associated with significantly increased susceptibility to MP compared with CC genotypes. Conclusions: Our study suggested that EPB41 gene may be involved in the susceptibility to MP. Future replications are warranted before definitive conclusion can be drawn.


0899 (116963)

Compressive Strength of Porcine Nasal Cartilage. A. NUNES, A. AL DAYEH, and S. HERRING, University of Washington, Seattle, WA

Objectives: To study the effects of location, orientation and loading speed on the compressive mechanical properties of porcine nasal septal cartilage.

Methods: Porcine nasal septa were extracted from freshly slaughtered specimens (N=23) and frozen in phosphate-buffered saline. Specimens were thawed and six samples were cut from each specimen, two vertical (anterior/posterior) and four horizontal (superior/inferior) to the palate at 8mm x 12mm x natural thickness. Samples were mounted between compression platens of an MTS testing machine.

Samples were preloaded to 2.5N, and then loaded at a speed of 1 or 0.1%length/second. Each sample was loaded to 5 different strain points (2, 4, 6, 8, and 10% of height) in randomized order. Stress was calculated as load divided by cross-sectional area and stress-strain curves were plotted. Elastic modulus (stiffness) was calculated as the slope of the linear part of the stress-strain curves.

Results: Larger strains were consistently associated with higher stiffness. The major variable affecting stiffness was loading rate. Samples loaded at high speed demonstrated higher elastic modulus (4.38±1.05 MPa) than those loaded at low speed (2.47±0.31 MPa, p<0.001, paired t-test). When loaded at the higher rate, there was no difference between superior and inferior horizontally loaded specimens, and no difference between these and the anterior vertically loaded specimens. However, vertically loaded anterior samples demonstrated higher values (3.93 MPa±1.15) for elastic modulus than vertically loaded posterior samples (2.74±0.50 MPa, p<0.001, paired t-test).

Conclusions: Loading speed is the major determinant of septal cartilage mechanical properties. In addition, the posterior location is less stiff than other regions, at least under vertical loading.

Supported by T32DE07132 and R01DE08513.


0902 (119074)

Facial suture plating alters maxillary sinus in Sus scrofa. K.E. SWENSON1, N.E. HOLTON1, R.G. FRANCISCUS1, S.D. MARSHALL1, M.A. NIEVES2, and T. SOUTHARD1, 1University of Iowa, Iowa City, IA, 2Iowa State University, Ames, IA

Objective: Paranasal sinus development and function is not completely understood.  In order to investigate their role, the present study analyzed the effect rigid plating of circummaxillary sutures would have on maxillary sinus growth.

Methods: Sus scrofa female pigs from 10 birth cohorts of 3 sibs (total n=30, 2 months old) were randomly divided into three groups.  The experimental group (n=10) had rigid pediatric miniplates affixed across the zygomaticomaxillary and nasofrontomaxillary sutures bilaterally using monocortical screws.  A sham group (n=10) had screws inserted but no plates affixed, and a control group (n=10) did not undergo surgery.  All environmental variables, including diet, were kept constant.  At six months, the pigs were euthanized and their skulls were prepared.  Computed tomography imaging was performed.  Maxillary sinus volumes (cm3) were measured.  Sinus outlines (transverse plane) were obtained from CT scans and analyzed using elliptical fourier analysis.  To maximize the sample, left sinuses were mirrored to the right side.  Variation among sinus shape was examined by subjecting each elliptical fourier coefficient to principal component analysis.  Individual principal component scores were used to examine the relationship between sinus shape and volume.  Volumes and principal component scores were analyzed using one-way ANOVA (α<0.05).

Results: Volume was found to be significantly reduced in the experimental (plated) group (4.10cm3±0.49, p<0.0001) relative to the sham (8.31cm3±0.52) and control (8.33cm3±0.52) groups.  No significant difference was found between left and right sinus volume.  Principal component scores for the transverse sinus shape were significantly different (p<0.001) for the experimental group than the control or sham pigs.  Sinus shape in the experimental group was characterized by a reduced expansion in an anteromedial dimension and a reduced medial-lateral diameter.

Conclusion:  Rigid fixation of zygomaticomaxillary and nasofrontomaxillary sutures in Sus scrofa alters sinus shape and volume.  Support: University of Iowa, Dental Research Grant.


0903 (120423)

CBFA1 (RUNX2) Mutational Analysis of Two CCD Families. K. SANDIFER, J. DONG, Y. WU, P. WAITE, and M. MACDOUGALL, University of Alabama at Birmingham, Birmingham, AL

Cleidocranial dysplasia is an autosomal dominant disorder characterized by delayed tooth eruption, supernumerary teeth, and bone abnormalities. Various mutations in the transcription factor core binding factor alpha 1 (CBFA1), also known as Runx2, have been associated with CCD. Objectives: 1) To characterize the dental phenotype of the probands from two identify CCD families; and 2) perform mutational analysis of the CBFA1 gene in these families. Methods: Both probands from these families (CCD-005 & CCD-006) were clinically diagnosed with CCD and ascertained through the UAB School of Dentistry, Department of Oral Maxillofacial Surgery. Both families agreed to participate in this study by signing consent forms. Surgically removed supernumerary teeth were used to establish primary pulp cell cultures from each proband. DNA was extracted from the cells using the Wizard Genomic DNA extraction kit. The exons and introns of CBFA1 were amplified by polymerase chain reaction (PCR) using gene specific primers. PCR products underwent bidirectional sequencing reactions in order to detect DNA sequencing alterations. Results: Both probands presented with typical CCD clinical skeletal features such as abnormal clavicle bones. However, their dental profiles varied in the number and position of supernumerary teeth. Mutational analysis identified a known polymorphism (c.240A>G, p. A80A) in both probands. Interestingly,no pathogenic mutations in the coding and exon-intron boundaries of CBFA1 were detected in either CCD family. Conclusion: As found in this study, approximately 30% of CCD families do not have a mutation in the coding and exon-intron boundaries of CBFA1. Currently, we are studying other possible mechanisms of CCD in these families such as a large deletion or copy number changes in CBFA1. This work was supported by PreDART Program, ADEA William Gies Research Award and the UAB SOD/IOHR and Graduate School.


0904 (120513)

A Novel Mutation in Osteoclasts Resulted in Osteopetrosis & Odontoma. Y. XIE1, X. LU2, H.F. RIOS3, B. JIANG4, G. LUO5, and J.Q. FENG1, 1Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX, 2Case Western Reserve University, Cleveland, OH, 3University of Michigan, Ann Arbor, MI, 4Baylor College of Dentistry, Texas A&M Health Science Center, Dallas, TX, 5Case Western Reserve University, Cleveland

OBJECTIVES: to study roles of osteoclasts in tooth root formation. METHODS: genetic mapping; x-ray, histology, TRAP and cell cultures were used. RESULTS: We report on the identification and phenotypic characterization of a spontaneous mouse mutant with severe autosomal recessive osteopetrosis with odontoma. The mice form tartrate-resistant, acid phosphatase-positive multinucleated osteoclasts but these osteoclasts have no ruffled border and do not resorb bones on the dental slices. The mutation is recessive. The mutant mice also display severe dental defects, including no central spongiosa in the jaws, no tooth eruption and no root formation. All the aged animals developed odontoma. These bone and dental phenotypes could be fully rescued by transferring wild type embryonic liver cells to the mutant cells, indicating that the defect is intrinsic to the bone-resorbing osteoclasts. The genetic mapping data indicate that the disease-causing mutant allele is located within a genetic interval of 3.2 cM on mouse chromosome 17. This region contains only one known osteopetrosis disease-causing gene, the Clcn7gene. However, the analysis of the Clcn7 gene in this mutant did not support Clcn7 as the disease-causing gene, suggesting that a novel osteopetrosis disease-causing allele presented on mouse chromosome 17. Our working model, challenging the current dogma, is that the defects in the osteoclasts lead to a lack of bone marrow spaces for the tooth root, and that the perturbation of the homeostasis of the tooth root odontogenic and amelogenic precursors, rather than of the tooth germs, is primarily responsible for the development of odontoma.

CONCLUSION: Osteoclasts play critical roles in tooth root formation


0905 (120992)

Changes in CP27 Localization during Cell Cycle Progression. T. JIN, Y. ITO, X. LUAN, and T.G.H. DIEKWISCH, University of Illinois - Chicago, Chicago, IL

CP27 is a unique gene product that affects viability, proliferation, attachment and gene expression in vitro and is necessary for cell survival and differentiation during tooth morphogenesis. Defining CP27 subcellular localization is an important aspect of understanding CP27 function. Objective: To define the localization of CP27 during cell cycle progression. Methods: A GFP fusion construct was generated in order to trace CP27 over extended periods of time. For this purpose, the CP27 gene was inserted upstream of the GFP coding sequence of the pEGFP-N plasmid. Gene expression of the CP27-GFP fusion protein was under the control of the CMV Immediate Early gene promoter. The construct was transfected into the MDCK cell line, and cells stably expressing the CP27-GFP fusion protein were selected by G418. Cells were monitored using confocal microscopy, and selected areas were digitally recorded using time-lapse micro-cinematography. In order to verify CP27 nuclear localization, nuclear proteins from mice ES cells were extracted and subjected to Western Blot analysis using our anti-CP27 antibody. Results: Using time-lapse movies to monitor CP27 localization during mitosis, a continuous change in GFP-CP27 fusion protein distribution was documented. Prior to cell division, CP27 was localized in the nucleus of non-dividing cells. During the prophase, CP27 was released into the cytoplasm. In metaphase nuclei, CP27 co-localized with the microtubules of the mitotic spindle. During the anaphase, there was intense CP27 fluorescence surrounding the separating daughter chromosomes. During the final stage of mitotic division, the CP27 fusion protein was distributed throughout the entire telophase nuclei. CP27 nuclear localization was confirmed on Western blots. Conclusion: CP27 was expressed in interphase nuclei. During cell division, CP27 was released into the cytoplasm, surrounded metaphase microtubules and anaphase chromosomes, and then returned to the nuclei of daughter cells. Funding by NIH grant DE13095 to TGHD is gratefully acknowledged.


0906 (121068)

Hertwig's Epithelial Root Sheath Cell Fate Analysis. Y.P. HUNG, X. HUANG, and Y. CHAI, University of Southern California, Los Angeles, CA

Root development begins as the cervical loop elongates and moves away from the newly completed crown area to form Hertwig's epithelial root sheath (HERS). HERS is derived from the connection of the inner enamel epithelium (IEE) and outer enamel epithelium (OEE). Morphologically, HERS is a structural boundary between two dental ectomesenchymal tissues: dental papilla and dental follicle. This kind of intercrossed structure indicates an important role for HERS. However, the fate of HERS and its function remain unclear. Objective: The purpose of this study is to investigate the morphological fate of HERS cells in vivo. Methods: K14-Cre;R26R mice were generated to observe HERS cells from postnatal day 0.5 to 60.5 by X-gal staining. Results: HERS cells are detectable on the surface of the root from the beginning to the completion of root formation and do not disappear. Most of the HERS cells are attached to the surface of the cementum, while others separate to become epithelial cell rests of Malassez. HERS cells secrete extracellular matrix components onto the surface of dentin before dental follicle cells penetrate the HERS network to contact dentin. HERS cells participate in the formation of cellular cementum and can become cementocytes, which express BSP, a marker for cementoblasts. During root development, HERS is not interrupted, and HERS cells may continue to communicate with each other through a network structure. Conclusion: HERS cells remain on the surface of the root throughout root development and participate in cementogenesis. The network of HERS cells may play an important role in their interaction with the cranial neural crest-derived dental mesenchyme to guide root development. Supported by R01 DE012711 and R01 DE014078, NIDCR, NIH.


0907 (117350)

Extra-Alveolar Hard and Soft Tissue Measurements by Computer Tomograghy. Y.-J. CHEN1, C.-T. KAO2, H.-S. LUK1, and M.-J. SU3, 1Chung Shan Medical & Dental College, Taichung, Taiwan, 2Chung Shan Medical University,Institute of oral biology and materials, Taichung, Taiwan, 3chung Shan Medical & Dental College, Taichung, Taiwan

Objective: The aim of present study was to evaluate the extra alveolar hard and soft tissue by cone beam volumetric computer tomograghy (CBVCT) and to establish guidelines for safe insertion sites of temporary anchorage device (TAD).

Methods: The hard and soft tissue of oral cavity were evaluated on 10 patients (5 male & 5 female, with informed consent) by CBVCT (i-CAT imaging system, Imaging Sciences international Inc., USA). The age range was 20 to 36 years old. Ten extra-alveolar regions of interest were selected based on anchorage requirements. The soft tissue depths were only measured at premaxillary and midpalatal regions, while the cortical bone thicknesses were measured in all the other sites. Data were collected and compared by statistical software.

Results: In most of the extra-alveolar insertion sites, the mean thickness of hard tissue is more than 10 mm, except for Infrazygomatic ridge and midpalatal region. The soft tissue depth of premaxillary region is thicker than that of midpalatal region (p< 0.05). Huge variation of hard tissue depth was observed at the infrazygomatic ridge. The cortical bone thickness was increasing from mesial to distal at both the buccal and lingual area in the mandible.

Conclusion: The CBVCT image can provide well guideline on placing TAD. The present study showed by inserting TAD at these 10 extra-alveolar sites could significantly decrease the root injury risks.


0908 (117673)

Skeletal Asymmetries in Normal Adolescents: Cone Beam Computed Tomography Analysis. D. SANDERS, P. RIGALI, F. URIBE, and R. NANDA, University of Connecticut, Farmington, CT

Background: An accurate diagnosis of asymmetry is critical for orthodontic and orthognathic surgical treatment. Cone Beam Computed Tomography (CBCT) allows clinicians and researchers the ability to examine maxillary and mandibular structures with improved accuracy over traditional radiographic methods. However, normative values have not been established for the asymmetries present in normal patients.

Objectives: To evaluate the characteristics of facial and dental asymmetries in a normative population.

Methods: In accordance with an IRB protocol approved by the University of Connecticut, CBCT scans were obtained from two orthodontic offices that routinely use 3D imaging. The sample group consisted of thirty consecutive patients (n=30) presenting for comprehensive orthodontic treatment. The inclusion criteria were as follows: (1) class I molar relationship, (2) all permanent teeth erupted, including second molars, (3) no malformed or missing teeth, (4) coincident dental and facial midlines, (5) no dental or skeletal asymmetries on clinical exam, (6) no previous orthodontic treatment, (7) no crossbites, (8) no history of facial trauma or medical conditions that may have altered growth, (9) symmetrical spacing or crowding up to 3mm per arch, (10) age from 10-18. Dental, maxillary, mandibular, and cranial base variables were measured with Dolphin 3D Imaging. CBCT analysis consisted of digitizing 34 anatomical landmarks modified from orthodontic cephalometric points. All reference points were digitized in three-dimensions and analyzed using 297 skeletal and dental variables. Measurements are represented below as the average±S.D.

Results:
Deviation from Facial Midline
  • Maxillary Incisors: 0.41±0.31mm
  • Mandibular Incisors: 0.44±0.34mm
  • Menton Deviation: 0.48±0.49mm
  • Pogonion Deviation: 0.47±0.50mm
  • Chin Angulation: 1.75±1.73deg
  • ANS Deviation: 0.39±0.31mm
Right-Left Discrepancies
  • Mandibular Length: 1.23±0.97mm
  • Ramus Height: 1.42±1.13mm
  • Corpus Length: 0.98±0.70mm
  • Gonial Angle: 1.75±1.78deg
  • Ramus Inclination: 2.40±2.03deg
  • Mandibular Plane Angle: 2.54±1.64deg

Conclusion: The results indicate that small asymmetries may be a common occurrence in the human craniofacial complex.


0909 (118736)

Combined-Imaging-Technique for Planning and Monitoring Canine Distalization Using Miniscrew Anchorage. R.C. SANTIAGO, G. CERRONE, Jr., R.W.F. VITRAL, and M.V.Q. PAULA, Universidade Federal De Juiz De For a, Juiz de Fora, Brazil

Objectives: this study introduces and tests the reliability of a combined-imaging-technique for planning and monitoring canine distalization using miniscrew anchorage. The accuracy of a surgical guide, bone quality in miniscrew sites and miniscrewxs stability 90 days after surgery were evaluated. Methods: multi-slice Computed Tomography (CT) exams were made and Denta Scan software (General Electric–Medical Systems, Milwaukee, WI) used to verify the Bone Mineral Density (BMD) in future miniscrew sites, 24 areas between the maxillary second premolar and the first molar (right and left side of 12 patients), and 6 areas mesial to the second premolars (3 patients). Results were confronted to NORTON and GAMBLE scale for the posterior maxillary region. Miniscrew Radiographic Stability (MRS) was assessed through comparing the linear distance between miniscrew and 2 established cephalometric points (Orbital and Nasion) in right and left lateral oblique radiographs (45°) obtained soon after miniscrew placement (T1) and 90 days after activation (T2). Success Index (SI) of miniscrew clinical stability was determined by absence of mobility and calculated as the percentage of total miniscrews stationary in T2. Pearson`s correlation test and ANOVA (in BMD determination) and Student`s t test for paired samples (in MRS) showed that the operator was calibrated. Surgical guides were adjusted and its accuracy was evaluated through periapical radiographs. Results: BMD values ranged from +167HU to +660.80 HU (mean + 420.63 HU), mean values close to the maximum value of NORTON and GAMBLE scale for the areas (0 to +500 HU). Surgical guide allowed optimal positioning during miniscrew insertion in all cases. Paired t test showed no statistically significant difference (p<0.05) in positions of miniscrews in T1 and T2, assessed through cephalometric outlines on lateral oblique radiographs. SI was 100%. Conclusion: complete success of miniscrew anchorage in 30 maxillary sites was observed when combined-imaging-technique was performed.


0910 (118754)

Age-Dependent Cone-Beam Computed Tomography Evaluation of Midpalatal and Zigomatic-Maxillary Sutures. G. CERRONE, Jr., M.T. MARTINS, and M.V.Q. PAULA, Universidade Federal De Juiz De For a, Juiz de Fora, Brazil

Introduction: difficulties and side effects during Nonsurgical-Rapid-Maxillary-Expansion-in-Adults (NRMEA) have been reported. Maxillary disjunction is related directly to Midpalatal Suture (MS) and indirectly to other cranial sutures, mainly the Zigomatic-Maxillary Suture (ZMS). Anterior papers suggested that after puberal growth and sutural obliteration the conservative maxillary expansion is unsuccessful; however, recent studies that investigated the MS through Computed-Tomography (CT) indicated that its obliteration is not age-dependent and that Mineral Density (MD) in sutural areas may be a limiting factor for application of NRMEA. Objectives: evaluate normal MD in MS and ZMS of 30 patients (age ranging from 10 to 70) submitted to Cone-Beam CT (i-CAT® Cone Beam 3-D Imaging System, Hatfield, PA). Methods: divided in 6 groups (10 to 20; 21 to 30; 31 to 40; 41 to 50; 51 to 60; and, more than 61 years old) patient's sutures were measured (in Pixiel's Digital Density-PDD) using the software Xoran-CAT (Imaging Sciences International Inc., Hatfield, PA) and compared to its own gold-standard maxillary PDD (Canine Fossa Region-CFR). In each MS 4 Areas of Interest (AOI) were defined in sagital images while densities values from these specific same areas were taken in 1 axial and 4 coronal images, then each patientxs mean value was calculated. In each right and left ZMS 3 AOI were defined and measured in standardized panoramic reconstructions, then patient's mean value was calculated. Results: Student's t test for paired samples showed that 21 individuals (70%) had significant different mean values between midpalatal and zigomatic-maxillary suture's PDD and canine fossa region's PDD and 9 individuals (30%) did not showed significant statistical differences (p<0,05). Individuals with mean values of sutural PDD lower than the ones seen in the CFR were found in all age groups. Conclusions: obtained data indicates, according to MD, that results suggest that sutural obliteration is not age-related.


0912 (116198)

Alternative Orthodontic Bonding Protocol Using Self Etching Primer. R.-B. CALDWELL, E. TUFEKCI, P.C. MOON, S.J. LINDAUER, and B. SHROFF, Virginia Commonwealth University - VCU/MCV, Richmond, VA

Objective: The purpose of this study was to develop a bonding protocol that would leave a minimum amount of adhesive on the enamel during debonding while providing adequate bond strength during orthodontic treatment. Methods: 100 human teeth were randomly assigned into five groups (N=20, each): Conventional acid etch (CAE), standard self etching primer (SEP), SEP applied with a light brush stroke (altered SEP 1), SEP applied directly to the composite of pre-coated bracket (altered SEP 2), and Primer only (control) groups. Brackets were debonded using an Instron universal testing machine in the shear mode and the mean bond strength values were calculated. Enamel surfaces were also examined under a light microscope to determine the location of failure using adhesive remnant index (ARI). Results: The Primer only group had significantly lower mean shear strength (0.14 MPa) than the CAE (13.87 MPa), SEP (12.10 MPa), altered SEP 1 (10.80 MPa), and altered SEP 2 (11.43 MPa), (p<0.05). However, these groups were not significantly different from each other (p>0.05). When ARI scores of 4 and 5 -indicating 10% or less resin left on the tooth surface- were taken into consideration, statistically significant differences were found among the groups (p<0.05). 85% of teeth in the altered SEP 2 group had 10% or less composite left on the tooth surface upon debonding (p<0.05). Conclusion: The application of SEP directly to the composite resin of the pre-coated brackets may be an ideal bonding method by providing adequate bond strength and leaving a minimum amount of composite resin on the tooth surface during debonding. Future in-vivo studies are needed to confirm the findings obtained from the current in-vitro study.


0913 (116218)

White Spot Lesions around the Brackets: An in-Vitro Study. C.M. FARAH, E. TUFEKCI, P.C. MOON, O. GUNEY-ALTAY, and S.J. LINDAUER, Virginia Commonwealth University - VCU/MCV, Richmond, VA

Enamel decalcification adjacent to brackets during orthodontic treatment may be a concern in patients with poor oral hygiene. Objective: the aim of this in-vitro study was to evaluate the cariostatic potential of a resin modified glass ionomer cement (RMGIC) (Fuji Ortho LC, GC America Inc, Chicago, IL) and amorphous calcium-phosphate (ACP) containing composite resin (Aegis Ortho, The Bosworth Co, Skokie, IL) to that of a resin control (Transbond XT, 3M Unitek, Monrovia, CA). Methods: Brackets were bonded to human molars with Fuji Ortho LC (n=15), Aegis Ortho (n=15) and Transbond XT (n=15). In addition, 15 teeth with no bonding agent were used as control. Prior to bonding, acid-resistant varnish was applied to the buccal surfaces of teeth leaving 2 mm exposed sound enamel around the brackets. Samples were immersed in 20 mL of demineralization solution at 37 ºC for 14 days. Decalcification of enamel surrounding orthodontic brackets was evaluated using visual examination under 2.5X magnification and Diagnodent. Data were analyzed with Fisher's test and statistical significance was set at P<.05. Results: In both Aegis Ortho and Fuji Ortho LC groups 80% of teeth were noted as without decalcification as compared to 50% in the Transbond group. However, these results were not statistically significant (P>0.05). All three groups were statistically significantly different than the control group (P<0.05). The degree of decalcification in the experimental groups was found to be slight so that Diagnodent was not able to detect white spot lesions. Conclusions: Even though the teeth bonded with ACP containing composite resin and RMGIC exhibited caries inhibiting trends, no statistically significant differences were shown due to possibly small sample size and/or length of the immersion in the demineralization solution which need further investigation.


0914 (116303)

Compliance with retainers in the first two years after treatment. K. KACER, M. VALIATHAN, M.G. HANS, and S. NARENDRAN, Case Western Reserve University, Cleveland, OH

Objectives: The purpose of this descriptive study was to estimate retainer wear and compliance among orthodontic patients in the first two years following active orthodontic treatment. Methods: A random sample, of 1200 orthodontic patients, was selected from four offices. Data were collected by a self-administered questionnaire that consisted of six items: type of retainer prescribed, age, gender, length of time since debond, and the hours per day and nights per week that patients were wearing their retainers. Responses were solicited by mail or the internet. Data were gathered on a categorical scale and analyzed using SPSS®. Results: Overall response rate was 36% during a six-week period. In the first three months after debond, 60% of patients are wearing their retainers more than 10 hours during a 24 hour cycle and 69% were wearing the retainers every night. At 19-24 months after debond, 19% of patients were not wearing retainers at all and 81% of patients are wearing their retainers at least one night per week. Compliance rates during the 0-3, 4-6, 7-9, 10-12, 13-18 and 19-24 month period were 69, 76, 55, 62, 45 and 45 percent, respectively. Age, gender and type of retainer did not influence the levels of compliance. Conclusions: The majority of patients continue to wear their retainers at least one night per week with compliance rates, as defined, tending to decrease in our sample. It is encouraging to note that 81% of the patient's in this sample would largely maintain their orthodontic result.


0915 (117004)

Elastomeric-Ligated Versus Self-Ligating Appliances: Plaque Retention Following 1-Year Orthodontic Treatment. T. BUCK, R. SAUERWEIN, P. PELLEGRINI, D.C. LAFFERTY, T. NIELSEN, I. RISTOVSKA, D. POON, D. COVELL, Jr., T. MAIER, and C.A. MACHIDA, Oregon Health & Science University, Portland, OR

Objectives: Formation of white spot lesions and enamel decalcification are common risk factors associated with fixed orthodontic appliance treatment. The objectives of this study were to measure levels of total plaque bacteria at the bracket-tooth interface of elastomeric-ligated (EL) vs. self-ligating (SL) brackets following one year of treatment, and to compare levels of plaque bacteria after an additional 5 weeks of use with elastomeric chains.

Methods: Thirteen patients, dental age 12-19 years, had fixed appliance treatment where one upper lateral incisor was bonded at random with either EL or SL brackets, and the contralateral incisor bonded with the other bracket type. Mandibular laterals received the reverse configuration. Plaque samples were obtained from facial surfaces of the lateral incisors at 1 week (T1), 5 weeks (T2), 1 year (T3) and 1 year plus 5 weeks (T4). Placement of elastomeric chains occurred at T3. Total plaque bacteria were quantified using plating on blood agar and ATP bioluminescence. Measurements were compared using paired t-tests.

Results: At T1 and T2, teeth bonded with EL brackets exhibited higher numbers of plaque bacteria than those bonded with SL brackets (p<0.05). ATP bioluminescence values strongly correlated to numbers of total plaque bacteria (r=0.895). At T3, there were no differences in bacterial load surrounding EL versus SL brackets. At T4, after 5 weeks of chain use, significant differences were found in the upper arch, with higher numbers of plaque bacteria present at the periphery of SL brackets compared to EL brackets (p<0.05).

Conclusions: Although SL brackets promote reduced retention of plaque bacteria early in orthodontic treatment, this difference disappears after 1 year of treatment. Furthermore, when elastomeric chains are introduced to close spaces, higher numbers of plaque bacteria were present at the periphery of SL compared to EL brackets (upper arch only).

Supported by OHSU Foundation Orthodontic Fund


0916 (117539)

Bacterial Adherence on Orthodontic Brackets and Titanium Miniscrew Implants. E.C. KAO1, L. JACKFERT2, J. THOMAS1, P. NGAN1, M. GLADWIN1, and E. GUNEL3, 1West Virginia University School of Dentistry, Morgantown, WV, 2Private Practice, Charleston, WV, 3West Virginia University, Morgantown, WV

Objectives: The purpose of this study is to determine the in-vivo and in-vitro bacterial accumulation and subsequent biofilm formation on miniscrews as compared to metal orthodontic brackets. Methods: In-Vivo: Plaque samples were taken from gingival base of orthodontic brackets on maxillary and mandibular centrals, and miniscrew heads placed according to treatment plan. Patients(n=5) were recalled once a month for 3 months after appliance placement. Samples were cultured in Streptococcus mutan-, Lactobacillus casei-, and Porphymonas gingivalis-specific media. Colony forming units(CFU's) at different sites and recall times were analyzed (ANOVA and Tukey-Kramer Test, p=0.05). In-vitro: Four metal brackets and titanium miniscrews were randomly placed inside three sterile tubings(n=12). After initial artificial saliva wash, the appliances bathed in a mixture of S.mutan, L.casei and P.gingivalis, and incubated in an anaerobic chamber. At weekly intervals for three weeks, the type and amount of microbial adherence (CFU's) on the two appliances were counted. Data were analyzed with ANOVA and student t-tests, p=0.05. Results: In-vivo study: For each bacteria studied, ANOVA revealed no significant differences in collection site and exposure time. There was an overall increase in all three bacterial species from first to second month; and a decrease from second to third month. In-vitro study: ANOVA revealed significant differences with regard to appliance type(p<0.001), bacterial species(p<0.0001), and their interactions(p<0.03). There was significantly greater accumulation of bacteria on metal brackets than titanium miniscrews. For both in-vivo and in-vitro studies,the CFU's found on all appliance types were S.mutans >L.casei >P.gingivalis. Conclusions: Similar amount and type of bacteria that accumulate on metal brackets can harbor around miniscrew implants. Since the presence of orthodontic appliances impairs plaque removal and oral hygiene maintenance,it is the responsibility of the orthodontist/dentist to provide proper oral hygiene education for patients, and to help eliminate any possibility of excess plaque/biofilm formation around these appliances.


0917 (118144)

Retrospective survey of Temporary Anchorage Devices Utilization in University Practice. T.J. RAY, F.M. BECK, and S.S. HUJA, Ohio State University, Columbus, OH

Introduction: Temporary Anchorage Devices (TAD's) provide the orthodontist the ability to move teeth without anchor loss and are being increasingly used in clinical practice. Objective: The goal of this retrospective study was to detail TAD utilization at one University Graduate Orthodontic and Faculty Practice. Methods: After IRB approval, patient data relating to age, health status, gender, together with clinical information such as TAD location, type/manufacturer of device used, timing and duration of loading, realization of desired outcome were gathered from 54 patient records. The study collected data from a 35 month period commencing October 2005. Results: A total of 128 TAD's were analyzed with the mean patient age being 23.7 yrs. The TAD's were placed by Orthodontic faculty (37.5%), Orthodontic residents (36.7%), Periodontists (20.3%), and Oral Surgeons (5.5%). Devices from nine manufactures were used, the majority (64.9%) being from two companies. Self-drilling TAD's were primarily (94.5%) used with majority of the TAD's being used for retraction (53.6%) and protraction (27.2%). The maxillary posterior region (54.7%) was the most common placement location and the majority (90.6%) of TAD's were placed in attached gingiva. The majority (81.3%) of the TAD's received direct loads, with a mean time prior to loading of 4.9 days post-insertion. The treatment outcome was realized for 66.4% of the TAD's. Twelve (9.4%) of the TAD's failed within 1 month of placement. Mean duration of TAD use was 7.8 months. Discussion: To the best of our knowledge, no other report of TAD utilization in a US University-based program exists. With multiple clinicians of varying experience, success rate is lower than typically reported. The location and intended tooth movement are similar to those reported in literature. Conclusion: A multi-University comparison is required and will serve to provide a more accurate representation of TAD utilization within the US academic institutions.


0918 (118313)

Effect of Orthodontic Aligner Laminate Thickness on Stress. P. NAMIRANIAN, T. KALILI, A. CAPUTO, and P. TURLEY, University of California - Los Angeles, Los Angeles

Objective: Orthodontic aligners have increased popularity due to enhanced esthetics and ease of application by the general practitioner. Studies have demonstrated inclusion of soft internal liners in aligners allows less localized stress to teeth and bone. Question is raised as to optimum aligner thickness required to exert sufficient load for orthodontic movement to minimize the potential risk of unwanted occlusal changes. The purpose of this study was to assess stress distribution as a function 0f laminated aligner thickness.

Methods: “Unaltered” photoelastic model of dentulous adult maxilla was fabricated using different teeth and bone simulants. PVS impression was taken of the unaltered model for CT scan and an “altered” model was fabricated using CAD/CAM technology after making the following lingual movements: Maxillary lateral incisors 0.3mm and maxillary central incisors 0.6mm. Thick laminated aligner (1.0mm) and thin laminated aligner (0.6mm) were fabricated from the digitally altered model. The two aligners were inserted over the photoelastic model to assess stress distribution, observed in the field of a polariscope and photographed.

Results: Both thick and thin laminated aligners demonstrated mild stress to laterals and moderate stress to centrals. However, the number and proximity of fringes associated with the thicker laminated aligner demonstrated greater concentration and intensity of stress. The amount of stress outside of the maxillary laterals and centrals was minimal for both thin and thick aligners tested.

Conclusion: Results indicate potential for greater degree of tooth movement and longer duration of tooth movement by using the thicker laminated aligner. The indicatethat faster orthodontic treatment may be achieved by using the 1mm laminated aligner as compared to the 0.6mm laminated aligner.


0920 (119197)

Effects of nickel-titanium and stainless steel leveling archwires. R. MORESCA1, J.W. VIGORITO2, G.C. DOMINGUEZ2, and A. MORO1, 1Positivo University, Curitiba, Brazil, 2School of Dentistry, University of São Paulo, São Paulo, Brazil

Objectives: To study the effects of leveling phase performed with heated activated nickel-titanium (NiTi) and stainless steel archwires evaluating the possible changes in lower incisors position in extraction cases as well as its correlation with treatment time. Methods: The sample was composed of 36 subjects, male and female, white Brazilians, mean age of 15 years and 5 months, with Angle Class I and II malocclusion, arranged in two groups. In group 1 (n=17), the leveling phase was performed with sequence 1, using three archwires: NiTi heated activated .016" and .019"x.025" and stainless steel .019"x.025". In group 2 (n=19), sequence 2 was tested, in which only stainless steel archwires were used (.014", .016", .018", .020" and .019"x.025" with passive torque in lower incisors). The data were collected using the computerized cephalometry and were compared by Student's t test at significance level of 5%. Results: In group 1, lower incisors tipped lingually and only the crown presented a lingual movement that was statistically significant (1.6mm). In group 2, the lower incisors remained unchanged. There was no vertical change in either group. Conclusions: Sequence 2 showed better control of the lower incisors and no changes in their position were observed whereas sequence 1 allowed torque expression of brackets prescription with lingual tip of these teeth. Treatment time was shorter using sequence 1. Both biomechanical variations studied showed advantages and disadvantages that should be known and evaluated by the orthodontist during case planning.


0921 (120392)

Acute Palatal Expansion Strains Alveolar Bone and Facial Sutures. Z. SUN, H. KIM, and S. HUENI, Ohio State University, Columbus, OH

Objectives: Rapid palatal expansion (RPE) is a common orthodontic technique that can potentially load and cause changes to the alveolar bone and facial sutures. This study was undertaken to measure mechanical strain (deformation) at the alveolar bone and some facial sutures during acute RPE. Methods: Eight pig heads (3- and 6-month-old) were used. A standard 2-band Hyrax palatal expander was fabricated and cemented on the third primary molars (M3, abutment tooth). Two 3-element rosette strain gages were attached to the buccal alveolar bone of M3 and the adjacent primary second molar (M2, non-abutment tooth), respectively. Single element strain gages were attached to the maxillary-premaxillary (MP), maxillary-zygomatic (MZ) and zygomatic-temporal (ZT) sutures. The expander was acutely activated up to 5mm (0.25mm/90seconds), during which strains were collected. Intermolar width change was measured from dental models. Results: Alveolar bone strain of both tested teeth increased linearly with expansion (Pearson correlations, r>0.9, p<0.05). Bone strain accumulated significantly faster in the abutment tooth (M3) than the non-abutment tooth (M2) (paired t-tests, p<0.05). The principle compressive strain was significantly higher at M3 than at M2 (paired t-test, p<0.05), while their principle tension was similar. Average intermolar width increased 1-2mm after 5mm of expansion and was significantly more for M3 than for M2 (paired t-tests, p<0.05). All tested facial sutures were strongly deformed during expansion but only the ZT suture strain was linearly correlated with expansion. Strain polarity was consistently compressive at the ZT suture, but varied in the MZ and MP sutures. Both suture and bone strain tended to be higher in the younger group but not statistically significant (2-sample t-tests, p>0.05). Conclusion: In this porcine model, midpalatal suture expansion causes compression accumulation at the abutment-tooth buccal alveolar bone and strongly deforms facial sutures. Partly supported by American Association of Orthodontists Foundation.


0922 (115275)

Morphological changes of midfacial complex treated with maxillary protraction appliances. P.H. LIU, I-Shou University, Kaohsiung Country, Taiwan, and H.-P. CHANG, Kaohsiung Medical University, Kaohsiung, Taiwan

Objective: The objective of this study is to investigate the morphological changes of the midfacial complex in subjects with the skeletal Class III malocclusion treated with maxillary protraction treatment. Methods: The subjects of the skeletal Class III malocclusion were consisted of 33 Taiwanese children (18 boys and 15 girls) with age ranging from 9 to 11 years, and the average treatment time was 1.4 years. The mean configurations of the midfacial complex in the pre- and post-treated stage were computed by Procrustes analysis. The thin-plate spline analysis (TPSA), with the consecutive grid deformation to present the growth or treatment effects, was used to evaluate the morphological changes. The statistical test (ANOVA) will be utilized to determine whether the mean configurations between pre- and post-treated stages differed significantly in this study. Results: The statistical tests indicated significant differences (p < 0.05) at the overall comparisons. The grid deformation of the TPSA showed the vertical compression of the configuration between pterygomaxillary fissure superior (Ptms) and posterior nasal spine (PNS) accompanied by obvious anteroposterior expansion between midpalatal point (MPP) and anterior nasal spine (ANS). The apparent anteroinferior elongation of the incisor alveolus between subspine (A) and prosthion (Pr) was also detected. Furthermore, the graphical results of the TPSA indicated that the midfacial complex of the Class III subjects through with the maxillary protraction treatment revealed the effect of a counter-clockwise rotation. The evidences of morphological change of regrowing midface were mainly located in the anterior half-regions of the midfacial complex. Conclusions: The maxillary protraction treatment is effective in correcting the skeletal Class III subjects due to maxillary undergrowth. The major contributions caused by maxillary protraction treatment consisted of forward displacement and elongate length of the maxillary complex. This research was supported by a grant from National Science Council of Taiwan, NSC 96-2221-E-214-056-MY2.


0923 (115250)

Lip Morphological Changes in Orthognathic Treatment for Class III Malocclusion. M.R. ISLAM, T. KITAHARA, L. NAHER, H. ATSUSHI, and S. NAKATA, Kyushu University, Fukuoka, Japan

Objectives: One of the most important opportunities of orthodontic treatment is to improve the esthetic and morphological harmony as well as the function of the oral and maxillofacial region. The objective of this study is to evaluate the morphological changes in the lips and to determine the degree of improvement in the smile after orthognathic surgery for Class III malocclusion.

Methods: The sample subjects were consisted of 30 adult female patients with Angle Class III malocclusion and 28 adult female volunteers with normal occlusion. Frontal photographs were taken both before and after orthognathic treatment and 35 landmarks were placed on each tracing made from the photograph. Thereafter, landmarks were digitized into an x and y coordinates system with the subnasal point as the origin. The pretreatment rest and smile conditions were compared with the posttreatment conditions, respectively, using paired t-tests. In addition, two sample t-tests were used to test for differences between the patients in the Class III and the control group.

Results: Both upper and lower lips in the smile of Class III pretreatment group were positioned downward, and the upward movement of the upper lip and mouth corners was smaller in comparison to control group. When smiling, the horizontal direction of the mouth corners was statistically significantly different between the pretreatment and posttreatment, whereas these were wider in the posttreatment than in the pretreatment. These characteristics of the Class III smile were improved after orthognathic treatment, but the differences with control group remained unchanged immediately after treatment.

Conclusion: The soft tissue morphology shows a relative improvement after orthognathic treatment. However, the soft tissues need a certain period of time for their functional adaptation. In future studies on morphological changes of the soft tissue in the lip area using such quantitative analyses are therefore expected to be useful.


0924 (117610)

Graduate orthodontic cases evaluated with the Objective Grading System: 2002-2006. M. FLINT, University of Oklahoma, Oklahoma City, OK, and G.F. CURRIER, University of Oklahoma Health Sciences Center, Oklahoma City, OK

Objective: The American Board of Orthodontics (ABO) recently completed the Objective Grading System (OGS) for orthodontic models and panoramic radiographs. The OGS is used in completed cases presented for Board Certification. This project evaluated the results of all orthodontic patient cases completed by graduate students in the University of Oklahoma Orthodontic Program from 2002-2006 using the OGS.

Methods: The OGS criteria and rational include alignment, marginal ridges, buccolingual inclinations, overjet, occlusal contacts, occlusal relationships, interproximal contacts, and root angulation. 490 cases completed by 22 orthodontics resident students were graded using this OGS criterion. The cases were consecutive without discrimination of patient age or case difficulty. Only cases that went to completion were evaluated. Scores <20 are considered passing. The scores 21-30 are considered possible passing cases. Cases scoring >30 would not pass Board Certification. Finally, the OGS scores were then compared to types of initial problems as identified by the ABO Discrepancy Index (DI).

Results: 246 cases had an OGS score <20. Of those 87% had a DI of >10, meaning they were difficult enough to be considered for Board Certification cases. 195 had an OGS score of 20 to 30, 94% of those being considered difficult enough for board certification. 49 had a score >30, with 86% of these with a DI >10. Of the 8 evaluation criteria, buccolingual inclination (mean=4.2) and occlusal contacts (mean=3.6) accounted for the greatest amount of points assigned for each case on average; and the majority of these involved second molars.

Conclusions: 81% of the cases treated met both the DI and OGS criteria for Board certification. These newly developed criteria can be useful in advanced education for patient assignment as well as for assessing and improving the quality of treatment outcomes. Supported by the J. Dean Robertson Society.


0925 (115532)

Effects of Orthodontic Treatment on Sagittal Jaw Relationship. T.-M. XU, and B. HAN, Peking University School of Stomatology, Beijing, China

Objectives: To investigate the general effects of orthodontic treatment on sagittal jaw relationship. Methods: 2147 orthodontic treated cases with complete pre- and post-treatment lateral head films were collected from about 11000 x-ray records taken from 1997 to 2000 at Radiology Department of Peking University School of Stomatology. Computerized cephalometric measures were done by 3 fourth-year-residents. The average landmarks of their three were used for cephalometric analysis. For this special study, we focus on the comparison of pre- and post-treatment SNA, SNB and ANB angle between patients below and above 18 years old. Results: Most of the changes during treatment except those of Class I and Class II cases show significant differences between patients below or above 18 years old (see table). If taking Class I as control group, ANB decreased by Class II treatment mechanics only in growing patient by reducing SNA and increasing SNB, while ANB increased by Class III mechanics in both ages' group, but significant changes exists only in growing patient by increasing SNA.

SNA

SNB

ANB

age

<18           »18

<18           »18

<18            »18

Cl I

-0.00±1.50     -0.11±1.30

0.15±1.40 ***  -0.27±1.14

-0.13±1.24  **   0.16±1.12

Cl II

-0.39±1.53     -0.11±1.36

0.37±1.52 ***  -0.15±1.15

-0.78±1.24  ***  0.02±1.09

Cl III

1.00±1.78  *** -0.03±1.40

0.15±1.62 **   -0.57±1.43

0.93±1.53   *    0.56±0.94

Conclusion: As far as sagittal jaw correction is concerned, in growing patient, Class II treatment mechanics works for both maxilla and mandible while Class III mechanics works for maxilla only.


0926 (116308)

Perception of Esthetic Outcomes of Invisalign Versus Fixed Appliances. S.D. WADDOUPS, E. TUFEKCI, and S.J. LINDAUER, Virginia Commonwealth University - VCU/MCV, Richmond, VA

Although a comprehensive orthodontic treatment may be achieved using Invisalign, there have been concerns regarding what this appliance can and cannot do. Although there are previous investigations that assessed the treatment outcomes, no studies have attempted to compare the perception of treatment outcome of fixed orthodontic appliances versus Invisalign. Objectives: The purpose of this study was to compare the difference in perception of treatment outcome esthetics between Invisalign and conventional fixed orthodontic appliances among orthodontists, general dentists, first and fourth year dental students, and laypersons. Methods: There were five groups (n=45 each): orthodontists, general dentists, first year and fourth year dental students, and laypeople. Evaluators were asked to fill out a questionnaire by rating the attractiveness of smile photographs on a 100-mm visual analogue scale (VAS). Six of the photos with ideal and poor occlusions served as controls. The individual ratings were measured in mm with a digital caliber to determine the rater's score. Mean VAS scores were calculated and ANOVA was used to compare the results among the different groups. Statistical significance was set at P<0.05. Results: There were no statistical differences in the perception of treatment outcome esthetics between the Invisalign and conventional fixed appliances in any groups (P>0.05). Individuals in the laypeople group were found to rate the esthetics of smile photographs significantly less attractive than the evaluators in the other groups (P<0.05). There were significant differences between the female and male raters; females gave significantly lower scores than the males (P<0.05). Conclusions: The results of this study suggest that there were no significant differences in the attractiveness of smile photographs treated with either Invisalign or conventional fixed appliances.


0927 (116321)

Effects of Expansion in Class I: Evaluation One Year Follow-up. I. WASSERMAN, Sr., Universidad del Bosque, Bogota, Colombia

Objectives: To compare the changes in dental arches and cephalometric measurements in a one-year treatment with two removable arch expansion appliances during mixed dentition period in class I crowded patients.

Methods: A clinical randomized trial with two treated groups with Frankel Function Regulator type I (FR-1) (n=44), Schwarz appliance (Sz) (n=46), and an untreated Control group (C) (n=41), ages ranging from 6 to 10 years was done. Models to T0 (pre-treatment) and T1 (a year later) were taken and 12 cephalometric measurements and 3 measures on the inferior arch were evaluated: Little's irregularity index, intercanine and intermolar distance. Changes were statistically evaluated with Student's test, Wilcoxon test and ANOVA.

Results: Variables like SNA, ANB, SN-MP and ANS-Mn showed a significant increase associated to changes produces by growth. At T1 there were not any statistically significant differences between the untreated, the FR-1, and the Schwarz groups for Little's irregularity index (p>0.05). L1-MP angle increased in the treated groups (FR-1: p<0.001, Schwarz: p<0.05) in contrast with the control group. Intercanine distance increased significantly from T0 to T1 (p<0.05) and was not influenced by the type of treatment or time (p>0.05).

Conclusion: One year after the observation there were no significant differences between the C, the FR-1, and the Sz groups regarding the irregularity of the mandibular incisors. The cephalometric and dental casts variables showed increase associated with growth but not with therapy. L1-MP angle increased in the treated group regardless of the appliance used.


0929 (117882)

Three-dimensional evaluation of the attractiveness of average faces. W. MIYASHITA, The Nippon Dental University Hospital, Tokyo, Japan, and R. NAKAHARA, The Nippon Dental University, School of Life Dentistry at Tokyo, Tokyo, Japan

Objectives: Many studies have demonstrated attractive facial forms to establish a facial standard for orthodontic treatment. However, whether a face is attractive or not depends on a subjective judgment by the evaluator. To produce an attractive facial form objectively and automatically, average faces were reported, but there are no reports evaluating their 3-dimensional attractiveness on a theoretical basis. The aim of this study was to evaluate the attractiveness of average faces 3-dimensionally. Methods: Animation shows were prepared from each 3-dimensional facial image of 52 subjects (26 males and 26 females), obtained with a laser scanning device, Voxelan HEV-300M (Hamano Engineering co. ltd., Kawasaki, Japan) and their 3-D average facial images. Then a panel of 20 persons consisting of 10 orthodontists group (5 males and 5 females) and 10 lay persons group (5 males and 5 females) was asked to judge the attractiveness of each animation show. For statistical analyses, mean scores and standard deviations were calculated by judge's group, gender, range of age, and overall. We used Wilcoxon signed-ranks test and Speaman's rank correlation coefficient between groups and genders, Freedman's test and Kendall's coefficient of concordance between ranges of age, and Wilcoxon signed-ranks test between the average face and the subjects scored at first to fifth. Results: There were significant differences in judgment scores between groups, but were not found between genders. Generally, the result showed that average faces were most attractive in all images. For both males and females, there were significant differences in attractiveness scores between average faces and all subjects excluding the most highly rated male. Conclusion: It was demonstrated that average faces were extremely attractive even 3-dimensionally. Therefore, they could become the 3-D facial standard with attractiveness and objectivity.


0930 (116975)

A comparison of five cephalometric planes evaluating lower lip position. K. FRETTY, P. CAMPBELL, and P.H. BUSCHANG, Baylor College of Dentistry, Dallas, TX

Objectives: To determine which, if any, of five commonly used lip profile planes best describes horizontal lower lip orthodontic treatment changes. Methods: Pretreatment and post-treatment cephalograms of 79 patients 12.4±2.8 years of age, including 22 female nonextraction cases, 16 female extraction cases, 22 male nonextraction cases, and 19 male extraction cases. For each patient, nine landmarks were digitized twice on separate occasions and averaged. Lower lip (labrale inferiorus) changes over time were measured relative to five lip profile planes, including Burstone's B line, Sushner's S2 line, Rickett's E line, Holdaway's H line, and Steiner's S1 line, using Viewbox 3.0 software. As independent measures of treatment change, the horizontal changes in infradentale, lower incisor tip, and labrale inferiorus were measured relative to a stable reference plane registered on sella and oriented on the SN-7„a. Results: The five profile planes showed no significant sex differences in the treatment changes. While all five profile planes measured greater treatment effects for extraction than nonextraction cases, only Holdaway's H line demonstrated statistically significant group differences. The E line (s2=2.66mm) showed the greatest variation among the subjects, while the H line (s2=1.28mm) showed the least variation. While lip changes based on the five profile planes demonstrated moderately high to high inter-correlations, ranging from 0.81 to 0.97, they showed only weak correlations (r<.35) with the horizontal changes of infradentale and labrale inferiorus. Conclusions: While all five planes measured a similar aspect of positional change, none of them closely reflected the actual lower lip changes that occurred. This research was supported by Baylor Oral Health Foundation.


0931 (118329)

3D soft tissue changes following Class III surgical correction. C. KIEFER1, L.H.S. CEVIDANES2, D. GRAUER2, M. STYNER2, H. ZHU2, and C. PHILLIPS2, 1University of North Carolina, Cary, NC, 2University of North Carolina, Chapel Hill, NC

Objective: To determine the correlation between 3D skeletal changes with Class III surgical correction and 3D soft tissue changes at splint removal.

Methods: This prospective observational study assessed pre-surgery and at splint removal cone-beam CT scans of 19 subjects with skeletal Class III malocclusion. Hard and soft tissue 3D virtual surface models were registered and superimposed on the cranial base to assess positional changes in the chin and maxilla. These changes were visually displayed and quantified using three-dimensional color maps. Pearson correlation coefficients were used to assess whether hard tissue 3D changes were correlated with soft tissue 3D changes for each region.

Results: The 3D hard and soft tissue changes of the maxilla (r=0.61, p=0.005) and chin (r=0.91, p<0.0001) were positively correlated. The soft changes (mean maxilla= 4.72 ± 1.84mm; mean chin= 3.35 ± 2.14mm) at splint removal were slightly larger than hard tissue changes (mean maxilla= 3.96± 1.98mm; chin mean 2.5± 2.11mm), as patients still present some post-surgical swelling at splint removal.

Conclusions: The findings from this preliminary study indicate that soft tissue post-surgical changes are closely related to the amount of skeletal displacement in the chin and maxillary regions. Future studies including larger samples to assess soft tissue changes 1 year after surgery will further elucidate these relationships for application in 3D surgical predictions (Supported by NIDCR DE017727 and DE005215).


0933 (118868)

Orthodontic Trend Assessment of Four Decades using DI and ABOGS. P. PATEL1, C.A. DEMKO, PhD2, M.G. HANS1, and M. VALIATHAN1, 1Case Western Reserve University, Cleveland, OH, 2Case School of Dental Medicine, Cleveland, OH

Objective: To compare pre-treatment case complexity and treatment outcomes using the Discrepancy Index (DI) and American Board of Orthodontics Grading System (ABOGS) respectively. Materials and Methods: Corresponding pre- and post- treatment dental casts were assessed using DI and ABOGS to evaluate case complexity and quality of outcomes, from a sample drawn from 1960-2005. Information gathered included, but was not limited to, duration of treatment, mandibular canine and first molar width, and extractions. A total of 655 randomly selected cases (148 from 1960's, 194 from 1970's, 215 from 1980's, and 98 from 2000's) were evaluated by a single, self-calibrated operator. Results: Reliability tests (intraclass correlations) revealed good reliability with values of 0.987(DI) and 0.781(ABOGS). Individually, the evaluating scores showed statistical significance as a total (p=0.00) and between 1960's, 1970's, and 1980's compared to the 2000's (p=0.00). DI had mean scores of 14.36 ± 5.98, 14.56 ± 7.98, 12.39 ±7.06, 9.714 ± 5.82, respectively to the progressing decades. Variables of significance included overjet (p=0.00), overbite (p=0.003), and occlusion (p=0.002). ABOGS had means of 14.59 ± 7.53, 17.65 ± 8.56, 14.64 ± 6.69, 8.586 ± 5.92, respectively, to consecutive decades. Almost all variables within the ABOGS showed statistical significance (p<0.005) expect Bucco-lingual (BL) inclination. Discussion: Orthodontic post-treatment results illustrated an improvement between the decades with the 2000's having the lowest scores indicating the best results. A similar decrease in pre-treatment scores suggested that cases were less complex over the decades studied. For ABOGS, BL inclination was not significant possibly suggesting that occlusal relationship and occlusal contacts are more representative of occlusal correction. Conclusions: A directly proportional improvement in DI and ABOGS throughout the decades indicated that a more functional outcome was achieved with less complex cases.


0934 (117850)

Forty Years of Orthodontic Case Complexity and Outcomes Using ICON. M. HALL, C.A. DEMKO, M.G. HANS, and M. VALIATHAN, Case Western Reserve University, Cleveland, OH

Objectives: To evaluate orthodontic case complexity and outcomes over four decades at an established graduate clinic, using the Index of Complexity, Outcome and Need (ICON). Methods: Pre- and post-treatment study models for 657 patients, who received treatment from the 1960s to mid-2000s, were randomly selected from the orthodontic department archival area. Occlusal traits of the models were scored by a single, self-calibrated examiner using the ICON. Results: Mean pre-treatment ICON scores were as follows: 1960s: 70.33±18.81 (SD), 1970s: 68.72±18.91, 1980s: 63.45±18.49, and 2000s: 59.68±19.43. The ANOVA statistical test revealed a significant difference (p<0.000) between pre-treatment ICON scores for each decade. The least squares difference (LSD) statistical test determined significance when the 1960s and 1970s were independently compared to the 1980s and 2000s (p≤0.005). Mean post-treatment ICON scores were as follows: 1960s: 25.02±9.85, 1970s: 27.81±11.67, 1980s: 24.65±10.08, and 2000s: 18.42±6.87. The ANOVA test found a significant difference (p<0.000) between decades for post-treatment ICON scores. The LSD test revealed that all decades, except the 1960s compared to the 1980s, were significantly different (p≤0.012). The degrees of improvement were as follows: 1960s: -29.75±39.27, 1970s: -42.54±49.95, 1980s: -35.14±40.15, and 2000s: -14.00±32.09. The ANOVA test established significance (p<0.000) between decades. The LSD test determined that the 1960s compared to the 1970s, and the 1960s, 1970s, and 1980s independently compared to the 2000s, were all significant (p≤0.005). Intra-examiner agreement for both pre- and post-treatment casts was good [0.76 and 0.81 respectively, measured with the Intraclass Correlation Coefficient (ICC)]. Conclusions: Case complexity from the 1960s to the present decreased. Accordingly, treatment outcomes improved from the 1970s to the present. A concurrent increase in degree of improvement indicates improved quality of treatment and outcomes at the orthodontic clinic of CWRU.


0935 (119672)

Determining Orthodontic Outcomes Over Four Decades Using the PAR Index. A. AMINOSHARIAE1, C.A. DEMKO2, M.G. HANS1, and M. VALIATHAN1, 1Case Western Reserve University, Cleveland, OH, 2Community Dentistry, Case Western Reserve University, Cleveland, OH

Objective: To determine the quality of orthodontic outcomes and evaluate the trends over the past 40 years using the Peer Assessment Rating Index (PAR). Method: Using the protocol described by Richmond et al. (1992), 655 pairs of pre-treatment and post-treatment dental stone models were scored to determine pre-treatment complexity and post treatment outcomes. The dental casts from the 1960's to the mid-2000's are archived in the Department of Orthodontics. Percent reduction was determined by the difference in PAR over Pre-treatment PAR, multiplied by 100. Intraclass Correlation using SPSS software was utilized to determine reliability. Results: Reliability was determined to be 0.96 and 0.88, for pre-treatment and post-treatment, respectively (95% Confidence Interval, n = 16). The means and standard deviations of pre-treatment PAR scores (1960 – 27.1, 8.4; 1970 – 27.2, 8.9; 1980 - 25.2, 8.9; 2000 - 24.2, 9.6) are significantly different between decades recorded (p = 0.011). However, only Total Overjet subscore demonstrated a difference within the decades (10.8, 5.4; 10.2, 5.5; 8.8, 5.7; 7.8, 5.6) (p < 0.000). Post-treatment PAR scores (6.5, 4.7; 6.5, 5.1; 5.5, 4.8; 3.6, 2.8) displayed trends throughout the decades not only in overall score (p < 0.000) but in many of the subscores using a 95% Confidence Interval (Total Maxillary Anterior Alignment, Total Right Buccal Occlusion, & Total Overbite). Percent Reduction was shown to be significantly different in each of the decades (75.5, 17.9; 75.4, 22.1; 77.7, 19.0; 83.6, 12.6) (p = 0.003). Conclusion: The largest discrepancies in PAR scores were evident during the earlier decades. Higher case-complexities were shown in the 1960s and 1970s. Ultimately, statistical as well as clinical trends were demonstrated throughout each decade with a considerable focus on overjet and overbite evaluations.


0936 (120816)

Longitudinal Linear Measurements of Treated Children During the Post-Growth Period. U. JADAV1, C.H. KAU2, T. NGUYEN1, and S. RICHMOND3, 1University of Texas - Houston/Health Science Center, Houston, TX, 2University of Texas Dental Branch at Houston, Houston, TX, 3University of Wales, Cardiff, United Kingdom

OBJECTIVE: The aim of this study was to determine post-growth period (>14.5 years) facial changes that occurred in a group of children.

METHODS: The sample consisted of 22 subjects (with orthodontic treatment) studied longitudinally for 3 years. The mean age (Males = MNT, Females = FNT) was 14.5 years. A previously-validated three-dimensional laser surface scanner system was employed. The laser scanning system consisted of two high-resolution Minolta Vivid VI900 3D cameras operating as a stereo-pair, with a reported manufacturing accuracy of 0.3 mm. Rapidform 2006 Plus Pack 2 was used to process final images. Sixteen anthropometric landmarks were identified on each scan (Figure 1.1). Eleven linear measurements were tabulated.  Only subjects that had greater than two annual measurements were included.

RESULTS:  21 children (Males = 10, Females = 12) were included in the final sample.  On average, the MT group had larger landmark differences in their features as compared to FT. The growth of characteristics such as biocular distance, nose length, soft nose width, lip width, and morphological face height increased at a faster rate in the MT group.  Figure 1.2 demonstrates the differences in the post-growth period of treated males and treated females. Biocular distance and nose length increased by a rate about six times greater than the females counterparts. Lip width of the males increased at a rate almost seven times greater than the females. The growth in the physiognomical upper face height from T5 to T7 in males was over twenty-eight times greater than females.

CONCLUSIONS: This study demonstrates the changes in growth of untreated males versus females after 14.5 years of age, the post-growth period. Males tended to have more facial changes during the post-growth period.  This study also demonstrates that facial changes still continue to occur in males after the pubertal growth spurt.

 

LINEAR MEASUREMENTS (Figure 1.1)

Intercanthal Distance: 1, 2                       Lip Width: 13, 14

Biocular Distance: 3, 4                            Nose to Mentis: 6, 15

Nose Length: 5, 6                                    Morphological Face Height: 5, 15

Soft Nose Width: 7, 8                             Physiognomical Upper Face Height: 5, 16

Inner Nostril Width: 9, 10                       Lower 1/3 Face Height (calc): 15, 16

Upper Lip Point Distance: 11, 12

 

 Figure 1.2

1. Intercanthal Distance (mm)

2. Biocular Distance (mm)

3. Nose Length (mm)

4. Soft Nose Width (mm)

5. Inner Nostril Width (mm)

6. Upper Lip Point Distance (mm)

7. Lip Width (mm)

8. Nose to Mentis (mm)

9. Morphological Face Height (mm)

10. Physiognomical Upper Face Height (mm)

11. Lower 1/2 Face Height (mm) calculated

MALES

 

 

 

 

 

 

 

 

 

 

T5

34.95

84.40

52.93

33.53

14.11

12.28

46.96

64.65

112.10

74.14

37.96

T6

35.02

85.53

54.03

33.82

13.81

12.60

47.42

66.44

114.84

76.22

38.63

T7

34.89

87.17

55.05

34.84

14.17

12.59

49.48

67.03

116.45

77.31

39.14

Growth (T5-T7)

-0.05

2.77

2.13

1.31

0.06

0.30

2.52

2.38

4.34

3.16

1.18

 

FEMALES

 

 

 

 

 

 

 

 

 

 

T5

34.69

91.41

50.67

29.89

17.60

12.04

43.62

59.28

108.54

70.27

38.28

T6

34.43

92.32

50.75

30.25

17.57

11.97

43.56

59.72

108.87

70.32

38.55

T7

34.14

91.89

51.02

30.40

17.41

12.16

43.98

59.27

108.47

70.38

38.09

Growth (T5-T7)

-0.55

0.48

0.35

0.51

-0.19

0.12

0.36

-0.01

-0.08

0.11

-0.18


0937 (118664)

Cone Beam Computed Tomography Guided Localization of Canal Lumina. N. CHUGAL1, C. MAUPIN1, D. ELASHOFF2, T.-L. CHANG1, G. LONGHURST1, M.K. KANG1, S. WHITE1, and S. TETRADIS1, 1University of California Los Angeles, School of Dentistry, Los Angeles, CA, 2University of California Los Angeles, Los Angeles, CA

Essential part of endodontic treatment comprises locating and negotiating infected root canals. Calcified canals pose diagnostic and treatment challenges. The origin of canal lumen and distance from CEJ is estimated by conventional projection radiography. Cone-beam computed tomography (CBCT) has the potential to offer improved visualization and accurate localization of root canals. Objective: The purpose of this study was to compare the efficacy of CBCT and conventional projection radiography for detection of canal lumina in extracted human teeth. Methods: Forty three teeth/roots (n=43) appearing to have partially calcified canals by conventional radiography were selected from an existing collection of extracted teeth. Two imaging systems were compared for their ability to detect any evidence of a root canal lumen: CBCT images (3DX Accuitomo, J. Morita, Kyoto, Japan), and periapical F-speed film radiographs (PA). The test teeth were mounted in a dry sagittally-sectioned mandible and CBCT scans and periapical radiographs were taken. The distance of the canal lumen origin was measured in millimeters from the apical extent of the CEJ on periapical radiographs and CBCT scans. The CBCT and PA radiographs were evaluated by three endodonists. The CBCT images were evaluated dynamically in the axial, sagittal and coronal planes. Results: Root canal lumina were detected in an average of 98% of the roots using CBCT and 64% of roots using PA radiographs. The increase in the detection frequency was 34% (p<0.05). The average agreement between observers was 98% for CBCT and 60% for PA radiographs. The level of agreement between observers found in CBCT versus PA radiograph was significant (p≤0.007). The detection of distance of the canal lumen from the CEJ was significantly shorter in CBCT scans compared to PA radiograms (p<0.05). Conclusion: The 3DX Accuitomo images proved to be superior in its ability to localize canal lumina compared to conventional periapical radiographs.


0938 (116127)

Root Canal Systems in Mandibular First Premolars with C-shaped Root. B. FAN1, J. YANG1, J. GUTMANN2, and M.W. FAN1, 1School & Hospital of Stomatology, Wuhan University, Wuhan, China, 2Texas, Dallas, SK

Objectives:to investigate the morphology of the radicular grooves and root canal cross sections in mandibular first premolars that exhibit a C-shaped root using micro-computed tomography. Methods:86 mandibular first premolars with C-shaped roots were selected from 358 mandibular first premolars in a Chinese population and scanned from the coronal to anatomical apex using µCT80. The location, length and depth of the radicular grooves were measured. The cross-sectional morphology of root canal systems were evaluated at 11 levels. Results were subject to the Kruskal-Wallis test. Results:Of the 86 C-shaped roots, a total of 93 radicular grooves were noted. Most of grooves (78.5%) were located on mesial lingual surface of the root. The C-shaped canal could be seen to vary considerably in shape at different levels(p<0.005), and the incidence of double canals at the middle and apical was 21% and 80%, respectively. Conclusion:This study demonstrates that radicular grooves of mandibular first premolars may present relevant morphological variations in the root canal system when the C-shaped root is present. This study was supported by the National Natural Science Foundation of China (Grant No.30572042) and the Key Technologies R&D Programme of Hubei Province,China (Grant No.2007AA302B06).


0940 (117400)

Anatomical Relationship between the Interorificial Distance and Root Canal Configuration. G. KARAMAN, M. ÜNGÖR, and E.O. ÖNAY, Baskent University, Ankara, Turkey

Objectives: The purpose of this study was to investigate the relationship of the distance between mesiobuccal (MB) and mesiolingual (ML) orifices (interorificial distance) in the pulp chamber floor and the canal morphology of MB root in maxillary first and second molars.

Methods: The freshly extracted teeth investigated were 100 first molars (50 men, 50 women; age range, 16-77 years), and 100 second molars (50 men, 50 women; age range, 19-79 years) were obtained over a 1-yr period of time by 1 endodontist from the Public Dental Services located in Ankara, Turkey. The crown of each tooth was sectioned 1mm to the cemento-enamel junction coronally using a diamond disc. To measure the interorificial distance, each section was digitally imaged using a stereomicroscope (Leica Microsystems, Heidelberg GmbH, Mannheim, Germany) at a magnification of ×10 with a CCD camera. Each image was then transferred to a personal computer and analyzed by using a CoralDRAW 11 (Corel Corp. 2002, USA) image processing software. Size 08 K-files (MANI Inc., Tochigi, Japan) are placed into the canals until they were clearly visible as they penetrated the apex. The teeth were radiographed in both the buccolingual and mesiodistal directions and the canal configuration of the MB root was classified according to the Weine classification. Data were analyzed using the Mann-Whitney U test. All levels of significance were set at p<0.05.

Results: The mean interorificial distance in both maxillary first and second molars was significantly shorter in type II (3.16±0.32mm; 3.09±0.22mm, respectively), compared to type III (3.8±0.26mm; 3.89±0.23mm, respectively) (p<0.05).

Conclusion: A longer interorificial distance may be an important clinical finding in predicting the occurrence of Weine type III canals in the MB root of maxillary first and second molars


0941 (115756)

Shaping ability of EndoSequence rotary NiTi system. M. AL OBAIDA, and F. ALONAIZAN, King Saud University, College of Dentistry, Riyadh, Saudi Arabia

Objectives: The aim of this study was to assess the shaping ability of EndoSequence rotary NiTi system and compare it with three commonly used rotary NiTi systems. Materials and Methods: A total of forty resin simulated root canal blocks were instrumented with ProTaper, RaCe, EndoSequence and Profile to size #30 as MAF (n=10). Pre- and post-instrumentation images were superimposed and evaluated for presence of zipping, ledging or perforation. Further analysis was done by calculating the amount of transportation at the middle and the apical thirds. Data were analyzed using appropriate statistical methods. Results: EndoSequence and RaCe groups took significantly less instrumentation time compared with Profile and ProTaper groups (p-value<0.05). Non-significant difference was found among the groups in terms of zipping, ledging and perforation (p-value>0.05). Conclusion: Under the conditions of this study EndoSequence rotary NiTi files prepared simulated canals rapidly and safely, with minimal canal aberration.


0943 (115808)

Effectiveness of chlorhexidine solution with calcium hydroxide against Candica albicans. S. AL NAZHAN, and M. AL OBAIDA, King Saud University, College of Dentistry, Riyadh, Saudi Arabia

Objective: The purpose of this investigation was to examine the in vitro susceptibility of Candida albicans to a mixture of chlorhexidine and calcium hydroxide using a tube dilution test. Materials and Methods: A suspension containing C. albicans was exposed to 2% chlorhexidine solution, calcium hydroxide paste and 2% chlorhexidine mixed with calcium hydroxide in plastic tissue culture wells. The tested agents were incubated with C. albicans for 1, 24 or 72 hours. Results: All agents were effective anti-fungals at all experimental time periods tested, with the exception of exposure to calcium hydroxide for 1 hour. Conclusion: A mixture of 2% chlorhexidine and calcium hydroxide therefore is a very effective anti-fungal agent against C. albicans.


0944 (113914)

Particle size and shape of calcium hydroxide in Endodontics. T. KOMABAYASHI1, R.N. D'SOUZA1, P.C. DECHOW1, K. SAFAVI2, and L.S. SPÅNGBERG2, 1Texas A&M Health Science Center Baylor College of Dentistry, Dallas, TX, 2University of Connecticut, Farmington, CT

Objectives: Calcium hydroxide aqueous slurry is widely used as an interim (interappointment) antimicrobial dressing in root canal treatment. Less than 0.2 % of the slurry is dissolved into calcium and hydroxide ions, leaving mostly undissolved particles. While it is known that the penetration of particles into dentin tubules is determined by size and shape, the precise physical properties of the particle are not known. The aim of this study was to use image analysis to establish particle length, width, perimeter, and aspect ratio of calcium hydroxide powder using a flow particle image analyzer (Sysmex FPIA-3000, Japan). Methods: Five sample groups each with 10 mg calcium hydroxide (Sigma-Aldrich) were mixed with 15 mL of alcohol and sonicated. Samples were run using High Power Field mode at an effective size range of 0.5-40μm. Digital images of particle samples were taken and statistically analyzed using one-way ANOVA. Results: Overall Average±S.D. among five groups for particle length (μm), width (μm), perimeter (μm), and aspect ratio were 2.255±1.994, 1.620±1.464, 6.699±5.598, and 0.737±0.149, respectively. No statistical significance was observed among five groups in the analysis of all parameters. When the total of 46818 particles from all five groups were classified into the five length categories at 0.5μm increments, length category 2 (1.0-1.5μm) and length category 1 (0.5-1.0μm) were the highest in frequency and aspect ratio, respectively. ANOVA showed there were significant differences in width, perimeter, and aspect ratio among the five length categories (all p-values<0.0001).Conclusions: The cumulative percentage of particles length between 0.5 and 2.0 μm, which is smaller than the reported size of dentin tubules in root dentin, was 63%. Calcium hydroxide fine particles can be possible to penetrate into open dentin tubules, and its shape is not round but irregular.

Acknowledgement: Hosokawa Micron Ltd. & Malvern Instrument Ltd. /NIH KL2RR024983(TK), UL1 RR024982.


0945 (115751)

Antimicrobial and Tissue Dissolving Capabilities of Different NaOCl Concentrations. P. VAN DER VYVER, F. BOTHA, and F.A. DE WET, University of Pretoria, School of Dentistry, Pretoria, South Africa

Objective:The objective of this in vitro study was to establish the antimicrobial efficacy and the potential to dissolve vital pulp using different concentrations of sodium hypochlorite (NaOCl) solutions. Materials and Methods: The following solutions were tested: (1) 2% NaOCl (Thick Jik); (2) 3.5% NaOCl (Jik); (3) 6% NaOCl (Vista); (4) 6% NaOCl (Dent-Ionics); (4) 6% NaOCl (Chlor-Xtra) and (5) Water (Control). Antimicrobial Effects: A MacFarland 1 suspension was prepared from an overnight culture of E. faecalis and spread onto 15 CASO-Agar plates. The prepared plates were randomly divided into 5 groups (n=3). Ten microlitres of each solution were dispensed onto four five millimetre diameter filter paper disks on each plate and incubated anaerobically at 37ºC for 24 hours respectively. The antibacterial activity of materials was apparent from circular clear inhibition zones forming around the filtration paper. Measurements were done after incubation at three different positions for each paper disk. An average was calculated for the nine measurements per paper disc on each plate. Tissue dissolving ability: Vital pulp tissue was removed from 4 freshly, extracted, human, third molar teeth and divided into 25 equal portions according to weight. Each specimen was immersed into 40ml of the selected irrigation solution (n=5). The time taken to dissolve the pulp tissue was recorded by means of a digital video camera. Averages between the five recording times for each solution were calculated. All the data was collected and statistically analyzed (Student–t test). Results: No significant inhibition of E. faecalis was observed with sterile water (control) and 3.5% NaOCl. However, the 2% NaOCl and all the other 6% NaOCl solutions showed significant inhibition against E. faecalis. Chlor-Xtra dissolved the pulp tissue in significantly less time compared to all the other groups (p<0.05). Conclusion: Chlor-Xtra demonstrated the best antimicrobial properties as well as tissue dissolving capabilities.


0946 (116771)

Pilot Study to Measure the Inhibition Zones of Pulpotomy Medicaments. M.L. CANNON1, C. WAGNER2, J.Z. THOBABEN2, X.T. ZHENG1, and R.V. JOHNSON2, 1Northwestern University, Chicago, IL, 2Childrens Memorial Hospital, Chicago, IL

Objective: To determine the effectiveness of pulpotomy medicaments in the inhibition of bacterial growth.

Methods: Suspensions at an appropriate turbidity of the three standard bacterial cultures (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli) were separately streaked in at least three directions over the surface of Mueller-Hinton agar plates to obtain uniform growth. Then six disks with each of the following medicaments were placed on the plates (two experimental and one control per plate): ciprofloxacin (positive control), 20% ferric sulfate (experimental), chlorhexidine 2% with Portland cement suspension (experimental), dilute Buckley's formocresol (clinical standard), 20% ferric sulfate with 1.2% chlorhexidine (experimental) and distilled water (negative control). Following overnight incubation, the diameter of the zone of growth inhibition around each disk was measured to the nearest whole mm.

Results: The dilute formocresol disks inhibition zones were less than the zones measured for the positive control by a factor of 50 %. The 2%chlorhexidine and Portland suspension disks had less than moderate zones of inhibition with Pseudomonas aeruginosa compared to the positive control and were more effective in inhibiting bacterial growth than the clinical standard, dilute Buckley's formocresol. However, the 2% chlorhexidine and Portland disks were as effective in inhibiting S. aureus as the positive control disks. The ferric sulfate disks had similar zones of inhibition to the negative control and were less effective in inhibiting bacterial growth than the clinical standard, dilute Buckley's formocresol.

Conclusion: The tested pulpotomy medicaments varied in their ability to inhibit bacterial growth with the 2%chlorhexidine and Portland cement group demonstrating greater effectiveness than the ferric sulfate and dilute formocresol groups. The 2% chlorhexidine and Portland cement group had almost as much effectiveness as the positive control, ciprofloxacin. Disks with a 50% mixture of ferric sulfate (ViscoStat) and 1.2% chlorhexidine (Peridex) zones of inhibition were as effective as formocresol.


0947 (119073)

Biologic and Clinical Evaluation of Formaldehyde Paste Filling in Endodontics. R. BLOCK, University of Connecticut, Longboat Key, FL, P. SUPAN, Private Practice, Leesburg, VA, and K. LANGELAND, University of Connecticut, Farmington, CT

Objectives:The purpose of this study was to evaluate the immunologic, radioisotopic, and histopathologic response to ZOE paste material containing 6.5% paraformaldehyde in endodontics.

Methods: 10 healthy Mongrel dogs were used in these studies. Immunologic responses were analyzed for antibody responses(Stavisky ) and cell mediated immunity-lymphocyte stimulation (Bach ).Immunization occurred via 20 root canals over a 28 day period in 5 dogs.In 5 other dogs, endodontics was performed on 5 teeth per dog , using ZOE containing C-14 labelled 6.5% paraformaldehyde paste.In each animal, the radioactivity was measured over 1 hr. 1, 7,14,21,and 28 days in the blood,biopsy specimens of the submandibular lymph nodes, kidney, and liver. At 28 days, all the animals were sacrificed.The teeth and the surrounding bone were processed for light microscopy . Semiserial sections ( 5-8 microns), stained with hematoxlin and eosin, and examined in diffuse and polarized light.The sections were evaluated for: the occurrence of acute and chronic infammatory cells, foreign body cells, extravasated,disintegrating erythrocytes, the occurrence of brown pigment, the presence and location of tissue disintegration products, and the location of paste particles in the cells, vessels and tissues. Results: 1)Pulp altered by 6.5% paraformaldehyde -ZOE paste produced specific antibody and cell mediated responses over a 28 day period in dogs.2)When dog root canals were obturated with C-14 labelled paraformaldehyde-ZOE paste within the confines of the canal, the radioactivity was detected in the blood, submandibular lymph nodes, kidney and liver over 28 days .3)Histopathologic evaluation demonstrated periapical tissue,cell, vessel, bone inflammation and damage adjacent to the paste material.Polarized light was used to verify the presence of paste material in the cells and vessels. Conclusions: The use of ZOE containing paraformaldehyde paste should not be used in endodontics. (This paper is a tribute to Dr. Langeland who passed away this past year)


0948 (117917)

Evaluation of calcium carbonate effect on pulpotomy. P. LU1, K. ARAI2, C. TAKAHASHI3, S. MASUI4, Y. TSUJIMOTO4, K. MATSUSHIMA4, and T. MAEDA2, 1Department of Pediatric Dentistry, Graduate School of Dentistry at Matsudo, Nihon University, Chiba, Japan, 2Department of Pediatric Dentistry, Nihon University School of Dentistry at Matsudo, Chiba, Japan, 3Nihon University graduate school of dentistry department of endodontics, Chiba, Japan, 4Nihon University School of Dentistry at Matsudo department of Endodontics, Chiba, Japan

Objectives: Calcium hydroxide-based materials have been extensively used for pulpotomy because of their hard tissue repair potential which enhance pulpal protection. However, they have harmful effect to dental pulp cells because of high alkalinity. Therefore, we used calcium carbonate as a new pulpotomy agent which has almost neutrality pH to compare with calcium hydroxide. This study investigated the reparative process of mechanically exposed pulp tissue covered with calcium carbonate.

Methods: Sixty maxillary first molars of 5-week-old rats were treated pulpotomy with calcium hydroxide and calcium carbonate and examined by micro CT(R_mCT®) at 0, 3, 7, 14 and 28 days after treatment. After dehydrating and Paraffin embedding, the specimens were serially sectioned at 4μm on a microtome. Hematoxylin-eosin staining and immunoreactivity for osteopotin were analyzed at 1, 3, 7, 14 and 28 days.

Results: The average calcified area in the image reconstructions of the median sagittal plane of micro-CT pictures were calculated as 26.28, 30.48, 34.94mm2 for calcium carbonate group and 26.94, 30.30, 34.68 mm2 for calcium hydroxide group on 7, 14, 28 days, respectively using with Software I-View® (J. Rigaku, Japan), no significant differences were found between two agents. Inflammatory reaction and dentin-like hard tissue structure were observed in both groups. Osteopotin immunoreactivity was observed in the matrix at 1 day in both groups, especially just beneath the necrotic layer in calcium hydroxide group. At 7 days, immunoreactivity remained evident along the superficial layer of the newly formed dentin bridge matrix in both groups.

Conclusion: Our findings indicated that the calcium carbonate-induced reparative dentinogenic process is basically similar to the process induced by calcium hydroxide, which follows the proliferation, migration and differentiation of progenitor cells. Calcium carbonate induced to formation of dentin-like hard tissue, and might show less toxic effect than traditional calcium hydroxide agents.


0949 (118863)

In vivo antibacterial efficacy of 1%chlorhexidine gel as intracanal medication. R. ARAUJO LIMA1, T. RODRIGUES RIBEIRO1, C. BARRETO MANO DE CARVALHO1, M.C. FONTELES2, and C. FONTELES1, 1Universidade Federal Do Ceara, Fortaleza, Brazil, 2Universidade Federal do Ceará, Fortaleza, Brazil

Objective:Evaluate antibacterial efficacy of 1%chlorhexidine gel(CHX) as intracanal medication in necrotic primary molars, compared to a combination of calcium hydroxide+camphorated paramonochlorophenol(Ca(OH)2+CPMC) in a randomized, blind, split-mouth clinical trial. Methods:Ten healthy, 4-8-year old children with 2 necrotic primary molars were selected to participate in the study. Twenty teeth were randomly divided into 2 different groups, which received either Ca(OH)2+CPMC(CallenPMCC®)(G1) or CHX(G2). All participants received both treatments. Each tooth was anesthetized and isolated with a rubber dam. Pulp chambers were accessed and initial microbiological samples were immediately collected using sterile size-15 paper-point that was kept in place for 60 seconds and transferred to a test tube containing RTF. Instrumentation-irrigation was performed using Sodium Hypochloride, root canals were dried and filled with the selected medication, teeth were temporarily sealed with glass ionomer. After 14-days root canals were re-opened following the same protocol and medication was removed. Root canals were left empty and teeth were temporarily restored. After 48-hours a second sample was collected as previously described. For detection of mutans streptococci(MS), samples were diluted, plated on MSB medium, incubated at 37oC, during 48-hours, under microaerofilic conditions. For anaerobic bacteria detection, samples were plated on Brucella-blood-agar, incubated for 7 days in anaerobic jars. Bacterial counts were expressed as CFU/mL. To reduce asymmetries, data was converted to natural logarithm for statistical analysis. Results:When comparing initial versus final anaerobe levels in G1(9.96±2.45 versus 6.57±3.84,Paired t-test, p=0.024) and G2(11.21 versus 8.75, Wilcoxon test,p=0.020), treatments were equally effective(p=0.88).G1 did not significantly reduce MS(4.39±4.12 versus 4.52±4.76,Paired t-test,p=0.94),but G2 caused significant MS reduction(7.77±4.47 versus 4.07±4.75,Paired t-test,p=0.002). Conclusion:Ca(OH)2+CPMC was ineffective against MS and 1%CHX gel demonstrated great efficacy in the reduction of anaerobes and MS in root canals of necrotic primary molars. This work was approved by Federal University of Ceara(Brazil) Ethics Committee and was partly funded by FUNCAP(Brazil).


0950 (118920)

Evaluation of apical biofilm and root resorption in primary teeth. C.T. ROCHA1, P.M. FERNANDES1, M.A. ROSSI2, M.R. LEONARDO1, L.A.B. SILVA1, and P. NELSON-FILHO1, 1Faculdade de Odontologia de Ribeirão Preto - Universidade de São Paulo, Ribeirão Preto - SP, Brazil, 2Faculdade de Medicina de Ribeirão Preto - Universidade de São Paulo, Ribeirão Preto - SP, Brazil

Objectives: The aim of this study was to evaluate, by scanning electron microscopy (SEM), the presence of biofilm and root resorption on the external surfaces of the apical third of roots of human primary teeth with vital or necrotic pulps with and without radiographically evident periradicular pathosis. Methods: Eighteen teeth were selected: group I – normal pulp (n=5), group II – pulp necrosis without radiographic evidence of periapical pathosis (n =7) and group III – pulp necrosis with well-defined radiographic periapical pathosis (n =6). After extraction, the teeth were washed with saline and immersed in 0.03g/mL trypsin solution for 20min.The teeth were then washed in sodium cacodilate buffer and stored in receptacles containing modified Karnovsky solution. The teeth were sectioned, dehydrated in an ethanol series, critical-point dried with CO2, sputter coated with gold and the external root surface in the apical third examined by SEM. Results: In the teeth of groups I and II, the apical root surfaces were covered by collagen fibers, with no evidence of bacteria and root resorption (100%). In the teeth of group III, the root apices had no collagen fibers but revealed resorptive areas containing microorganisms (cocci, bacilli, filaments and spirochetes) in all cases (100%). Conclusion: It was observed that apical biofilm and root resorption were detected only in primary teeth with pulp necrosis and radiographically visible periapical pathosis.


0951 (116109)

Facilitated Chemical Delivery through Human Enamel/Dentin with AC-iontophoresis. H. IKEDA, and H. SUDA, Tokyo Medical & Dental University, Tokyo, Japan

Objectives: We have shown monomeric substances can pass through intact human enamel and dentin that are defensive barriers against external irritation. The objectives of the present study were to quantitatively evaluate chemical permeability through human enamel/dentin with conductometry and to clarify the effect of AC iontophoresis on its permeability.

Methods: Electrical impedance of different concentrations of LH was measured using a bipolar platinum electrode. The relation between concentration and conductance of the solution was examined. Two chambers were used; one was filled with ultrapure water and the other with different concentrations of LH. Six premolars were extracted for orthodontic treatment and were sectioned at the cementoenamel junction. Tooth crowns were held between two chambers with a double O-ring. The enamel side chamber was filled with LH, the pulp side one with ultrapure water. A simulated interstitial pulp pressure was applied to the pulp side chamber. Change in the concentrations of LH was measured every 2 minutes with a platinum recording electrode positioned at the center of the pulp side chamber. Two platinum plates were set at the both ends of the chambers to pass alternating current. Passive diffusion without the iontophoresis was used as control. After the measurements, the enamel surfaces of sample teeth were examined by scanning electron microscopy.

Results: One sample that had enamel cracks was excluded from the study. Electrical conductance (G, mho) correlated closely to the concentration (x, mmol/L) of LH (G=2.16x2+0.0289x+0.000376, r2=0.999). LH that passed through enamel/dentin against dentinal fluid flow increased with time.

Conclusions: Conductometry showed LH diffusion through enamel/dentin was increased in quantity by AC iontophoresis. Anion delivery through human enamel/dentin may be affected by ζ-potential.


0952 (119240)

Efectiveness of photodynamic therapy without intracanal optical fiber use. M.R. NUNES, D.P. RALDI, S.M. HABITANTE, S.S.F. SANTOS, J.M.F. MEDEIROS, and J.L. LAGE-MARQUES, Universidade de Taubate, Taubaté, Brazil

Objectives: the aim of this study was to evaluate in vitro the photodynamic therapy effectiveness on the reduction of Enterococcus faecalis using or not intracanal optical fiber associated with different parameters of irradiation.

Methods: sixty human single-root teeth were selected. After instrumentation the root canals were inoculated with E. Faecalis and randomly divided into six groups (n=10). Four groups received a solution of 0.01% methylene blue for 5 min followed by irradiation using a diode laser at a wavelength of 680 nm, than according to the employed parameters they were divided in: G1- irradiated with 216 micron intracanal optical fiber, at a power output (P) of 90mW and irradiation time (t) of 1min 30s;G2- irradiated with 600 micron hand peace placed on the root canal orifice (without intracanal optical fiber), P=100mW and t=1min 30s, G3- irradiated with intracanal optical fiber, P= 90mW and t=3min; G4- irradiated as the same way as the group G2 (without optical fiber), P= 100mW and t=3min. The two other groups served as control: G5 (positive control)- treated with 1% sodium hypochlorite solution for 15min and G6 (negative control)- did not undergo any intervention. Bacterial samples were taken before and after irradiation. In each of the samples, the number of colony-forming units (CFU) was counted.

Results: all treatments resulted in reduction of microrganisms and the mean decrease in CFU was: G1- 99,48%, G2-99,41%, G3-99,65 %, G4-99,64% and G5-100%, with no significant difference between the irradiated groups (p>0.05).

Conclusions: the photodynamic effectiveness with the irradiated parameters employed in this study was independent of the use of intracanal optical fiber.


0953 (116338)

Effects of residual microbial presence and diversity on endodontic outcomes. A. ORGEL1, P. CHAND1, M.L. HICKS1, R. NANDAKUMAR1, S.M. BARBUTO2, B.J. PASTER2, and A.F. FOUAD3, 1University of Maryland Dental School, Baltimore, MD, 2Forsyth Institute, Boston, MA, 3University of Maryland, Baltimore, MD

Objectives: The purpose of this study was to determine the relationship of persistent root canal bacteria, identified with sensitive molecular techniques, with changes in periapical radiographic status following one year as determined using the Periapical Index (PAI).

Methods: Twenty-eight endodontic specimens were included: 20 from cases with necrotic pulps and 8 from cases requiring retreatment for persistent disease. Specimens were obtained at the second endodontic visit, following chemomechanical preparation and irrigation with NaOCl, 17%EDTA, and finally with 2% CHX at both visits, with an interappointment Ca(OH)2 medicament. PCR with broad range 16S rDNA bacterial primers was performed, and for positive reactions, the products were cloned into the vector pCR 2.1-TOPO TA and transformed into E. coli One-Shot TOP10. Plasmid DNA from clones was purified and sequenced. Phylogenetic analysis was performed to reach final identity. Sequences with less than 98% similarity with published sequences were excluded.  Radiographs were taken post-operatively and again at 12 months using polyvinylsiloxane stents.  Calibrated endodontists independently scored the radiographs and a consensus PAI determined healed versus non-healed periapical status.

Results: Overall, 18 (64.3%) of the cases healed at 1 year (PAI: 1 or 2). Eight cases (29%) did not have detectable bacteria in their post-operative specimens; 7 of them (88%) healed, whereas 11 (55%) of the cases with bacteria healed (Fisher's Exact test; p=0.12). Cases treated to the radiographic apex were less likely to have detectable bacteria (p=0.003) and more likely to heal (p=0.049). When bacteria persisted, two phylotypes were significantly more prevalent in non-healed cases: Enterococcus casseliflavus/flavescens/gallinarum ( p=0.039) and Bacillus sp. clone DQ128250 (p=0.041).

Conclusions: Incomplete elimination of bacteria from the root canal may adversely affect clinical outcome. Certain bacterial phylotypes are more frequently associated with non-healed cases.  (Supported by grant DE015320-01-A1 from NIDCR).


0954 (119320)

A case series of pulpectomies in traumatized primary incisors. P.N. TANNURE1, T.K.D.S. FIDALGO1, R. BARCELOS2, L. PRIMO3, and L.C. MAIA4, 1Universidade Federal Do Rio De Janiero, Rio de Janeiro, Brazil, 2Federal University of Rio de Janeiro; Salgado de Oliveira University, Rio de Janeiro, Brazil, 3Federal University of Rio de Janeiro, Brazil, 4Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

Objective: The aim of this retrospective study was to evaluate after 12 months the success rates of 22 cases of traumatized maxillary primary incisors submitted to pulpectomies. Methods: A review of all dental records of Dental Trauma Project in the Department of Pediatric Dentistry, Federal University of Rio de Janeiro, Brazil, yielded 471 patients who had one or more primary/young permanent teeth with traumatic injuries. Only patients with irreversible inflammation or pulp necrosis leading to pulpectomy with 12 months' follow-up were included. A total of 22 maxillary primary incisors from 17 children 36.4 (±0.05) months old, and free from systemic disease, were treated. Results: Subluxation led to pulpectomy in 63% of cases; however, this type of trauma was not associated with therapeutic success (p=0.233). ZOE paste was the root-filling material in 65%, while iodoform paste was described in 45%. Pulpectomy was considered successful in 77.3%. Success was statistically associated with the absence of periapical infection before treatment (p=0.005). Although all cases of failure (n=5) occurred in children older than 36 months, there were no significant differences between success and the child's age (p=0.266). Conclusion: The findings of this study indicate high success rates in pulpectomies and should be considered a therapy option for traumatized maxillary primary incisors with irreversible inflammation or pulpal necrosis.


0955 (119365)

Histopathologic and SEM analysis of primary teeth with pulpectomy failure. P.N. TANNURE1, R. BARCELOS2, M.B. PORTELA3, R. GLEISER1, and L. PRIMO4, 1Universidade Federal Do Rio De Janiero, Rio de Janeiro, Brazil, 2Federal University of Rio de Janeiro; Salgado de Oliveira University, Rio de Janeiro, Brazil, 3Universidade Federal Do Rio De Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil, 4Federal University of Rio de Janeiro, Brazil

Objective: The aim of this descriptive study was to identify the probable factors associated with pulpectomy failure of primary teeth through qualitative analysis by histopathology (HIST) and scanning electron microscopy (SEM). Methods: A longitudinal clinical investigation of the relative efficacy of pulpectomy was carried out with 66 children aged 3–8 years with irreversible inflammation or necrotic pulp. One hundred thirty primary teeth received instrumentation with Kerr files followed by irrigation with sodium hypochlorite and saline solution, then filled with zinc-oxide-and-eugenol (ZOE) paste. Results: At 18 months' follow-up, 86.1% (112) of the teeth were considered to have been successfully treated. Of the 18 teeth extracted due to treatment failure, 8 presented sufficiently undamaged roots to be randomly selected for analysis. Four teeth were chosen for HIST and four were analyzed in a SEM. Necrotic tissue and chronic inflammatory cells were observed in all specimens submitted to HIST analysis. Two specimens had root canal bacteria. Another common finding was external radicular resorption associated with Howship's lacunae. In SEM analysis, apical and furcation areas were heavily infected, and microorganisms were present in all specimens. Howship's lacunae were commonly observed on radicular apical surfaces. Conclusion: The findings of this investigation suggest that the main factors responsible for pulpectomy failure were technique limitations associated with the morphological irregularities created by external and inflammatory resorption.


0956 (113364)

Evaluation of the Quality of Root Canal Fillings in Mumbai,India. S. ABICHANDANI, Pad.Dr.D.Y.Patil Dental College & Hospital, Mumbai, India

AIM:

to evaluate the prevalence and quality of root canal fillings and peri-apical status of root canal filled teeth in a sector of population of mumbai,india.

METHODS:

complete mouth peri-apical radiographs were obtained from 208 patients that presented as new patients at Padmashri.Dr.D.Y.Patil Dental College & Hospital. the quality of root canal fillings were assessed for individual roots according to the apical extent of root canal fillings and its density.the periapical status was evaluated using Periapical Index Scoring System with a value greater than 2 indicating periapical disease. the presence of posts, coronal restorations were also considered.statistical analysis was performed with chisquare test with significance level test at P < 0.05%. RESULTS:

of 6200 teeth examined, 2.6% were root filled. PAI > 2 was attributed with 55.1% of filled roots.only 15.7% of the root canal fillings were technically acceptable and 24.2% of those were attributed PAI > 2.in roots with unacceptable root canal fillings, 60.5% had PAI > 2. a permanent coronal restoration wsa present in 76.5% of the filled roots of which 48.7% had PAI>2 vs 73.7% for no permanent restorations. at least one periapical lesion was seen in 57.6% ofthe subjects.

CONCLUSION:

results show low prevalence of teeth with radiographic periapical disease, low prevelance of root filled teeth and high prevelance of unacceptable root canal fillings.


0957 (119534)

Comparison of Root-end Preparation by Ultrasonic Retrotip and Er:YAG Laser. K. JARU-AMPORNPAN, M. NAWACHINDA, and S. KIATPONGSAN, Chulalongkorn University, Bangkok, Thailand

OBJECTIVE: To compare in vitro the cutting efficiency of an ultrasonic retrotip vs Er:YAG laser, and to evaluate the prepared root surface and seal after root end filling.

METHODS: 49 single-rooted extracted human teeth were sectioned at the cemento-enamel junction. Root canals were prepared with step-back technique to file size #45 apically and obturated with laterally condensed gutta percha and zinc oxide eugenol based sealer. The root tip was resected at 90° 3 mm from the apex. Teeth were randomly divided into 3 groups each of 13 teeth (10 for leakage, 3 for SEM analysis), and 2 groups each of 5 teeth served as controls. In the 3 experimental groups, apical cavities were prepared using an ultrasonic retrotip and contact tips of an Er:YAG laser with two different power settings (80 and 100 mJ at 10 pps). Working time was recorded. The surfaces of the retrograde cavity walls were examined using SEM. Leakage was measured after retrograde filling with SuperEBA cement; after immersion in India ink for 7 days, teeth were cleared and evaluated for linear leakage under x20 magnification. Microleakage and working time were analyzed by ANOVA and Scheffe test.

RESULTS: There were no significant differences in dye leakage among ultrasonic and laser-treated groups. Significantly (p<0.05) more working time was required in the 80 mJ laser group than in the ultrasonic and 100 mJ laser groups. Morphological examination of prepared dentin walls showed no debris or smear layer in the laser-treated groups but slight to moderate smear layer was present in the ultrasonic group. Dentin walls in the lased groups were irregular and scale-like.

CONCLUSIONS: Er:YAG laser has the potential to be applied to root end preparation. This research was partially supported by NRCT-JSPS Core University Program.


0959 (117222)

Adhesive Cements as Core Build-ups for Postendodontic Restorations. G. STERZENBACH1, M. ROSENTRITT2, T. NETTESHEIM1, and M. NAUMANN1, 1Charité-Universitätsmedizin Berlin, Berlin, Germany, 2University of Regensburg, Regensburg, Germany

Objectives: Recently composite resin core build-up materials were introduced as cements to retent endodontic posts. Thus, the question arises whether it would be possible to place endodontic posts and built up the core in an one-stage procedure with a self-adhesive composite resin cement. The null-hypothesis tested was that a self-adhesive cement in combination with a glass fiber post for post-and-core restoration is as able to withstand functional forces during thermocycling and mechanical loading (TCML) and additional linear loading as an etch-and-rinse approach with a conventional composite resin core buid-up material.

Methods: Human caries-free maxillary central incisors were divided into 4 groups (n=10). Teeth were endodontically treated and decoronated 2mm above the cemento-enamel junction. Specimens were restored using glass fiber posts luted with different cements and composite resins for core build-up (cement/resin; cc=chemical curing; dc=dual curing): (I) RelyX Unicem/Clearfil Core-cc, (II) RelyX Unicem/ RelyX Unicem-dc (not indicated by manufacturer), (III) RelyX Unicem/LuxaCore-dc, and (IV) LuxaCore/Clearfil-cc. A 2mm-ferrule preparation was always performed. All specimens received adhesively luted all-ceramic crowns and were exposed to TCML (1.2 million loading cycles; 6,000 thermocycles 5° / 55°C) before static loading until failure.

Results: Three specimens of group III and two of group II and IV, respectively failed during TCML (log rank: p=0.379). For these specimens the load capabilty value was set at 0N. The median fracture load values (min/max) in [N] were: group I = 295 (209/445), II = 166 (0/726), III = 241 (0/289) and IV = 201 (0/371) (Kruskal-Wallis test: p=0.091). The group I showed the highest percentage (80%) of restorable failures followed by group II (60%) (Chi-square test: p=0,028).

Conclusion: It appears that – even if not indicated by the manufacturer yet - in the future self-adhesive composite resins may be an alternative to conventinal composite resin core materials.


0960 (117236)

Self-adhesive resins for post-and-core build-ups: chewing simulation after one-year storage. M. NAUMANN1, M. ROSENTRITT2, and G. STERZENBACH1, 1Charité-Universitätsmedizin Berlin, Berlin, Germany, 2University of Regensburg, Regensburg, Germany

Objectives: Composite resin cements – even though to date not indicated - are supposed to be appropriate to perform post-and-core procedures at one stage. However, mechanical loading and hygroscopic expansion may cause fracture of all-ceramic restorations. Therefore, the in-vitro performance of a self-adhesive resin cement core build-up and a conventional etch-and-rinse composite core build-up were compared.

Methods: Human maxillary central incisors were divided into 4 groups (n=10). Teeth were endodontically treated and decoronated 2mm above the cemento-enamel junction. Specimens were restored using glass fiber posts as follows (cement/resin; cc=chemical curing; dc=dual curing): RelyX Unicem/RelyX Unicem-dc (U-Udc), RelyX Unicem/RelyX Unicem-cc (U-Ucc), RelyX Unicem/Clearfil-cc (U-Ccc), and RelyX Unicem/LuxaCore-dc (U-Ldc). 2mm-ferrule preparation was always performed. All specimens received adhesively luted all-ceramic crowns (Empress II). The crowns were examined for cracks after 3, 6, 9 and 12 month storage in a 0.5% chloramin solution at 37°C. Specimens surviving long term storage were exposed to TCML (1.2 million loading cycles; 6,000 thermocycles 5°/55°C) before subsequent static loading until failure.

Results: Three specimens each of group U-Udc and U-Ldc did not survive long term storage (visible crack propagation, Chi-square: p = 0.07). Three specimens of U-Udc, U-Ucc and U-Ccc, respectively and six specimens of U-Ldc failed during TCML (log rank: p=0.081). For these specimens the load capability for subsequent static load tests were set at 0N. The median fracture load values (min/max) in [N] were: U-Udc= 0 (0/737), U-Ucc= 339 (0/529), U-Ccc= 0 (0/443) and U-Ldc= 0 (0/417) (Kruskal-Wallis test: p=0.25). U-Ucc showed the highest percentage (80%) of restorable failures. The fracture patterns differed significantly between all groups (p=0.014).

Conclusion: It appears that the application of self-adhesive cements for both adhesive glass fiber cementation and core build-up may – even if not indicated by the manufacturer - be recommandable.


0961 (117269)

Micro-tensile Bond Strength of Experimental Resin Core System. K. YASUMOTO1, S. HOSHIKA1, H. SANO1, and D. SELIMOVIC2, 1Hokkaido University, Sapporo, Japan, 2University of Louis Pasteur, Strasbourg, France

Objectives: The purpose of this study was to examine the micro-tensile bond strength (MTBS) of a experimental dual-cured resin core system compared with two conventional resin core systems under two different curing strategies, light curing and dark curing.

 

Methods: Three dual-cured resin core systems used in this study were: ECQ (experimental, Tokuyama, Japan), DC Core Automix (DC; Kurarey Medical, Japan), UniFil Core (UC; GC, Japan). Twelve human molars were used in this study. The flat grownd surfaces of dentin were polished with 600-grit silicon carbide paper under running water. Firstly, the dentin surface of the light curing group was bonded using one of the three resin core systems with light curing strategies according to the manufacturers' intstuctions. Secondly, the dark curing groups were prepared following manufacturers' intstuctions without light curing in the darkroom. All the resin core composites were built up to approximately 5 mm height on flat surfaces of dentin. They were sectioned into beam specimens (cross-sectional area 1 mm2) after storage in 37°C water for 24 hours. The specimens were subjected to MTBS test and fracture modes   were observed by SEM (Hitatchi S-4000). The Games-Howell test was used for the statistical analysis of the MTBS (p<0.05).

 

Results: The result of the MTBS is listed in Table and Figure.

Identical letters indicate that the values are not statistically different (p>0.05).

 

Conclusions: The result of this study revealed that the MTBS of the three dual cure resin core systems showed no significant difference between light and dark curing strategies. However, for light curing strategy, the MTBS of the ECQ was significantly greater than that of DC and UC. As for the dark curing strategy, the MTBS of ECQ and UC were significantly greater then DC.


0962 (118443)

Push-out Bond Strength of Fiber Posts Cemented with Different Cements. B.A.C. BARROS1, L.C.C. VIEIRA1, and L.N. BARATIERI2, 1Universidade Federal De Santa Catarina, Florianópolis, Brazil, 2Universidade Federal De Santa Catarina, Florianopolis, Brazil

Objectives:The aim of this in vitro study was to evaluate the shear bond strength (push-out) when luting fiber posts (FRC Postec Plus) to intraradicular dentin using three different types of cement.

Methods: Thirty four maxillary anterior teeth were selected. After removing the coronal portion, all teeth were endodontically treated and dowel spaces were prepared using post drills provided by the manufacturer. The specimens were randomly divided into five groups, according to the cement: Group 1, Variolink II +Excite DSC; Group 2, Relyx ARC + Scotchbond Multi-Purpose Plus; Group 3, Relyx Unicem; Group 4, Multilink; and Group 5, Zinc phosphate cement (SSWhite). After storage for one week, the teeth were serially-sectioned in 6 slices (1mm thick), two from each third (cervical, middle, and apical). Push-out shear testing was performed in a Universal Testing Machine (Instron 4444, cross-head speed of 0.5mm/min). The data were submitted to Kruskal Wallis test.

Results: The results revealed that there was no difference between Groups for cervical and middle thirds, regardless of the cement. In the apical third groups 2 and 4 exhibited statistically significantly lower mean bond strengths.

Conclusion: It is concluded that resin cements can not increase the bond strength of fiber posts, when compared to zinc phosphate cement.


0963 (118463)

Bond Strength to Root Canals Rinsed with 2% Chlorexidine Digluconate. M.C. GONÇALVES, Sao Paulo State University, São José dos Campo, Brazil, R.M. MELO, Sao Paulo State University, Sao Jose dos Campos, Brazil, M.R. ALEXANDRE, São Paulo State University (UNESP), São José dos Campos, Brazil, and M.A. BOTTINO, UNESP SJC, Sao Jose dos Campos, Brazil

Objectives: The aim of this study was to test the bond strength of the resin cement/self-etch bonding agent/root canal dentin interfaces after rinsing with 2% Chlorexidine Digluconate or distilled water, in different time periods. Methods:Forty bovine teeth were decoronated and the pulp was removed. The root canals were then prepared with #2 bur of the FRC Postec system (Ivoclar). The roots were randomly assigned to 4 groups (n=10): G1 and G3- rinsed for 60 s with 2% Chlorexidine Digluconate and tested after 24 h and 3 m, respectively; G2 and G4: rinsed for 60 s with distilled water and tested after 24 h and 3 m, respectively. The ED Primer bonding agent (Kuraray) and Panavia F resin cement were used for treatment of the dentin walls and filling of the root canal. The specimens were stored in artificial saliva at 37 °C. Six transverse sections (~1.5 mm) were cut up to 4 mm short of the root canal apex and submitted to push-out testing in a universal testing machine (1 mm/min; 10 Kgf). Results:The results (MPa) were analyzed statistically through a non-parametric test (Mann-Whitney, p<0.05%). The groups that were stored could not be analyzed due to extremely low bond (“zero”) bond strengths. The results obtained after 24 h with 2 % Chlorexidine Digluconate (1.67 ± 1.56 MPa) or distilled water (1.07 ± 0.57 MPa) were not statistically different. Conclusions: It was concluded that 2% Chlorexidine Digluconate rinsing of the root canal was not able to improve and/or preserve the bond strength at the resin cement/self-etch bonding agent/root canal dentin interfaces.


0964 (118528)

Pullout Strength of Fiber Post: Evaluation of Different Luting Cements. S.C. ZAMBONI1, M.C. GONÇALVES2, L.F. VALANDRO3, M.A. BOTTINO4, T. ZAMBONI5, and L. NOGUEIRA JUNIOR1, 1Sao Paulo State University, Sao Jose dos Campos, Brazil, 2Sao Paulo State University, São José dos Campo, Brazil, 3Federal University of Santa Maria, Santa Maria, Brazil, 4Paulista State University, São José dos Campos, Brazil, 5Universidade Est. Paulista Julio Mesquita, Sao Paulo, Brazil

Objectives: To evaluate the interfacial strength between fiber post with seven luting agents and the influence of nonadhesive, dual and self-adhesive systems on load capability of postendodontic retention was studied. Methods: Seventy bovine single-roots (N=70) (standardized size of 16mm) were prepared with a work-length of 12mm with a custom bur of a double-tapered glass-FRC post (White Post DC #2), embedded in acrylic resin up to the most coronal portion of the specimen and divided into 7 groups (n=10): G1- 3-step etch&rinse adhesive+RelyX; G2- RelyX without adhesive; G3- self-etch adhesive+Multilink; G4- self-etch adhesive+Panavia; G5- self-adhesive resin cement (Maxcem); G6- self-adhesive resin cement (U100); G7- self-adhesive resin cement (Unicem). The fiber posts were etched with 37% H3PO4 for 1 min and silanized (Porcelain Primer), and then cemented. The specimens were stored for 24 h. For pull-out testing, the coronal part of fiber post was grabbed, the inferior part was attached to the testing machine, and the post was the pulled-out (1 mm/min). Results: G1 (199.3±23.9a), G2 (211.2±49.1ab), G3(221.7±25.8ab), G4 (198.7±48.2b), G5 (46.8±29.1c), G6 (223.6±33.5ab), G7 (248.6± 21.7a) (1-way Anova, Tukey, a=5%). G5 displayed the worst pullout strength when compared with the others groups which were statistically similar. Conclusions: One self-adhesive resin cement had the worst bonds. Two self-adhesive resin cements showed high retentive strength comparable to the conventional adhesive approach (3-steps etch&rinse and self-etch adhesives). These findings are stimulating, but the simplified techniques need be investigated further with regard to the resin bond durability


0966 (118817)

Comparative analysis of mechanical properties among glass fibers and dentin. R.G. COSTA1, G.M. CORRER1, E.C.C. MORAIS1, M.D. MICHEL2, P. SOARES3, F. BERTELLI4, and A. MIKOWSKI5, 1Positivo University, Curitiba, Brazil, 2Universidade Estadual De Ponta Grossa, Ponta Grossa, Brazil, 3Pontificia Universidade Catolica do Parana, Curitiba, Brazil, 4Universidade Estadual de Campinas, Campinas - SP, Brazil, 5Universidade Federal do Paraná, Curitiba, Brazil

Objectives: to evaluate the modulus of elasticity (E) and modulus of rupture (σ) of glass fibers used for resin reinforcement, comparing with the dentin properties. Methods: two glass fibers were selected: G1-Fibrex-Lab and G2-Vectris. Thirty specimens of each material were prepared following the manufacturer's instructions and the ISO 4049 standard parameters. The specimens were stored at 37ºC for 24 hours, and then submitted to a flexural test in a universal testing machine with a load rate 50 N/min. The modulus of rupture (σ) and modulus of elasticity (E) were calculated and the data were submitted to ANOVA and Tukey's test (p<0.05) and two-parameter Weibull statistic (m-Weibull modulus and σ0–normalizing parameter). Fractographic analysis was carried out using SEM. The linear elastic stress in glass fibers was analyzed by numerical simulations using the finite element method. The modulus of elasticity of the dentin was obtained by instrumented indentation technique and calculated using Oliver and Pharr method. Results: the values of σ (MPa), E (GPa), m and σ0 (MPa) were, respectively: G1: 809.3±115.2, 24.0±6.2, 8.4±0.5, 857.5±689.0; and G2: 1076.8±103.3, 37.1±6.0, 12.7±0.5, 1120.4±605.6. There was significant difference between the materials and both materials showed significantly higher modulus of elasticity than that of dentin (21.9±0.5 GPa). The fractographic analysis showed lower diameter and better distribution of the glass fibers for G1 than for G2. The von mises stress in glass fibers are in the range of 20 MPa to 0.5 GPa, being lower than E of glass fiber (70 GPa). The values of M, m and E for G2 showed higher fracture strength than for G1. Conclusion: Vectris showed significant higher mechanical properties than Fibrex-Lab, although these properties values were much higher than those of dentin. Systems for resin reinforcement should present mechanical properties as close as possible from those of the dental structure.


0967 (118988)

Direct Cementation of Individually Formed FRCPost; Bond Strength and Microleakage. P. VALLITTU, D. MAKAREWICZ, A.-M. LE BELL-RÖNNLÖF, and L. LASSILA, University of Turku, Turku, Finland

Abstract:

Purpose: The aim of this study was to evaluate the effect of two different cementation techniques of individually formed E-glass fiber-reinforced composite (FRC) post on bond strength and microleakage.

Materials and methods:

The crowns of extracted third molars were removed at the cemento-enamel junction. Post preparation was carried out with parapost drills (diameter 1.5 mm) and cements were applied according to the manufacturer's instructions. Individually formed semi-IPN resin matrix FRC posts (everStick POST, diameter 1.5 mm) were cemented into the post spaces with two different dual-cured luting cements: ParaCem®Universal and self-adhesive RelyX™Unicem. Individually formed FRC posts were cemented either with 1) a “direct technique”, where the post and the cement were polymerized together in situ at root canal or 2) “indirect technique” where the prepolymerized post was polymerized with normal cementation technique with dual curing luting cement in root canal. After water storage of 48 hours, the roots were cut into discs of thickness of 2 mm (n = 20/group). A push-out force was applied until post was dislodged. Microleakage test, using dye penetration solution (basic parafuchsine, 24 hours, 37° C) was carried out to evaluate the sealing capacity of the post-canal interface of the intact roots. Dye penetration depth was measured under a stereomicroscope at 10x magnification.

Results:

Higher bond strength values (ANOVA p<0.05) and less microleakage (ANOVA p<0.05 ) between cement and dentine were obtained with the “direct technique” of polymerization compared to the “indirect technique”. None of the semi-IPN resin matrix FRC posts revealed any dye penetration between the post and the cement.

Conclusions:

The “direct technique” of polymerization may be beneficial when cementing individually formed FRC posts.


0968 (119272)

Effect of Endodontic Solutions on the Bond Strength of Sealers. J.V.B. BARBIZAM1, C. CUCCO1, M.P. PARANHOS2, and B. CARLINI-JUNIOR1, 1Universidade de Passo Fundo, Passo Fundo-RS, Brazil, 2Pontificia Un Catolica Rio Grande Do Sul, Porto Alegre, Brazil

Objective: to evaluate in vitro the bond strength of Sealer 26™ resin-based sealer and Grossman zinc-oxide and eugenol-based sealer to dentin walls after irrigation with different solutions.

Methods: Fifty extracted single-rooted human teeth were randomly assigned to five groups (n=10) and enlarged using a 1.5 mm diameter post drill associated to irrigating solutions: G1= 2.5% NaOCl + EDTA 17%; G2= 2% CHX + EDTA 17%; G3= 2.5% NaOCl; G4= 2% CHX and G5= saline solution (control). Following chemo-mechanical preparation, the root canals were filled with Sealer 26™ or Grossman sealers. After 48 hours of storage in 100% humidity at 37°C, the specimens were transversally sectioned into 2-mm-thick disks. Push-out tests were performed using an Universal Testing Machine (1 mm/min) and the maximum load of failure was recorded in MPa.

Results: Two-way Anova test showed a statistically significant increase in the bond strength values when Sealer 26 (12.16 ± 1.09 MPa) was used in comparison with Grossman sealer (1.95 ± 0.93 MPa) (p<0.01). No statistical differences were found between the irrigating solutions (p>0.05).

Conclusion: Sealer 26 presented higher bond strength to dentin walls when compared to Grossman sealer, and the irrigating solutions had no effect on the bond strength values.


0969 (113903)

Influence of Adhesive Application on Enamel Bonding of Single-step Systems. K. TSUBOTA1, A. RIKUTA1, H. KUROKAWA1, T. TAKAMIZAWA1, S. ANDO1, M. MIYAZAKI1, and M. LATTA2, 1Nihon University, Tokyo, Japan, 2Creighton University, Omaha, NE

Objective: This study was carried out to examine the relationship between the adhesive application duration and enamel bond strength of several single-application systems.

Methods: The restorative single-application systems used were: Bond Force (BF, Tokuyama Dental), Clearfil tri-S Bond (CT, Kuraray Medical), iBond Self Etch (IB, Heraeus), and OptiBond All-in-One (OB, Kerr). Bovine mandibular incisors were mounted in self-curing resin and wet ground with 600 grit SiC to expose labial enamel. Adhesives were applied for 10, 20, and 40 sec, and resin composites were condensed into a mold (ø4x2 mm) on the enamel and light activated. Ten samples per test group were stored in 37°C water for 24 h, then shear tested at a crosshead speed of 1.0 mm/min. One-way ANOVA and Tukey HSD test (p<0.05) were done. SEM observations of the treated enamel surface were also conducted.

Results:

10 seconds

20 seconds

40 seconds

BF

13.6 ±3.3

16.1 ±2.4

17.8 ±3.4

CT

13.6 ±2.3

13.9 ±2.7

15.9 ±1.8

IB

14.3 ±2.8

15.7 ±1.8

16.2 ±2.4

OB

13.4 ±2.8

17.5 ±2.0

19.8 ±3.4

Significant increases in bond strengths were found for the 40 sec application duration groups except for IB. From the SEM observations, demineralization of the enamel surfaces were more pronounced with the longer application duration.

Conclusion: The data suggest that the duration of the single-application bonding systems was a crucial factor for determination of enamel bond strength, and morphological changes were observed on the enamel surface.


0970 (119456)

Bond Strength of fiber posts luted with self etch adhesive. N.Ç. BERIAT, G. GÜLAY, Z. YILMAZ, and A.A. ERTAN, Hacettepe University, Ankara, Turkey

Objectives:

To evaluate the push-out bond strengths of fiber posts luted with self etch self adhesive luting agent.

Methods:

Twenty six extracted single-rooted teeth were randomly divided in two groups and restored using D.T. Light Post and the following luting agents: Variolink II/ExciteDSC/37% phosphoric acid (Ivoclar-Vivadent) and Maxcem (Kerr). For push-out bond strength measurements, thirteen roots per group were tested. Each posted root was cut horizontally into 1mm-thick slices at coronal and apical portions. On every slice the post was loaded by means of an adequately sized punch that pushed the post segment in an apical-coronal direction until the post-root bond failed. This was manifested by the extrusion of the post segment from the root slice, and the load recorded at this time was divided by the area of the post-root interface, in order to express the bond strength in MPa

Results: The mean bond strength achieved by Variolink at apical portion (14.77 ± 4.31 MPa), Variolink coronal portion (14.60 ± 4.09 MPa) and Maxcem apical (13.98 ± 4.58 MPa), Maxcem coronal (13.58 ± 4.93 MPa) .

Conclusion: The push-out bond strength was not statistically significantly different between the coronal and apical sections for each luting agent (p>0,005). The highest push-out bond strength was measured for Variolink however it was not statistically significant from Maxcem (p<0,005).


0971 (119556)

Influence of Irrigation Solutions on Bond Strength of Resin Cements. A. ROTHER, H.-G. SCHALLER, and C.R. GERNHARDT, Martin-Luther-University Halle-Wittenberg, Halle, Germany

Objectives: The aim of this study was to evaluate microtensile bond strength of a self-etching resin cement (Bifix SE, Voco, Germany) after irrigation with different endodontic irrigants (0.2% chlorhexidine, 1% sodium hypochloride, 19% EDTA) on root dentin in vitro. Methods: 75 single rooted extracted teeth, stored in saline for a maximum of fourteen days after extraction were included. All teeth were specially prepared allowing the evaluation on root canal dentin. The specimens were randomly assigned to five experimental groups of fifteen samples each: Group 1: Control, Bifix SE/ no irrigation solution; group 2: Bifix SE/ chlorhexidine (CHX); group 3: Bifix SE/ sodium hypochloride (NaOCl); group 4: Bifix SE/ chlorhexidine and sodium hypochloride; group 5: Bifix SE/ EDTA. The different solutions were applied five times for 2 minutes each. Microtensile bond strength was measured 15 minutes after application using an universal testing machine (Z005, Zwick). All materials were applied as recommended by the manufacturer and light-cured for 60 seconds.  Results: For the five test series following microtensile bond strengths were evaluated (mean value and standard deviation in MPa):

 Group

 1

 2

 3

 4

 5

 Irrigant

 None

 CHX

 NaOCl

 CHX/ NaOCl

 EDTA

 Bond Strength

 37.0

 27.5

 27.6

 27.5

 42.3

 +/-

 2.8

 3.6

 2.8

 3.0

 3.2

Bifix SE showed the highest bond strengths after the use of EDTA as iirgation solution  (p< 0.05, Bonferroni-Holm). Focusing on the different solutions, significant lower bond strengths values compared to the control were observed in group 2, 3 and 4 (p< 0.05, Bonferroni-Holm). Conclusions: Within the limitations of an in vitro investigation it can be concluded that all irrigation solutions used in this study influenced bond strength of the self-etching resin cement. Only the use of EDTA improved microtensile bond strength significantly.


0972 (120106)

Effects of Endodontic Irrigants on Bond Strength of Epiphany Sealer. N. RATANAPOB1, S. PIMKHAOKHAM2, and S. POOLTHONG2, 1Angthong Hospital, Angthong, Thailand, 2Chulalongkorn University, Bangkok, Thailand

The uses of combined irrigants to eliminate infection and smear layer may affect the bond strength between sealer and root dentin due to contamination left over after irrigation.

Objectives: To measure bond strength of Epiphany sealer to radicular dentin and to investigate areas of debris deposit on dentin surface after irrigation with different types and sequences of endodontic irrigants.

Methods: Human radicular dentin blocks (n=80) were prepared and divided into 5 groups. They were soaked in irrigants with different sequences as followed. Group I: samples were soaked only in distilled water. Group II, III, IV and V: samples were soaked in 2.5% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA) followed with distilled water (Group II), 2% chlorhexidine (CHX) (Group III), 2%CHX and 2.5% NaOCl (Group IV), 2.5% NaOCl and 2% CHX (Group V). Halves of dentin blocks in each group were investigated under scanning electron microscope. Areas of debris deposit were calculated. The other halves were bonded to composite resin blocks with Epiphany sealer and were subjected to modified microshear test.

Results: SEM investigation showed relatively wide areas of debris deposit in Group I and Group III. Multiple paired comparisons (ANOVA, Scheffe's test) revealed that Group III had significantly greater bond strength among all groups (p<0.05). Inspection of bonded surfaces demonstrated mostly adhesive failure for all groups. There is no correlation between areas of debris deposit and bond strength (Spearman's rank correlation coefficient = 0.075, p>0.05).

Conclusion: Use of 2.5% NaOCl followed by 17% EDTA and 2% CHX respectively, provided greatest bond strength between Epiphany sealer and radicular dentin.

This research was supported by Chulalongkorn University Graduate School Thesis Grant.


0973 (120310)

Push-out Bond Strength of Parallel and Tapered Posts to Dentin. J.-H. PHARK1, J. WELCH1, D. DIETSCHI2, and A. SADAN1, 1Case Western Reserve University, Cleveland, OH, 2Bibliotheque De La Faculte de Medecine, Geneve, Switzerland

Objective: to evaluate push-out bond-strength (PBS) of glass-fiber reinforced posts with two different designs using three different luting cements with and without following manufacturers' recommendations for cementing. Methods: 90 teeth were decoronated, root canal treated, and divided into 15 groups. 11 mm long post-spaces were drilled into each tooth using a parallel drill for 45 samples and a tapered drill for the rest. Corresponding parallel (P; ParaPost Fiber Lux) and tapered (T; ParaPost Taper Lux) posts were cemented using two cement systems (Panavia F2.0 (PAN) and Paracore (PAR)) using their corresponding self-etching adhesives, and a self-adhesive cement, Unicem (UNI). In half of the samples cements were used according to manufacturers' recommendations (NE) in the other half dentin was etched (E) with phosphoric acid for 15 seconds before application of the adhesive. Control groups with parallel post spaces but without posts were filled with one of the three cements only. Two teeth of each group were subjected to 20,000 cycles of thermal-cycling (TC). All teeth were sectioned in 1 mm thick disks and a total of 593 disks were tested for PBS. Kruskal-Wallis tests were used with an adjusted α=0.002. Results:

 

PBS in MPa

Before TC

After TC

P-PAN-NE

13.91±4.01

8.31±2.48

T-PAN-NE

13.99±4.21

9.50±3.20

P-UNI-NE

14.77±4.45

10.58±3.30

T-UNI-NE

16.36±4.81

11.36±4.47

P-PAR-NE

16.55±3.16

14.10±6.74

T-PAR-NE

16.08±3.13

10.88±2.69

P-PAN-E

10.32±4.17

8.39±4.53

T-PAN-E

13.51±5.02

6.34±3.36

P-UNI-E

13.23±5.09

11.06±5.41

T-UNI-E

10.72±3.07

10.29±5.24

P-PAR-E

9.85±4.56

11.51±5.62

T-PAR-E

13.66±4.55

12.81±4.88

Control-PAN-NE

13.36±9.24

10.36±3.97

Control-UNI-NE

12.25±6.02

13.04±4.59

Control-PAR-NE

20.77±7.02

11.96±4.34

Conclusion: In this study, artificial aging by TC and etching of the dentin before bonding reduced PBS significantly. Design of posts had no influence on PBS, which was also similar to control groups without posts. Paracore and Unicem achieved significantly higher PBS than Panavia F2.0.

0974 (120969)

Bonding of FRC-Posts - Influence of Different Posts and Aging. T. SCHLUTTIG1, J.M. POWERS2, A. PETSCHELT1, and C. BERTHOLD3, 1University of Erlangen-Nuremberg, Erlangen, Germany, 2University of Texas Dental Branch at Houston, Houston, TX, 3University of Erlangen, Erlangen, Germany

Objectives: The purpose of this study was to evaluate the influence for ten different FRC-posts luted to root canal dentin with a self-etching dual-cured adhesive luting system and the influence of aging using thermal cycling on bond strength.

Methods: 220 extracted human single-rooted teeth were randomly assigned to ten groups and one control group (n=20), sectioned, root canals enlarged, post spaces (13mm) prepared and posts (table) bonded using Rely X Unicem (3M Espe, Neuss, Germany) following manufacturers' instructions. Ten teeth for each group were aged with thermal cycling (40000 cycles; 5/ 55°C). Roots were sectioned in five 1mm slices and the bonding area was calculated by measuring slice thickness and post diameter. Micro-push-out test, for each slice, was performed; bond strength was calculated and analyzed using ANOVA and LSD post-hoc test (p<0.001). The assessment of failure mode was made under a stereomicroscope.

Results: Significant differences between bond strength, depending on posts, were predominantly found within groups 4, 5, 6, 7, 8 and control. Significant differences, before and after aging, were found for groups 3, 5 and 6. Thermal cycling caused an increase of bond strength in groups 1, 2, 3 and 10 while all the other groups resulted in a decrease. Bond strength, after aging, for groups 5 and 6 were lower than in the control group.

 

Group

Luting system

Mean Bond Strength (MPa)

Initial

Aging

1

FotoTech

14.5±2.4

16.2±3.4

2

Tech 2000Xop

11.2±5.0

13.3±4.7

3

Tech 21Xop

12.0±4.8

15.3±3.9

4

FRC Postec

16.0±5.6

13.7±5.3

5

Everstick Post

15.3±3.5

8.6±3.6

6

Fibermaster

12.8±5.2

8.7±3.3

7

Rely X Post

12.3±5.3

9.4±5.5

8

LuxaPost

18.0±7.9

15.5±6.2

9

DT White Post

12.4±5.4

11.1±6.4

10

DT Light Post Illusion

11.7±5.6

11.7±6.2

control

ER-Titanium-Post (Ketac cem)

11.0±5.6

9.3±5.9

Conclusion: The post system and aging influenced the bond strength of adhesively luted FRC-posts.


0975 (120973)

Influence of irrigating substances on adhesion of Epiphany to dentine. F.J.A. RACHED-JUNIOR1, W.V. VILANOVA2, C.E.S. MIRANDA2, M.D. SOUSA-NETO3, and Y.T.C. SILVA-SOUSA4, 1University of Ribeirão Preto, Araraquara, Brazil, 2University of Ribeirão Preto - UNAERP, Ribeirão Preto, Brazil, 3University of São Paulo, Ribeirão Preto, Brazil, 4University de Ribeirao Preto - Unaerp, Ribeirão Preto, Brazil

Objectives: The study evaluated the bond strength of AH Plus and Epiphany sealers to radicular dentine treated with auxiliary substances of biomechanical preparation in solution and gel form. Methods: Roots of 100 canines were sectioned in the cementoenamel junction and 4mm below this section in the apical direction, providing dentine discs. After the preparation of root canals with tapered diamond bur, the specimens were assigned to 5 groups (n=20) according to the surface treatment: I. 1% NaOCl (control); II. 1% NaOCl/17%EDTA; III. 17% EDTA; IV. 24% EDTA (gel) and V. 2% Clorexidina (gel). Two specimens of each group were prepared for SEM analysis. Each group was subdivided into 2 groups (n=9) according to the tested sealer: AH Plus and Epiphany. The specimens were submitted to the push-out test in Universal Testing Machine and the results were transformed in MPa. Failure modes after test were analyzed at 25X. Results: AH Plus sealer had higher bond strength (8.74±2.75) than Epiphany (6.74±3.97) (p<0.05). Among the surface treatments, 1% NaOCl/17% EDTA promoted the higher bond strength (10.88±3.05), statistically different from the other treatments (p<0.05). 17% EDTA (8.75±1.75); 24% EDTA (gel) (7.48±3.48) and 2% chlorhexidine (gel) (7.89±3.41) had intermediate values, statistically similar among themselves (p>0.05) and 1% NaOCl presented the smallest means (3.70±0.86). In the interaction between surface treatment and sealer, superior bond strength was observed for AH Plus with 24% EDTA gel (10.33±1.10) and 2% chlorhexidine gel (10.74±2.01) and for Epiphany with 1%NaOCl/17%EDTA (12.76±2.93), statistically different from the other treatments (p<0.05). SEM showed that 24% EDTA gel and 2% chlorhexidine gel caused smear layer removal and opened dentinal tubules. Failures analysis showed the prevalence of cohesive-type failure. Conclusion: The bond strength of the sealers to dentine was influenced by the surface treatment and the both sealers had different performance.


0976 (121000)

Retention of quartz fiber posts using different luting cements. P. BALDISSARA1, C. MONACO1, L.F. VALANDRO2, and R. SCOTTI1, 1University of Bologna, Bologna, Italy, 2Federal University of Santa Maria, Santa Maria, Brazil

Objectives: To determine the effect on the pull-out strength of threads cut into the surface of quartz fiber post cemented with three luting materials.

Methods: 42 human single-rooted, crownless teeth were treated endodontically and randomly assigned to six fiber posts groups: 1) to 3) were restored with Macro-Lock#3 posts (RTD); 4) to 6) with control posts made of the same material but lacking threads (RTD). The posts were cemented 12mm deep using Panavia(Kuraray), RelyX Unicem (3M ESPE), and Fuji Plus (GC) following the manufacturer instructions. The specimens were subjected to 5000 thermal cycles at 5 and 55°C and wet stored. Retentions were made on the emerging portion of the controls using a diamod bur, then a composite core was made using a mold. A pull-out stress was applied by clamping the core with an Instron machine (2mm/min speed). The pull-out strength was recorded for each group and compared (alpha=0.05). After the test, the specimens were observed under the stereomicroscope to determine failure patterns.

Results: The Macro-Lock demonstrated higher retention with all the luting materials employed, statistically significant when RelyX and Fuji were used (P<.05), suggesting that the threads on their surface are effective to improve the pull-out strength. The highest retention of Macro-Locks was obtained using the Fuji GIC and the self-adherent cement (RelyX). The resin cement coupled with an adhesive system (Panavia) showed lower retention forces, probably caused by the “C” factor dynamics.

Conclusion: The grooves on Macro-Lock surface are effective to improve the retention; these posts could be used safely with low cost, easy to use materials such as resin modified GIC. Control posts were less retentive, particularly when RelyX Unicem was used. This could be explained by the smooth surface and lack of any thread.


0977 (121042)

Bonding Of FRC-Posts - Influence Of Different Adhesive Cements and Localization. T.A. MACKERT1, A. PETSCHELT1, J.M. POWERS2, and C. BERTHOLD3, 1University of Erlangen-Nuremberg, Erlangen, Germany, 2University of Texas Dental Branch at Houston, Houston, TX, 3University of Erlangen, Erlangen, Germany

Objectives: The purpose of this study was to evaluate the influence for different adhesive luting systems and the influence of root canal region on bond strength of an adhesively luted glass-fiber-reinforced [FRC] posts.

Methods: 90 extracted human single-rooted teeth were randomly assigned to nine groups (n=10), sectioned, root canals enlarged, post spaces (13mm) prepared and posts (FRC-Postec, Ivoclar-Vivadent, Liechtenstein ) bonded using nine adhesive luting systems (table) following manufacturers' instructions. Roots were sectioned in five 1mm slices and the bonding area was calculated by measuring slice thickness and post diameter. Section 1 was defined as coronal, section 3 as middle and section 5 as the apical root region. Micro-push-out test for these slices were performed; bond strength calculated and analyzed using ANOVA and LSD post-hoc test (p<0.001). The assessment of failure mode was made under a stereomicroscope.

Results: Significant lower bond strength was only found within group 3. Significant differences on bond strength, between coronal, middle and apical root region for each adhesive luting system were not detected.

 

Group

Luting System

Mean Bond Strength (MPa)

coronal

middle

apical

1

ED-Primer II_Panavia F2.0

15.0±6.1

15.3±4.2

14.2±4.5

2

AdheSE_Multicore flow

14.1±5.4

15.0±6.0

14.0±4.6

3

Syntac_Variolink II

5.3±2.8

5.0±2.3

5.8±2.2

4

Excite DSC_Variolink II

12.6±5.6

9.8±2.9

12.4±4.0

5

ED-Primer_Panavia 21

13.8±5.7

13.2±2.5

13.3±4.2

6

MultilinkPrimer_Multilink

11.5±3.4

10.9±4.8

11.8±5.2

7

ED Primer II_Clearfil Esthetic Cement

13.7±4.9

11.6±3.2

12.4±4.3

8

Rely X Unicem

17.2±4.7

15.8±6.8

17.3±4.1

9

LuxaBond_LuxaCoreZ

15.7±5.8

16.0±7.7

15.3±3.1

Conclusion: Only one luting system influenced bond strength significantly. The lower bond strength values obtained, in this group, might be the result of an incomplete cure of the light-cured adhesive. The root canal region did not influence the bond strength.


0978 (121069)

Bonding Of FRC-Posts - Influence Of Different Posts and Localization. B. HOLZSCHUH1, A. PETSCHELT1, J.M. POWERS2, and C. BERTHOLD3, 1University of Erlangen-Nuremberg, Erlangen, Germany, 2University of Texas Dental Branch at Houston, Houston, TX, 3University of Erlangen, Erlangen, Germany

Objectives: The purpose of this study was to evaluate the influence of the use of ten different FRC-posts luted to root canal dentin with a self-etching dual-cured adhesive luting system, although the influence of root canal region on bond strength.

Methods: 100 extracted human single-rooted teeth were randomly assigned to ten groups (n=10), sectioned, root canals enlarged, post spaces (13mm) prepared and posts (table) bonded using Rely X Unicem (3M Espe, Neuss, Germany) following manufacturers' instructions. Roots were sectioned in five 1mm slices and the bonding area was calculated by measuring slice thickness and post diameter. Section 1 was defined as coronal, section 3 as middle and section 5 as apical root region. Micro-push-out test for each slice was performed while bond strength were calculated and analyzed using ANOVA and LSD post-hoc test (p<0.001). The assessment of failure mode was made under a stereomicroscope.

Results: Significant differences between bond strength, depending on the post, were found within groups 4, 5, 7 and 8. Significant differences, on bond strength, between coronal, middle and apical root region for each post were not detected.

 

Group

Luting system

Mean Bond Strength (MPa)

coronal

middle

apical

1

FotoTech

13.8±2.4

14.5±3.0

15.4±1.6

2

Tech 2000Xop

8.8±3.4

12.7±4.8

13.9±6.8

3

Tech 21Xop

13.1±4.9

9.5±3.4

14.9±5.2

4

FRC Postec

17.2±4.7

15.8±6.8

17.3±4.1

5

Everstick Post

19.0±3.3

14.1±3.6

14.4±2.2

6

Fibermaster

15.7±6.0

13.1±4.2

10.4±4.5

7

Rely X Post

14.5±7.5

12.1±5.7

9.5±3.9

8

LuxaPost

19.6±6.3

18.5±7.2

17.5±9.3

9

DT White Post

11.0±4.0

12.4±8.5

15.5±3.8

10

DT Light Post Illusion

9.8±4.5

11.8±5.9

14.2±4.1

Conclusion: In some cases the post system influenced the bond strength while the root canal region did not.


0979 (121109)

Push-out bond strength of self-adhesive resin systems to human dentin. A. URANO, T.B. SAB, A.F. MONNERAT, and H.R. FILHO, Universidade Do Estado do Rio de Janeiro, Rio de Janeiro, Brazil

Objectives: Evaluate the push-out bond strength between coronal dentin of human molars and IPS Empress® 2 (Ivoclar-Vivadent) ceramic cylinders by using four different adhesive resin cement systems.

Methods: Sixteen teeth were selected. Conventional resin cement RelyXTM ARC (3M ESPE) was used as control group. Three self-adhesive resin cements RelyXTM Unicem (3M ESPE), Experimental DFL (DFL) e Maxcem® (Kerr) were tested. The coronal portion was cut in the cement-enamel junction and embedded in self-curing epoxi resin. They were ground flat using water-cooled mechanical polisher to obtain a 2.10mm thick specimens. Two cylindrical cavities 1.90mm in diameter were made perpendicular to the flattened surfaces using a round tip carbide bur. The teeth were than randomly divided into four groups (n=8): Group 1 - Adper Single BondTM (3M ESPE) adhesive system and RelyXTM ARC; Group 2 - RelyXTM Unicem; Group 3 - Experimental DFL; Group 4 - Maxcem®. Specimens were stored in distilled water for five days and than termal cycled for 1000 cycles between 5º/55ºC (dwell time of 30 seconds at each temperature; transfer time of 5 seconds). All specimens were submitted to wet ground with silicone carbide grinding paper to achieve 2.0mm thick. For the push-out test, the specimens were mounted in a universal testing machine Emic® with a custom-made metal jig 1.0mm in diameter and loaded with a cross-head speed of 0.5mm/min. The push-out bond strength was calculated as the ratio of the load, which was necessary to extrude the ceramic cylinders from the cavities, and the size of the bonding area.

Results: One-way ANOVA revealed significant differences between groups (p<0.05). SNK Test detected that RelyXTM Unicem showed the highest push-out strength value. Groups 1, 3 and 4 revealed no statistically significant difference in push-out values.

Conclusion: RelyXTM Unicem showed de highest push-out values in coronal dentin of human teeth.


0980 (116658)

Bond Strength of Color-changing Orthodontic Adhesives to Bovine Enamel. M. DUERS, J. ENGLISH, J.C. ONTIVEROS, J.M. POWERS, H.I. BUSSA, G.N. FREY, R. GALLERANO, and M. RUSHING, University of Texas Dental Branch at Houston, Houston, TX

Objective: To evaluate the shear bond strengths of three color-changing orthodontic adhesives and a conventional light-cured adhesive to bovine enamel. Materials and Methods: Two hundred forty extracted bovine incisors were randomly divided into 8 groups of 30 teeth. The teeth were etched with 35% phosphoric acid (Transbond XT etching gel) and a primer (Transbond XT Primer) was applied. Metal orthodontic brackets (LP Twin Mini Master Series 0.022, American Orthodontics) were bonded directly to each tooth with three color-changing adhesives [Blugloo (BG, Ormco), Grengloo (GG, Ormco), Transbond PLUS (TP, 3M Unitek)], and a control [Transbond XT (TXT, 3M Unitek)]. The specimens were stored for 15 minutes and 24 hours in sodium azide at 37°C. The specimens were debonded in shear on an Instron at 1.0 mm/min. The data were analyzed by two-way analysis of variance and post-hoc comparisons (Fisher's PLSD) at the 0.05 level of significance. Results: Means (n=30) with standard deviations in parentheses are listed. Fisher's PLSD intervals for comparisons of means between 2 times and within 4 adhesives were 0.8 and 1.2 MPa, respectively. Means with the same superscripted letters are not different statistically (P>0.05).

Bonding Agent 15 min 24 hrs

GG 9.9 (4.7) 6.4 (3.0)

TXT (Control) 7.6 (2.9)ab 7.8 (4.0)ac

BG 7.3 (2.7)b 8.2 (1.8)c

TP 6.6 (3.0)b 7.7 (3.7)c

Conclusions: When comparing bond strengths at 15 minutes and 24 hours, there was no significant difference only for adhesive TXT. GG had decreased bond strength whereas BG and TP had increased bond strength after 24 hours. All four orthodontic adhesives demonstrated bond strengths between 6 and 10 MPa, which is considered to be clinically acceptable.


0981 (117123)

Orthodontic bracket bonding by applying one-step self-etch adhesive system. M. TOKUNAGA, N. NISHIYAMA, and K. KASAI, Nihon University, Matsudo, Chiba, Japan

Objectives: In order to minimize the intervention to the intact enamel and prevent the enamel fracture, we designed the novel bonding system of the orthodontic bracket by applying a one-step self-etch adhesive system. The purpose of this study is to control the fracture portion at the debonding of the bracket from the enamel. Methods: Resin cements (Superbond C&B [SB, Sun Medical], Transbond XT [TB, 3M Unitek]), one-step self-etch adhesives (G-Bond [GB, GC], Tri-S bond [TS, Kuraray Medical]) and extracted human premolars were used. After one-step self-etch adhesive was applied to the enamel surface and polymerlized, the brackets were bonded to the adhesive layer with resin cements. The brackets were bonded to the enamel surface, etched by phosphoric, with resin cements as a control. Measurement of shear bond strength and observation of fracture surface were performed. Results: Mean shear bond strengths obtained from the experimental groups were lower than that obtained from the control groups. However, mean bond strengths of the experimental groups were more than 11.3MPa, and the interfacial failure was observed at the adhesive layer and resin cement interface. Contrast, the enamel fracture was observed in the control group. Conclusion: The application of a one-step self-etch adhesive system to the bonding of the bracket to the enamel for orthodontic treatment exhibited noticeable high bond strength and controlled the fracture portion. This bonding technique is very powerful to prevent the enamel fracture at the debonding of the bracket from the enamel surface.


0982 (117848)

Shear Bond Strength of Four Different Esthetic Brackets. G. SALAS, J.D. ENGLISH, D. SAN MARTIN, A.M. SALAS, K.R. MCGRORY, J.C. ONTIVEROS, J.M. POWERS, and G.N. FREY, University of Texas - Houston/Health Science Center, Houston, TX

ABSTRACT

Objective: The purpose of this investigation was to compare the shear bond strength of four different esthetic brackets in combination with a commonly used bonding system as well as to assess bracket failure with vertical forces.

Methods: Four of the most common ceramic brackets were used in this study: Clarity by 3M/Unitek, Ice by Ormco, InVu by TP Orthodontics, and Radiance by American. Each company provided 70 upper right incisor brackets and they were tested with the same light-cured bonding system (Transbond XT). Bonding procedures were performed on four equal groups of 70 bovine teeth. Shear bond strength tests were performed on an Instron machine at 5 minutes and at 24 hours after the teeth were bonded. Data were analyzed by two-way analysis of variance (StatView) at the 0.05 level of significance. Means were compared using Fisher's PLSD intervals.

Results: There were no bracket failures or enamel damage evident upon debonding the four groups of ceramic brackets. Five minutes after bonding, Ice and InVu showed significantly higher bond strength than Radiance and Clarity, p< 0.01, while bond strength for Radiance was significantly lower than for all other brackets 24 hours after bonding.

Conclusions: Bond strengths were different among the different brackets and at different time intervals; and bond strengths for all brackets were significantly higher 24 hours after bonding than at 5 minutes.

KEY WORDS

Esthetic brackets, ceramics, bovine teeth

Materials sources: 3M Unitek, Ormco, TP Orthodontics and American Orthodontics


0983 (119249)

Effect of Bracket Recycling Procedures on Shear Bond Strength. L.V. LAÉRCIO1, M.C.Q. SIMEÃO2, A.G. JESUS1, A.J.S. SANTOS1, C.T. MACHADO1, and C.F. SARMENTO1, 1Universidade de Potiguar, Natal, Brazil, 2Universidade de Potiguar, Fortaleza, Brazil

Objectives: The aim of this in vitro study was to evaluate the effect of immediate methods of bracket recycling and the enamel surface treatment on shear bond strength. Methods: Metal brackets (Dental Morelli) were bonded to the buccal surfaces of 160 teeth bovine incisors using the Transbond XT Light Cure Adhesive (3M Unitek). After detachment, the brackets were separated into 12 experimental groups (n=10): G1 and G2, 50-£gm particle aluminum oxide blasting (AOB) + multilaminated bur (MB); G3 and G4, green stone grinding (GS) + MB; G5 and G6, AOB + shofu bur; G7 and G8, GS + shofu bur; G9 and G10, OAB + carbide bur (CB); and G11 and G12, GS + CB. The recycled brackets, before bonding, were treated with one coat of adhesive in G1, G3, G5, G7, G9 and G11 groups. The samples were submitted to shear bond strength test (Shimadzu - 0.5mm/min). The data were analyzed by Three-Way ANOVA, Turkey post-test and Dunnett (ƒÑ=0.05). Results: Statistical differences were no showed for enamel treatment (p=0.852). There are statistical differences for bracket recycling method (p=0.0005) and adhesive application (p=0.036). Brackets recycled by the 50-£gm AOB (9.39 and 8.77 MPa) showed the greater shear strength means than GS (8.25 and 7.36 MPa), with and without adhesive, respectively. The adhesive application increased the shear strength means, independently of other treatment. The association between 50-£gm AOB and adhesive application (9.39 MPa) presented no statistical difference of control 1 group (9.83 MPa), where was used the enamel without pre-bond step and new brackets. The MEV analyses showed that #1558 carbide bur used in low-speed presented the more regular enamel surface. Conclusion: The bracket recycling using 50-£gm AOB and adhesive one coat on bracket mesh, was efficient and technically simple, and might provide cost reduction for orthodontists and patients alike.


0985 (119960)

Bond strengths and SEM study of four orthodontics adhesive systems. E.C.A. SANTOS, J. KINA, F.M. ARANTES, L.M.B. PIGNATTA, J.R. KINA, and C.C.M. GOUVÊA, Universidade Est. Paulista Julio Mesquita, Araçatuba, Brazil

Objective: This study was to evaluate four orthodontics adhesive systems. Method: 160 incisors bovines were used and randomly divided into four groups: G1- Enlight; G2- Transbond XT; G3- Transbond XT with Transbond Self-Etching Plus; and G4- Fuji Ortho LC. The mechanical tests were done after 24h after bondind. After shear bond strengths test in the universal machine, to verify the debonding characteristics in enamel and the bracket the adhesive remanescent index (ARI) was done. The same specimens were used to verify the ARI was used to SEM evaluation. Results: Results were statistically evaluated using one way Anova, Tukey test. The values of shear bond strengths were for groups 1, 2, 3 and 4 was 8.17 MPa(a), 9.60MPa(a), 7.66 MPa(a) and 4.57 MPa(b). In relation to the values of the ARI, group 4 showed significant difference when compared with groups 1, 2 and 3. In group 4, it could observed more than 90% of adhesive, was possible to identify the presence of continuous cracks in the enamel-adhesive interface. In the groups 1 and 2, it was observed the close relation of the bonding material with the enamel surface. And in the group 3 it was difficult observe the definition between the enamel and the bonding material. Conclusion: G1, G2 and G3 offered more bonding strengths than G4. The composite materials presented greater apparent adhesive in interface material-surface of the enamel. The conventional composite (G1 and G2) materials presented an interface defined between enamel and adhesive with the presence of tags. This aspect it is not observed in SEM of Transbond XT with Transbond Self-Ettching Plus. The images in SEM of Ortho-Fuji LC demonstrated more preservation of the enamel prisms. However, the use of composites are better and the Ortho-Fuji LC as system of bonding for orthodontic accessories is limited.


0986 (120325)

Cementing of brackets: the use or not of bonding agents. L. VELMOVITSKY1, L.G. MOTTA1, U. MEDEIROS2, K. WEIG1, T. MAGALHÃES FILHO1, and F.M. MAGALHÃES1, 1Universidade Federal Fluminense, Rio de Janeiro, Brazil, 2Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

Giving quality public attention to a greater part of the population is a very huge challenge. In orthodontics, research in procedures that would use less time and material is fundamental. Objectives: With this in mind, the objective of this work is to verify the adhesive strength of cementing brackets, utilizing or not utilizing bonding agents; knowing that, on paper, the minimum adhesive resistance is 8MPa in stress and strain. Methods: Forty human teeth were used. The teeth were obtained from the teeth bank of the Federal Fluminense University (UFF). Bucal surfaces free from filling were utilized and were divided into two groups. Phosphoric acid 37% were applied to the teeth during 30sec. After this, they were washed and dried until the white parts were seen. Resin was applied without any bonding agent to group 1 teeth. For the group 11 teeth, resin was applied after the use of a bonding agent. The resin and bonding agent used were of the brand Concise™ 3M autopolimerisable. The teeth were put into PVC tubes, on a plane smooth surface, using type IV paris plaster. The Cps were then taken to the Universal Testing machine Kratos, with a cell charge of 200Kgf to 1mm/min. A metal table was adapted with screws to hold the teeth and to adjust the position of the brackets. Results: Group 1 obtained an average measurement of 13:78Mpa and Group 11, 16:91Mpa. After statistical analysis it was concluded that Group 1 is less resistant than group 11. Conclusions: Nevertheless, the teeth which were cemented without any bonding agent registered values much higher than the 8Mpa found in books, which brings us to believe that this procedure can be accepted as the routine necessary for clinical evidence.


0987 (116955)

Adhesive Properties of Several New Self-Adhesive Resin Cements. T.T. NGUYEN, T.D. NGUYEN, X. QIAN, and D. TOBIA, Kerr Corporation, Orange, CA

Objective: To measure and compare the bond strengths of four recently introduced dual-curable self-adhesive resin cements {Maxcem Elite (Kerr),  Unicem Clicker (3M ESPE), iCem (Kulzer), and SmartCem2 (Dentsply)} to following dental substrates: human dentin, bovine enamel, rexillium alloy, and Vitablocs Mark II (Vident) porcelain block.  Method:  All substrates were polished with 600 grit SiC paper.  Dentin and enamel substrates received no further treatment prior to bonding.  Rexillium substrates were air-abraded with aluminum oxide particles prior to bonding.  Vitablocs substrates were etched with 9.5% HF etchant (Gresco Products Inc.) prior to bonding.  A bonding jig with a cylindrical mold (D=2.38mm) was securely placed on the substrate surface.  Each cement was condensed into the mold and allowed to self-cure.  The specimens (n=6) were then stored under 85~90% relative humidity at 37°C for 24 hours before being subjected to shear force on an Instron mechanical tester.  Results:  ANOVA analysis revealed that the bond strength of Maxem Elite is significantly (p < 0.05) higher than those of other cements for all four substrates tested.   For dentin, enamel, and vitablocs substrates, the bond strengths of iCem, SmartCem2 and Unicem are not statistically different (p > 0.05) from each other.

 

Shear Bond Strength (SBS), MPa

Maxcem Elite

iCem

SmartCem2

Unicem

Dentin

23.5±2.2a*

9.5±3.1b

7.5±2.6b

8.1±2.0b

Enamel

19.4±2.0a

9.3±1.1b

6.7±4.2b

5.7±2.0b

Rexillium

41.5±5.0a

34.1±4.4b

24.4±2.0c

14.5±4.2d

Vitablocs

31.3±4.0a

23.9±3.0b

22.5±2.7b

21.3±4.2b

    *Means with different letters within the same row are statistically different at p < 0.05.

Conclusion:  Maxcem Elite had the best adhesive properties among four new self-adhesive resin cements tested in this study.


0988 (116155)

Simulation of cement removal on titanium surfaces. C. TREMPLER, M. BEHR, and G. HANDEL, University of Regensburg, Regensburg, Germany

Objectives: Fixed dentures become more and more luted on dental implants. Surplus of luting agents is considered to play a significant role in the occurrence of peri-implantitis.

Methods: The clinical procedure of cement removal was simulated using a model with titanium beams of 6mm diameter. Three investigators cleaned up 6 specimens which had a standardized layer of #1 zinc phosphate (Harvard, Hoffmann, Berlin, G), #2 glass ionomer (Ketac Cem, 3M Espe, Seefeld, G), #3 resin cement (Calibra, Densply, Milford, USA), #4 self-adhesive composite cement (RelyX Unicem, 3M Espe, Seefeld, G), or a #5 provisional eugenol-free cement (Provicol, Voco, Cuxhaven, G) using steel or plastic scalers. Each specimen was treated for 30sec under blinded standardized conditions. The cleaned surfaces were digitally recorded and cement remnants were evaluated using an image analysis program (Optimas Corporation 6). Statistical analysis: Mean, standard deviation, ANOVA.

Results:

Scaler

Steel scaler

Plastic scaler

Cement

#1

#2

#3

#4

#5

#1

#2

#3

#4

#5

Mean [%]

5.3

+/- 3

2.0+/- 25

14.0

+/- 7

77.9

+/- 29

*

18.3

+/- 2

4.5

+/- 30

*

*

64.3

+/- 15

* measurement not possible

Surplus of cement was found on all specimens after cleaning. The amount of remnants depended on the investigated cement and scaler type. Glass ionomer cement processed with a steel scaler showed significant less remains (p=0.08). However, in some cases glass ionomer cleaning was quite difficult, which explains the high standard deviation. Self- adhesive composite and provisional cement showed significant higher amounts of cement remnants after the cleaning procedure (p<0.001).

Conclusion: Regardless of cement type and scaling treatment there is always cement left on titanium surfaces. Clinicians should be aware of the potential risk of cements remnants by the luting procedure of fixed dentures on dental implants.


0989 (116614)

Sorption and solubility of conventional and self-adhesive resin cements. R. FULGENCIO1, M. TOLEDANO2, F.S. AGUILERA2, E. OSORIO2, R.M. CARVALHO3, G.H. HENOSTROZA4, and R. OSORIO5, 1Universidade Gama Filho, Rio de Janeiro, Brazil, 2University of Granada, Granada, Spain, 3University of São Paulo, Bauru Dental School, Brazil, Bauru, Brazil, 4Peruvian University Cayetano Heredia, Lima, Peru, 5Universidad de Granada, Granada, Spain

Objectives: to evaluate sorption and solubility of self-adhesive resin cements (Rely X Unicem, G-Cem, Bis-Cem) compared to conventional resin cements (Calibra, Panavia F2.0). Methods: Five disks of each cement were prepared (15.0 ± 0.1 mm diameter, × 2.0 ±0.1 mm thickness). The disks were placed in a desiccator to ensure dryness. They were weighed in an electronic balance (reproducibility- 0.0001 g) until a constant initial mass (M1) was obtained. All disks were transferred to separate containers with deionized water and stored in a 37°C incubator. The weight gain or loss of each disk was measured after, 1h, 6h, 24h and at 2 days intervals. They were weighed, and then returned to the water until obtain a constant wet mass (M2). Each disk was then placed in desiccator and weighed daily to a constant dry mass (M3). Sorption [(M2-M3)/ Volume] and solubility [(M1-M3)/Volume] values were obtained (ISO 4049) in µg/mm3. Data were analyzed with ANOVA and Student Newman Keuls (P< 0.05).  SEM analysis of surfaces was performed. Results: Mean values (µg/mm3) and standard deviation are presented. Same letters indicate no differences.

Sorption

Solubility

RelyX Unicem

+3.04 (0.50) a

-6.60 (0.80)   A

Calibra

+1,71 (0.04) a

-1.97 (0.72)   B

Panavia F 2,0

+3.34 (0.30) ab

+4.52 (0.74)  C

Bis-Cem

+7.54 (0.76) c

-6.56 (1.95)  A

G-Cem

+4.28 (0.84) ab

+3.76 (2.78) BC

Conclusions: Resin constituents seem to be determinant on the water sorption and solubility. The amount and nature of filler also have an important role in their behavior. (Grants number - CAPES# O565-07-5- JA-P08-CTS3944, CICYT/FEDER: MAT08-02347/MAT) and JA-P08-CTS3944.

 


0990 (114578)

Polymerization Influence on Water Sorption and Solubility of Resin-modified-glass-ionomer-cement. T.O. BALDO, N.R. SVIZERO, and M.T. ATTA, Bauru Dental School, University of São Paulo, Bauru, Brazil

Objectives: The objective of this study was to investigate the effect of polymerization mode on water sorption and solubility of a resin modified glass ionomer cement (Vitremer).

Methods: Disc-shaped specimens measuring 6.0mm diameter x 0.5mm thickness were prepared in a standardized Teflon mold. The material was manipulated according to the manufacturer's instructions, inserted in the mold, protected with polyester matrix band and pressed with a glass sheet to remove the material excess. Twenty-one specimens were made and divided into 3 experimental groups in agreement with the mode of polymerization: Group 1 (n=7) - light curing (40s), Group 2 (n=7) - dual polymerization (10 minutes delay + light curing for 40s), and Group 3 (n=7) - chemical polymerization (dark room). The volume of each specimen (V) was obtained to calculate water sorption and solubility. Data were submitted to one-way ANOVA and Tukey test.

Results: water sorption (µg/mm3): Group 1 (240.58±14.71), Group 2 (230.81± 12.07) and Group 3 (100.42±12.93). Solubility (µg/mm3): Group 1 (-31.20± 11.03), Group 2 (-32.68±8.62) and Group 3 (-122.49±23.58). Statistical analysis indicated no significant difference among Groups 1 and 2 in water sorption and solubility. However, both were statistically different from Group 3 (p<0,05).

Conclusion: The absence of photopolymerization of RMGIC affects water sorption and solubility of Vitremer. Grant from FAPESP # 06/05096-2.


0991 (116608)

Aging of three different endodontic cements assessed by Time-Domain NMR. M. GOMBIA1, V. BORTOLOTTI2, S. ANDREANA3, B. DE CARLO4, G. PITZOLU5, S. ZANNA4, R. MONGIORGI4, and P. FANTAZZINI1, 1Department of Physics, University of Bologna, Bologna, Italy, 2DICMA, University of Bologna, Bologna, Italy, 3Loma Linda University, School of Dentistry, Loma Linda, CA, 4Center of Biomineralogy, Crystallography and Biomaterials, University of Bologna, Bologna, Italy, 5Department of Dental Sciences, University of Bologna, Bologna, Italy

Objective: To demonstrate suitability of Time-Domain Nuclear Magnetic Resonance (TD-NMR) of 1H nuclei methodology in assessing chemical-structural changes and differences of endodontic cements. Methods: Specimens of ProRoot® MTA, USA, (GpA), TECHBIOSEALER® normal (GpB) and fluoridated (GpC), Isasan, Italy were prepared with de-ionized/double-distilled water (2:1 H2O/cement) and stored in a NMR glass-tube at 25°C. Quasi-continuous relaxation time distribution analysis of 1H signals was performed using multi-exponential inversion software (UPENWin) for both longitudinal (T1) and transverse (T2) components of nuclear magnetization. Determination of the two signal amplitudes of their ratio α and relaxation times distributions was recorded. Evaluations were performed for a time period up to 30 days. A specific data acquisition and computation was used for T1 distributions after “Solid” and “Liquid” signal separation. Statistical analysis was performed at significance level of p<0.01. Results: Statistical analysis showed a significant difference (p<0.01) within the mass values for GpA (p<0.01) and within GpB (p<0.01) at day 30 indicating mass loss. No significant difference was found within GpC values. Statistically significant mass loss was reported between GpA vs GpB and GpC, whereas there were no differences between GpB and GpC. Weight values indicated continuous dynamic changes recorded up to 1/1000gr values. Strong and rapid changes of the TD-NMR parameters during cement setting were detectable. There was an increase of “Solid” component. T1 and T2 distributions of the “Liquid” component shifted quickly towards shorter times, with different kinetics in the three cements. Creation of a “Solid” component in place of the “Liquid” one, was detected, event related to a transition of 1H nuclei from a higher mobility status to a lower one as cement aging proceeds (Table). Conclusions: 1H TD-NMR analysis provides useful information for the identification and quantification of components of endodontic cements. This methodology allows detection of the changes and differences among cements.


0992 (115016)

Shear strength of pressed porcelain veneers re-bonded to enamel. H. ST. GERMAIN, Jr., and T. ST. GERMAIN, University of Nebraska, Lincoln, NE

A reliable clinical protocol for re-bonding porcelain veneers when they are not cohesively fractured is desirable. Objectives: This research measured shear bond strength (MPa) and mode of shear failure (adhesive/cohesive) of veneers re-bonded to enamel after adhesive de-bonding. Methods: Three groups (n=10) of mounted molar teeth were finished flat using wet 600-grit silicon carbide paper. Thirty OPC® porcelain veneers (5.0mm x 0.75mm) were air abraded with 50µm Al2O3, etched with hydrofluoric acid, and silanated. The control group (A) veneers (n=10) were bonded to enamel using Optibond Solo Plus® and NX3 Nexus®. Groups B & C (n=10ea.) were prepared similarly to Group A with the exception that a removable die-spacer was placed before the veneer was positioned and the resin cement light-activated. The de-bonded veneers from Groups B & C were placed in a casting burn-out oven and heated to disintegrate the resin cement below the glass transition temperature (Tg) of the OPC® porcelain. The recovered veneers were then prepared for bonding. Group B enamel specimens were air abraded using 50µm Al2O3 while Group C enamel specimens were not. All specimens were thermo-cycled between 5°C and 55°C for 2000 cycles using a 30 second dwell time. Shear bond strengths were determined on an Instron® at a cross head speed of 1.0mm/minute. Results: Shear bond strength results in MPa for the groups were: A=10.3±2.5, B=9.0±2.7, and C=8.6±3.0. One-way ANOVA indicated that there were no significant interactions (p≤0.05). Tukey-Kramer post-hoc comparisons detected no significant pair-wise differences (p≤0.05). Adhesive shear bond failure was observed in all groups (A=20%, B=40%, and C=50%). Conclusions: Re-bonding veneers produced shear bond strengths that were not significantly different (p≤0.05) from the control group. No significant differences (p≤0.05) were observed when the re-bonded enamel surface was air-abraded. There was a higher incidence of adhesive bond failure with the experimental groups.


0993 (115128)

Color Stability of a New Composite Resin Cement. D. SMITH1, K. VANDEWALLE1, and G. HAMILTON2, 1USAF, Lackland AFB, TX, 2University of Texas at San Antonio, San Antonio, TX

A new composite resin cement (Nexus 3, Kerr), containing a proprietary amine-free activator, has been recently introduced that it is reportedly more color-stable. Objective: To compare the color stability of both light-and dual-cured versions of a new composite resin cement to more traditional resin cements. Methods: Three commercial resin cements were evaluated with three different curing conditions over two time periods. In this study, color changes were evaluated for light- and dual-cured versions of Nexus 3 (Kerr), Variolink II (Ivoclar), and Calibra (Dentsply) resin cements.  A teflon mold (Sabri) - 2mm in thickness and 8mm in diameter - was used to prepare 30-cylindrical specimens per each of the three restorative materials. The light-cured (base only) version of the cements was syringed into the mold and light cured for 20 seconds on each side (Bluephase 16i, Ivoclar). The dual-cured version of the cements was mixed according to the manufacturer's instructions (base and catalyst), syringed into the mold, and either light-cured as before or allowed to chemically set (n= 10).  Color was measured using a spectrophotometer (VITA Easyshade, Vident).  Specimens were measured against a white background after 24-hours (baseline), 3- and 5-months of storage in 370C distilled water.   Changes in L*, a*, and b* were calculated between baseline and each time interval.    The total color change Delta E was used to assess the amount of discoloration. A mean Delta E was determined per cement for each curing condition.  Data was analyzed with ANOVA/Tukey.  Results: A repeated-measures 2-factor ANOVA (alpha=0.05) found significant differences between groups based on cement (p<0.001) and curing condition (p<0.001), however, there was a significant interaction (p<0.001).  A repeated-measures single-factor ANOVA (alpha=0.01) found significant differences between cements per curing condition (p<0.01).  See table.  Conclusions: Nexus 3 was among the lower color change values (Delta E) for all three curing conditions.

  Curing Condition

  Mean Delta E (st dev)

  Nexus 3

  Calibra

  Variolink

  3 mo.

  5 mo.

  anova

  3 mo.

  5 mo.

  anova

  3 mo.

  5 mo.

  anova

  Light Cure

  1.8 (0.8)

  1.6 (1.1)

  ab

  2.0 (0.7)

  2.5 (1.2)

  b

  1.2 (0.3)

  1.1 (0.4)

  a

  Dual Cure with Light

  1.5 (0.5)

  1.1 (0.7)

  a

  4.1 (2.6)

  5.2 (2.2)

  b

  3.9 (1.7)

  4.2 (1.7)

  b

  Dual Cure, No Light

  4.5 (0.8)

  5.0 (0.8)

  a

  4.2 (1.9)

  5.3 (1.7)

  a

  14.6 (6.9)

  15.6 (5.6)

  b

  Groups with the same letter by row are not significantly different (p>0.05)

 

0994 (119457)

Long term colour stability of six dental cements. P.D. BRANDT, and F.A. DE WET, University of Pretoria, School of Dentistry, Pretoria, South Africa

Objective: An in-vitro study to determine the long term colour stability of six dental cements. Methods: Products evaluated were Rely X Veneer cement [RXV] (Light-cure {lc}, Translucent {tr} shade) [3M ESPE], Rely-X Unicem [UC] (Chemical cure, A2 Shade) [3M ESPE], Calibra [C] (Light-cure, Translucent shade) [Dentsply], MaxCem [MX] (Chemical cure, Clear {cl} shade) [Kerr], MaxCem Elite [ME] (Chemical cure, White {w}, White Opaque {wo} & Yellow {y} shades) [Kerr], Nexus 3 [NX3] (Chemical cure, Clear and White shades ; Light cure, clear shade) [Kerr]. Each cement was mixed/activated according to the manufacturers instructions, vibrated into a 3ml plastic syringe and allowed to chemically cure for one hour or light-cured well from all sides. Subsequently the cured cement was cut into 6-10, 1.5 mm thick disks and placed into marked containers. Using a GemShade instrument (MHT, Italy) the shade of each disk was taken at the centre of each disk and comparisons of shade between 1 hour and 18hrs, 1 month, 3months and 5 months were made using associated software. Shade and shade comparisons were recorded as Hue, Chroma, Value and Delta E. Results: Over a five month period Delta E values (1hr vs 5months) ranged from 3.06 ± 0.2 to 5.18 ± 0.34. The lowest changes in shade [Delta E] (no statistical difference) was found for ME y (3.4 ± 0.32), NX3 dc w (3.29 ± 0.6), NX3 lc cl (3.13 ± 0.29), UC A2 (3.08 ± 0.12), RXV lc tr (3.06 ± 0.2). Conclusion: All cements evaluated changed shade over time. Initially fast, due to drying out and aging and then more gradual. This study will be extended up to one year and some samples will also be re-hidrated and evaluated. Further studies need to be done on the same group of materials but in moist (in-vivo simulated) conditions.


0995 (120213)

Dentin pre-treatment to enhance bond strength of self-adhesive resin cements. S. PAVAN1, P.H. DOS SANTOS2, and A.K.B. BEDRAN-RUSSO1, 1University of Illinois - Chicago, Chicago, IL, 2Universidade Est. Paulista Julio Mesquita, Aracatuba SP, Brazil

Objectives: To evaluate the effect of tannic acid and polyacrylic acid on the microtensile bond strength of self-adhesive resin cements to dentin. Methods: Eighteen human teeth were ground flat to expose dentin and divided into three groups according to the dentin pre-treatment: (A) control, no surface pre-treatment; (B) 25% polyacrylic acid solution applied for 10sec – Ketac conditioner (3M ESPE); (C) 20% tannic acid applied for 10min. Tescera composite resin (Bisco) blocks were cemented to the dentin surfaces using two self-adhesive resin cements (Rely-X Unicem – 3M ESPE or Maxcem Elite - Kerr). All specimens were stored in distilled water for 24h, sectioned into beams (1mm2) and tested to failure in a microtensile tester at a crosshead speed of 1mm/min. The data were statistically analyzed using two-way ANOVA and Fisher's PLSD tests (p<0.05). Results: The polyacrylic acid improved the microtensile bond strength of Rely-X Unicem (14.92 ± 4.94 MPa) to dentin when compared to control (8.35 ± 1.99 MPa), while tannic acid (8.38 ± 2.67 MPa) had no effect on the bond strength. There were no statistically significant differences (p=0.3806) among the pre-treatment techniques for Maxcem Elite (control – 8.45 ± 3.21 MPa; polyacrylic acid – 9.53 ± 9.95 MPa; tannic acid – 6.89 ± 4.45 MPa). Conclusion: The effect of dentin pre-treatment on TBS was material dependant. The use of polyacrylic acid may be indicated as a surface conditioner to enhance the bond strength of self-adhesive cements during luting procedures. Supported by Fapesp #2008/03213-7.


0996 (117124)

Dentin Laser Treatment to Improve Bond Strength for Cementation. J.E.P. PELINO1, K.A. SCHULZE2, S.C. GOUW3, C. STREFEZZA4, E.R. ALMEIDA1, A. STREACKER2, and M.N. YOUSSEF1, 1Cruzeiro do Sul University, Sao Paulo/SP, Brazil, 2University of the Pacific, San Francisco, CA, 3Cidade Universitaria, Sao Paulo - SP, Brazil, 4Cidade Universitaria, Sao Paulo/SP, Brazil

Objectives: Three different laser's were used to treat dentin in order to improve the shear bond strength within root canals or on prepared crown surfaces, after cementation.

Methods: Eighteen human molars were cut mesio-distally to provide two 3mm thick specimens from each tooth (36). These dentin specimens were polished to 320-grit carbide paper and randomly divided into 6 groups containing 6 specimens each (n=6). Three control groups (ControlA,B,C), and three laser groups (LaserA,B,C). All of the specimens in the laser groups underwent laser treatment. Afterwards all samples from all groups underwent shear bond testing. The laser samples were irradiated with a fiber orientated at a 5o angle using sweeping motions and in contact with the dentin surface employing a 30s thermal relaxation time between the cycles. Group LaserA was irradiated with an Nd:YAG laser (Lares Dental, Chico, CA, USA) with settings of (1.5W, 15Hz, 100 mJ, 124.41J/cm2) at 8 cycles. Group LaserB was irradiated with an Er:YAG laser (Kavo Key laser, Germany) with settings of (6Hz,120mJ,71,34J/cm2) at 4 cycles. Group LaserC was irradiated with a Diode laser (Opus Dent 10, Israel) with settings of (2W,120mJ,169.85-297.24J/cm2, CW=continuous wavelength) at 4 cycles. Shear bond tests were performed for all dentin samples (36) in contact with RelyXUnicem (3M ESPE) cement using a universal testing machine (Instron1011, Norwood, MA, USA). Paired t-tests were conducted to statistically analyze the data.

Results: Control A (8.8MPa ±4) versus LASER A (12.8MPa ±4.8) as well as Control C (11.4MPa ±2.3) versus LASER C (10.9MPa ±2.9) were not statistically different with p=0.154 and p=0.632, respectively. The Er:YAG laser treatment(18.8MPa ±2.7) showed significantly greater bond strength compared to the control group(11.3 MPa ±3.3) with p=0.002.

Conclusion: Of the three laser's used in this study, only the Erbium–YAG laser treatment of the dentin surface, demonstrated improved shear bond strength.


0997 (115833)

Influence of Luting Techniques and Systems on Dentin Bond Strength. E. ROBERTY, G.C. LOPES, and S. MONTEIRO JUNIOR, Universidade Federal De Santa Catarina, Florianópolis, Brazil

Objectives: to test the hypothesis that different luting techniques and systems influence the microtensile bond strength of a leucite-reinforced ceramic (ProCad) to human dentin.

Methods: Twenty seven human third molars extracted were flatened to expose the mean depth dentin surfaces. After provisionalization for 1 week, 3 luting techniques were applied: C, adhesive system was not light-activated before seating the ceramic; P, adhesive system was light-activated before seating the ceramic; and S, the Immediate Dentin Sealing technique (IDS) was performed, where the adhesive is applied before the provisionalization, and again at the luting appointment. Each technique was performed using three luting systems (adhesive system /dual resin cement combination): OP, Optibond FL/Nexus2; SB, Adper Single Bond 2/RelyX ARC; and CF, Clearfil SE/Panavia F. After 24h-storage in distilled water, the teeth were prepared for microtensile bond testing. Sticks measuring approximately 0.64mm2 were tested in an Universal Testing Machine. Fracture patterns of all specimens were analyzed under SEM.

Results: Two-way ANOVA revealed a significant interaction between luting techniques and systems (p=.0055), and the alternative hypothesis was accepted. Tukey's test have shown that the C technique was superior for OP and SB systems (p<.05), all techniques were similar for CF system, OP system exhibited better results for C technique (p<.05), and SB was superior to OP and CF for S technique (p<.05). In addition, all systems were similar for P technique. Almost all fractures occurred within the adhesive interface.

Conclusions: bond strengths of a leucite-reinforced ceramic to dentin depends on the correct choose of the luting technique/system combination.


0998 (116935)

Dentin Bond Strength of Maxcem Elite Under Various Curing Modes. H. LU, H. BUI, X. QIAN, and D. TOBIA, Kerr Corporation, Orange, CA

A new self-adhering resin cement Maxcem Elite (Kerr) was recently introduced.  Objective: To study the effect of various curing modes on the dentin shear bond strength of Maxcem Elite and to investigate if light-curing Maxcem Elite immediately after placement would negatively affect its bond strength.   Method: Dentin surface was first flattened with 600 grit SiC paper.  A bonding jig with a cylindrical mold (D=2.38mm) was securely placed on the dentin surface.  Maxcem Elite was condensed into the mold, directly onto the un-etched and un-primed dentin surface.  The cement was allowed to cure in the following modes: (i) self-cure only; (ii) light-cure (30s) immediately without delay; (iii) light-cure (30s) after 2-minute delay; (iv) light-cure (30s) after 4-minute delay; (v) light-cure (30s) after 6-minute delay.   The bonded specimens  (n=6 for each group) were then stored in de-ionized water at 37ºC for 24 hours before being subjected to shear force on an Instron mechanical tester.  Results:  ANOVA analysis revealed that the dentin shear bond strengths of Maxcem Elite obtained under various curing modes are not statistically different (p > 0.05) from each other.

Curing Mode

Dentin Shear Bond Strength, MPa

Self-cure only

24.3±3.4a*

Light-cure immediately

23.0±3.2a

Light-cure after 2-minute delay

21.6±1.5a

Light-cure after 4-minute delay

22.7±1.7a

Light-cure after 6-minute delay

23.6±2.1a

    *Means with the same letter are not statistically different at p > 0.05.

Conclusion:  The dentin shear bond strength of Maxcem Elite is not influenced by various curing modes.  Light-curing Maxcem Elite immediately after placement does not negatively affect its dentin bond strength.

 


0999 (115614)

Longitudinal CLINICAL Evaluation of Atraumatic-Restorative-Treatment in Babies Affected by Early-Childhood-Caries. D. FAUSTINO-SILVA, Sr., M. FIGUEIREDO, M. SAMPAIO, M. OURIQUES, and A. BEZ, Federal University of Rio Grande do Sul, Porto Alegre, Brazil

Objectives:Evaluate the clinical performance of the Atraumatic Restorative Treatment restorations-ARTs realized with two different glass-ionomer restorative materials: Ketac Molar Easy Mix® (3M/ESPE) e Vitro Molar® (DFL) in babies affected by the Early Childhood Caries after a 12 months period.Methods:It was a randomized-clinical trial, double-blind, split-mouth. The sample was composed by 20 children with ages from 18 to 36 months old, in a total of 99 ARTs with two glass-ionomer restorative materials from different brands.The clinical evaluation was done by a trained and calibrated examiner, using the modified USPHS criteria. For comparison of the evaluated parameters between the materials, the Test Qui-Square (p<0,05) was used.Results:The success found was of 98% for Vitro Molar® (DFL) and 100% for Ketac Molar Easy Mix® (3M ESPE), no statistics difference was found between both materials (p>0,05).Conclusions:We have concluded that ARTs with both glass-ionomer restorative materials has shown excellent clinical performance, after a 12 months period during treatment for Early Childhood Caries.


1000 (118174)

Twenty-four months of CRT prospective clinical evaluation of ART restoration. P.A. SACRAMENTO1, A.F.S. BORGES1, A.R.F. CASTILHO2, and R.M. PUPPIN-RONTANI3, 1State University of Campinas, Piracicaba, Brazil, 2State University of Campinas, Bauru, Brazil, 3State University of Campinas, Piracicaba -SP, Brazil

Objective: The objective of this study was to compare in a clinical randomized trial the performance of 2 glass ionomer cements used in Atraumatic Restorative Treatment (ART) technique. Methods: Seventy-nine schoolchildren aged from 6 to 9 year-old, with at least two active caries in primary molar teeth (n=141, Class I and II restorations) from opposite hemi arches had been selected to participate in the experiment (split-mouth designed). Children were randomly divided into 2 groups: Group 1 - Ketac-Molar (K) and Group 2 - Fuji IX (F). Primary molars presenting open decayed cavities (≥ 3 mm) were handling excavated and filled according to ART approach. Restorative materials were randomly allocated in the primary teeth. Restorations were evaluated in baseline, 3, 6, 12 and 24 months. The data were submitted to the Wilcoxon, Mann-Whitney and t-test (p<0.05). Results: For Fuji IX Class I, there was no significant difference between the recalls, but for Ketac-Molar a significant reduction of the success occurred at 6 months and another decrease at 12 months. For Class II both materials showed similar performance, with significant success rate reduction at 3 months (K-29%; F-37%); Ketac-Molar showed another success rate decrease at 24 months, and Fuji after 6 months. No significant difference was found between both materials, in the same period of time for Class I and II, except at 24 months for Class I, when Ketac-Molar presented higher failure rate (75%). Conclusion: The 24-month survival rates for treating tooth decay in school children with the ART approach was shown to be appropriate and effective particularly in small Class II lesions for both materials. However, the Fuji IX glass ionomer cement presented better performance when used in Class I cavities.


1001 (121166)

Five-year Clinical Performance of a Glass-Ionomer Based Restorative Material. F. OZER, N. UNLU, and S. GUNAL, Selcuk University, Department of Operative Dentistry, Konya, Turkey

Objectives: The aim of this clinical study was to evaluate five- year clinical performance of a light cured glass-ionomer restorative material,which is a hybridization of glass-ionomer and composite resin “GIOMER” (Reactmer, Shofu), in class V cervical non-carious lesions.

Methods: 110 class V lesions in 19 patients (mean age 58, age range 52-71) were restored using fluoride releasing adhesive bonding system (Reactmer Bond, Shofu) and glass-ionomer restorative material (Reactmer, Shofu) according to the manufacturer's instructions. Each restoration was completed by the department staff who was well trained for more than ten years. Two examiners evaluated the restorations. Clinical performance of each restoration was evaluated by each operator just after treatment, 6 mounths, one year, two year and five year intervals according to the USPHS criteria. During the examination periods, missed restorations were also noted.

Results: Most of the patients returned after six months , one-year and two year recalls (96% recall rate). But after five years, 11 patients (52%) returned and 47 restorations (29%) were checked. 24 cervical restorations were missing due to retention loss after five years. And 3 teeth were capped with ceramic crowns. During each checking period of restorations, the main finding was protrusion of restorations from the cavities. Pulpal response, such as spontaneous pain , hot and cold stimulation and percussion pain was not observed after each time period . Moderate marginal discoloration was recognized in 15 restorations at the end of fifth year. Color change was not observed in any restoration.

Conclusions: The retention rate of this fluoride releasing material dramaticaly decreased after two years. It was concluded that the excessive water sorption of material mainly influenced marginal integrity and retention rate of the restorations during long clinical trial.


1002 (117038)

Six-months Clinical Evaluation of Giomer Posterior Restorations. N. AKIMOTO, K. OHMORI, M. HANABUSA, and Y. MOMOI, Tsurumi University, School of Dental Medicine, Yokohama, Japan

Objectives: The purpose of this clinical study was to evaluate the six months clinical performance of Giomer restorative system (FL-Bond II and Beautifil II, Shofu) in posterior restorations. Methods: IRB approval was obtained and consent forms were signed. 7 Class I (1 premolar and 6 molars) and 46 Class II (37 premolars and 9 molars) restorations were placed by three operators in 38 patients. All restorations were placed under rubber dam isolation and Giomer materials were used according to manufacture's instruction, and then the restorations were immediately finished and polished. Evaluations were assessed at baseline and at six months using the following modified USPHS criteria (Retention, Color Match, Marginal Adaptation, Marginal Discoloration, Anatomical Form, Surface Roughness, Surface Staining, Secondary caries, Contact, Fracture, Sensitivity) and Gingival status by the two operators. Additionally, all restorations were photographed at each evaluation and impressions were taken for SEM observations. Results: All restoration was examined after six months. Slight color change was showed in 4 cases and slight marginal change was observed in 14 restorations. The marginal change of all restorations demonstrated step irregularities when a sharp explorer was drawn across the tooth from the enamel toward the restoration interface. These marginal interfacial irregularity steps supposedly developed from chip fractures of the resin composite along the cavo-surface margin due to overfilling the composite resin onto the uncut enamel or dentin surface. Conclusions: The clinical performance of the posterior restorations placed using the Giomer materials was clinically acceptable after six months. This clinical study will continue for three years. Supported by Shofu Inc., Japan.


1003 (118304)

One-year clinical evaluation of resin glass ionomer. S.S. SÁBIO1, M.F.A. FREITAS1, J. MONDELLI1, T.J.E. BARATA2, F.C.P. GARCIA3, L. WANG1, and M.T. ATTA1, 1Faculdade de Odontologia de Bauru, Brasil, Bauru, São Paulo, Brazil, 2Department of Operative Dentistry, University of North of Paraná, Londrina, Brazil, 3Faculdade de Ceilândia, Universidade de Brasília, Brasília, DF, Brazil

Objective:This study aimed to evaluate the performance of a resin glass ionomer cement associated to one-bottle etch-and-rinse dentin bonding systems after 1 year performance in non-carious cervical lesions (NCCL). Methods: Thirty-five patients were selected presenting at least 3 NCCLs, totallyzing 110 NCCLs. Only one professional operated all clinical procedures. Under rubber dam isolation cavities were not treated with any mechanical preparation and only a prophylaxis was done before restorations. Cavities were randomly assigned according to the treatment: Group 1 (VP)- Vitremer primer + Vitremer; Group 2 (VSB)- Single Bond + Vitremer; and Group 3 (VPB)- Prime & Bond 2.1 + Vitremer. Two pre-calibrated examiners (Kappa=0.92) assessed the performance of the restorations according to modified USPHS criteria, regarding retention, marginal degradation, marginal staining, caries occurrence and sensibility. Color and superficial texture were also assessed. Data were statistically analyzed with Qui-square and Mcnemar tests (p<0.05). Results: Only one patient did not returned. After 1 year, retention of VP, VSB and VPB restorations were of 92.31%, 87.18% and 84.62% respectively. For all groups, more than 87% were categorized as satisfactory for marginal integrity and more than 94% for marginal discoloration. There was not detected significant superiority of any tested group. No secondary caries or sensibility was assessed after one-year. Color was considered satisfactory and surface texture became rougher. Conclusion: Resin modified glass ionomer associated with different dental adhesives performed successfully after 1-year in non-carious cervical lesions. As retention of the restorations in class V is the most clinical challenge, this study supports the indication of these systems.


1004 (119293)

Microflora underneath conventional or ultrasound-excited GIC restorations. E. BRESCIANI1, F. GU2, M.F.L. NAVARRO3, J.C. FENNO1, and M.C. PETERS1, 1University of Michigan, Ann Arbor, MI, 2University of North Carolina, Chapel Hill, NC, 3Bauru School of Dentistry - University of Sao Paulo, Bauru, Brazil

After minimally invasive (MI) treatment, remaining affected dentin still includes residual cariogenic bacteria that may show potential for future activity.

Objectives: Total bacteria and Lactobacilli of residual dentin were studied at baseline and after 3 months, using MI caries removal technique and glass ionomer cement (GIC) restoration with or without ultrasonic (US) command set to improve its adhesive properties.

Methods: Sixty carious teeth (32 patients) received standardized MI caries removal (polymer bur) and dentin biopsy (#4 round bur) of affected dentin followed by restoration (GIC or GIC/US). Three months after baseline, a second dentin biopsy was taken after restoration removal. Total bacterial DNA and RNA was quantified by real-time PCR and RT-PCR using universal and Lactobacilli specific primers. The number of bacterial cells was calculated based on standard curve with known cell numbers. Statistical analysis was performed using SAS repeated measurement procedure.

Results: Total bacterial DNA and RNA at baseline and 3-month re-entry (P>0.05) was not statistically different for both tested groups. Changes after three months were similar (P>0.05). Lactobacilli DNA was detectable in 44.4% of GIC group at both evaluation intervals. The GIC/US group showed a moderate reduction (P=0.066) of samples presenting detectable Lactobacilli levels: 46.4% (baseline) and 35.7% (3-month recall). No Lactobacilli RNA was detected in both groups at both intervals.

Conclusion: The overall bacterial DNA and metabolic activity of total bacteria was not changed after 3 months. Cariogenic bacteria, present in part of the samples, showed no metabolic activity. The use of ultrasound as a command set only slightly influenced the pattern of the entombed microflora.


1005 (116196)

Seven-Year Results of Alternative Treatments to Defective Amalgam Restorations. V.V. GORDAN, C.W. GARVAN, E. MONDRAGON, I. MJOR, and P. BLASER, University of Florida, Gainesville, FL

Objective: This prospective longitudinal cohort study assessed (1) the longevity of a group of defective amalgam restorations that were treated by either repair, sealant, refurbishing, or total replacement and (2) compared the longevity of these alternative treatments to replacement of restorations.

Methods: Thirty-five patients aged 21-77 (mean=55) years (20 female, 15 male) with 103 defective restorations which were independently diagnosed during treatment planning, participated in the study. Patients were assigned to five groups, repair (n=10), sealing of defective margins (n=23), refurbishing (n=23), replacement (n=22), and no-treatment (n=25) groups. A modified Ryge Criteria that included marginal adaptation, anatomy, contact, secondary caries, and sensitivity was used to evaluate the restorations at baseline, 6-month, one-, two-, and seven-year recall exams. Degradation in any of the criteria was considered a failure. A survival analysis was conducted using the LIFETEST procedure in SAS (version 9.1, Cary, N.C.).

Results: Eighty-three (81%) restorations were examined at one-year, 81 (79%) at two-year, and 47 (46%) at seven-year recall exams. The number of degradations observed over time for available cases were as follows: marginal adaptation (repair=1, sealing=9, refurbished=7, replacement=10, monitored=9); anatomy (repair=0, sealing=6, refurbished = 7, replacement=4, monitored=6); contact (repair=0, sealing=3, refurbished = 3, replacement=3, monitored=7); secondary caries (repair=0, sealing=0, refurbished = 1, replacement=1, monitored=3); and sensitivity (repair=0, sealing=0, refurbished=1, replacement=2, monitored=3). The survival estimates for each treatment were: repair (.667), sealing (.725), refurbishing (.356), replacement (.659), and no-treatment group (.569). The p-value for the log-rank test of equality over treatment groups was .2046 while the p-value of the Wilcoxon test was .1776.

Conclusions: The study showed that some degree of degradation of restorations occurred in all treatment groups after the 7-year recall exam. However, the survival estimates showed no differences among the various treatment groups and the replacement group.

This study was supported by UF-DSR research grant #01042678.


1006 (116284)

Clinical Evaluation Ndurance nano-dimer conversion technology dental composite. H. RITER, and S.S. LEE, Loma Linda University, Loma Linda, CA

A new low shrinkage, universal restorative composite material has been developed (Septodont, Louisville, CO) using a new dimer acid derived monomer as part of the comonomer system and a nanohybrid filler.

Objective: To evaluate the clinical performance of this material as an anterior restorative.  Materials and Methods:  Opti-Bond Solo total-etch (Kerr, Orange, CA) was used as the dental adhesive. Class III, IV, V, incisal edge repairs, diastema closures and direct veneer restorations were placed in anterior teeth.  With the IRB approval, a total of 40 restorations were placed in 23 patients.  Restorations were evaluated at two-week baseline period, 6 months and 1 year, and are planned to be recalled at 18 month and 2 years, with an optional evaluation at 3 and 4 years.  Restorations were evaluated for the following variables: Anatomic Form (AF), Color Match (CM), Marginal Adaptation (MA), Marginal Discoloration (MD), Surface Staining (SS), Retention (RT), Secondary Caries (SC), Fracture (FX) and Polishability (PL) using a modified USPHS evaluation system.  Results:  Results at one year indicated that all restorations  had excellent anatomic form, marginal adaptation, marginal discoloration, surface staining, retention, and secondary caries.  The following results are in percentages (%) at the one year evaluation.

                        AF       CM      MA      MD      SS       RT       SC      FX       PL

Alpha             100     94        100     100     100     100     100     94        88

Bravo             0          6          0          0          0          0          0          0          12

Charlie           0          0          0          0          0          0          0          6          0

Delta              0          0          0          0          0          0          0          0          0

None of the patients exhibited postoperative sensitivity or exaggerated gingival response.  In general, all the restorations were initially judged to be clinically satisfactory.  Conclusions:  The Ndurance composite produces good clinical results for anterior restorations at the one year evaluation with no postoperative sensitivity or gingival irritation. 

Sponsored by Septodont, Confi-Dental division


1007 (117989)

Clinical evaluation of a silorane restorative in class II cavities. A. SCHATTENBERG, S. STORCK, I. BUSEMANN, B. WILLERSHAUSEN, and C.-P. ERNST, Johannes Gutenberg University, Mainz, Germany

Objective: In this study the clinical performance of a new low-shrink Silorane-based filling material (Filtek Silorane) and a methycrylate-based composite (Grandio) was evaluated in class II restorations.

Methods: 37 patients (40.6 ± 13.1a) received at least one pair of class II restorations (n=102 in total) in a randomized way. Two comparable cavities were filled with either Filtek Silorane/ Silorane System Adhesive (3 M ESPE) or Grandio/ Futurabond NR (VOCO) according to manufacturers' instructions. After 12 months, restorations (n=97, 95% recall) and the clinical situation were evaluated (examiner-blinded) according to the new evaluation criteria of Hickel et al. (Clin Oral Investig 2007;11:5-33) establishing a new score-range of 1-5 (1-3 clinically acceptable, 4-5 clinically not acceptable). In addition enamel cracks were recorded. Statistical analysis was carried out with the Wilcoxon-test (Bonferroni adjustment).

Results: Scores (1/2/3/4/5) [%] were: Surface luster: Silorane (35/63/2/0/0), Grandio (16/80/4/0/0), Surface staining: Silorane (81/17/0/2/0), Grandio (86/14/0/0/0), Color stability/translucency: Silorane (29/54/17/0/0), Grandio (20/60/20/0/0), Anatomical form: Silorane (65/29/6/0/0), Grandio (57/43/0/0/0), Fractures and retention: Silorane (96/0/2/2/0), Grandio (98/2/0/0/0), Marginal adaptation: Silorane (50/48/2/0/0), Grandio (61/37/2/0/0), Wear: Silorane (52/44/4/0/0), Grandio (37/63/0/0/0), Contact point: Silorane (81/2/17/0/0), Grandio (86/2/12/0/0), Patients' view: Silorane (90/4/4/2/0), Grandio (94/4/2/0/0), hypersensitivity/tooth vitality: Silorane (92/2/6/0/0), Grandio (86/6/8/0/0), Tooth integrity: Silorane (48/44/8/0/0), Grandio (47/49/4/0/0), Periodontal response: Silorane (60/23/17/0/0), Grandio (49/24/27/0/0), Oral health: Silorane (79/17/4/0/0), Grandio (78/18/4/0/0). No recurrent caries was recorded in both groups. The enamel crack index was added up to 0,06 for the Silorane group and 0,07 for the Grandio group.

Conclusion: Both restoratives did not show any statistical significant differences in their clinical performance so far. Therefore, after one year, Filtek Silorane was found to be efficacious in clinical use.

This study was supported by 3M ESPE, Seefeld, Germany


1008 (117987)

Wear Resistance of Two Denture Tooth Materials in vivo. S. HEINTZE, Ivoclar Vivadent, Schaan, Liechtenstein, M. SCHMID-SCHWAP, Medical University of Vienna, University Clinic of Dentistry, Vienna, Austria, Vienna, Austria, I. GRUNERT, Universitaetsklinik fuer ZMK, Innsbruck, Austria, and E. PIEHSLINGER, Medical University of Vienna, Bernhard Gottlieb University Clinic of Dentistry, Vienna, Austria

Objective: To evaluate the clinical wear of two different denture tooth materials in two groups of subjects.

Material and Methods: Twenty-eight subjects received full dentures with two different materials at three centers. In center A (n=18, median age 64 years, 13 w, 5 m), the denture tooth material was based solely on PMMA with organic fillers (SR Postaris DCL, Ivoclar Vivadent, Liechtenstein). In centers B and C (n=10, median age 67.5 years, 3 w, 7 m) the denture material contained anorganic nanofillers (NFC, Candulor, Switzerland). At baseline and after 12 months impressions of the posterior teeth were poured with improved stone. After laser scanning (etkon es 1, Germany) the casts were superimposed and matched (Match 3D, etkon). Maximal vertical loss (µm) was calculated for each tooth type and subject by averaging the vertical loss of the buccal and oral wear facets of each posterior tooth and taking the maximal value of those. The data were logarithmically transformed to normalize their distribution.

Results: For the pooled data the mean vertical loss of the group with the composite material NFC was statistically significantly lower after 12 months than that of the group with the DCL material (ANOVA, p=0.013): median values NFC 150µm, DCL 253µm. The first molars showed statistically significant more wear than the first premolars in the DCL group (Wilcoxon test, p=0.03) whereas in the NFC group no such difference has been observed. The mean coefficient of variation was 27% for the NFC group and 60% for the DCL group.

Conclusions: The composite based denture tooth material NFC showed a statistically significant lower wear that the PMMA based DCL material after 12 months of service. The variability within the subject groups was substantially lower for the NFC compared to the DCL material.


1009 (119973)

In vivo analysis of enamel wear against ceramic materials. J. ESQUIVEL-UPSHAW1, W. ROSE2, E.R. OLIVEIRA, DDS2, and K.J. ANUSAVICE1, 1University of Florida, Gainesville, FL, 2Univ. of TX, HSC at San Antonio, San Antonio, TX

Objective: (1) To test the hypothesis that wear rates of ceramic are equivalent to the wear rates of their enamel antagonists; (2) To test the hypothesis that the wear rates of contralateral teeth are equivalent to the wear rates of ceramic crowns. Methods: Thirty six (36) teeth (from 31 patients selected) needing full coverage crowns were randomly assigned to receive either a metal-ceramic (D'Sign, Ivoclar, Vivadent) or an all-ceramic crown (IPS Empress2 or Eris EXC, Ivoclar, Vivadent). A single unit crown was fabricated from either one of two all-ceramic materials or a metal-ceramic material. A vinyl polysiloxane impression was made of the maxillary and mandibular arches to record the occlusal surfaces of the cemented crown, its antagonist tooth and its contralateral tooth, after one week, 1 year and 2 years, post cementation. Casts were poured in gypsum (GC Fujirock) and scanned using a 3D Laserscanner (Willytec, Germany). Maximum wear was calculated by superimposing the baseline one-week image with first and second year images. Results: The mean maximum wear rates for the ceramic crowns were 48.7±35.1 μm after year 1 and 58.8±36.5 μm for year 2. The mean maximum wear rates for the natural enamel antagonists were 54.9±23.6 μm for year 1 and 69.1±42.9 μm for the year 2. Teeth contralateral to the crowns exhibited a maximum wear of 42.4±23.4 μm maximum wear for the year 1 and 49.5±31.7 μm for year 2. One-way ANOVA (α = 0.05 ) revealed that there was no significant difference in the maximum wear rates between the ceramic crowns, their natural antagonists and their contralateral teeth. Conclusions: The new breed of ceramics is promising in that in vivo wear rates are within the range of normal enamel wear.

This study was supported by Ivoclar Vivadent.


1010 (118622)

The Clinical Longevity of Milled Bonded Pontics: 5-year results. R. KENNEDY1, J. KENNEDY1, D.C.N. CHAN2, R. CALLAN1, J. BLALOCK1, and W.D. BROWNING3, 1Medical College of Georgia, Augusta, GA, 2University of Washington, Seattle, WA, 3Indiana University School of Dentistry, Indianapolis, IN

Objectives: This five-year clinical trial compared clinical performance and retention in two groups of resin-bonded, fixed-partial dentures (RBFPD).  The treatment group, TG, received an all-porcelain (AP) RBFPD.  The control group, CG, received a metal framework (MF) RBFPD.  Retention was compared at the 5% significance level. Also, clinical performance was evaluated using modified Ryge criteria. 

Methods: A pre-existing group of 11AP RBFPDs was identified in a private practice.  A group of 5 MF RBFPDs was created.  Matching was on age and prosthesis location, mandibular or maxillary.  MF RBFPDs included tooth preparation; AP RBFPDs did not.  AP RBFPDs were milled from solid porcelain (Vitablocs Mark II).  At the baseline examination, the AP RBFPDs were one to two years old.  The CG restorations were new.  Partial or total loss of bond was considered failure.  Ryge criteria were modified by adding Alpha 2 (A2) and Bravo 2 (B2) ratings.  In the first year following the baseline exam, three of the five CG restorations but none of the 11 TG restorations debonded.  The difference was significant (Fischer's Exact Test; p = 0.018). 

Results: Baseline ratings for the abutment teeth were as follows:  For Color Alfa ratings for TG and CG respectively were 100% and 90%.  For Anatomic Form, Alfa ratings were TG 18% and CG 10%.  B2 ratings were TG 73% and CG 60%.   Five-year ratings:  For Color Alfa ratings for TG and CG respectively were 100% and 100%.  For Anatomic Form, Alfa ratings were TG 30% and CG 0%.  B2 ratings were 30% for TG and CG 0%.  The all-porcelain resin-bonded fixed-partial dentures exhibited superior retention compared to the resin-bonded, fixed-partial dentures. 

Conclusions: The all-porcelain resin-bonded fixed-partial dentures fabricated by a novel application exhibited superior retention when compared to the metal framework resin-bonded, fixed-partial dentures in five years. 


1011 (118702)

Soft tissue stability with zirconia abutments in the aesthetic zone. I. VOZZA, F. ZACCHEO, F. TEODORI, T. DI CARLO, and M. QUARANTA, Sapienza University of Rome, Rome, Italy

Aim: to evaluate the effect of zirconia abutments on soft tissues vertical stability at the facial aspect of dental implants. Methods: on 58 patients (30 women, 28 men, age range of 24 to 59 years, mean age 39 years, well-healthy and not smokers) 58 implants (Nobelreplace tapered groovy™, Nobel Biocare, Goteborg, Sweden) were placed in aesthetically demanding sites following 1-stage approach just after extraction. They were used Zirconia abutments (Procera, Nobel Biocare AB) and a provisional crown was placed at the same session while the definitive restoration after 2-4 months later. Endoral X-rays and digital photographs made perpendicularly to the facial aspect of the teeth were performed at the abutment placement, at 1, 3, 6 12, 18, 24 months and analysed by 2 different examiners. Vertical changes in soft tissue levels were measured and the definitive esthetic result was evaluated subjectively (poor to excellent). Results: vertical augmentation or no recession in soft tissue was observed in 88% of the situations and in no situation was recession greater than 0.6mm found. The gingival level remained stable at 12, 18, 24 months. The average esthetic outcome was rated as 4.5 (very good to excellent) on a 0- to 5-point scale. Conclusions: the abutments used in this study allowed soft tissue stability in the esthetic zone.


1012 (118775)

An Ormocer Restorative for Luting of Ceramic Inlays: Four-year Results. N. KRAMER, TU Dresden, Dresden, Germany, C. REINELT, Private Praxis, Nuremberg, Germany, A. PETSCHELT, University of Erlangen-Nuremberg, Erlangen, Germany, and R. FRANKENBERGER, University of Erlangen-Nuremberg, Erlangen Bavaria, Germany

Objective: The aim of the present study was to evaluate the ormocer Definite (Degudent) as resin luting cement.

Methods: In a controlled prospective clinical study, 57 Cergogold all-ceramic inlays (51 Class II inlays, 6 onlays; 35 premolars, 22 molars) were placed in 24 patients by four dentists. The restorations were luted with two different systems (MD = Definite Multibond + Definite; SV = Syntac + Variolink Ultra, Ivoclar Vivadent, Liechtenstein) without lining. At baseline, after 12, 24 and 48 months the ceramic restorations were examined according to modified USPHS codes and criteria.

Results: One patient including three restorations missed the four years recall (dropout). After 48 months of clinical service, two restorations had to be replaced due to chipping at the proximal ridge, and one due to tooth fracture at the occlusal margin, all other fillings were clinically acceptable (survival rate 93%; Kaplan-Meier algorithm). Except for the rate of hypersensitivity at baseline (MD: 27%; SV 0%; p<0.05), no differences were evident between the luting cements at all recalls (Mann-Whitney U-test; p>0.05). Between the four recalls (A baseline, B 1 year, C 2, and D 4 years) a statistically significant deterioration was detected for both groups [Alpha 1 / Alpha 2 / Bravo / Charlie] in %] regarding the criteria marginal adaptation (A 29/64/7/0; B 11/80/9/0; C 4/90/6/0; D 0/61/39/0), integrity filling A 96/4/0/0 B 87/9/4/0 C 77/8/15/0 D 37/31/30/2, and integrity tooth A 91/9/0/0 B 83/15/1/0 C 72/28/0/0 D 12/80/8/0 (Friedman test; p<0.001). After four years mainly, distinct deterioration with marginal fractures or chippings in proximal areas of the inlays were observed. No differences were found for the other criteria(p>0.05).

Conclusions: After four years of clinical service, both luting systems showed good clinical results and can be recommended to insert ceramic inlays. Supported by Degudent, Germany.


1013 (119437)

A Randomised 14-year Clinical Evaluation of 3 Ceramic Inlay Systems. M. MOLIN, Umea university, Umea, Sweden, and S. KARLSSON, Nordic Institute of Dental Materials (NIOM), Haslum, Norway

Objectives: To evaluate the clinical quality of three different ceramic inlay systems, 20 patients were treated with one Cerec, one Mirage and one Empress inlay respectively, inserted in a randomly selected order in the lower jaw. All patients were also treated with one gold inlay.

Methods: In total, 35 premolars and 45 molars were treated with inlays. The inlays were examined independently by two calibrated examiners immediately after luting, 1 year, 3 years, 5 years, 8 years and 14 years after luting.

The inlays were rated using the California Dental Association (CDA) quality evaluation system.

Results:A higher, but not statistically significant, survival rate was found for the gold inlays (85%) compared to the ceramic inlays (72.7 %). Gold inlays failed due to recurrent caries and to fractured tooth substance and ceramic inlays failed due to ceramic bulc fractures. The examination using the CDA-criteria showed an increased mismatch of color from 15% at baseline to 38% over 14 years. Inlays with slightly roughened surfaces increased from 0% to 62% over 14 years. A visible evidence of ditching along the margin increased from 5% to at most 92 % after 14 years. For the ceramic inlays an apparent discoloration of the margin between the tooth and the restoration increased from 0-5% at baseline to at most 80 %. Of the fractured ceramic inlays, 71 % had fractured after 5 years.

Conclusion: Gold inlays have a significantly higher survival rate over long periods of time compared to ceramic

inlays. Ceramic failures are related to fractures of the ceramic material, whereas failures of gold inlays are related to the surrounding tooth substance. The majority of fractures appear after 5 years. Based on the CDA- criteria

there was a significant deterioration from excellent conditions concerning surface texture and marginal adaptation.


1014 (120576)

Clinical Outcome of Posterior Fiber-reinforced Fixed Partial Dentures: 8-year Follow-up. A.S. MASOTTI1, M.S. CENCI1, P. RODOLPHO1, T. PEREIRA-CENCI1, A.A. DEL BEL CURY2, and F.F. DEMARCO1, 1Federal University of Pelotas, Pelotas, Brazil, 2Piracicaba Dental School - UNICAMP, Piracicaba, SP, Brazil

Objectives: Information on the longevity of fiber reinforced composite fixed partial dentures (FPDs) should be considered in the selection of materials, operative techniques and patient instructions related to prognosis and long-term cost-effectiveness. This study aimed to evaluate the long term survivals of fiber-reinforced adhesively bonded composite prostheses placed in posterior teeth. Methods: Patients that received adhesively bonded polyethylene FPDs in posterior teeth were selected from a private practice dental office and invited to evaluation. One dentist placed all FPDs using Ribbond as reinforcement and Tetric Ceram/Durafil or Charisma/Renamel-Micro composite combinations, according to manufacturer's instructions. Two independent calibrated operators performed the evaluation, using modified USPHS criteria. Survival functions of restorations were analyzed with Kaplan Meier and Log Rank test (a = .05) and displayed according to the variables material and teeth location. Results: The majority of restorations exhibited A or B scores for the USPHS criteria. Four FPDs fractured among the 22 FPDs evaluated. The mean estimate survival was 84 months (95% CI: 70.4 to 97.6). There were no differences between composites combinations or teeth location considering all clinical aspects evaluated and survival functions (p>0.05). Conclusion: The results of this study suggest that posterior fiber reinforced rehabilitation with the materials and techniques evaluated may be indicated for replacement of a single missing tooth in posterior region.


1015 (120690)

Clinical performance of fiber post restorations: 2-year results. M. FERRARI1, M. CAGIDIACO2, E. MAGNI1, M. CADENARO3, L. BRESCHI3, and C. GORACCI1, 1University of Siena, Siena, Italy, 2Association Odontology E. Cagidiaco, Livorno, Italy, 3University of Trieste, Trieste, Italy

Objectives: To evaluate the 2-year outcome of post-retained restorations of endodontically treated teeth. Methods: A consecutive sample of 45 patients was collected and 45 premolars (25 maxillary, 20 mandibular) were restored. RelyX Fiber posts (3M ESPE) were luted with RelyX Unicem (3M ESPE) following manufacturer's instructions. Filtek Flow (3M ESPE) was used to build-up the abutment, that was covered with an all-ceramic crown (Empress II, Ivoclar-Vivadent). Baseline factors such as tooth type and number of residual coronal walls were noted. After 23-25 months patients were recalled and two operators who had been previously calibrated separately performed a clinical and radiographic examination. The following events were considered as failures: post debonding, post fracture, root fracture, failure of the core portion requiring a new coronal restoration, displacement of the crown, endodontic and periradicular conditions requiring endodontic retreatment. Kaplan-Meier plots were constructed. The Cox regression analysis was applied to assess the influence of baseline factors on failure occurrence. Results: One patient could not be re-evaluated. Radiographic signs of periapical pathology were observed in 3 teeth, though symptoms were reported for only 1 of them. The 3 teeth showing periapical lesions also had the post debonded. Overall, 4 teeth with 2 residual coronal walls exhibited post debonding along with marginal leakage. All debonded posts were re-luted and the teeth were thus restored to function. The survival rate of post-retained restorations in this study was similar to the rates reported in previous clinical trials. The Cox regression analysis did not reveal any significant influence of baseline factors on failure occurrence. Conclusions: Restorations of endodontically treated premolars retained by fiber posts luted with a self-adhesive resin cement showed a satisfactory success rate after 2 years of clinical service. All the 4 recorded failures consisted of post debonding, while no irreparable failures such as root fracture occurred.


1016 (116687)

Gaps between filler and resin induced by polymerization shrinkage. L. FENG, and B.I. SUH, Bisco, Inc, Schaumburg, IL

Objective: Strong interactions between the resin matrix and the filler are essential for a dental composite to attain excellent physical properties. A gap present at their interface will undermine their interactions. This work investigated the effect of polymerization volumetric shrinkage on the formation of gaps.

Methods: A bis-GMA and TEGDMA blend plus photoinitiators was used as the resin matrix, into which 10 or 20 wt% non-silane-treated or silane-treated powders were added to make a lightly filled composite. The translucent composite was placed into a cavity (f6.4mm and 2.0mm deep) created by an aluminum ring and a polyester strip. The wall of aluminum ring was treated either with a silicone releasing agent for unrestricted polymerization shrinkage, or with a dental bonding agent for restricted shrinkage. After photocure, the formation of gap was assessed with light attenuation through the 2.0 mm thick sample disk. A lower intensity attenuated by the specimen suggested more gaps at the interface since more light was scattered by the mismatched refractive indices. SEM was used to verify the presence of gaps.

Results:

Measured light intensity (mW/cm2, n=4), attenuated from initial 500 mW/cm2 and analyzed with the t-test.

Filler (wt%)

Non-silane-treated

Silane-treated

Unrestricted

Restricted

Unrestricted

Restricted

Spherical 1 (20)

64(3) a

54(1)b

75(6) a

72(2) a

Spherical 2 (10)

118(6) a

91(6) b

147(4) a

110(10) b

Irregular 1 (10)

206(5) a

185(2) b

187(1) a

178(5) a

Irregular 2 (10)

202(5) a

192(2) b

208(4) a

208(2) a

Irregular 3 (10)

101(5) a

87(3) b

-

-

Conclusion: Restricted volumetric shrinkage created gaps between filler and resin matrix while free shrinkage did not. Good silane treatment on filler can prevent the gap formation by strengthening the filler-resin interaction.


1017 (117087)

Effects of solvent on photocuring of dental bonding agents (DBAs). J. ALCANTAR, L. FENG, B.I. SUH, and D. BROWN, Bisco, Inc, Schaumburg, IL

Objective: Insufficient cure of dental bonding agents undermines many of their properties and therefore needs be prevented. The present work investigated the effect of residual solvent on the rate of photocure.

Methods: Four DBAs were tested, including One-Step (OS, Bisco), Xeno III (XN, Dentsply), OptiBond FL (OB, Kerr), and Clearfil Protect Bond (PB, Kuraray). OS and XN contained solvents, which were either mostly retained or evaporated before curing. All the DBAs were photocured with a halogen light of 50 mW/cm2 in nitrogen. The rate of curing was assessed with differential scanning calorimetry (DSC) by measuring the heat of polymerization. To compare among the DBAs, a scaled degree of conversion (SDC) was used, which was defined as the ratio of the exotherm at a given time vs. that at 300s cutoff time.

Results:

DBA

Solvent, %

Irradiation time, s

SDC, %

20s

40s

60s

120s

OS

> 20

120

14

37

58

94

XN

> 20

120

4

15

27

60

 

OS

< 5

30

51

86

94

97

XN

< 5

30

34

79

91

95

OB

0

30

66

94

98

99

PB

0

30

52

91

97

99

The DBAs with solvent cured much more slowly than those without, even much longer irradiation did not significantly increase the rate.

Conclusion: The presence of residual solvent in a DBA could substantially reduce its rate of cure. It is essential to remove the solvent as much as possible to ensure an adequate conversion.


1018 (120979)

Synthesis of Silicon Containing Monomers. B.D. MILLER1, J.A. BURNESON2, R.A. WEILER1, and K.V. KILWAY3, 1University of Missouri -Kansas City, Kansas City, MO, 2University of Missouri -Kansas City, Kansas City, 3University of Missouri- Kansas City, Kansas City, MO

Silicon-based-epoxy resins (siloranes) have been identified as key targets for use in cationically-cured composites. The monomers, bis[2-(3{7-oxabicyclo[4.1.0]heptyl})-ethyl]methylphenyl silane (PHEPSI)1 and 2,4,6,8-tetrakis(2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl)-2,4,6,8-tetramethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane (CYGEP),2 have been selected as our initial targets for such systems. Objectives: We will develop and optimize the synthesis of relevant silorane monomers for use in the healthcare field.

Methods: PHEPSI was synthesized by heating solution of 4-vinyl-1-cyclohexene-1,2-epoxide, methylphenylsilane, toluene, and Wilkinson's catalyst to 100°C for 24h. Column chromatography was used (silica gel; solvent, 90:10 hexane:ethyl acetate) to isolate PHEPSI. CYGEP was synthesized by refluxing solution of 4-vinyl-1-cyclohexene-1,2-epoxide, 2,4,6,8-tetramethylcyclotetrasiloxane, and toluene with a Dean-Stark trap for 2h, then cooled (5-9°C). After Lamoreaux's catalyst3 (1 drop) was added, resulting mixture was allowed to warm to room temperature (17h). Column chromatography (silica gel; solvent gradient,hexanes,90:10,80:20,ethyl acetate) was used to isolate CYGEP. Extent of reaction monitored by IR spectroscopy for disappearance of Si-H peaks for PHEPSI and CYGEP (2160 and 2100cm-1), respectively. Excess ethyl acetate removed via vacuum for both monomers. Results: Disappearance of Si-H peaks indicated completion of reactions. After purification, PHEPSI isolated in average yield (41%) as confirmed by 1H-and 13C-NMR spectroscopy. Addition of the catalyst to the resulting mixture below 5°C resulted in polymerization of solution to a gel, due to the freezing of toluene and temps above 9°C due to activation of the catalyst. After purification, CYGEP was isolated in average yield (61%) as confirmed by NMR spectroscopy. Conclusion: Two silorane monomers of interest were reproducably synthesized using modified procedures. This work was supported in part by NIH/NIDCR Grant R21 DE018336, NIH/NIDCR T32 (DE07294), and Missouri Life Science Research Board Grant (#13234-2007). 1. J.V. Crivello and D. Bi, J. Poly. Sci.: Part A: Poly Chem. 1994,32,683-697. 2. J.V. Crivello and J. L. Lee, J. Poly Sci.: Part A: Poly Chem. 1990,28,479-503.

3. H. F. Lamoreaux,U.S. Patent 3,220,972,1965.


1019 (115619)

An Improved Photo-initiator System for Dental Composites. H. SHAH, J. VAIDYANATHAN, and T.K. VAIDYANATHAN, New Jersey Dental School, Newark, NJ

Objective: While significant improvement has been made over the past several years, inefficient polymerization and in-vivo discoloration in composites remain a challenge. Most of the commercially available composites comprise of camphorquinone (CQ) and ethyl-4-dimethylaminobenzoate (EDMA) as photo-initiator system. The objective of this research is to use diphenyl phosphine oxide (DPO) for possible dental applications.
Materials: Ethoxylated-bisGMA (BisEMA), triethyleneglycol dimethacrylate (TEGDMA), CQ, EDMA and DPO were obtained from Sigma-Aldrich, USA.
Methods: To compare the two Photo-initiator systems, 1% CQ-EDMA and 1% DPO were added in BisEMA, BisEMA-TEGDMA mixture (50:50 by weight) and TEGDMA. These six combinations were subjected to isothermal (37°C) photo-polymerization in a DSC to measure heat of cure. ATR-FTIR spectra were also obtained for BisEMA-TEGDM mixture before and after curing to measure %conversion. CIE L*a*b* values were measured by Chroma-Meter before and after UV (24hr) and humidity (37°C) exposure (24-hr, 15 and 30-days). Curing for all the samples was carried for 30-sec at 300-MW/cm2.
Results: Mean heat of cure for BisEMA, BisEMA-TEGDMA and TEGDMA with CQ were 62.8, 66.3 and 56.4kJ/mol, while 58.2, 71.0 and 77.0-kJ/mol with DPO respectively (p<0.03). Mean %conversion for BisEMA-TEGDM with CQ was 69.8 and 76.6% with DPO (p<0.0095). Analysis of exotherms in DSC and %conversion measurements indicated that DPO significantly accelerated the curing and enhanced the overall curing by 30-sec light cure vis-à-vis CQ. ΔE≤3 (p<0.0095) for the DPO samples corresponded to its improved color stability of cured composite when exposed to both water as well as to UV light.
Conclusion: Recent studies have demonstrated that Bisphenol A can cause xenoestrogenic effect and TEGDMA may promote the proliferation of cariogenic microorganisms like Lactobacillus acidophilus and Streptococcus sobrinus. The use of DPO as photo-initiator can limit these adverse effects by increasing %conversion in composite. Polymerization using DPO initiator also confers improved color stability.


1020 (116193)

Physical Characteristics of a Self-Healing Dental Composite. S. GROSS, M. LATTA, B. WERTZBERGER, and J. STEERE, Creighton University, Omaha, NE

Purpose: The objective of this study was to investigate the physical properties of a model dental compound formulated to autonomically heal cracks.  Methods: A visible light cured model resin consisting of TEGMA:UDMA:BisGMA (1:1:1) at 45% w/w with 0.7 µ silanated glass was formulated with a self-healing system consisting of encapsulated dicyclopentadiene spheres and Grubb's metathesis catalyst. The base resin was also formulated with the spheres and Grubb's catalyst alone. Fracture toughness (KIc) was assessed using a single edge notch specimen (2.5mm (B) x 5 mm (W) x 25 mm; a/w=0.5) in 3-point bend (n=12). Data was analyzed with ANOVA/Tukey's at p ≤ 0.05. Dynamic mechanical analysis (DMA) was performed from -150 ºC to 250 ºC at 1 degree/min and 1 Hz. Storage and loss modulus, glass transition temperature and tangent of delta was recorded for each material.

Results:

Sample

E' 109

E” 108

Tg

Tan Delta

K1c

Control

6.7

3.5

137

0.2342

1.21 ± 0.09

Spheres

5.1

3.1

125

0.2493

1.30 ± 0.07

Grubbs

7.7

4.2

131

0.2289

1.53 ± 0.17

Spheres+Grubbs

4.1

2.5

126

0.2460

1.10 ± 0.06

The self-healing material was loaded to failure for 24 hours and loaded a second time to failure. These specimens had a K1c of 0.68± 0.07 for a 65% recovery rate or the original fracture toughness. The modulus and fracture toughness of the self healing material statistically similar (p>0.05) to the control and the tan delta suggests no real loss of the material's ability to absorb energy by damping.

           

Conclusion: The self healing capability of a dental material was explored. Autonomic healing was demonstrated with a model dental composite and DMA data suggest favorable properties compared to a control material.   This study was supported by the Health Future Foundation. All materials were provided by Esstech, Kennsington PA.


1021 (116324)

Effect of photoinitiators on dynamic mechanical properties of dentin adhesives. J. PARK1, Q. YE1, E. TOPP2, A. MISRA1, and P. SPENCER1, 1University of Kansas, Bioengineering Research Center, Lawrence, KS, 2University of Kansas, School of Pharmacy, Lawrence, KS

Effective bonding at the prepared tooth/composite material interface requires dentin adhesives that provide superior properties and rapid polymerization under clinical conditions.  The reactivity and the mechanical behavior are influenced by the photoinitiator system and curing conditions. Objective: The aim of this study was to determine the effect of photoinitiator systems on dynamic mechanical properties of dentin adhesives. Methods: The adhesive formulation: HEMA, bisGMA 45/55 w/w was cured in the presence of 0 (A0), 8 (A8) and 16 (A16) wt% H2O to simulate wet bonding. The photoinitiators were: camphorquinone (CQ) as a photosensitizer, 2-(dimethylamin)ethyl methacrylate (DMAEMA) and ethyl-4-(dimethylamino)benzoate (EDMAB) as co-initiator and diphenyliodonium hexafluorophosphate (DPIHP). Beam specimens (1x1x11 mm3) were used for measurement of dynamic mechanical properties (TA Instruments Q800) and degree of conversion (LabRAM ARAMIS Raman spectrometer). The adhesives were cured for 40 s at 25°C with commercial visible-light, (Spectrum® 800, Dentsply, Milford, DE, USA), Intensity=550 mW cm-2. Results:DC ranged from 75-97% increasing w H2O content. The CQ/DMAEMA system was gel-like in H2O, but DPIHP addition led to comparable rubbery moduli in all systems regardless of water content. Tg-oC and storage moduli in the rubbery region (Er'-MPa):

Formulation

Initiator

0% H2O (SD)

8% H2O (SD)

16% H2O (SD)

Tg

Er'

Tg

Er'

Tg

Er'

F1

CQ/ DMAEMA

139 (1.1)

23.2 (0.8)

-

-

-

-

F2

CQ/ EDMAB

143 (2.2)

22.5 (1.1)

138 (3.1)

19.5 (1.4)

130 (1.0)

13.8 (0.7)

F3

CQ/ DMAEMA/DPIHP

152 (0.2)

25.2 (1.7)

151 (2.1)

27.6 (2.1)

155 (1.6)

23.3 (1.2)

F4

CQ/ EDMAB / DPIHP

150 (0.4)

28.6 (0.7)

156 (2.8)

33.0 (1.1)

159 (1.7)

38.9 (1.6)

Conclusions: The addition of DPIHP to either the CQ/EDMAB or the CQ/DMAEMA photoinitiator system improved the polymerization conversion, Tg and rubbery moduli of the polymer networks formulated in water to simulate wet bonding.   Supported NIH/NIDCR R01-DE014392.


1022 (117553)

Polymerization Kinetics of Experimental Resins: Effect of Composition and Light-Curing. R.C.B. ALONSO1, W.C. BRANDT2, R.R. MORAES3, L.G. CUNHA4, R.M. PUPPIN-RONTANI2, and M.A.C. SINHORETI5, 1University of Campinas - UNICAMP, Piracicaba, Brazil, 2State University of Campinas, Piracicaba - SP, Brazil, 3State University of Campinas, Piracicaba, Brazil, 4University of Taubaté - UNITAU, Taubaté, Brazil, 5State University of Campinas, Piracicaba -SP, Brazil

Objectives: The aim of this study was to evaluate the effect of the resin matrix and photoinitiator type on polymerization kinetics, conversion rate and degree of conversion (DC) of experimental resins photocured using LED and halogen (QTH) light curing units (LCU). Spectrum and intensity of the light of the LCU were also evaluated. Methods: Experimental resins containing 50wt% BisGMA and 50wt% TEGDMA (BT) or 29wt% BisGMA, 32wt% BisEMA, 32wt% UDMA and 7wt% TEGDMA (BBUT) were prepared in combination with the photoinitiators: CQ (Camphorquinone), PPD (1-Phenil-1,2-Propanodione) or both (CP). Photoactivation was performed using the LCUs XL3000 (QTH) and Radii (LED). A power meter and a spectrometer (USB 2000) were used to analyze total irradiance and wavelength spectrum distribution. Absorption curves of CQ and PPD were evaluated using a spectrometer (Varian Cary 5G). Real-time Fourier transform infrared spectroscopy (Shimadzu Prestige21) was used to assess the polymerization reaction over time (50s). Data were plotted, and Hill's three-parameter nonlinear regression was performed for curve fitting. DC at each second was calculated and curves DC x time were obtained. Results: Polymerization kinetics is significantly affected by all factors (LCU, resin matrix and photoinitiator). The matrix BBUT, photoinitiator CQ and LCU QTH produced higher polymerization speed. The combination BBUT/CQ showed higher conversion rate, it showed DC of 42% after 20s of photoactivation whereas BT/PPD after 20s showed DC of 24%. After 50s, the highest final values of DC were observed in the resins BT/CQ (56%) and BBUT/CQ (52%) and the lowest values were observed in the resins BT/CP (40%) and BT/PPD (43%) Conclusion: The resin matrix and the photoinitiator type interfere in the polymerization kinetics of resin materials. The composition is determinant on the conversion rate and DC. Polymerization speed of resins is reduced when they are activated using LED LCU.


1024 (117763)

Effect of Radical-amplified Photopolymerization Initiator System for Resin Composite. T. SUZUKI, H. AKIZUMI, C. TORIYABE, M. OGURI, and H. KAZAMA, Tokuyama Dental Corporation, Tsukuba-city, Japan

Objective: The purpose of this study was to evaluate the polymerization activity of a new photopolymerization initiator system; radical-amplified photopolymerization initiator (RAP) system.

Methods: Two types of resin composites (universal type and flowable type) using RAP technology were prepared and compared with those of the conventional photopolymerization initiator system, namely camphorquinone/ amine(CQ/amine). Polymerization activity was evaluated by means of Vickers hardness (VHN) and residual monomer amounts (RMA) with two different irradiation times (10 and 30 seconds). VHN was measured at the top surfaces of specimens (7-mm diameter and 1-mm thickness) polymerized in PTFE(Polytetrafluoroethylene) molds using halogen light (Optilux LCT), using a hardness tester (Matsuzawa seiki, MHT-1). RMA was measured by HPLC analysis of tetrahydrofuran-extracted moietis from grinded specimens (10-mm diameter and 0.5-mm thickness) polymerized in PTFE (Polytetrafluoroethylene) molds using said halogen light, using HPLC ( JASCO MD-2010-PLUS).

Results: The results of the VHN and RMA measurements are listed below.

Type of resin composite

Initiator system

VHN

RMA

10 sec

irradiation

30 sec

irradiation

10 sec

irradiation

30 sec

irradiation

Universal

RAP

43

47

14%

8%

CQ/amine

32

41

25%

19%

Flowable

RAP

37

42

5%

3%

CQ/amine

13

20

22%

16%

Conclusions: RAP system showed high activity and the resin composite was cured in high degree within a short curing time using the new initiator system.


1025 (117788)

A Newly Developed Dual-cured Adhesive System Containing a Borate Derivative. K. OKISHIO, K. FUJINAMI, A. DODOMI, H. GYAKUSHI, Y. AKAMATSU, and H. KAZAMA, Tokuyama Dental Corporation, Tsukuba-city, Japan

Objectives: Dual cured composite resin core build-up material requires the use of a dual cured or self cured adhesive. We developed a new dual cured adhesive containing a borate derivative that enhances bonding to teeth substrate. The purpose of this study is to evaluate the tensile bond strength of a dual cured resin core material to dentin using a newly developed dual cured adhesive system.

Methods: Dual cured resin composite was bonded to bovine tooth which were ground with 600-grit SiC paper under running water to expose the dentin surfaces using three different adhesives; DBO: dual cured adhesive containing a borate derivative, DBP: dual cured adhesive containing a benzoyl peroxide (BPO), DC: adhesive containing no self cure initiator. Samples treated with light irradiation (Light cure mode) or chemically cured (Self cure mode). The tensile bond strengths of the samples were measured after immersion in water at 37oC for one day.

Results: The results are shown in the table. The bond strength of the sample treated by the newly developed adhesive containing borate as an initiator (DBO) was significantly higher than DBP and DC.

Adhesive

Tensile bond strength / MPa(SD)

Light cure mode

Self cure mode

DBO

25.3 (1.6)

21.3 (1.9)

DBP

21.5 (6.9)

3.5 (1.0)

DC

20.4 (7.0)

0.0 (0)

Conclusion: The borate derivative greatly improves the adhesive ability of the self cure mode of the dual cured adhesive.


1026 (117803)

Evaluation of Newly Developed PMMA Based Adhesive Resin Cement. K. HIRATA, Y. HAMASUNA, M. KIMURA, and H. KAZAMA, Tokuyama Dental Corporation, Tsukuba-city, Japan

Objectives: We have developed the PMMA based adhesive resin cement, called TOKUYAMA MULTIBONDII (MBII). It consists of one liquid based on MMA, two shade powders based on PMMA and one bottle self-etching primer. The borate derivative is used as the chemical polymerization initiator system in MBII. The purpose of this study was to evaluate the tensile bond strength (TBS), tenacity and color change of MBII.

Methods: MBII, TOKUYAMA M-bond (TMB) (Tokuyama Dental Corp.) and C&B-Metabond (CBM) (Sun Medical) were used in this study. TBS; the surfaces of bovine dentin (n=8) were ground (600-grit), bonded to stainless steel rods according to manufacturers' instructions, stored in distilled water (37°C, 24hours), thermo-cycled (10,000 times, between 4°C and 60°C). TBS was measured using a universal testing machine (UTM) (cross-head speed 2.0mm/min). Flexural tests; each cement was cured in the Teflon mold (25mm x 2mm x 2mm) (37°C, 60min), stored in distilled water (37°C, 24hours), polished (1500-grit). Energy (tenacity) at the breaking point or 5.5mm displacement was calculated by three point flexural tests using a UTM (cross-head speed of 1.0mm/min). Color change (Δ b*) of cured cement stored in distilled water (37°C, one year) was analyzed using automatic color analyzer.

Results: After 10,000 thermo-cycles, TBS using MBII, TBM and CBM were 19.1±3.5MPa, 16.0±3.0MPa and 12.9±3.9MPa respectively. Energy of MBII and CBM at 5.5mm displacement was 96.6±4.6mJ and 77.6±4.0mJ respectively and those of TMB at the breaking point was 5.7±1.2mJ. Δ b* of MBII, TMB and CBM were 2.3, 10.3 and 0.5 respectively.

Conclusion: Because of the chemical polymerization initiator system (borate derivative), TBS, tenacity and color of MBII were satisfactory.


1027 (118624)

Fluoride-releasing dental composites reinforced with zirconia-silica ceramic nanofibers. G. GUO, J. YUAN, Y. WANG, Y. FAN, J. HAGAN, J.P. BENNETT, and X. XU, Louisiana State University, New Orleans, LA

Objective: To prepare dense zirconia-silica ceramic nanofibers and to study their reinforcement effects on fluoride-releasing dental composites. Method: Zirconia-silica nanofibers were prepared by a reactive sol-gel electrospinning method using a mixture of zirconia/silica (80/20) sols prepared by hydrolysis of zirconium propoxide and tetraethyl orthosilicate (TEOS), respectively. As-prepared gel nanofibers were dried and calcinated. The resulting ceramic nanofibers (100-200 nm) were treated with silane before mixing with the fillers. Nine groups of experimental composites (n=10) were formulated using 70 wt% F-releasing glass filler (mean 0.8µm, Caulk/Dentsply), part of which (0, 2.5% or 5%) were replaced by nanofibers, and 30 wt% monomers (BisGMA:EBPADMA:HDDMA 40:40:20; or for fluoride-releasing composites: BisGMA:EBPADMA:HDDMA:F-releasing-monomer 30:30:20:20). The specimens were prepared by either heat-cure (1%BPO, 100oC for 2 hrs) or light-cure (Optilux 501, 80s each in three segments) in 2×2×25mm stainless steel molds. The specimens were tested on Instron 5566 testing machine (crosshead speed 1 mm/min) for flexure strength, flexure modulus and energy at break after they were stored in 37°C deionized water for 24h. Fluoride release from some light-cured composites was also measured. The data were analyzed using ANOVA and Tukey's B tests.

 

Results: (mean ± SD)

Composites

Nanofiber Content (wt%)

Flexure strength (MPa)

Flexure Modulus (GPa)

Energy at break (mJ)

Heat-cured

Control-1

0

104.2±14.8b

8.55±0.64c

7.33±2.57b

Exp-1

2.5

128.2±22.3a

9.08±0.59b,c

10.7±4.08a

Exp-2

5

122.7±27.3a

8.93±0.57b,c

9.71±3.56a

Light-cured

Control-2

0

102.6±9.4b

8.43±0.32c

8.15±1.76b

Exp-3

2.5

142.7±17.1a

9.59±0.7a,b

11.9±2.61a

Exp-4

5

137.7±21.0

10.07±0.63a

10.84±3.67a

Light-cured            F-releasing composites

Control-3

0

91.4±13.8c

8.42±1.02c

5.18±1.55b

Exp-5

2.5

126.8±16.1a

9.83±0.71a,b

8.41±2.16a,b

Exp-6

5

126.3±17.2a

9.87±0.61a,b

7.56±3.47b

The groups with the same superscript letters have no significant difference (p>0.05)

Conclusion: zirconia-silica ceramic nanofibers were successfully prepared. Incorporation of 2.5wt% zirconia-silica ceramic nanofibers can significantly increase the mechanical properties of fluoride-releasing composites. Sponsored by NIH/NIDCR grant 1R21DE18349.


1028 (119936)

Water sorption/solubility and percent conversion of acetone-solvated adhesives. J. ZANON-MALACARNE1, A. ANIDO-ANIDO2, D.H. PASHLEY3, K. AGEE3, M. DE GOES4, H.R. LEWGOY5, R. AMORE5, and M.R.O. CARRILHO6, 1University of Campinas/ Piracicaba School of Dentistry, Piracicaba, Sao Paulo, Brazil, 2Bandeirante University of Sao Paulo, Sao Paulo, Brazil, 3Medical College of Georgia, Augusta, GA, 4UNICAMP-Faculdade De Odontologia De Piracicaba, Piracicaba, Brazil, 5Universidade Bandeirante de São Paulo, São Paulo, Brazil, 6University of Campinas/FOP and Bandeirante University/UNIBAN, Sao Paulo, Brazil

Objectives: This study evaluated the kinetics of water diffusion and percent conversion in neat versus acetone-solvated resins that were formulated to be used as dental bonding agents.

 

Methods: Five methacrylate-based resins (R1, R2, R3, R4 and R5) of known hydrophilicities were used as reference materials. These resins were evaluated as neat bonding agents (100% resin) or they were solvated with absolute acetone (95% resin/5% acetone or 85% resin/15% acetone). Specimens were prepared by dispensing the uncured resin into a circular brass mold (5.8 mm x 0.8 mm). Photo-activation was performed for 80 s. The water sorption/diffusion/solubility measurements were made gravimetrically, while the degree of conversion (DC) was calculated by infrared spectroscopy.

 

Results: Water sorption/diffusion increased with the hydrophilicity of the resin blends. In general, the acetone-solvated resins exhibited significantly higher water sorption, solubility and water diffusion coefficients when compared to their corresponding neat versions (p<0.05). The only exception was resin R1, the least hydrophilic resin, in which neat and acetone-solvated versions exhibited similar water sorption (p>0.05). Addition of acetone increased the DC of all tested resins, especially of the least hydrophilic, resins R1 and R2 (p<0.05). Despite of the increased DC of acetone–solvated methacrylate-based resins, it occurs at the expense of an increasing in their water sorption/diffusion and solubility values.

 

Conclusions: Negative effect of residual acetone on water sorption/diffusion was more critical for the most hydrophilic resin blends.

 


1029 (120892)

Investigation of the Chemical Cationic Polymerization of a Silorane Resin. R.A. WEILER, D. SYLVESTER, K. HENDRICKS, J.D. EICK, and K.V. KILWAY, University of Missouri -Kansas City, Kansas City, MO

There are two different initiation systems for cationically-cured resins, photoinitiated and chemical. The former requires irradiation of a light, which in some cases such as dental lamp cases bone and cell damage.

Objective: The objective of this work is to investigate a number of chemical cationic initiation systems for a mixture of SilMix® (3M ESPE), 50:50 bis[2-(3{7-oxabicyclo[4.1.0]heptyl})-ethyl]methylphenyl silane and 2,4,6,8-tetrakis(2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl)-2,4,6,8-tetramethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane.

Methods: The general procedure was as follows. Approximately, SilMix (1 g) and the acid catalyst were combined in a planetary mixer and mixed for 5 minutes. After which, the material was placed on a microscope slide and tested for hardness after 15 minutes using a Gillmore needle (one pound for pass/fail). Tests were continued for 30 minutes, 1 hour, 24 hours, and 48 hours.

Results: A total of fourteen acids were used at varying concentrations. Hydrochloric (2, 5, 10, 14, and 18 wt%), sulfuric (8 wt%), pentafluoropropionic (4, 15, and 18 wt %), acetic (5 wt %), triflic (2 and 4 wt%), p-toluenesulfonic (11.5 wt%), hydroiodic (6 wt%), trichloroacetic (9 wt%), hydrobromic (7.5 wt%), and trifluoroacetic (7 wt%) acid failed in all cases. Typical Lewis acids such as aluminum chloride (13 wt%) and tin (IV) chloride (7.4 wt%) also failed even after 48 hours. The only acid that passed the Gillmore needle test at all listed concentrations was hexafluorophosphoric acid (2.5, 4, 4.6, and 5 wt%). The amount of acid increased the rate of reaction (i.e., fifteen minutes for 4.6 and 5 wt%; thirty minutes for 2.5 and 4 wt%). The consistency of the polymerized material varied depending on the wt % of hexafluorophosphoric acid catalyst.

Conclusion: It was found that SilMix was able to be chemically-cured.

This work was supported in part by NIH/NIDCR Grant R21 DE018336, NIH/NIDCR T32 (DE07294), and Missouri Life Science Research Board Grant (#13234-2007).


1030 (121037)

The Study of the Stability and Decomposition of Bis[2-(3{7-oxabicyclo[4.1.0]heptyl})ethyl]methylphenyl silane. J.A. BURNESON, University of Missouri -Kansas City, Kansas City, B.D. MILLER, University of Missouri -Kansas City, Kansas City, MO, and K.V. KILWAY, University of Missouri- Kansas City, Kansas City, MO

This investigation is on the stability and decomposition of an interesting monomer, bis[2-(3{7-oxabicyclo[4.1.0]heptyl})ethyl]methylphenyl silane.

Objectives: The objective of this identification is to identify the decomposition products using standard identification techniques.

Methods: Bis[2-(3{7-oxabicyclo[4.1.0]heptyl})ethyl]methylphenyl silane was synthesized by heating solution of 4-vinyl-1-cyclohexene 1,2-epoxide, methylphenylsilane, toluene, and Wilkinson's catalyst to 100 °C for 24 h using a modified procedure of Crivello.1 The reaction was monitored for completion by IR spectroscopy for disappearance of the Si-H peak at 2160 cm-1. Column chromatography was used (silica gel; solvent, 90:10 hexane:ethyl acetate), followed by removal of the solvent under vacuum to isolate pure product (41% yield).

Results: Even though the product was kept at 0 °C and under argon, new peaks in the 1H NMR spectrum were observed. These peaks increase with respect to time, and the decomposition products can be removed using column chromatography as described previously. When the pure bis[2-(3{7-oxabicyclo[4.1.0]heptyl})ethyl]methylphenyl silane is mixed in equal proportions with 2,4,6,8-tetrakis(2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl)-2,4,6,8-tetramethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane, the material is stable for over two weeks. The degradation products will be further elucidated using NMR spectroscopy as well as other standard identification techniques.

Conclusion: It was found that bis[2-(3{7-oxabicyclo[4.1.0]heptyl})ethyl]methylphenyl silane is not stable even with the exclusion of light and air. It is only stable for no more than four days. When mixed in equal proportions of 2,4,6,8-tetrakis(2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl)-2,4,6,8-tetramethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane, the mixture is stable for over two weeks.

This work was supported in part by NIH/NIDCR Grant R21 DE018336, NIH/NIDCR T32 (DE07294), and Missouri Life Science Research Board Grant (#13234-2007).

1. J.V. Crivello and D. Bi, J. Poly. Sci.: Part A: Poly Chem. 1994, 32, 683-697.


1031 (120680)

Fracture Toughness of resin-modified glass ionomer with silica nanofibers. C. MCENTIRE1, A. SWARN2, D. CAKIR1, X. XU3, and J.O. BURGESS1, 1UAB School of Dentistry, Birmingham, AL, 2University of Alabama at Birmingham, Birmingham, AL, 3Louisiana State University, New Orleans, LA

Glass ionomer restorations frequently fracture and chip during clinical use.

Objectives: To measure the fracture toughness of a resin-modified glass ionomer (RMGI) with different nanofiber additions.

Methods: Silica nanofibers were fabricated using an electrospin technology and substituted for a percentage of the powder in an encapsulated RMGI. Three groups were created by replacing aluminosilicate powder with 5 or 10% by weight  silanated nanofibers or 5% by weight of the unsilanated nanofibers (negative control). 0, 5 or 10% weight fractions of the RMGI powder were removed from the capsule and replaced with an equal weight of nanofiber. Each capsule was mixed at 4000 CPM for 10 seconds.  The mixed materials were light-cured (Coltolux LED: 858.5±43.2 mW/cm2) in a 2x2x25mm Teflon mold with a 1mm notch at the midline for 20 seconds at 3 overlapping points on each exposed surface, while pressed between glass slides. All specimens were stored in deionized water at room temperature for 24 hours. Peak failure load was measured by placing the specimen, notch side down, on a 3 point bend fixture in an Instron 5565 with a crosshead speed of .1mm/min. Fracture toughness was calculated as Kic determined using the following equation: Kic = PLf(x)/(bw^1.5). Particle size analysis (mean .4 um) and scanning electron micrographs showed aglomerization of the “A” nanofibers. “B” nanofibers did not. ANOVA and Tukey B tests determined intergroup differences. 

Results:

 

% Fiber

0%

 

5% Unsilantated

5% Silanated

A*

10% Silanated

A*

10% Silanated

B*

n

10

4

5

4

6

Kic (MN/m3/2)

1.2±0.1

1.03±0.1

1.23±0.1

1.31±0.05

1.43±0.05

Nanofibers in groups A* and B* underwent varying silane treatments.

Conclusion:   Adding 10% silanated nanofibers significantly increased the fracture toughness of a RMGI (p<.05).  Improved mechanical and possible clinical benefits may result from incorporating nanofibers into RMGI.

Acknowledgements: NIDCR T32DE017607 Dental Academic Research Training Program.


1032 (114698)

Effects of N-vinylcaprolactam containing polyacids on fracture toughness of GICs. A. MOSHAVERINIA1, F. ZHENG1, N. ROOHPOUR2, S. ANSARI1, and S. SCHRICKER1, 1Ohio State University, Columbus, OH, 2Queen Mary University of London, London, United Kingdom

Objectives: This study investigates the effect of N-Vinylcaprolactam (NVC) containing terpolymers on the fracture toughness and flexural strength of conventional GIC.

Methods: A terpolymer of acrylic acid (AA) - itaconic acid (IA) – N-vinylcaprolactam (NVC) with 8:1:1 (AA:IA:NVC) molar ratio was synthesized by free radical polymerization and characterized using 1H-NMR, FTIR. The experimental GIC samples were made from a 50% solution of the synthesized terpolymer with Fuji IX powder in a 3.6: 1 P/L ratio. Specimens were mixed and fabricated in room temperature, based on the manufacturer instruction. Plane strain fracture toughness (KIc) was measured in accordance with ASTM Standard 399-05.33. Minicompact specimens with a precrack were formulated. Biaxial flexural strength test was conducted using disc shaped samples with 10 mm diameter and 1 mm thickness. The specimens were conditioned in distilled water at 37oC for one week (N=7). Fracture toughness and flexural strength testing were conducted on a screw-driven universal testing machine using a cross speed rate of 0.5 mm/min. The mechanical strength values were evaluated and compared with the control group (Fuji IX GIC). The mean data obtained was subjected to one way analysis of variance (ANOVA) at α = 0.05.

Results: NVC modified GIC exhibited significantly higher fracture toughness and flexural strength in comparison to commercially available Fuji IX GIC. Results are summarized in the following table.

GIC Group

Fracture Toughness (MPa*m1/2)

Biaxial Flexural Strength (MPa)

Control Group (Fuji IX)

0.47 ± 0.09

41.3 ± 10.5

NVC containing GIC

 0.67 ± 0.2*†

 68.9 ± 12.1*

* p< 0.05

The large standard deviation (SD) for the experimental sample is due to one data point which might have been a defective sample but it could not be excluded. After the elimination of the outlier the SD would be 0.08.

Conclusions: It was concluded that NVC containing polymers are capable of enhancing the fracture toughness and flexural strength (two clinically relevant mechanical properties) of conventional glass-ionomer cements. This type of glass ionomers are promising restorative dental materials with improved mechanical properties.


1033 (113402)

Mechanical Properties of a New Silorane-Based Restorative System. W. LIEN, and K. VANDEWALLE, USAF, Lackland AFB, TX

Objectives: To determine the mechanical properties of a new silorane-based (Filtek-LS) restorative material in comparison to six restorative materials representing the tooth-colored continuum: resin-modified glass-ionomer (Fuji-II LC), compomer (Dyract eXtra), nanofill (Filtek-Supreme), giomer (Beautifil-II), and two micro-hybrid composites (Esthet-X and Filtek-Z250).  Methods: Compressive, diametral tensile, flexural strength/modulus, fracture toughness, microhardness, and polymerization shrinkage were examined.  Ten specimens were fabricated per group.  For compressive and diametral tensile strength testing, cylindrical specimens were prepared in 6x4mm diameter and 3x4mm diameter aluminum molds, respectively; light cured all sides (Bluephase 16i, Ivoclar) for 20-seconds each, stored 24-hours in 37oC water, and loaded to failure in a universal testing machine (Model-5543, Instron) at a crosshead speed of 1-mm/min.  For flexural strength/modulus and fracture toughness testing, rectangular beam and single-edge notched specimens were created in a 2x2x25mm mold (1-mm preformed notch – fracture toughness); light cured in three over-lapping segments per side, stored, and tested in 3-point flexure as above (crosshead speed=0.25mm/min).  Flexural modulus was determined from the slope of the linear region of the load-deflection curve.  For Knoop hardness testing, specimens were made in a 2x8mm diameter mold, light cured, stored as above, and indented (LM-300AT, Leco) using a 200-gram load and a 10-second dwell time.  For polymerization-shrinkage testing, specimen was placed on the pedestal in the AcuVol volumetric shrinkage-device (Bisco); light cured for 40-seconds, and recorded at 5-minutes.  A mean and standard deviation were determined per group.  See table below. A 1-way ANOVA/Tukey was performed per mechanical property (alpha=0.05).  Results: Significant differences were found between groups per property (p<0.001).  Conclusions: Compared to the methacrylate-based composite resins, the new silorane-based restorative material, Filtek LS, had the lowest polymerization shrinkage, but an overall mixed mechanical performance.  Filtek LS had relatively higher flexural strength/modulus and fracture toughness, but relatively lower compressive strength and Knoop hardness.

  Restorative Material

  Mechanical Property:  Mean (Standard Deviation)

  Material (Shade A-2)

  Type

  CS (MPa)

  DTS (MPa)

  FS (MPa)

  FM (GPa)

 FT KIC (MPa m1/2)

  KHN (Kg/mm2)

  Shrinkage (%)

  Filtek-Z250   (3M/ESPE)

  Micro-Hybrid

 394.09 (17.5) a

  57.55 (6.7)  a

 136.20 (17.31) a

  8.34 (1.31) b, c

 0.670 (0.071) a

  61.29 (1.8)  a

  2.69 (0.12) b

  Filtek-Supreme   (3M/ESPE)

  Nanofill

 355.18 (26.6) a, b

  52.49 (9.8)  a

 113.89 (16.80) b

  6.91 (1.09) d

 0.590 (0.108) a, b

  57.72 (2.5)  b

  2.47 (0.09) c

  Beautifil II   (Shofu)

  Giomer

 326.30 (28.2) b, c

  51.40 (6.6)  a

 116.49 (10.66) b

  10.38 (0.81) a

 0.590 (0.075) a, b

  51.58 (1.8)  c

  2.62 (0.10) b

  Esthet-X   (Dentsply)

  Micro-Hybrid

 312.37 (49.8) c

  51.31 (9.2)  a

 93.71 (12.44) c

  7.75 (0.59) c, d

 0.578 (0.119) a, b

  41.75 (1.6)  d, e

  3.00 (0.15) a

  Filtek LS   (3M/ESPE)

  Silorane

 252.40 (32.1) d

  49.12 (9.2)  a

 122.33 (7.98) a, b

  9.33 (1.09) a, b

 0.688 (0.068) a

  43.96 (1.8)  d

  1.46 (0.09) d

  Dyract eXtra   (Dentsply)

  Compomer

 296.15 (33.2) c

  48.96 (6.2)  a

 115.49 (15.17) b

  8.50 (0.95) b, c

 0.449 (0.082) c

  39.47 (1.9)  e

  3.12 (0.11) a

  Fuji-II LC   (GC)

  RMGI

 168.92 (12.2) e

  23.66 (4.0)  b

 43.94 (10.92) d

  6.62 (0.96) d

 0.480 (0.100) b, c

  27.27 (1.5)  f

  Not Determined

 

  Groups with the same letter per column are not significantly different (p > 0.05)


1034 (120124)

Fracture resistance and failure pattern of different cavity designs. B. CARLINI1, I. CANAL JR1, A.E. PEVETTA1, M.E. BITTENCOURT1, and L.M. CAVALCANTE2, 1The University of Passo Fundo, Passo Fundo, Brazil, 2University of Manchester, Manchester, United Kingdom

Objective: To evaluate the effect of cavity design on fracture resistance and failure pattern of molars fully restored with resin-composite or associated with glass ionomer.

Methods: 60 extracted third molars were divided into 6 groups (n=10): G1: sound teeth (control); G2: non-restored mesio-occlusal-distal (MOD) preparation being the vestibular cusp in enamel without dentin support (negative control); G3: MOD + glass ionomer (Vidrion R/SSWhite) to substitute the dentin support + resin-composite (Tetric-Ceram/Ivoclar-Vivadent); G4: similar to G3 but fully restored with resin-composite; G5: part of the enamel in the vestibular cusp was removed and fully restored with resin-composite; and G6: the enamel without dentin support in the vestibular cusp was completed removed and cavity fully restored with resin-composite. The adhesive system used for all groups was Scotchbond Multi-Purpose/3MESPE. Teeth areas were calculated and specimens submitted to compression test in a universal testing machine (DL2000, EMIC) at a constant speed of 0.5 mm/min. Specimens were loaded until fracture. Fracture patterns were classified according to five types based on reconstruction possibilities (direct, onlay, indirect crown, endodontic treatment+ posts + indirect crown and extraction). Data were submitted to ANOVA and Tukey's test or Kruskall-Wallis (5%).

Results: G6 was the only group that showed fracture resistance similar to the control G1 (19.5±3.4). No statistical difference was observed among G3 (11.0±4.7), G4 (10.5±3.1), G5 (13.3±3.9) and G6 (15.1±2.5). Lower fracture resistance values were observed in G2 (5.6±2.8). According to fracture pattern, in 71% of the cases it was possible to reconstruct the teeth either with direct or onlays restorations. Teeth allocated in G5 and G6 showed higher rate (35%) of catastrophic failure than G3 and G4 (0%).

Conclusion: Cavity design had no influence on fracture resistance but in the failure pattern. Either glass ionomer or resin-composite can be used to substitute the dentin in vestibular cusps.


1035 (120985)

Hardness of Resin-Modified Bioactive Glass Ionomer Cement. J.W. RUCKER1, E. TUFEKCI1, J.C. MITCHELL2, H.B. DAVIS2, P.C. MOON1, and S.J. LINDAUER1, 1Virginia Commonwealth University - VCU/MCV, Richmond, VA, 2Oregon Health & Science University, Portland, OR

Bioactive glass containing bonding agents may reduce the formation of white spot lesions in orthodontic patients with poor oral hygiene. Objective: This study evaluated Knoop hardness of resin-modified bioactive glass ionomer cements (RM-BGIC) containing various amounts of bioactive glass (BAG). Methods: Two bioactive glass compositions (Group A: 65%SiO2, 31%CaO, and 4%P2O5; Group B: 85%SiO2, 11%CaO, and 4%P2O5) were synthesized by sol-gel methods, sieved and ground to <1.0 µm using a micronizer. BAG-RMGIC powders were obtained by mixing BAG and Fuji ORTHO LC powders in volume ratios of 0:1 (100% Fuji control), 1:4 and 1:1. The BAG-RMGIC powders were mixed with standard Fuji liquid, placed into cylindrical molds (5x2mm), and pressed between two glass slides. Discs were light cured for 60 seconds per side and stored in simulated body fluid at 37°C until testing. Knoop hardness indentations were made at 24 hr and 2 weeks with a 25g weight (20 seconds), and three separate indentations on each disc (n=5) were measured under 200X. Data was analyzed with ANOVA/Tukey. Statistical significance was set at P < .05. Results: At 24 hr, the mean hardness values were 4.14±0.83, 6.14±1.04, 5.93±0.45 and 9.15±1.06 kg/mm2 for A1 (1:1), A2 (1:4), B1 (1:1) and B2 (1:4) groups, respectively. The mean value for the control group was 17±1.53 kg/mm2. All of the groups were statistically significantly different from each other (P < .05). At 2 weeks, the measurements were 20.7±2.44, 30±2.23, 14.4±2.14, 17.8±1.70, and 18.7±1.28 kg/mm2 for the A1, A2, B1, B2, and control groups, respectively. A1 and A2 groups showed increased hardness compared to the remaining groups. There were not significant differences between the B1, B2 and the control groups (P > .05). Conclusions: Our results suggest that at the end of 2 weeks the novel RM-BGIC exhibit similar or better hardness values compared to the control group.


1036 (120561)

Curing and %Fillers' Influence on S53P4 Bioglass Surface Hardness. S.W. DIXON, and P.C. MOON, Virginia Commonwealth University - VCU/MCV, Richmond, VA

Bioactive fillers in composites can leach ions that can prevent demineralization and enhance mineralization in their immediate oral environment. The index of refraction of the glass filler and resin monomers influence visible light curing of composites. Purpose: The project was designed to determine if S53P4 bioactive glass additions to a model monomer system affected curing by measuring surface hardness. Materials and Methods: A model matrix resin composed of 49%BisGMA, 49%TEGMA,1.2%Camphorquinone, & 0.9% DAEMA was formed. Additions of 10micron S53P4 bioactive glass were hand mixed at 0%, 8%, 16% and 24% by volume. Flat Knoop hardness specimens (n=3) were molded and tested (n=5) in a Tukon hardness tester with a 50 gram weight. Two methods of curing were evaluated: “DentVLC” = light cured for 40sec with a Dentsply Smartlight IQ curing light (550mw/cm2) or “Colt-HC&LC” = Coltene DI500 heat and light curing unit with an 8min cycle time at ~110°C. Results: The “DentVLC” hardnesses for 0%, & 8% were: 8.7+/-.3; & 5.2+/- .6 Kg/mm2 respectively, but 16% and 24% were insufficiently cured to test. The Colt-HC&LC” hardnesses for 0%, 8%, 16% and 24% filler were: 20.5+/-.3; 23.1+/-.4; 23.5+/-.6 and 28.3+/-2.2 respectively. Student–t hardness comparison (p<.05) for the curing methods at all fillers showed DentVLC cure was inadequate. The ANOVA and Newman-Keuls (p<.05) comparison of Colt-HC&LC hardnesses indicated an increase with filler content except for the 8% and 16% which were not different. The estimate index of refraction for the monomer system was 1.50 and for S53P4 glass of 1.56. Conclusions: The differences in refractive index inhibited light penetration for VLC which is overcome by combined heat and light curing, but a higher refractive index monomer is needed for cure of direct restorations with S53P4 glass.


1037 (114259)

Control of decomposition rate of PLLA scaffold. M. NAKAGAWA, F. TERAOKA, and T. SOHMURA, Department of Oromaxillofacial Regeneration, Osaka University, Osaka, Japan

Objectives: The purpose of our study is to control the decomposition rate of the biodegradation polymer scaffold after forming. In this study, we carried out an accelerated decomposition examination using the enzyme for the injection-molded poly(L-lactide)(PLLA) plates, which had various crystallinities by applying heat treatment, and elucidated the relation between the crystallinity, the decomposition rate and the mechanical properties. Methods: Specimens having a size of 60 x 10 x 2.5 mm were prepared by melting the PLLA pellets (Lacty 5000, Shimazu, Kyoto, Japan). These specimens were labeled PLLA-4.The PLLA-4 injection molded specimens were heat-treated for one hour at 75, 80, 100, and 140°C. The enzyme solution was prepared by mixing 10 ml of Tris-HCl (Sigma, Missouri, USA), 2mg of proteinase K (Sigma, Missouri, USA), and 2mg of sodium azide (Nacalai Tesque, Kyoto, Japan), and by adjusting the pH to 8.6. The decomposition experiment was carried out by placing the specimen in the enzyme solution and keeping the mixture for 1, 2, 3, 7, and 14 days while rotating with a bio-shaker at the rate of 130 rpm at 37°C. Weight loss (%) = (W0/Wt) x 100. We are evaluated X-ray diffraction analysis, DSC, flexural test and surface observations. Results: The crystallinity of PLLA-4, PLLA-75, PLLA-80, PLLA-100, and PLLA-140 were 0 ± 0, 14.3 ± 2.0, 21.7 ± 2.2, 41.7 ± 3.6, and 62.9 ± 3.2%, respectively, and a high positive correlation was observed between the heat treatment temperature and the crystallinity. Using the obtained empirical formula, it became possible to calculate the required period to decompose a certain amount of the PLLA if the heat treatment temperature was known. Conclusions: The decomposition rate of the scaffold after forming is able to be arbitrarily controlled by changing the crystallinity of the scaffold.


1038 (116079)

Comparison of different mixing methods of a self-etching luting composite. N. BARABANTI1, F.J.T. BURKE2, F. MANGANI3, A. PUTIGNANO4, G. MERLATI5, and A. CERUTTI1, 1University of Brescia, Brescia, Italy, 2University of Birmingham, Birmingham, United Kingdom, 3University of Rome - Tor Vergata, Rome, Italy, 4Polytechnic University of Marche, Ancona, Italy, 5Universita degli Studi di Pavia, Pavia, Italy

Introduction:The aim of this study is to evaluate the influence of different mixing-procedures and application methods of a self-etching-auto-luting composite on fiber post adaptation and adhesive-cementetion quality.

Methods: Forty freshly extracted mono-radicular teeth (n=40) were endodontically treated and randomly divided into four groups. In all groups the same self-etching luting composite RelyX Unicem (3M-ESPE) was used to adhesively lute the fiber posts (RelyX Fiber Post 3M-ESPE). In group A we used Relyx Unicem Aplicap (3M Espe, USA) mixed by an amalgam-vibrator then applied directly on the post , in Group B the cement was applied using the Elongation Tip into the root canal, in Group C Relyx Unicem Aplicap (3M Espe, USA) was mixed by Rotomix and then directly applied into the root canal. In group D Relyx Unicem-Clicker (3M Espe), following the manufacturer's instructions for mixing, was applied using the Centrix system (Needle Tube 20 Ga). Teeth were then thermocycled according to the ISO/TR11405 protocol and immersed for 24-hours in a 2% methylene-blue solution. Each tooth was sectioned with a diamond-coated saw (Isomet-Buhler, Buffalo, NY,USA) from CEJ to apex to obtain 1 mm thick slices. Each slice was examined by means of stereoscopic microscopy (30x) for dye infiltration degree, the presence of gutta-percha remnants, voids and bubbles. Mann-Whitney and ANOVA statistical analysis (p<0,001) were performed for all results.Results:No-statistical significances were evidenced for guttapercha presence, dye-infiltration. Voids were present mostly in Group A. The difference was statistically significant and was due to the handling and positioning of the material. A significant reduction of microbubbles in group C and D using the mechanical mixer Rotomix was observed.

Conclusions:Materials and protocols for fibre-glass posts cementation are fundamental for the clinical success. Self adhesive luting cements, if used correctly, could be an acceptable and fast luting agent for post cementation.


1039 (121389)

Radiopacity of A New Bonding System Applying PRG technology. K. SHINNO, A. NAGAFUJI, T. NAKATSUKA, M. DEGUCHI, and N. NEGORO, SHOFU INC, Kyoto, Japan

Objectives: We previously reported the performance of 2-step fluoride-releasing bonding system "FL-BOND II" (Shofu Inc.) containing S-PRG filler, in terms of release of various ions, acid buffer capacity, and bonding ability (IADR2007#1589). The aim of this study was to investigate the radiopacity of "FL-BOND II" and clarify its clinical utility.

Methods: "FL-BOND II" and "FL-BOND" which S-PRG filler isn't contained were used for materials. The bonding agents placed in a mold was irradiated with visible light for 3min. The radiopacity of bonding materials were measured by ISO 4049:2000(E). Human tooth was formed delomorphous cavity and cavity was filled with BEAUTIFIL II (Shofu Inc.) using "FL-BOND" and "FL-BOND II".Then X-ray photography was taken.

Results: It was observed that FL-BOND II had high radiopacity equivalent to a 1.1mm aluminum plate compared to FL-BOND (equivalent to 0.2mm aluminum plate). In radiographic observation of the natural tooth which was restored with each adhesion system and BEAUTIFIL II, the adhesive layer of FL-BOND was observed as a black image, unlike BEAUTIFIL II and tooth substance, whereas the adhesive layer of FL-BOND II could not be distinguished from BEAUTIFIL II and tooth substance, and was observed as a continuous white image.

Conclusions: Since the adhesion layer of FL-BOND which has low radiopacity was shown as a black image that is different from other parts (composite resin, tooth substance) on the radiograph, it may be mistaken as a gap produced at the time of the filling or secondary caries, however, FL-BOND II has high radiopacity, and it appeared as the same image as other parts on the radiograph. It was thus clear that FL-BOND II is a clinically useful material for more accurate diagnosis and observation immediately after filling restoration or at subsequent follow-up.


1040 (115897)

Comparison of Different Mixing Methods of Two Self-Adhesive Luting Composites. P.A. ACQUAVIVA, N. BARABANTI, L. MADINI, A. KROKIDIS, A. SPERANZA, and A. CERUTTI, University of Brescia, Brescia, Italy

Objective: The aim of this study is to evaluate the influence of different mixing procedures and application methods on fibre post adaptation quality.

Methods: Forty freshly extracted mono-radicular teeth (n=40) were endodontically treated and randomly divided into three groups. Posts (RelyX Fiber Post - 3M ESPE) were cemented respectively with two different self-adhesive luting composites: RelyX Unicem (3M ESPE) and the new iCem (Heraeus). In group A Relyx Unicem Aplicap (3M Espe, USA) mixed by RotoMix (3M Espe) and applied in the root canal using the Elongation Tip was used. In group B Relyx Unicem Clicker (3M Espe, USA), following the manufacturer's instructions for mixing, was applied using the Centrix system (Needle Tube 20 Ga). Group C - iCEM (Heraeus) was mixed using automixing tip, then applied using the Centrix system (Needle Tube 20 Ga). Teeth were then thermocycled according to the ISO/TR 11405 protocol and immersed for 24 hours in a 2% methylene-blue solution. Each tooth was sectioned with a diamond-coated saw (Isomet-Buhler, Buffalo, NY,USA) from CEJ to apex to obtain 1 mm thick slices. Each slice was examined by means of stereoscopic microscopy (30x) for dye infiltration degree, the presence of gutta-percha remnants, voids and bubbles. Mann-Whitney and ANOVA statistical analysis (p<0,001) were performed for all results.

Results: No statistical significances were evidenced for gutta-percha presence, dye infiltration. Voids were present mostly in Group B. The difference was statistically significant and was due to positioning and handling of the material. A significant reduction of microbubbles in group A mixed with Rotomix was observed. No observation was relevant in group C.

Conclusions: Materials and protocols for fibre-glass posts cementation are fundamental for the clinical success. Self adhesive luting cements, if used correctly, could be an acceptable and fast luting agent for post cementation.


1041 (118533)

Quantitative characterization of clinically-relevant rheological properties of luting cements. D. SHIN, J.W. LEE, and B. SUH, Bisco, Inc, Schaumburg, IL

Objectives: To investigate clinically-relevant, quantitative methodology to characterize rheological properties of three different types of luting cements. Methods: Three different types of dual-cured luting cements (self-adhesive, composite luting, and metal bonding/luting) were tested using a rheometer (AR-2000ex, TA instruments). Time sweeps were performed to determine working time and setting time under varying frequency and amplitude of stress inputs in self-cure mode. Material response (strain) was monitored at each stress frequency and amplitude. In all experiments, normal force control was used to account for sample shrinkage during cure. All samples were tested under room temperature using disposable aluminum spindles and cups. Results: During testing, optimum frequency and stress inputs were identified for each type of luting cement. Crossover points of storage and loss moduli and onset of plateau in storage modulus were well agreed with working time and setting time, respectively, which were measured by clinicians qualitatively. Typical peak strain outputs were below 1000 microstrain and tracing patterns of strain outputs were more consistent comparing with results measured using custom-made oscillating rheometer (Fig. 1). Conclusion: The identified rheological testing methodology with experimental parameters is less disruptive. Therefore, it is expected that this methodology will have minimal interference with the polymerization process of the tested materials. This methodology is not only more quantifiable but also more clinically relevant. This methodology might be also useful for characterizing other restorative dental materials such as different types of composites, etc.


1043 (118153)

Viscosity and Activation effects on the Polymerization of Resin Cements. M. DI FRANCESCANTONIO1, C. ARRAIS2, T.R. AGUIAR3, M.C.Q. ANTONELLI4, C.U. DAVANZO4, and M. GIANNINI3, 1Dental School of Piracicaba - UNICAMP, Piracicaba, SP, Brazil, 2University of Guarulhos, Guarulhos - SP, Brazil, 3State University of Campinas, Piracicaba, Brazil, 4University of Campinas - Chemical Institute, Campinas, Brazil

Objectives: To evaluate the effects of the curing mode and viscosity on the degree of conversion (DC) of two resin cements.

Methods: Eight experimental groups were evaluated (n=8), according to the dual-cured resin cements (Nexus 2/Kerr Corp. and Variolink II/Ivoclar Vivadent), curing modes (light activation or self-cure) and viscosities (low and high). The resin cements were applied to surface of a horizontal attenuated-total-reflectance unit, and were polymerized either with self-cure (SC) or light exposure (XL3000/3M ESPE). Infrared spectra were obtained after 5 minutes and 24 hours (Nicolet 520 FT-IR/Thermo Scientific Inc.). DC was calculated using standard techniques of observing changes in aliphatic-to-aromatic peak ratios pre- and post-curing. Data were analyzed by three-way ANOVA and Tukey's test (p=0.05).

Results: For Nexus 2, it was observed significant differences between viscosity x curing mode x time (p=0.01), and for Variolink II, significant differences was observed between curing mode x time (p=0.01), and between viscosity (p=0.01). The DC means (SD) are displayed in Tables 1 and 2, respectively (%):

Table 1

Activation

Time

Viscosity

high

low

Nexus 2

light activation

5min

63.5(1.9)Bb*

64.4(1.8)Ba*

24h

86.8(1.5)Aa*

89.9(0.9)Aa*

self-cure

5min

44.7(2,1)Bb

48.6(3.2)Ba

24h

77.3(1.1)Aa

78.8(0.8)Aa

Capital Letters – compare time within viscosity and curing mode; Small Letters – compare the viscosity within curing mode and time. Asterisc -  compare curing mode within time and viscosity.

Table 2

Viscosity

Time

Activation

light activation

self-cure

Variolink II

high

5min

62.3(1.8)Ba

43.7(2.0) Bb

d

24h

84.9(1.4)Aa

75.8(1.3) Ab

low

5min

63.7(1.7)Ba

46.1(2.0)Bb

c

24h

87.7(1.2)Aa

77.5(1.3)Ab

Capital Letters – compare time inside viscosity and curing mode; Small Letters – compare curing mode inside time and viscosity. Letters d and e -  compare viscosity.

Conclusion: The light activation, after 24h, significantly increased the DC for both resin cements. The low viscosity version from light-activated or self-cured exhibited higher DC than high viscosity version.

Supported by FAPESP (#06/57998-0).


1044 (115175)

Retentive Properties of a Novel Resin-Modified Glass-Ionomer Temporary Cement. H.T. BUI1, R. DELONG2, A. FALSAFI1, J.D. OXMAN1, and A. PATEL1, 13M ESPE Dental Products, Saint Paul, MN, 2University of Minnesota, Minneapolis, MN

Objective:  The goal of this study was to compare the retentive properties of an experimental resin-modified glass ionomer (RMGI) temporary cement (ExpTC, 3M ESPE) with commercial zinc-oxide and resin-based temporary cements.  The cements evaluated included TempBond NE (TBNE, Kerr) a zinc oxide non-eugenol cement, and NexTemp (NT, Premier) a resin cement.  ExpTC, TBNE, and NT are paste/paste auto-mixed systems.  Method:  For each group five lower-molar-shaped metal preparations were made and mounted in a mold filled with curing resin. Subsequently, ProtempTM Crowns were adapted and cemented on the metal preps using the above temporary cements per manufacturers' recommendation.  Excess cement was removed and molded preps were kept in 37C oven for 15 minutes, after which they were mounted onto artificial oral environment (MDRCBB, University of Minnesota) and subjected to bruxing against a ceramic ball under 22 N of force at 2 Hz while lubricated with 37C water.  Up to 15 segments of 1000 bruxing cycles were conducted. At end of each segment visual inspection of the margin was performed to detect any crown movement, and an attempt was made to remove the crown with finger pressure.  If unable to remove, another 1000 cycles of bruxing would follow.  Results:   The mean values including their standard deviations in the parentheses are summarized in the following table:

Cement

Chemistry

Format

 Number of Cycles Survived

Experimental (ExpTC)

RMGI

Paste/Paste            auto-mixed

13608(2027)

TempBond NE (TBNE)

Zinc-Oxide        Non-Eugenol

Paste/Paste            auto-mixed

    2716(1186)

NexTemp (NT)

Resin

Paste/Paste            auto-mixed

    15000 (0)

Conclusions:  ANOVA with Tukey's comparison was performed at p < 0.05.  Experimental RMGI Temp Cement (ExpTC) showed significantly higher crown retention compared to TempBond NE, and was statistically as retentive as the resin Temp Cement (NT).


1045 (115817)

Validation of poly(methyl-methacrylate) as bonding substrate in polymerization stress test. L. BOARO1, F. GONÇALVES2, and R.R. BRAGA2, 1University of Sao Paulo, Sao Paulo, Brazil, 2University of São Paulo, São Paulo, Brazil

Objective: to validate the use of poly(methyl methacrylate), PMMA, as bonding substrate in the polymerization stress test by correlating the results with those obtained in microleakage tests. Methods: Five composites were tested: Filtek Z250 (FZ), Z100 (Z1), Concept (CO), Durafill (DU) and Heliomolar (HM). Polymerization stress (ópol) was determined in 1-mm height specimens, inserted between two rods (diameter=5mm) of either PMMA or glass. Nominal stress was calculated by dividing the maximum contraction force recorded by the cross-sectional area of the rod. Composites' elastic modulus (E) was obtained by three-point bending. Data from ópol and E were submitted to one-way ANOVA/Tukey's test (alfa=0.05). For the microleakage test (MI), bovine incisors received cylindrical cavities with all margins in enamel (diameter=5mm, high=2mm), which were restored in bulk. After 24 h storage in water, specimens were subjected to dye penetration using AgNO3 as tracer. Specimens were sectioned twice, perpendicularly, and microleakage was measured under 20x magnification. Data from MI were submitted to Kruskal-Wallis test. Results: Means (SD) of ópol (MPa) using glass/PMMA were FZ: 7.5(1.8)A/2.5(0.2)bc; Z1: 7.3(0.5)A/2.8(0.3)ab; CO: 6.8(1.1)A/3.2(0.5)a; DU: 4.5(0.7)B/2.0(0.2)bc; HM: 3.5(0.2)B/2.3(0.3)c. ópol values obtained using PMMA rods were 34-67% lower than with glass. MI means (SD) for tooth average/tooth maximum were FZ: 0.92(0.19)B/1.53(0.30)a; Z1: 1.19(0.21)A/1.75(0.20)a; CO: 1.26(0.25)A/1.78(0.24)a; DU: 0.83(0.30)B/1.68(0.46)a; HM: 0.81(0.27)B/1.64(0.54)a. The regression analysis between ópol and average MI showed a stronger relationship when PMMA rods were used (R2=0.927) compared to glass rods (R2=0.485). Conclusion: PMMA can be considered an interesting alternative to the use of glass as bonding substrate in the polymerization stress test due to the strong relationship shown with microleakage results.


1046 (119348)

Curing Methods and Flasking Types: Influence in a Dimensional Alteration. L.R. SILVA-CONCILIO1, C.M. RIZZATTI-BARBOSA2, L.G. CUNHA3, A.C.C. NEVES4, and S.M. RODE4, 1Taubaté University - UNITAU, Taubaté, Brazil, 2University of Campinas State Piracicaba, Piracicaba, SP, Brazil, 3University of Taubaté - UNITAU, Taubaté, Brazil, 4Universidade de Taubate, Taubaté, Brazil

Objectives: This study purporsed to investigate how different flasking techniques using monomaxillary and bimaxillary flasks and heat curing techniques by microwave irradiation and water bath affect occlusal vertical dimension after acrylic resin curing. Methods: Forty pairs of complete dentures waxed with the artificial teeth positioned in maximum intercuspation were divided into four groups of ten pairs each: G1 – monomaxillary flasking and water bath curing (control); G2 – monomaxillary flasking and microwave irradiation curing; G3 – bimaxillary flasking and water bath curing; G4 – bimaxillary flasking and microwave irradiation curing. Occlusal vertical dimension was measured using a digital caliper before and after acrylic resin curing and three measurements were taken for each pair of dentures. Data were analyzed to statistical analysis by ANOVA and Student's t-test at 5% significance. Results: These demonstrated that all groups showed positive variation for the occlusal vertical dimension, the mean values in mm of the difference before and after polymerization were: G1= 2.43; GII= 3.37; GIII= 2.64; GIV=3.30. Conclusion: All groups presented an increase in vertical dimension, monomaxillary metallic flasks shows lower mean values of vertical dimension of occlusion.


1047 (118128)

Effect of reinforcing wires on bending strengths of denture resin. N. OKAMOTO, D. KURIHARA, H. SHIMPO, Y. SUZUKI, C. OHKUBO, T. HOSOI, Y. MIYAMA, and Y. MIZUNO, Tsurumi University, Yokohama, Japan

Objectives: To prevent breakage in acrylic dentures, reinforcing wires are frequently embedded in the denture base, particularly, in parts that are mechanically weak. Currently, several types of stainless steel wire have become commercially available and are being used to replace those made of Cobalt-chromium alloy. In this study, the effectiveness of using stainless steel reinforcing wires with acrylic resins in denture bases was evaluated.

Methods: Three 18-8 stainless steel wires [a semicircle of 1.4 mm, 1.6 mm, or 2.0 mm diam. (Yamahachi, Japan)], twisted wires [2.0 mm (Dentsply Sankin, Japan)], two 18-8 stainless steel bending bars [Lingual bar and Palatal bar (Dentsply Sankin)], and a Co-Cr clasp wire [1.2 mm diam. (Dentsply Sankin)] were used as reinforcing wires. All wires were sandblasted with 50m m Al2O3 particles, and the Alloy Primer (Kuraray, Japan) was applied on their surfaces. Acrylic resin plates [2.5 x 10.0 x 65.0 mm, ParaXpress (Heraeus Kulzer, Germany)] were fabricated by embedding the wires. As a control, resin plates were prepared without the wire. After the specimens were stored in distilled water for 48 hours, the bending strengths were measured by a simple bending test using autography (Instron 5565). The data (n=5) were analyzed using a one-way ANOVA/ Tukey's Multiple Comparison Test (a=0.05).

Result: The bending strengths of the Palatal bar and Lingual bar were the highest among those of all specimens tested (p<0.05). Reinforcing wires, including twisted wire, showed significantly higher strengths than the control (p< 0.05). Of the semicircle wires, the 2.0 mm wire exhibited the greatest strengths (p< 0.05).

Conclusion: Excluding two bars, the 2.0 mm semicircle of stainless steel wire exhibited the highest strength. In view of both ease of handling and reinforcing effectiveness, the 2.0 mm semicircle of stainless steel wire might be recommended for fabricating the unbreakable acrylic denture.


1048 (118066)

Bending strengths of repaired acrylic resin with reinforcing wire. Y. YAMAGUCHI, K. ASHIGAKI, H. SHIMPO, J. KAWANISHI, C. OHKUBO, Y. SUZUKI, T. HOSOI, and Y. MIYAMA, Tsurumi University, Yokohama, Japan

Objectives: When damaged dentures are repaired, a reinforcing wire is frequently embedded in and around the broken parts to prevent further damage. Reinforcing stainless steel wires have recently become commercially available and they are used instead of cobalt-chromium alloy ones. This study assessed the bending strengths of a repaired denture base with stainless steel wires.

Methods: Acrylic resin plates (2.5 x 10.0 x 65.0 mm, ParaXpress, Heraeus Kulzer) were fabricated and cut for making half-sized plates (2.5 x 10.0 x 31.5 mm). Paired cut plates were assembled while keeping a repair space of 2.0 mm in a jig; the plates were attached with three auto-polymerized resins [Unifast III (GC, Japan), Unifast Trad (GC), and Provinice (Shofu, Japan)] using a brush-on technique. The reinforcing stainless steel wires (semicircle of 2.0 mm in diameter, Yamahachi, Japan) were embedded so that they were vertically positioned to the joining surface. Before embedding, the wires were sandblasted with 50 mm alumina particles, and an Alloy Primer (Kurare, Japan) was applied on them. As controls, specimens were prepared without the wire and original resin plates. After the specimens had been stored in distilled water for 48 hours, the bending strengths were measured using the tree-point bending test (supporting lengths 30.0 mm) using autography (Instron 5565). The data were analyzed using a one-way ANOVA/ Tukey's Multiple Comparison Test (a=0.05).

Result: There were no significant differences in the repaired resins (p> 0.05). Specimens with reinforcing wires showed a significantly greater bending strength than those without them (p< 0.05).

Conclusion: The bending strengths of the repaired denture base with reinforcing wires using Unifast Trad were comparable to those of an undamaged denture base. Reinforcing wires should be embedded to prevent a repaired denture from becoming damaged again. Partially supported by a research grant from the Japan Dental Association.


1049 (118089)

Reinforcing effectiveness of stainless steel wire to denture base resin. K. OMORI, R. AIBARA, D. KURIHARA, N. OKAMOTO, H. SHIMPO, C. OHKUBO, T. HOSOI, Y. MIYAMA, and Y. MIZUNO, Tsurumi University, Yokohama, Japan

Objective: When acrylic dentures are reinforced by stainless steel wires, the reinforcing effectiveness might differ according to the embedding positions of the wire and/or the size of the denture base. This study investigated the effect of the wire positions and the thickness/widths of the denture base on the reinforcing effectiveness. Methods: After 18-8 stainless steel wires [a semicircle of 2.0 mm diam. (Yamahachi, Japan)] were sandblasted with 50 mm Al2O3 particles, the Alloy Primer (Kuraray, Japan) was applied on their surfaces. Acrylic resin plates (ParaXpress, Heraeus Kulzer, Germany) were fabricated in four different sizes (2.0 x 10.0 x 65.0 mm, 2.5 x 10.0 x 65.0 mm, 3.0 x 10.0 x 65.0 mm, and 2.5 x 5.0 x 65.0 mm) with the wire embedded. As a control, resin plates without wires were also prepared. In the 2.5 x 10.0 x 65.0 mm resin plates, the reinforcing wires were embedded into three positions (0.5 mm, 1.25 mm, and 2.0 mm from the bottom surface). After the specimens were stored in distilled water for 48 hours, the bending strengths (N) were measured using Autography (Instron 5565, Instron Japan) at a cross-head speed of 2.0 mm/min. The data (n=5) were analyzed using a one-way ANOVA/ Tukey's test (a= 0.05). Result: In all sizes of the specimens, the bending strengths of specimens with wires were significantly greater than those of specimens without them (p< 0.05). Thinner and narrower specimens exhibited greater reinforcing effectiveness. The wire embedded in the tensile side had a significantly greater strength than that in the compressive side (p< 0.05). Conclusion: When a bending force is applied to a denture base during a masticatory function, the reinforcing wire should be embedded in the tensile side. The reinforcing wire should be used in denture bases that are particularly thin and narrow.


1050 (116102)

Mechanical Properties of Heat-curing Resins by Stress-Strain Diagrams. C. BORTUN1, A. CERNESCU2, N. FAUR2, L. SANDU1, and S. POROJAN1, 1Victor Babes University of Medicine and Pharmacy Timisoara, University School of Dentistry, Timisoara, Romania, 2Politehnica University Timisoara, Timisoara, Romania

Objectives: General objectives were based on multidisciplinary research of biomaterials used in dental medicine and are focused on the mechanical properties of dental prostheses.

Materials and Method: We evaluated the mechanical properties of heat-cure resins, such as Meliodent (Heraeus Kulzer, Senden, Germany) and Royaldent Plus (Palatinal Foggyarto Kft., Budapest, Hungary). In accordance with complete-denture technology, we made samples from these materials, which were tested with Zwick Roell equipment (testXpert software).

Results: There were noticeable differences, depending on material type. Based on tensile tests, we determined stress-strain diagrams for the comparative evaluation of Royaldent and Meliodent mechanical properties: (for Royaldent) ultimate tensile  strength,  71.5 MPa; yield strength, 4.24 MPa; total elongation, 8.46 %; Young's modulus, 1019.25 MPa; (for Meliodent) ultimate tensile  strength, 63.29 MPa; yield strength, 4.22 MPa; total elongation, 7.9 %; Young's modulus, 1215 MPa. Based on data tests and processed statistics and diagrams, stress-strain was determined by a theoretical characteristic curve of linear variation according to the equation: (σ – Tensile Stress [MPa]; ε – Strain [%]). To determine a and b parameters, we used the program Table CurveTM 2D, where stress and specific deformation registered values were defined, based on defined data from which we selected, as a theoretical characteristic curve, the diagram that best described the represented points set.

Conclusions: The methods allowed for the evaluation of the tensile strength of dental prostheses, and the certification of dental materials' quality. The registered results showed the brittle characteristics leading to material breaking, illustrated by stress-strain shape diagrams and samples breaking without registering massive plastic deformation.


1051 (118111)

Reinforcement of various denture base resins using stainless steel wire. T. SAKURAI, Y. SATO, J. KAWANISHI, H. SHIMPO, T. OSADA, Y. SUZUKI, C. OHKUBO, and T. HOSOI, Tsurumi University, Yokohama, Japan

Objectives: Denture bases without a framework have less bending strength than those with framework; as a result, acrylic dentures frequently fail. The use of stainless steel reinforcing wire is an effective means of increasing the bending strength of dentures. This study evaluated the bending strengths of acrylic resins used in denture bases with stainless steel wires. Method: Three denture base resins using different polymerization methods [a pour-type resin, Palapress vario #1 PINK (Heraeus, Germany); a heat polymerization resin, Acron #3 PINK (GC, Japan); a microwave-curing-type resin, Acron MC #3 PINK (GC)] were used in this study. After the stainless steel wires [semicircle of 2.0 mm in diameter, (Yamahachi, Japan)] were sandblasted with 50 mm Al2O3 powder, the Alloy Primer (Kuraray Medical, Japan) was applied on their surfaces. Resin plates (2.5 x 10.0 x 65.0 mm) with and without embedded wires were fabricated with three resins using a stainless steel jig according to the manufacturer's instructions. After the specimens were stored in distilled water for 48 hours, the bending strengths (crosshead speed: 2 mm/min) were measured with a three-point bending test using autography (Instron 5565, Instron, Japan). The data (n=5) were analyzed by an ANOVA/Tukey's test (a=0.05). Results: The bending strengths [N, Mean(SD)] of specimens with and without wires were: Palapress vario, 53.35(3.20) and 37.56(4.85); Acron, 52.27(9.51) and 34.42(2.39); and Acron MC: 63.65(13.47) and 42.86(4.49). There were no significant differences in the three resins either with or without wires (p>0.05). In all denture base resins, specimens with wires had significantly greater bending strengths than those without them (p<0.05). Conclusion: Irrespective of the polymerization methods, the bending strengths of denture base resins were increased by the use of reinforcement wires. To prevent damage to acrylic dentures, reinforcement wires should be used in the weakest parts of the denture bases.


1052 (115937)

Influence of Chopped Carbon Fiber on Acrylic Resins. P.N. GOMES1, A.A. DEL BEL CURY1, M.R. MOYSÉS2, J.C.R. RIBEIRO2, and S.C. DIAS2, 1Piracicaba Dental School - University of Campinas, Piracicaba, Brazil, 2Department of Clinical Dentistry, Vale do Rio Verde University - UNINCOR, Três Corações, Brazil

Acrylic resin has been widely used in dentistry, but it still presents limitations regarding shrinkage polymerization and mechanical properties. Objectives: This study aimed to assess the polymerization shrinkage, flexural and impact test strength of two self polymerized acrylic resins: Pattern (P) and Duralay (D) added with chopped carbon fiber. Methods: For each resin, 3 groups were made: P and D- without carbon fiber (control groups), P5 and D5- with 5% carbon fiber and P10 and D10- with 10% carbon fiber. The amount of fiber was determined by the weight of the polymer. Twenty specimens were made for each group for 3-point flexural (n=10) and impact test (n=10). The polymerization shrinkage was determined before the tests using light microscope with precision of 1 µm and the fractures were analyzed by scanning electronic microscopy, in order to observe the carbon fiber bond to the matrix of resins. Data from all mechanical tests were submitted to two-way ANOVA and mean values were compared by Tukey test (p<0.05). Results: Polymerization shrinkage (mm): P(0.11±0.02)bc, P5(0.09±0.03)cd and P10(0.06±0.02)d ; D(0.20±0.05)a, D5(0.15±0.03)b, D10(0.13±0.03)bc,. Flexural Strength (MPa): P(60.53±4.14)b, P5(57.28±4.16)bc, P10(58.29±3.21)bc, D(69.74±5.21)a, D5(54.70±7.73)bc and D10(51.47±8.14)c. Impact strength (J): P(0.14±0.01)d, P5(0.15±0.03)d, P10(0.21±0.04)bc, D(0.23±0.05)ab D5(0.28±0.52)a, D10(0.16±0.02)cd. SEM observation showed that the carbon fiber adhered only to the matrix of the Pattern resin. Conclusion: The addition of carbon fiber was efficient for reducing polymerization shrinkage for both acrylic resins and Pattern resin with 10% carbon fiber exhibited lower polymerization shrinkage and better mechanical properties.


1053 (119815)

Bend Strength Properties of Jute Fiber-Reinforced Denture Base Material. S. KONDO, Biomass Materials Research, Sapporo Hokkaido, Japan, Y. NODASAKA, Hokkaido University, Sapporo, Japan, and H. SHIMOKOUBE, Emeritus Professor Hokkaido University, Sapporo Hokkaido, Japan

Objective: This research was to develop the denture base material having both a biocompatibility and environmental adaptability by using plant fiber of sustainable natural resources as reinforcement. Methods: Jute fiber (Takasho, Co.LTD., Japan) was used as plant fiber. Jute fiber was chopped into 10mm length, washed with ethanol three times and then dried on oven at 110 °C for 3h to remove moisture. Bend specimen (2.5x10x65 mm) was fabricated according to a conventional heat-cure type denture processing (curing cycle:30min in 70 °C water, then 1h in boiling water).Dough mixture was prepared using Polymer (P) and Liquid (L) of Acron (GC, Japan) as control (P/L=10g/4.5ml).The chopped-jute fiber was formulated to 5,10 and 15 by mass % of P. The specimen surfaces were finished in a wet condition using a SiC abrasive paper up to 2000 grit (CC-Cw, Sankyo Rikagaku Co.LTD., Japan).The specimens were stored in distilled water at 37 °C for 3 days. Flexural test was carried out at a crosshead speed of 5mm/min using a calibrated universal testing machine with a 500N load cell (EZ Test, Shimazu, Japan).Bend strength properties were statistically analyzed using one-way ANOVA and Fisher's PLSD. Results: Flexural strength properties (mean and SD, n=6) are presented in the following table.

Jute fiber/Acron's Polymer Ratio

0/100

5/95

10/90

15/85

Bend strength MPa

79(5)

65(9)

62(7)

66(2)

Elastic Modulus GPa

2.11(0.01)

2.11(0.01)

1.93(0.03)

2.05(0.02)

Fracture energy N-mm

272(47)

185(46)

177(28)

191(12)

Mean values of bend strength and fracture energy decreased with increasing the incorporation of jute fiber compared to the control (p<0.05). Elastic modulus of jute fiber-reinforced materials did not show a significant difference compared to control (p>0.05).Conclusion: Chopped jute fiber-incorporated composites did not improve bend strength properties. Further studies regarding surface treatment and aspect ratio of jute fiber should be performed to improve the bend strength.


1054 (116607)

Repair strength of microwave-polymerized acrylic resin with surface treatments. C. BURAL, G. BAYRAKTAR, I. AYDIN, and I. YUSUFOGLU, University of Istanbul, Istanbul, Turkey

Objectives:

Restoring the original strength of the denture base and avoiding recurrent fractures are the main goals for denture repair. This study investigated the mechanical properties of microwave-polymerized specimens repaired with auto-polymerizing resin after the repair surfaces were treated with monomers or acetone to promote better adhesion.

Methods:

Specimens (n=36) (65x10x2.5-mm) polymerized using a microwave-polymerized resin (Acron MC, GC Corp) under 500 W for 3 min. Specimens (n=30) were sectioned into halves to clinically simulate the denture fracture and the gap was 3-mm. Butt-designed repair sites were pre-treated with heat-, auto- and microwave-polymerizing monomers and acetone for 180 s and then repaired with auto-polymerizing resin (Mega-Dur, Megadental). Intact specimens (n=6) and specimens repaired with no surface treatment were used as controls. After repairs, specimens were stored in water at 37ºC and subjected to 3-point bending test using an universal testing machine at a 5.0 mm/min. Flexural strength, strain, fracture load, modulus of elasticity and deflection values of repaired specimens were statistically analyzed with LSD test to evaluate the effect of application of different agents (p ≤0.05).

 

Results:

Overall flexural strength (21,288±6,21 MPa)  and fracture load  (20,38± 10.15 N) of repaired specimens were approximately 27% of those of the intact specimens (76.1±7.44 MPa and 74.33±9.75 N, respectively). Modulus of elasticity of specimens treated with heat-polymerizing monomer was significantly higher than the control specimens with no surface-treatment (p ≤0.05). Strain values of acetone treated specimens were significantly lower than the control specimens with no surface-treatment (p ≤0.05). The differences in other mechanical variables tested were not statistically significant within the repaired groups (p≥0.05).

Conclusion:

When repaired with auto-polymerizing resin, repair surfaces of microwave-polymerized denture bases can be treated with heat-polymerizing monomer to achieve a stronger repair. Use of an auto-polymerizing monomer can be a second choice in repairing a microwave-polymerized denture base.


1055 (115917)

Relative Fracture Toughness of Bis-Acryl Provisional Resin Materials. L. KNOBLOCH, R. KERBY, M.T. PULIDO, N. CLELLAND, S. SHARPLES, and W.M. JOHNSTON, The Ohio State University College of Dentistry, Columbus, OH

Objective: The purpose of this investigation was to evaluate the relative fracture toughness (KIc) of four chemical-cure (Protemp Garant 3, PerfecTemp II, Integrity, Temphase) and one dual-cure (Luxatemp Solar) Bis-acryl provisional resin materials at 1 hour and 24 hours set-time.  Methods: Disc-shaped min-compact test specimens (n=18) with introduced precracks as described by Kovarik, et al (1991) were prepared in a pre-heated split-mold and maintained at 37°C ± 5°C for five minutes during curing in order to simulate clinical conditions.  Curing temperature was monitored with an infrared digital thermal analyzer.  Specimens were then stored in distilled water at 37°C ± 2°C and tested at 1 and 24 hours on an Instron at 0.05 mm/min displacement water.  Results: Mean volume with standard deviation (SD) are listed below:

                            KIc in MPa · M ½

Resin

                  1 Hour

                24 Hours

Temphase

            0.63     (0.09)

            0.78     (0.13)

Protemp Garant 3

            0.57     (0.09)

            1.02     (0.15)

Luxatemp Solar

            0.50     (0.05)

            0.72     (0.12)

Integrity

            0.43     (0.06)

            0.84     (0.13)

PerfecTemp II

            0.36     (0.05)

            0.73     (0.13

ANOVA (p<0.001) and REGW multiple comparison tests (p<0.025) showed significant differences in fracture toughness between provisional resins at both 1 and 24 hours.  The initial (1 hour) fracture toughness value of Temphase and Protemp Garant 3 were significantly greater than Integrity and PerfecTemp II.  Conclusions:  Post-gelation polymerization seems to play an important role in determining the fracture properties of both chemical and dual-cure Bis-acryl resins within the first 24 hours.


1056 (119730)

Characteristic Viscoelasticity Of Denture Liner Using Vinyl Ester/PEMA Paste. J. TANAKA1, Y. HASHIMOTO2, M. NAKAMURA2, J.W. STANSBURY3, J.M. ANTONUCCI4, and K. SUZUKI5, 1Okayama University, Okayama, Japan, 2Osaka Dental University, Osaka, Japan, 3University of Colorado School of Dentistry, Aurora, CO, 4National Institute of Standards and Technology, Gaithersburg, MD, 5Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan

Objectives: This investigation seeks to evaluate the characteristic viscoelasticity behavior of an alcohol free soft denture liner without an environmental endocrine disruptor using the aliphatic vinyl ester (VE)/poly(ethyl methacrylate) (PEMA) paste which enables various use matched to the purpose by the same material. Methods: The alcohol free soft denture liner was prepared by the mixing of PEMA powder (M.W.: 4 x 105, Particle size: 40µm) and an aliphatic VE liquid (Divinyl sebacate (DVS) or Methyl vinyl sebacate (MVS)) as a plasticizer at the P/L ratio of 6/5(g/ml). The influence of water immersion on the viscoelasticity of a novel soft denture liner and five kinds of commercial tissue conditioners (TC) were evaluated based on the stress relaxation behavior measured for 10 min by using the rheometer (AR2000, TA Instruments) at 25°C. Results: The influence of water immersion on the viscoelasticity behavior of VE/PEMA paste was quite different from those of commercial TC. The stress relaxation behavior of VE/PEMA paste had not been changed statistically over the whole step though those on 5 kinds of commercial TC had been greatly changed in immersed in dist. water at 37°C for 2 weeks. Especially, the viscoelasticity behavior at the initical stage of stress relaxation of all commercial TC had been greatly affected by the water immersion. Moreover, the modulus after stress relaxation for 10 min of VE/PEMA paste in immersed in dist. water at 37°C for 2 weeks decreased by 14-19% compared with the initial value measured at 2 hrs after mixing in spite of increasing those of commercial TC by 36-330%.(ANOVA, Turkey's, p<0.05) Conclusions: The viscoelastic behavior of the novel soft denture liner composed of the aliphatic VE and PEMA had almost no change over the whole stage by the water immersion for 2 weeks.


1057 (120635)

Roughness of reline resin after toothbrushing and immersion cleansers. F.E. IZUMIDA, R.C. RIBEIRO, E.B. MOFFA, M.F.M. BASSO, E.T. GIAMPAOLO, and A.L. MACHADO, São Paulo State University (UNESP), Araraquara Dental School, Araraquara, Brazil

Objective: The purpose of this in vitro study was to evaluate the effect of toothbrushing and immersion cleansers on surface roughness of hard chairside reline resin after 30 days. Methods: one hundred specimens (40 X 10 X 2mm) of Tokuyama Rebase II were prepared following the manufacturer's instructions and divided into 10 groups (n=10). In control group, specimens were stored in distilled water at 37ºC. For test groups, specimens were subjected to toothbrushing test (30 cycles per day) with distilled water, slurry of dentifrice-water or slurry of coconut soap-water in combination with one of this solutions (10 minutes per day): distilled water, sodium perborate 3.78% or digluconate chlorhexidine 2%. Roughness measurements (Ra) were made using a profilometer (Mitutoyo Surftest SJ-400), before treatments and after 7, 15 and 30 days. Data were analyzed by ANOVA (p=0.05). Results: The reline material exhibited roughness values from 0.47 to 0.64 Ra. The results showed no significant differences among treatments for all period. Comparison among periods revealed that there were no significant differences on the surface roughness of evaluated material. Conclusion: Surface roughness of Tokuyama Rebase II was unaffected independent of treatments used until 30 days.

Grants: FAPESP – 07/02118-8 and 07/04548-0


1058 (120956)

Surface roughness alterations of acrylic resins after ozonized compound disinfection. P.C. PEREIRA1, G. MORAIS2, F. GALLO2, L.V. ZOGHEIB3, S.M.A. MICHIDA1, A.A. CASTILHO1, A.L.S. BORGES4, T. ARRUDA PAES2, R.N. TANGO2, and E. KIMPARA5, 1UNESP SJC, Sao Jose dos Campos, Brazil, 2Universidade Est. Paulista Julio Mesquita, São José dos Campos, Brazil, 3Sao Paulo State University (UNESP), São josé dos Campos, Brazil, 4Universidade Est. Paulista Julio Mesquita, Sao José dos Campos, Brazil, 5Paulista State University, São josé dos Campos, Brazil

Objectives: This work assessed the interaction among disinfection agents and complete denture's acrylic resins. The superficial roughness (Ra, ìm) of two acrylic resin were measured after disinfection with different agents and time periods. Methods: Forty cylindrical specimens (10mmX2mm) were prepared. Group I (n=20) was composed by microwave heat-cured acrylic resin discs and the Group II (n=20) was composed by conventional heat-cured acrylic resin. Each group was subdivided in 4 subgroups (n=5) according to disinfection agents: Group A(control) - distilled water; Group B - 0,2% clorhexidine; Group C – 0.2% peracetic acid and Group D – 2% Ozone. The roughness evaluation times were initial and after equivalent times from one to five years according each agent posology. Data were analyzed using 3-way ANOVA and Tukey's test (p<0.05). Results:There were not statistical difference to the variables acrylic resin (p=0,83), disinfection agent (p=0,26), except to time variable

(p<0.0001). This last factor showed significant interaction with other variables. Conclusions: No one disinfection agent promoted superficial degradation of evaluated acrylic resins. However, the store time determined significant alterations among the groups.

KEYWORDS: Complete denture; Acrylic resins; Disinfection; Ozone; Peracetic acid.


1060 (119151)

Effect of Repeated Chemical Disinfection on Denture Base Resins. E.J.T. RODRÍGUEZ-ACOSTA, L.R. PINTO, F.F.F. TÁVORA, P.M.B. SILVA, M. JACOBINA, and V.C. PORTO, Bauru Dentistry School - São Paulo University, Bauru, Brazil

Objective: This study evaluated the effect of chemical disinfection on the hardness and surface roughness of three hard chairside resins and one denture base resin after 180 disinfection cycles. Methods: A total of 240 circular specimens (30 X 6mm) were fabricated using Lucitone 550 (n=60) Jet; n=60, Kooliner; n=60, Tokuyama rebase II fast; n=60. The specimens were immersed in water (control), and five disinfecting solutions (1%, 2% and 5,25% sodium hypochlorite; 2% glutaraldehyde; 4% chlorhexidine gluconate) and tested for knoop hardness (KHN) and roughness (Ra-µm) before and after 180 disinfection cycles. Data were analyzed by ANOVA and Tukey's test 5%. Results: For Lucitone 550 (from 20,61 ± 1,36 to 15,44 ± 1,26 KHN), Jet (from 18,74 ± 0,47 to 13,75 ± 0,95 KHN), Kooliner (from 14,09 ± 1,63 to 7,52 ± 0,88 KHN), Tokuyama rebase (from 12,57 ± 0,94 to 8,28 ± 0,39 KHN) significant decrease in hardness was observed regardless of the solution used. No significant interactions were observed for Kooliner roughness. Between Lucitone (from 0,06 ± 0,01 to 0,20 ± 0,02µm) and Jet, (from 0,07 ± 0,01 to 0,23 ± 0,04µm) there was a significant increase in roughness regardless of the disinfectant used; Jet showed significant increase in roughness after immersion in water. Tokuyama rebase showed no significant differences in roughness when immersed in water, 2%, 5.25% sodium hypochlorite, and 2% glutaraldehyde. Conclusion: this study showed that Lucitone 550 exhibited significant decrease in hardness regardless of the disinfection solution used; However, no significant differences were noted between all disinfectants, for hard chairside resins. The solutions 1 and 2% sodium hypochlorite and 4% chlorhexidine gluconate caused more alteration in roughness of Lucitone 550. These solutions and 5,25% sodium hypochlorite caused an increase in the roughness of Jet, while Tokuyama rebase did not shows difference between solutions.Grant: FAPESP-04/15528-1


1061 (115280)

Morphological Characterization of a New Temporary Crown and Bridge Material. A. SEZINANDO, University of Lisbon, Lisboa, Portugal, and J. PERDIGAO, University of Minnesota, Minneapolis, MN

 

Objectives: to characterize the ultra-morphology (AFM, FESEM) and surface characteristics (Profilometry) of 4 bis-acryl composite resins for provisional fixed restorations. Methods: Materials: (1) Integrity Fluorescence (INT, Dentsply); (2) Luxatemp Fluorescence (LUX, DMG); (3) Protemp Plus (PRP, 3M ESPE); and (4) Structur Premium (STP, Voco). AFM/FESEM - 3 unpolished disks from each material were fabricated; 3 AFM readings were taken randomly from each specimen, same magnification. The specimens were coated with Au-Pd and observed under a FESEM (X5,000-X50,000). Nanoprobe Profilometer - 3 unpolished and 3 polished (Sof-Lex XT, 3M ESPE ) specimens from each material were analyzed with the Nanoprobe Profilometer in 3 different areas of each specimen.  Separate statistical analyses (ANOVA, Duncan's, p<0.05) for polished/unpolished specimens were computed with SPSS14.0 (SPSS Inc). Results: AFM -Surface topography of PRP was distinct from the other materials. Smooth surfaces were observed consistently across the PRP specimens as opposed to the irregular topography for the other materials; FESEM –The morphology of INT and LUX was similar, showing filler particles up to 3µm-wide with empty areas resulting from detachment of filler particles and gaps at the interface between the particle and the surrounding matrix. For STP, the biggest particle size was under 2µm, with areas displaying clustered microfiller particles. For PRP, the particle size resembled that of a nanofilled composite (20-30nm), with dispersed spherical particles in the range of 40-50nm. Profilometry (nm) – For polished specimens, PRP resulted in the lowest roughness (0.86×103) which was significantly lower than the other materials (INT–1.60×103; LUX–1.36×103; STP–1.90×103). The pairs LUX/ INT and INT/STP ranked in the same subset. For unpolished specimens, INT (7.51×103) resulted in significantly greater roughness than the other materials. PRP resulted in the lowest roughness (1.27×103). Conclusion: PRP resulted in smoother morphology than the other 3 materials. Supported by 3M ESPE.


1062 (115742)

Physical Properties of Temporary Crown & Bridge Materials. T. NEUMANN, M. DANEBROCK, and R. MALETZ, VOCO GmbH, Cuxhaven, Germany

 

Objectives: Temporary restorations have to protect prepared teeth from chemical, physical and mechanical influences and should preserve occlusal function, aesthetics and phonetics. Therefore they have to fulfil a lot of requirements. This study compares temporary crown & bridge Materials and shows their physical properties.

Methods: The materials studied were: Luxatemp®Fluorescence (LF, DMG), IntegrityTM (IN, Dentsply), ProtempTM3 Garant (PG, 3M Espe), Systemp®C&B (SY, Ivoclar Vivadent), Kanitemp Royal (KR, Kanidenta), Structur Premium (SP, VOCO), Structur 2 SC (ST, VOCO) and Experimental 4:1 (EX, VOCO). Specimens (5mm x 5mm) for flexural strength (FS) and modulus of elasticity (ME) were prepared and measured according to ISO 4049. Cylindrical specimens (3mm x 6mm) were prepared for compressive strength (CS) measurements. After storage (1h or 24h, 37°C, water) the specimens were measured with a universal testing machine Zwick version 1446. Data were analyzed by one-way ANOVA followed by Duncan's multiple analysis on the .05 level.

Results:

 

LF

IN

PG

SY

KR

SP

ST

EX

FS 1h

[MPa]

35.4±4.1b,c

34.9±4.2c

62.7±3.0a

47.8±4.8b

30.4±4.5c

76.5±8.4a

81.5±5.3a

79.2±5.1a

FS 24h

[MPa]

84.9±4.2b

90.1±7.4b

106.8±9.5b

88.1±10.0b

79.9±6.5b

125.4 ±22.7a,b

118.8±7.8a

112.6±12.9a,b

ME 1h

[MPa]

347.2 ±46.2d,e

304.4 ±33.6d,e

520.0 ±28.3c

462.8 ±37.1c,d

305.5 ±38.1e

702.4 ±32.5b,c

762.4 ±104.0b

841.9 ±175.6a

ME 24h

[MPa]

930.2 ±45.2a

947.9 ±63.5a

887.4 ±49.8a

854.2 ±42.2a

879.5 ±48.0a

996.5

±93.0a

951.9 ±58.8a

949.1 ±158.8a

CS 1h

[MPa]

281.9 ±44.8b,c

295.2 ±52.6b,c

333.1 ±51.1c

263.5 ±37.5c

217.7 ±51.9c

445.3 ±42.9a

337.1 ±28.2b

298.4  ±37.4c

CS 24h

[MPa]

298.6 ±43.4a,b,c

308.4 ±36.0c

383.2 ±50.5a,b

272.4 ±33.9b,c

248.6 ±33.8b,c

457.5 ±69.7a

360.6 ±26.9a,b

323.4  ±45,5a,b,c

Conclusion: This study demonstrates that for some chemical cured temporary C&B materials it is advisable not to load the temporaries in the first hours after preparation since the curing is not completed yet and they don't fulfil minimum requirements in their physical properties.

 


1064 (114940)

Relationship between Heat Treatment Temperature and Fatigue Failure of Titanium. T. YOSHIDA, K. TAMURA, M. YAMAZOE, T. MIZOGUCHI, Y. KAWASE, T. NIIRO, S. NAGASAWA, and M. ITO, Matsumoto Dental University, Nagano, Japan

Objectives:

Working strain is present in titanium used for implants, and also implants produced with titanium.

In this report, after annealing titanium plates at 350, 400, and 450°C, we evaluated the bending test and fatigue failure of the titanium materials.

Methods:

ASTM Grade 2 Titanium plates (25 x 2 x 1 mm) were used as the specimens for the bending test (n = 5). Heat treatment of the specimens was performed at 350, 400, and 450°C in air for 40, 60, and 80 minutes, respectively.

Using a universal testing machine, we measured the bending strength and strain of the specimens.

After producing a groove (2 x 0.5 mm) on the titanium plates used for the bending test, we performed a fatigue failure test, using a fatigue testing machine, applying a strain of 250 µm to an area 3 mm from the fulcrum.

The fracture surface was observed by electron microscopy.

Results:

The bending strength of the specimens decreased after heat treatment. As a result of two-way ANOVA, there were significant differences for heat treatment temperature (p < 0.01).

Cycle times until fatigue-induced fracture were greater in the specimens treated at 400°C for 80 minutes, and at 450°C for 40 minutes. As a result of two-way ANOVA, there were significant differences for heat treatment temperature and the interaction of temperature and duration (p < 0.01).

The fracture surface was smooth in AS specimens, but striation structures and large granular structures were observed in heat-treated specimens.

Conclusion:

As a result of the observation of the fracture surfaces of the specimens after the fatigue failure test, we confirmed the striation structure and minute cracks.

We considered that minute cracks were caused by repetitive stress application, and when these cracks grew, brittle fracturing occurred.


1065 (117265)

Behavior of Ni-Cr dental alloys to postweld heat treatments. S. POROJAN, L. SANDU, and F. TOPALA, Victor Babes University of Medicine and Pharmacy Timisoara, University School of Dentistry, Timisoara, Romania

Objectives: The aim of the study was to evaluate the behavior of different Ni-Cr alloys to postweld heat treatment (PWHT) by destructive and nondestructive analyses.

Materials and methods: Cast plates of 5 Ni-Cr dental alloys were prepared and welded in a butt joint configuration, bilaterally, using a microplasma welder. The spot overlapping was more than 60%, using 1 mm in diameter wolfram electrode. The power step was varied (4 and 5), the pulse delay was maintained at 40 ms and the argon quantity at 5-6 l/min in all cases. 20 samples resulted, 4 for each tested alloy. Half of the welded specimens were heat treated 60 min at 800°C. They were analyzed macroscopically, radiographic and metallographic, the microhardness was determined in the base metal (BM), weld metal (WM) and heat affected zone (HAZ).

Results: The welding imperfections could be detected during these nondestructive analyses. Metallographic analyses showed cracks along the joining line and propagated along the grain boundaries. The base metal showed a dendrites microstructure that became finer after heat treatment. The microstructure of the welded zone appeared very fine. PWHT could increase the microhardness in the HAZ and produce fragile structures. Associated with welding defects, like voids and cracks, these can lead to an early degradation of the welded structure.

Conclusion: Even the chemical composition of all the alloys was similar, the weldability and their behavior at heat treatment was different. Therefore it is important that the new welding procedures be particularized for each alloy type. (TD_319)


1066 (117931)

Anodizing of Titanium alloy with Different Temperature of Electrolyte. J.M. PARK, I.S. PARK, J.G. KIM, and M.H. LEE, Chonbuk National University, Jeonju, Jeonbuk, South Korea

Objectives: This study evaluated the effects of the electrolyte temperature during the anodic spark oxidation of titanium alloy, and the surface characteristics of anodized oxide layer and hydrothermally treated layer. Methods: Electrochemical treatments were performed while applying the pulse current from 230 V to 320 V during anodic spark oxidation of Ti-6Al-7Nb alloy. A mixed solution of 0.015M DL-a-GP (DL-a-Glycerophosphate Disodium salt) and 0.2M CA (Calcium Acetate) was used as the electrolyte. During the surface treatment, the temperatures of electrolyte were maintained at 5, 25, and 45 oC, respectively. After Anodic spark oxidation, hydrothermal treatment was performed at 300 oC for 2 hours. Results: The time required for anodic oxidation increased with the temperature of electrolyte, and the breakdown voltage decreased. Numerous micropores < 3 mm in diameter were distributed homogeneously on the surface of the anodic oxide layer. After hydrothermal treatment, polygonal shaped and thin needle shaped HA crystals were precipitated on the surface. Anatase and rutile phases were observed on the anodized surface, and the hydroxyapatite phase was detected on the hydrothermally treated surface. The surface roughness was increased by anodic oxidation, it can have a direct effect on the higher bonding strength with bone. A good bioactivity of hydrotherally treated surface was observed after immersion in Hanks' solution for 2 weeks. Conclusion: The results of this study indicate that the anodic spark oxidized titanium alloy by applying pulse current has good bioactivity for implant materials. "This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD, Basic Research Promotion Fund) (KRF-2008-E00075)."


1067 (117933)

Compressive Strength of Seven Amalgams Under Different Conditions of Handling. I. SOLER, J. ELLAKURIA, I. SANCHEZ, A. GARCIA, P. CEARRA, G. TRIANA, G. IBASETA, and G. RODRIGUEZ, Basque Country University, Leioa, Spain

“Objectives:”

 

The objective of this investigation is to evaluate the  influence of condensation pressure and trituration time on  compressive strength, at one hour and seven days, of seven modern dental amalgams.

 

“Methods:”

 

Seven alloys precapsulated for dental amalgam were selectioned in this study: Ana 2000 (AN) and Cavex Avalloy  (CA) with lathe cut morphology, Tytin  (TY), and Megalloy  (ME) with spheric morphology, Dispersalloy  (DI),  and Permite C  (PE) with admixed morphology  and Tytin FC  (TFC) with hybrid morphology or spheres deformed by heating them. For testing the  compressive strength, five cylindrical specimens of each material were prepared  according to procedures in standard  ISO:1559,  tritured in a  Silamat® and tested after 1h and after 7 days in a testing machine INSTROM®. Two different amalgam preparation parameters were analyzed: Trituration time, five specimens with +50% overtrituration and five specimens with -50% undertritutation of manufacturerxs recommendations. The other parameter was condensation pressure, five specimens with 2,8 MPa of pressure and five  with 7 MPa of pressure. The specimens were tested after 1 h. and seven days of their preparation. The data were analyzed by Anova and Tukey tests for multiple comparison among the means, p<0.05.

 

“Results:”

 

Mean and standard deviations of the results obtained can be found in the table below:

 

 

MATERIAL

ISO:1559

2,8 MPa

7 MPa

+ 50%

- 50%

AN

1 h

87

35*

51*

81

57*

7 d

477

191*

335*

323*

376*

CA

1h

49

68*

31*

154*

38*

7 d

476

379*

350*

295*

371*

TY

1 h

183

123*

142

144

98*

7 d

486

416*

462

499

416*

ME

1 h

158

158

196

152

121*

7 d

416

410

366

392

335*

DI

1 h

76

52*

54*

105*

49*

7 d

472

362*

266*

366*

389*

PE

1 h

226

108*

169*

145*

144*

7 d

468

379

360*

460

398*

TFC

1 h

185

141*

142*

144*

97*

7 d

492

416*

462

499

420*

“Conclusion:”

 

All alloys showed a significant loss of compressive strength in undertrituration conditions. Lathe cut alloys were more affected than the sferic and hybrid. The compressive strength of admixed and hybrid morphology alloys prepared with a less condensation pressure showed significant lower values at one hour than at seven days.   


1068 (118119)

Development of TiNbZr alloys for dental implant: physiochemical characterization. A.L.R. RIBEIRO1, R. CARAM, Jr.2, F.F. CARDOSO2, M.F. LIMA1, and L.G. VAZ1, 1São Paulo State University-UNESP, Araraquara, Brazil, 2State University of Campinas-UNICAMP, Campinas, Brazil

The biomaterial titanium (Ti) is largely used in medical and dentistry areas to substitute biological structures due to its excellent properties. The mechanical properties can be improved when alloys elements are added to Ti. Actually, Ti-6Al-4V is an important alloy used for dental implant, but it is necessary to find a new Ti alloy to substitute it due to the toxicity of aluminum and vanadium elements. A suggestion is the addition of niobium (Nb) and zirconium (Zr) to Ti, once both elements have good biocompatibility. Objectives: The aims of this work are to formulate two experimental Ti alloys, Ti-35%Nb-5%Zr (alloy 1) and Ti-35%Nb-10%Zr (alloy 2) (wt%), and study its chemical and physics characteristics. Methods: The alloys ingots were arc melted under an argon atmosphere. The ingots were homogeneized (1000°C/8h), machined as discs (6mm x 5mm) and heat treated (1000°C/1h). The chemical analysis of the samples was accomplished by X–ray fluorescence (EDX), and the microestrutural evaluation by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Vickers hardness (n=8). Samples were prepared by standard metallographic techniques used for Ti and its alloys and etched with Kroll's reagent. Results: The EDX results indicated that the final alloys compositions are closed to the planned. The XRD diffractograms showed the precipitation of α and β phases in alloy 1 and only β phase in alloy 2. The SEM exhibited β grains with coarse boundaries that can indicates, probably, the presence of α phase at those boundaries in alloy 1 and the presence of β phase in alloy 2. The mean values of hardness were 240±28HV for alloy 1 and 185±14HV for alloy 2 (p<0.0001). Conclusions: It is possible to formulate a biocompatible Ti alloy for dental implants, and alloy 1 is characterized as α+β type and alloy 2 as β type. Financial support FAPESP (2006/06253-4).


1069 (118173)

Mechanical Properties of Titanium Cast with Al2O3-based Investment. Q. GUO1, H. SHIMPO2, M. KOIKE1, and T. OKABE1, 1Baylor College of Dentistry, Dallas, TX, 2Tsurumi University, Yokohama, Japan

Objective: This study investigated the mechanical properties of titanium castings made with a newly-introduced investment material.

Methods: Dumbbell-shaped specimens (gauge length: 20.0 mm; 3.0 mm dia.) (n=4) and plate specimens (10.0x5.0x2.0 mm) (n=2) were cast using commercially pure Ti (CPTi; ASTM Grade 2) in a MgO-based investment (Selevest CB, Selec, Japan) or a new Al2O3-based investment (Invest TiM, Selec) with a centrifugal-casting machine (Ticast Super R, Selec, Japan) or a pressure-casting machine (Autocast HC-III GC, Japan). Yield strength (YS, MPa), tensile strength (TS, MPa), and percent elongation (El, %) were evaluated. Vickers hardness was measured at 25 μm (HS) and 500 μm (HB) from cast surfaces. The thickness (tα) of the α-case layer was determined based on the hardness profiles. The data were statistically analyzed using two-way ANOVA (α=0.05).

Results: The results are as follows: [Means (SD); identical letters indicate no statistical differences (p>0.05)].

Mechanical Properties

YS

TS

El

HS

HB

tα

Ticast

Selevest CB

463(32)a

555(27)a

8.7(0.7)a

522(49)a

199(11)a

175(22)a

 Invest TiM

425(27)a

523(21)a

17.4(4.0)b

417(22)b

206(12)a

80(6)b

Autocast

Selevest CB

432(51)a

524(51)a

9.3(2.4)a

508(43)a

201(8)a

159(19)a

Invest TiM

417(23)a

504(8) a

15.3(3.5)b

458(37)b

203(12)a

90(12)b

Percent elongation of castings with the Al2O3-based mold was significantly higher than castings with the MgO-based mold (p<0.05). The HS of castings with the MgO-based mold was significantly harder than castings with the Al2O3-based mold (p<0.05). The castings with the MgO-based mold had a thicker α-case layer than castings with the Al2O3-based mold.

Conclusions: The limited ductility of titanium cast with the MgO-based investment was much more improved when cast with the Al2O3-based investment because of less reaction between the metal and the mold. This study was partially funded by NIH/NIDCR grant DE 11787.


1070 (119210)

SEM Analysis of Dental Amalgam Intermetallic Whisker Growth. T. BONSTEIN1, L.M. MIKULSKI2, M. BUSH3, and P.J. BUSH3, 1University of Manitoba, Winnipeg, MB, Canada, 2University at Buffalo, Buffalo, NY, 3State University of New York - Buffalo, Buffalo, NY

Objectives: The aim of this study was to investigate the influence of medium temperature and time on dental amalgam Hg intermetallic whisker growth using Field Emission Scanning Electron Microscopy FESEM and Energy Dispersive X-Ray Spectroscopy (EDS). Methods: Amalgam capsules (Valiant Ph.D Ivoclar VIVADEN) were triturated using amalgamator (Silamat Ivocclar VIVADENT) for 6 seconds. The amalgam mass was hand condensed into a split mold with dimension of 4mm x 8mm. Following the condensation the samples surfaces were burnished. The samples were removed from the split mold after 20 minutes and were randomly divided into 80 groups (n=5) according to the following conditions: 4 storage conditions (in air, purified water, tap water or saline) 4 different temperatures (at 4 C°, 24 C°, 36 C°, 56C°). SEM surface analysis was done at the following times after condensation: 1 hour, 24 hours, 2 weeks, 4 weeks or 2 year. Results: Examination of the amalgam surfaces revealed metal whiskers of different shapes and size in 22 out of the 80 groups tested. Storage in tap water and Saline solution induced whisker growth. Increase in temperature and storage time promoted whisker growth and increased whisker length. No metallic whiskers were found when amalgam was stored in air, purified water or when samples were evaluated one hour following condition. See Table-1. EDS evaluation identified the intermetallic whiskers to be composed of mercury and silver. Conclusion: The mechanism of whisker growth is unknown. This study identified that time temperature and media may influence this whisker growth in amalgam


1071 (119263)

Mechanical Properties and Microstructure of Alloys Casted Under Different Conditions. J.R.O. BAUER1, A.H. BASSO2, M.M. PINTO3, L.E. RODRIGUES-FILHO3, and A. REIS4, 1Universidade Bandeirantes, São Paulo - SP, Brazil, 2Universidade de São Paulo, São Paulo, Brazil, 3Universidade de São Paulo, São Paulo - SP, Brazil, 4Universidade Estadual De Ponta Grossa, Ponta Grossa, Brazil

Objectives: The purpose of this study was to evaluate the ultimate tensile strength (UTS), elongation (EL), microhardness (KHN), microstructure and fracture pattern of basic alloys (Ni-Cr, Co-Cr) and noble Pd-Ag alloy for metalloceramic restorations after casting under different conditions. Methods: Two Ni-Cr alloys (Wiron 99 [Bego, Germany] and Suprem Cast-V [Talladium, USA), one Co-Cr alloy (Remanium CD [Rematitan, Germany]) and one Pd-Ag alloy (W-1 [Willians Ivoclar/Vivadent, USA]) were employed. The casting conditions were: induction-Argon (IA); induction-Vacuum (IV); Induction/no atmosphere control (IN) and gas/oxygen blow pipe (BP). 16 specimens (25mm high and 2.5mm diameter) were prepared for each condition. The ultimate tensile strength (UTS) and elongation (EL) were evaluated in a testing machine and the Vicker's microhardness (VHN) was also measured (n=5 indentations in each specimen). The microstructures of the alloys were revealed and they were analyzed under SEM-EDS. Fractured specimens were evaluated under SEM. The data were submitted to a two-way ANOVA and Tukey test (0.05). Results: The Suprem Cast alloy showed the highest UTS means (MPa) (1027.0±XX) regardless the casting condition; Remanium CD reduced its UTS means when casted under controlled atmosphere. The UTS means of Wiron 99 and W-1 were the lowest and dependent on the casting condition. All alloys showed lower elongation when casted under the BP condition. Wiron 99 showed the highest EL (49%). The microhardness values were lower under the IA condition (277.4±72). Higher VHN values were observed for Suprem Cast alloy (359.6±17.1) compared to the others. Dendritic formation was observed for all alloys; however the volume of the interdendritic region was different one another. The fracture mode confirmed the fragile nature of the alloys with low EL as W-1 and Suprem Cast. Conclusions: The atmoshphere control during the casting procedure does not add any advantage in the mechanical properties of the alloys evaluated.


1072 (119709)

Critical Analysis on Cyclic Fatigue Testing of Rotary Endodontic Instrument. C.-W. CHI, and C.-P. LIN, National Taiwan University, Taipei, Taiwan

Objectives: Different methods have been used for cyclic fatigue testing of rotary instrument. Rigorous analysis on the strain and deformation of the instrument has seldom been made and testing results may not be interpreted on a common basis. In the current work, the effects of canal geometry and analysis method has been investigated to provide more understanding on the testing and analysis techniques.

Methods: The deformation of Maillerfer Dentsply ProTaper „¥ F2 rotary instrument in curved canals has been analyzed with the finite element (FE) method. Twenty-Seven parametric combinations involving 3 types of canals varying from snug to loose fit, 3 canal curvatures and 3 extents of insertions have been compared. Experimental verification of the fracture position has been carried out by operating the instruments in artificial canals formed by two matching metal blocks. The experimental results have been examined against a parallel finite element analysis, which provided the magnitudes and locations of the maximum bending strain in different canals.

Results: Results from a detailed FE model and a simple geometric model are discussed in the light of the current results. It was found that the commonly used canal curvature and extent of instrument insertion alone cannot quantify the severity of bending. The diameters and taper development of the canal and the instrument also played important roles. According to the trend of insertion or radius decrease, the transition of the maximum strain position is more close to the tip.

Conclusion: The magnitude and location of the maximum bending strain on a rotary instrument in a curved canal can be predicted with acceptable accuracy using the current FE model.


1074 (120389)

A Short Heat Cycling Spinel-based Investment for Titanium Casting. G.L. ADABO1, F. NOGUEIRA2, L.M. FAIS2, R.G. FONSECA2, and G.P. ROCHA3, 1Dental School of Araraquara, São Paulo State University, Araraquara/SP, Brazil, 2Dental School of Araraquara, São Paulo State University-UNESP, Araraquara/SP, Brazil, 3Federal University of São Carlos, São Carlos, Brazil

Objective: Traditional investments for titanium casting demand long heat cycling. The aim of this study was to evaluate the castability and the marginal misfit of titanium copings using two conventional investments and a novel spinel-based investment dried in microwave. Methods: Mesh pattern (15X15mm) and wax-up copings over implant abutment were used in the tests of castability (n=10) and marginal misfit (n=10), respectively. The investments used were phophate-based Rematitan Plus (RP), spinel-based Rematitan Ultra (RU) and the novel spinel-based Trinell (Group TR). The investments RP and RU were handled according to the manufacturer`s directions (Dentaurum) using a heat cycling of 9 hours (RP) or 7 hours (RU). The novel investment Trinell (TR) was dried into microwave oven at a low power for 8 minutes and was put in an oven preheated at 400oC, with 5 hours of heat cycling. The mold filling was calculated (%). The titanium coping was tightened to 10 Ncm torque on the abutment. The marginal misfit measures were performed with an optical microscope (15X) in 6 point around the abutment/coping interface (µm) using image analysis. Data of castability and marginal misfit test were analyzed by non-parametric test (Kruskal-Wallis). Results: The mean and SD of mold filling and marginal misfit were summarized in the Table.

TR

RU

RP

Mold filling (%)

69.13±16.18

55.61±14.74

9.33±3.08

Marginal Misfit (µm)

8.03±1.47

8.66±2.05

20.76±7.10

No significant difference was found between TR and RU for castability test (P=.358) but TR was significantly higher than RP (P=.0019). The TR marginal misfit was similar to RU (P=.8589), however the RP was significantly higher than TR (P=.0001). Conclusion: The novel investment TR with short heat cycling might produce suitable titanium castings, similar to the conventional spinel-based investment RU.

Supported by The State of Sao Paulo Research Foundation (FAPESP) - Grant 2007/00203-8


1075 (120718)

Effect of Palladium on the Corrosion Behavior of CoCr. D. SARANTOPOULOS, K.A. BECK, R. HOLSEN, and D.W. BERZINS, Marquette University, Milwaukee, WI

Recently introduced to the market has been an entirely new subclass of casting alloy composition whereby palladium (~approximately 25 wt%) is added to traditional base metal alloys such as CoCr and NiCr.

Objectives: The objective of this study was to evaluate the corrosion properties of a new CoPdCr alloy and compare it to a traditional CoCr alloy.

Methods:  Two casting alloys were investigated: CoPdCr (NobleCrown NF, The Argen Corporation) and CoCr (Argeloy N.P. Special, Argen).  As-cast cylinders were assessed electrochemically in an artificial saliva at 24oC.  The open circuit potential (OCP) was monitored for 20 hrs followed by polarization resistance and cyclic polarization tests.  OCP at 20 hrs, polarization resistance (Rp), and corrosion current density (Icorr) were compared using a t-test (n=6/alloy). 

Results:  The enclosed table displays the measured corrosion parameters (mean ± standard deviation).

Alloy

OCP (mV vs. SCE)

Rp (MOhms)

Icorr (nA/cm2)

CoPdCr

36 ± 60 A

3.6 ± 1.1 A

231 ± 186 A

CoCr

-133 ± 13 B

13.8 ± 4.8 B

34 ± 15 B

Different letters denote significant differences (p<0.05) between alloys. The palladium containing alloy possessed a significantly greater open circuit potential, however its corrosion current density was nearly 7 times greater than the traditional CoCr.  Additionally, a greater incidence of pitting was observed in the CoPdCr alloy. 

Conclusion: Inclusion of palladium in a CoCr alloy resulted in increased nobility but decreased corrosion resistance compared to a traditional CoCr alloy.


1077 (114942)

Hardness and Metallographic Structure of Commercial Titanium wires and Implants. K. TAMURA, T. YOSHIDA, M. YAMAZOE, T. MIZOGUCHI, T. NIIRO, Y. KAWASE, S. NAGASAWA, and M. ITO, Matsumoto Dental University, Nagano, Japan

Objectives:

Most implants are produced by metal machining, cutting titanium wire materials with several diameters suitable for fixtures. It is known that the mechanical properties of metals change with cold-working.

In this study, titanium with different diameters, titanium alloy wire materials, and implant products were compared, and the cause of fracture was evaluated from the results of hardness tests and the observation of metallographic structure.

Methods:

Titanium (ASTM Grade 2, Grade 4) with different diameters, titanium alloy wire materials, and implant fixtures were used as materials. Wire materials were cut into specimens of 5 mm in length, under running water and with the use of a precision cutting machine. The wire specimens and implants were fixed perpendicularly and embedded. Thereafter, with an automatic polishing machine, mirror polishing was performed up to the central area of the specimens.

Vickers hardness of the outer, middle, and central areas of the surfaces was measured (n = 5). After the specimens were etched in hydrofluoric acid solution, the entire metallographic structure was observed by laser microscopy.

Results:

The hardness of wire materials was higher in the order of Ti-6Al-4V > Grade 4 > Grade 2.

The hardness of the Grade 2 material was highest when the diameter was 2 mm, and lowest when the diameter was 3 mm. As a result of two-way ANOVA, there were significant differences for diameter and area, and for the interaction of diameter and area (p < 0.01).

Metallographic structure images changed with differences in diameters and measurement areas. The longitudinal section surface showed structure images stretched in the direction of the wire drawing. Metallographic structure images differing in diameters and measurement areas were also observed in implants.

Conclusion:

The processing degree changed with differences in diameter in titanium, titanium alloy wire materials, and implants. Furthermore, areas with different processing degrees were detected, and this may be a cause of fracture.


1078 (115240)

Comparison of Different Generations of Recasting for Palladium-Silver Porcelain Alloys. C.-C. HUNG, C.T. YEH, P.L. LAI, C.F. TSAI, and W.-C. CHEN, Kaohsiung Medical University, Kaohsiung City, Taiwan

Objective: Pd-Ag alloys are one of the favorable alloys for PFM restorations. The advantage of the argon casting machine is the elimination of the oxidation reaction during the casting procedure. In this study, the argon casting machine was used to evaluate recasting Pd-Ag alloys through four generations.

Methods: A phosphate-bonded investment (Fujivest II, G.C., Alsip, IL, USA) was used for investing. Jelstar (Pd 60%, Ag 28%, J.F. Jelenko, Armonk, NY, USA) was used for recasting, and to each generation was added 50% new alloy. An argon casting machine (Castmatic-S, Osaka, Japan) was used for casting. Each group had 3 samples. Comparisons were taken for marginal fit, surface hardness, surface roughness, and interfacial reactivity of these castings. Data were analyzed with a paired t test (p < 0.05). Results: The first-generation castings showed the least marginal gap and surface roughness (only between 1st- and 2nd- generation: p < 0.05). There was no significant difference in surface hardness, VHN (p > 0.05). The first-generation castings showed the least interfacial reactivity, and the alloy composition measured by EPMA showed no significant difference (p > 0.05).

Conclusions: The use of an argon casting machine can improve the oxidation activity and surface hardness of castings, even through four generations. There is a significant difference between 1st (31.1 ± 9.7 µm) and 2nd generations


1081 (121177)

Dental Amalgam Pollution in Trinidad and Tobago – Quantity and Mitigation. A. PARYAG1, A.S. PARYAG2, A. PILGRIM2, and R.N. RAFEEK1, 1University of the West Indies - Faculty of Medical Sciences - St. Augustine, Mt. Hope, Trinidad and Tobago, 2University of the West Indies, St. Augustine, Trinidad and Tobago

Objectives: The WHO has a Drinking Water Guideline of 0.001 mg mercury/L (0.001 ppm), which applies to all forms of mercury. In Trinidad and Tobago, no previous research has been done to estimate levels of mercury output from dental practices. The objective of this study was to assess the level of mercury released via dental amalgam waste into the environment in Trinidad and Tobago, and a review of the environmental impact and possible mitigation measures, including legislation.

Methods: Samples of wastewater during removal of 160 amalgam fillings were collected and analyzed for the amount of mercury present by Atomic Absorption Spectrometry. The number of amalgam fillings placed and removed over a weekly and monthly period from a random sample of dental practices in Trinidad and Tobago was obtained via questionnaires. The amount of mercury entering the environment from these practices was estimated.

Results: A mean concentration of 0.0759 ppm (or mg/L) mercury was found to be dissolved in solution (filtrate from the wastewater samples). The release per practice from solid and wastewater deposits was very high. 74.4% of respondents to the questionnaire used pre-capsulated mercury. 79.1% used only chairside traps and filters, and 0% had amalgam separators in their surgery.

Conclusions: The level of mercury released via dental amalgam waste into the environment in Trinidad and Tobago may be too high. With wastewater treatment plants being ill-equipped to handle mercury, legislation to protect the environment from this source of mercury is required.


1082 (113882)

Electrochemical behaviour of titanium in fluorides and chlorexidine antiseptics. A. QUARANTA, F. DI CARLO, L.F. RONCONI, S. CIAVARDINI, and I. VOZZA, University of Rome, Rome, Italy

Objectives: Titanium (Ti) is widely used in dentistry. It was observed that fluorides at acid pH could destabilize Ti oxide and make it susceptible to corrosion.

The behaviour of IV grade machined Ti disks in 5 electrolytic solutions: Fusayama artificial saliva (Fas),ammine fluoride-stannous fluoride (Am-SnF2), 0.2% Chlorexidine (CHX), 0,20%Fas with 20% Am-SnF2, and Fas with 20% CHX was evaluated.

Methods: Open circuit potential was determined by submerging 15 Ti disks (3 for each solution) for 24 hours in an electrochemical cell containing the solutions; potential changes were measured until reaching a stable value (Ecorr).

Examination by SEM (Scanning Electronic Microscope) was then performed.

Citotoxicity of the disks was determined trough 72-hours direct contact with fibroblasts l-929 of mouse connective tissue. Activity of succinate-deidrogenasy was evaluated.

Mean and standard deviation of all values were calculated .

One way analysis of variance(ANOVA) was used to determine the presence of significant differences of all the values .

The level of significance was p=0.05.

Results: One way Anova analysis showed a significant difference of Ecorr values regarding the 5 solutions

(p<0,001).

Highest values were observed for CHX (-87.6mV), intermediate for Am-SnF2(-81mV) and lowest for Fass

(-37.6mV).

SEM analysis of disks submerged in CHX showed a localized corrosion, while the other solutions showed no corrosive action on Ti surface.

Fibroblasts grew in monolayer on Ti, no evidence of cell damage was detected with microscopic examination. There was no significant difference of succinate-deidrogenasy activity of fibroblasts cultured on Ti (p=0.90).

Conclusions: Within the limits of this study it was observed that machined Ti do not form cytotoxic products of corrosion in different solutions.

All the specimens maintained biocompatibility

When considering corrosive potential range in oral cavity, Ti had an excellent behaviour on both antiseptics evaluated, however polarization curve in CHX showed a localized corrosion.


1084 (117871)

Influence of Peroxide-containing Alkaline Solution on Corrosion of Titanium Alloys. S. TAKEMOTO, M. HATTORI, M. YOSHINARI, E. KAWADA, and Y. ODA, Tokyo Dental College, Chiba, Japan

Objective: A number of studies have reported discoloration of denture plates with exposure to alkaline-peroxide in denture cleaner agents. This study investigated discoloration and dissolution of several titanium alloys with immersion in peroxide-containing alkaline solutions.

Methods: Commercially pure titanium (TI), Ti-6Al-4V (TAV), Ti-6Al-7Nb (TNB), and experimental Ti-20Cr (TCR) were used. The polished titanium alloys were immersed in hydrogen peroxide-containing alkaline solutions for up to 60 min. Three different concentrations of 50, 100, and 150 mM hydrogen peroxide (H2O2) in 154 mM NaCl solution were prepared. The pH in the solutions was 10, which was adjusted by the addition of small amounts of 1 M NaOH. Following immersion, changes in the color and glossiness of each specimen and released elements in the solution were determined.

Results: Color change (DE*ab) in TI immersed in 150 mM H2O2-containing solution for 10, 30, and 60 min was 0.7, 4.2, and 13.6, respectively. The DE*ab of TI increased with time of immersion (p<0.05). Color change in 50 and 100 mM H2O2-containing solution was similar to that in 150 mM H2O2-containing solution. Comparison of color change in titanium-based alloys after 60 min immersion revealed a larger DE*ab change in TAV and TNB than in TI, whereas TCR showed minimal color change. Difference in glossiness of TI decreased significantly with immersion in H2O2-containing alkaline solutions (p<0.05). Amount of released titanium from TI increased with time of immersion and concentration of H2O2. Total amount of elements released with 60 min immersion from TI, TAV and TNB in 150 mM H2O2-containing solution was 36.0, 56.4, and 66.5 mg/cm2, respectively, whereas it was less than 3 mg/cm2 from TCR.

Conclusion: Experimental Ti-20Cr showed minimal color change and the lowest degree of dissolution among the alloys tested with immersion in H2O2-containing alkaline solution.


1086 (117298)

Cast versus Laser-Sintered Cr-Co alloys: Study on mechanical characteristics. A. NATALI1, E. BASSOLI2, L. DENTI2, A. BERZAGHI1, M. FRANCHI3, S. BORTOLINI1, and U. CONSOLO1, 1Università di Modena e Reggio Emilia, Modena (MO), Italy, 2Università di Modena e Reggio Emilia, Modena, Italy, 3Universita di Ferrara, Ferrara (FE), Italy

Objectives:

Additive Layer Manufacture of dental prostheses allows the direct fabrication of parts from CAD data, replacing a human-sensible process with a faster reliable automatic one. Direct Metal Laser Sintering (DMLS) of Cr-Co alloys produces parts to be directly finished with ceramic and employed. Their clinical application requires a solid know-how on mechanical and functional characteristics, with respect to traditional cast parts.

Methods:

Tensile specimens were built (ASTM E8M) both by DMLS and traditional lost-wax casting, using the same Cr-Co alloy. An experimental plan was designed to evaluate the effect of all process phases. Standard parameters were used on EOSINT-M270 to fabricate the laser-sintered specimens. A group was left as-sintered (DMLS_L) and the others were heat-treated for stress-relief (DMLS). Wax parts were built by drop-on-demand, invested in ceramic and burnt away before casting (CAST). Then, two groups of specimens were subjected to the high temperature treatment used in ceramic covering without deposition (DMLS_H, CAST_H). On all specimens (6 for each of 5 groups) thickness was measured through a measuring microscope. Roughness was determined on Lm=4,8mm. Specimens were tensile tested obtaining UTS and percent elongation.

Results:

No significant dimensional variations were noticed among different processes. Sintered parts are on average rougher than cast ones (Ra~3.8vs2.6µm). UTS of all sintered specimens (~1400MPa) is almost double than of cast ones, where many porosities were found. Unlike cast parts, heat-treatment increases UTS for DMLS. Laser-sintered specimens are also much more fragile than cast ones (εb~5 vs 20%).

Conclusion:

DMLS of Cr-Co alloys produces excellent strength and absence of defects with respect to traditional casting. Low εb values are not critical, since deformation of the final prostheses is limited by the ceramic layer fragility. Slightly higher roughness of DMLS parts is likely to improve mechanical bonding with the ceramic layer or might be smoothed.


1087 (118422)

Cyclic Fatigue Resistance of Rotary and Reciprocating Endodontic Files. B.J. RASIMICK, R.P. SHAH, B.L. MUSIKANT, and A.S. DEUTSCH, Essential Dental Systems, South Hackensack, NJ

Objective:

To evaluate the cyclic fatigue resistance of endodontic files when subjected to a torsional load.

 

Methods:

The 2 brands of instruments tested in this study were rotary K3 files driven at 250 RPM and reciprocating SafeSiders driven at 2,500 RPM.  Instruments of size 15 0.02, 30 0.02, and 30 0.04 were tested.  The instruments were inserted into simulated root canals fabricated from stainless steel tubing.  X-ray analysis verified that the files were bent with curvature of 45±5° and an arc length of 8.5±0.5 mm.  The apical 3±1 mm of the instruments were embedded in acrylic resin and inserted into a micro-torque wrench capable of applying a adjustable load.   The total toque experienced by the instrument was measured with a micro-torque gauge.  Each brand/size combination was tested at 3 levels of total applied torque.  Instruments (8/gp, 144 total) were run and the time until breakage was recorded.  If no breakage was observed within 15 minutes, testing on that instrument was discontinued.  The survival of the two different brands was compared using log-rank analysis of the Kaplan-Meier curves.  The Bonferroni corrected significant P value is 0.006.

 
Results:

Size

Torque (N·cm)

Survival Time (min)

Significant Difference

SafeSiders

K3

15 0.02

0.05

15

15

 

0.15

15

0.19±0.18

P<0.001

0.25

15

0.05±0.02

P<0.001

30 0.02

0.05

15

15

 

0.15

15

7.76±3.52

P<0.001

0.25

15

3.07±0.58

P<0.001

30 0.04

0.2

10.56±4.43

4.55±1.06

P<0.001

0.3

9.08±4.95

1.82±0.98

P<0.001

0.4

3.10±2.19

0.69±0.57

P=0.002

Conclusion:

The reciprocating stainless steel 15 0.02 and 30 0.02 SafeSiders did not fracture under the tested conditions and the reciprocating nickel titanium 30 0.04 lasted 2  to 4 times longer than a comparable rotary K3 instrument.


1088 (116242)

Cyclic loading and stretching to asses denture adhesive performance. J.-C. DURAND, EA 4203 MONTPELLIER 1 UNIVERSITY, FRANCE, Montpellier, France, J. MARGERIT, EA 4203, MONTPELLIER 1 UNIVERSITY, FRANCE, Montpellier Cedex 5, France, M. WATTS, Pierre Fabre MEDICAMENT, Castres, France, H. VERCAUTEREN, Pierre Fabre Oral Care, Castres, France, and F.J. CUISINIER, EA4203, Montpellier Sud de France university, Montpellier, France

Objectives: In vitro evaluation of denture adhesives is usually described by tensile strength measurements. We present new tests based on cyclic loading and cyclic stretching.

Methods: Cycles are repeated in isotonic saline solution between acrylic resin samples on a universal testing machine. 3 g of the adhesive was applied to a dry and highly polished surface of the resin cylinders (PMMA, COLTENE - WHALEDENT) moulded to 25 mm in diameter. Then the cylinder was compressed on an equivalent counterpart in a thermostatic tub (isotonic saline solution at 37°C ± 1°C) with a 20 Newton force for 15 seconds. The patterns of rupture at the end of cycles are analyzed by environmental SEM.

Results: We have determine the best loading and retraction rate during loading cycle and stretching cycle taking into account the physiological values. It is important to note that the denture adhesion is increasing during cycling for one adhesive.

Conclusion: These new method of evaluation of denture adhesive is closer to the reality and mimic the movement of prosthesis during chewing.


1089 (117473)

Effect of Ricinus communis on the properties of denture liners. M.X. PISANI, C.H. SILVA-LOVATO, H.F.O. PARANHOS, R.F. SOUZA, and A.P. MACEDO, Universidade de São Paulo, Ribeirão Preto, Brazil

Objectives: This study evaluated the effects of sodium hypochlorite and Ricinnus comunis solution on the color alteration and hardness of soft denture liners. Methods: Sixty specimens of materials Mucopren Soft and Elite Soft were randomly distributed in three Groups (n=20): control - immersion in distilled water 370C; positive control - immersion in sodium hypoclorite 1%; experimental - immersion in Ricinus communis solution. The experimental period was 3 years of immersion for 20 minutes daily (T1), and 1 and a half year of immersion for 8 hours daily (T2). The color changes were measured by spectrocolorimeter to obtain the color differences of the specimens before and after the immersion; hardness was measured in a Shore A durometer. The data was submitted to Anova (P<.05). Results: For hardness, after T1, there was difference between the materials (P=.007) and solutions (P=.0002) and the sodium hypochlorite and the Mucopren presented the highest values; after T2, hardness changes were observed with some liners and solutions combinations (P=.0013). Sodium hypochlorite caused hardness increase for Mucopren and the Elite suffered a largest increase in hardness after the immersion in all solutions. For color changes, in T1 and T2, sodium hypochlorite caused a highest color alteration (P=.00) and the Elite soft suffered more alteration than Mucopren (P=.0010). After T2, Mucopren Soft suffered a higher color alteration than Elite when immersed in the experimental solution. Conclusion: After 3 years of immersion for 20 minutes daily, the Mucopren presented most color stability than Elite and an increase in the hardness. After 1 and a half years of immersion for 8 hours daily, the Mucopren was more stable in color alteration and hardness than Elite. The solution that most affected the properties of this study was the sodium hypochlorite. The experimental solution showed similar results of the negative control group.

(Finantial Support: CAPES)


1090 (114948)

Shock Absorption Characteristics of Commercial Custom-made Sports Mouthguard Materials. T. TAKAMATA, K. HASHII, T. YAMAKI, H. NUMAO, Y. KATO, and N. OKAFUJI, Matsumoto Dental University, Nagano, Japan

Objectives:The purposes of this study were to compare the shock absorption characteristics of commercially available custom-made sports mouthguard materials(MGs) and to evaluate the ratio of attenuation of impact force. Methods:Nine MGs (2.0mm thick) and eight MGs(4.0mm thick) were used. Seven specimens for each material and 63 specimens from nine materials(3.0mm x 3.0mm x 2.0mm thick)were made and 56 specimens were made from eight materials(3.0mm x 3.0mm x 4.0mm thick). A steel ball-drop test apparatus, comprising an impact device, three load cells, a connect box, a voltage box for the magnetic sysytem, and a memory recorder & analyzer, was used. All specimens were stored in temperature-controlled water bath at 37C for three minutes before measurements. The information obtained from the force transducer was used to determine the highest recorded force value observed for each material and each sheet thickness. Results:The most effective energy absorption of material(2.0mm thick) was polyolefin (PO)and polyolefin-polystyrene block copolymer(POPS)(4.0mm thick)(p<.05, ANOVA, Tukey's).Conclusions:Although there are many custom-made MGs on the market, we have no standards for selecting materials for use. From this study, it seems that the standard of choice was greater than 4.0mm in thickness and with a ratio of attenuation for energy absorbing materials greater than 85%. The results show PO and POPS were better materials than EVA(Ethylene Vinyl Acetic Acid) for MGs.


1092 (121045)

Scanning electron microscopic analysis of periodontal procedures on indirect restoration. P.B.F. SOARES, C.J. SOARES, A.J. FERNANDES-NETO, D. MAGALHÃES, P.C.F. SANTOS-FILHO, and P.V. SOARES, Universidade Federal de Uberlândia, Uberlândia, Brazil

Objectives: Adaptation and marginal integrity of restorations in the gingival area are crucial for periodontal health and longevity of the restoration. The aim of this study was to evaluate the influence of different periodontal procedures on the restoration surface and marginal integrity of indirect restorations, analyzed using scanning electron microscopy (SEM).

Methods: sixty extracted single-root human teeth were selected and randomly divided into 12 groups (n=5). Inlay cavity preparations were performed in the buccal region of the enamel-cementum junction, and restored with laboratory processed resin (Adoro) bonded with dual cure resin cement (Variolink). Samples were subjected to 12 periodontal procedures: C-without treatment (control); Rc-manual scaling with Gracey curette; Pa-prophylaxis with prophylactic paste; Pp-prophylaxis with pumice; Jb-sodium bicarbonate jet; Rc+Pa; Rc+Pp; Rc+Jb; Ru-ultrasonic scaling; Ru+Pa; Ru+Pp, Ru+Jb. The specimens were analyzed by SEM at 100 to 5000 magnification. Images of the restoration surfaces and interfaces were scored by 3 operators, where the scores were defined as: (1) no alteration; (2) moderate alteration; (3) severe alteration. Data were submitted to Kruskall-Wallis test (P<.05).

Results: No surface alteration found when only prophylactic pasted was used (score 1). Prophylaxis with pumice promoted growers on the restoration surface (score 2). Manual scaling with curette and ultrasonic scaling promoted growers and marginal fractures of the restorations (score 3). Sodium bicarbonate jet caused degradation of resin cement at the tooth-restoration interface (score 2).

Conclusion: According to qualitative analysis of the SEM images, it was concluded that, except for the prophylactic paste, all periodontal procedures affected the restoration surface and marginal integrity. Negative effects increased with multiple procedures.


1093 (119849)

Matrix Metalloproteinases in Human Radicular Dentin. J. SANTOS1, M.R.O. CARRILHO2, C. FERRAZ3, T. SORSA4, T. TERVAHARTIALA4, L. BRESCHI5, A. MAZZONI6, D.H. PASHLEY7, and L. TJADERHANE8, 1UNICAMP-Faculdade De Odontologia De Piracicaba, Piracicaba, Brazil, 2University of Campinas/FOP and Bandeirante University/UNIBAN, Sao Paulo, Brazil, 3University of Campinas, Piracicaba, Brazil, 4University of Helsinki, Helsinki, Finland, 5University of Trieste, Trieste, Italy, 6University of Bologna, Bologna, Italy, 7Medical College of Georgia, Augusta, GA, 8University of Oulu, Oulu, Finland

Objectives: Matrix metalloproteinases (MMPs) have been found entrapped in sound coronal dentin and may play a role in degradation of collagen networks. This study aimed to investigate whether these enzymes can also be detected in root dentin.

Methods: Crown and root sections of human third molars were separated and then pulverized into powder. Dentin powder from crown and root dentin was divided in aliquots that were separately submitted to a protocol for protein's extraction using guanidine-HCl and EDTA (Martin De-las Heras 2000). Zymography and Western blotting were used to characterize and identify the gelatinolytic enzymes extracted from these experimental samples.

Results: Zymography revealed gelatinolytic activity in both crown and root dentin samples, with bands corresponding to the molecular weight of MMP-2 and MMP-9 isoforms. Truncated forms of enzymes were also detected, as well as complexed, high molecular weight forms. MMP-2 activity was more evident in demineralized root dentin, whereas MMP-9 was mostly extracted from the mineralized compartment of dentin and presented an overall lower expression. Western Blot analysis was able to detect collagenase 2 (MMP-8) equally distributed in crown and root dentin.

Conclusion: The same MMPs that have previously been detected in coronal dentin are present also in root dentin, although some differences in the relative amount of each enzyme may occur. The impact of the activity of MMPs in the degradation of resin-dentin bonds should therefore be also addressed in the development of restorative strategies for the root substrate, including endodontic procedures.


1094 (116673)

Comparison of surface-hardness, surface-roughness and debris-retention of dentoform-tooth with alternative-materials. D. CHAMCHONG1, S. ARWACHANAKAN1, N. SOOKSUNTISAKOONCHAI1, and J. SUWANPRATEEB2, 1KHON KAEN UNIVERSITY, Khon Kaen, Thailand, 2National metal and materials technology center, Pathumtani, Thailand

Introduction: Dentoform tooth has long been used by dental students for dental laboratory practice. Since its price is getting higher, alternative materials that have lower cost would be beneficial. Thermosetting polymer such as epoxy resin is a material of choice for this study.

Objectives: To compare surface hardness, surface roughness and debris retention of dentoform tooth with four different alternative materials.

Methods: The specimens were divided into five groups (n=15/group): group1= dentoform tooth, group2=epoxy resin with 50%alumina, group3=epoxy resin with 60%alumina, group4=epoxy resin with 70%alumina and group5=polymethyl methacrylate. Each specimen was cut to 3mm thick and vickers hardness was measured by using 300gf for 15 seconds. Preparation for surface roughness and debris retention was carried out by cutting surface of each specimen with round-ended taper diamond bur. The surface roughness of each cut surface was measured by using contact stylus tracing profilometer (Leicester, England). The areas of debris retention on each cutting bur were investigated under stereomicroscope (Nikon, Japan).

Results: One-way ANOVA revealed the highest vickers hardness, the lowest surface roughness value and the lowest debris retention in group1 when compared to other groups with a statistically significant difference (p<0.05). Comparing within the groups of epoxy resin with alumina specimen, group4 showed the highest vickers hardness which was higher than group5 for 1 fold. Group3 showed the highest surface roughness value, however, the value was not statistically significant different from other epoxy resin groups. Group5 showed the highest debris retention and the lowest vickers hardness.

Conclusion: Although the epoxy resin with alumina material showed less promising quality of its surface hardness, surface roughness and debris retention compared to those of dentoform tooth, it is clearly superior than those of polymethyl methacrylate. Therefore, epoxy resin with alumina should be considered as a cost-effective alternative material for the development of dentoform tooth.


1095 (117336)

Fluoride and Aluminium Release from Restorative Materials Using Ion Chromatography. Z. OKTE1, S. BAYRAK2, U.R. FIDANCI3, and T. SEL3, 1Ankara University, Faculty of Dentistry, Ankara, Turkey, 2University of Ondokuz Mayis, Faculty of Dentistry, Samsun, Turkey, 3Ankara University, Faculty of Veterinary, Ankara, Turkey

Objectives: The aim of this study was to determine the fluoride and aluminium release from different restorative materials after storage in artificial saliva and double distilled water by ion chromatography.

Materials and method: Twenty disk specimens were prepared from each material; conventional glass ionomer (Kavitan Plus (KP), resin-modified glass ionomer cement (Vitremer)(V), polyacid modified composite resin (Dyract Extra)(DE) , and a composite-resin (Surefil) (S). Fluoride and aluminium concentrations in the solution were determined daily during the first week and then once weekly at 14 and 21 days. The amount of fluoride and aluminium was measured by using ion chromatography. Data were statistically analyzed using a two-way ANOVA and Duncan's multiple range tests (p<0.05).

Results: Vitremer released the highest amount of fluoride at all times in double distilled water(p<0.05). Except for difference between DE and S, statistically significant differences were observed in fluoride release in the first day among the test material (p<0.05). All materials released significantly more fluoride in double distilled solution than artificial saliva ( p<0,05). Vitremer released the highest amount of aluminum in double distilled water in the first day, followed by KP. Except for the first day, aluminium release from all materials in double distilled water and artificial saliva were not detected. No correlation was found between fluoride and aluminum release in double distilled water and artificial saliva.

Conclusion: In conclusion, the storage media and the method used should be taken into account when the fluoride and aluminium release from dental materials is assessed.


1096 (118617)

Assessing Fluoride Concentration and Leachability in Dental Varnishes. J.M. MCCRACKEN, B.D. SCHMUCK, and C.M. CAREY, Paffenbarger Research Center, Gaithersburg, MD

Clinical studies have suggested that for children at high risk for developing oral caries, semi-annual topical application of Anti-Caries fluoride-releasing dental varnish to primary dentition enamel can reduce the prevalence of dental decay. Variations in commercial product formulas can cause fluoride to be released at different initial rates, which should be measurable by a standard procedure.  Objective: To develop complementary standard methods to measure total fluoride and the fluoride leachability of two commercial varnishes that contain 5% NaF with different resin matrices.  Methods: Total Fluoride: 0.1-0.2g of varnish are combined with 4 mL chloroform and 10 mL TISAB II (Orion Research).  Place a stir bar in the vial, cap and stir for 1.5 h at room temperature then let stand without stirring 30 min to allow separation.  Leachable Fluoride: A known amount of dental varnish is applied in a thin layer on the end of a microscope slide (24x24mm) and permitted to air dry for 15 min.  Samples are submerged in 25 mL of dH2O in 50 mL centrifuge tubes and stirred.  1 mL samples of the bathing solution are taken and replaced with dH2O at 2, 4, 24, 96 and 168 h for analysis.  Fluoride concentration is determined by fluoride ion-selective electrode in 50% TISAB II solution.  Results: The total NaF measured was 5.03±0.43% (n=12) and 4.96±0.62% (n=12).   The two varnishes released fluoride at different rates.

 

 

Conclusions: The two methods are acceptable for the determination of total fluoride and fluoride release from F-varnishes.  Fluoride release from the F-varnish with the synthetic resin matrix was faster than that from the F-varnish with the natural resin matrix. Supported by the ADAF, NIST and DE14707.


1097 (114337)

The Effect of Sealant Types on Demineralization of Surrounding Enamel. A. ALSAFFAR, R. FEIGAL, D. TANTBIROJN, and S. BEIRAGHI, University of Minnesota, Minneapolis, MN

Purpose: To determine the differences between types of dental sealants in protecting surrounding enamel from demineralization challenge.

Methods: Fifty extracted human mandibular molars were used in this in vitro study. The occlusal surfaces were sealed using 5 different sealants: UltraSeal XT® plus (control), Fuji Triage® (glass ionomer), Clinpro® (fluoride), Bosworth Aegis® (amorphous calcium phosphate), and experimental self-etched sealant (fluoride). The sealed molars were immersed individually in a lactic acid gel for 20 days to produce artificial caries lesion. Then a cross sectional microhardness test was performed at 0.5 mm away from the sealant margin. The hardness values were converted to mineral content (volume%), the total mineral loss was calculated and subjected to ANOVA and Student-Newman-Keuls test.

Results: Means(SD) total mineral loss were: 1801(512), 87(124), 1004(420), 1274(375), and 1334(725) volume%-microns for UltraSeal XT® plus, Fuji Triage®, Clinpro®, Bosworth Aegis®, and experimental self-etched sealant, respectively. Glass ionomer sealant (Fuji Triage®) was significantly more effective in protecting the surrounding enamel 0.5 mm from the sealant margin than other sealants (p<0.05). Resin-based sealants with added fluoride (Clinpro® and experimental self-etched) or amorphous calcium phosphate (Bosworth Aegis®) had some protective effect when compared to the non-fluoride control (UltraSeal XT® plus) (p<0.05).

Conclusions: Resin-based sealants containing fluoride or amorphous calcium phosphate showed some protective effect on surrounding enamel from demineralization challenge. Glass ionomer sealant is the most effective in protecting surrounding enamel from demineralization.


1098 (119431)

Development of Fluoride Strips for Prophylaxis of Dental Caries. H.-T. WANG, and B.-S. LEE, National Taiwan University, Taipei, Taiwan

Oral health is closely pertinent to the overall health of human beings. Among the numerous factors influencing the oral health, the caries itself and the subsequent problems it causes play a great role in jeopardizing the oral condition. The fluoridated water is not used in Taiwan. In addition, the currently used caries prevention methods such as fluoridated rinse, fluoridated gel, fluoridated tablet, pit and fissure sealants, and glass ionomer cement, either cause tooth substance loss or fluoride intake by human body.

objectives:The main purpose of this project was to develop fluoride-releasing membrane composed of sodium fluoride and carbopol for caries prevention.

methods:We measured fluoride concentration on the enamel surface by using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and evaluated the efficiency of fluoride-releasing membrane on demineralization-inhibition and remineralization-promotion by using calcium electrode.

results:The results demonstrated that fluoride concentration on enamel surface gradually increased and reached the maximum after 8 hours of application. Using membrane 2 times a week with 4 hours each time could inhibit enamel demineralization. In addition, the membrane could promote enamel remineralization after 4 hours of application for one time.

conclusions:We concluded that fluoride-releasing membrane can inhibit enamel demineralization and enhance remineralization in this in vitro study. Its usage exhibits great potential on prophylaxis of dental caries.


1100 (115231)

Surface-Modified Filler Effects on Composite Properties. S. SUBRAMANI1, T.P. SCHUMAN1, J.D. EICK2, K.V. KILWAY3, E.L. NALVARTE4, and D.E. DAY1, 1Missouri University of Science and Technology, Rolla, MO, 2University of Missouri -Kansas City, Kansas City, MO, 3University of Missouri- Kansas City, Kansas City, MO, 4University of Missouri -Kansas City, School of Dentistry, Kansas City, Kansas City, MO

OBJECTIVES: The durability of dental composites are limited by polymerization shrinkage and stress, adhesion, strength, and toxicity. We are attempting to develop dental composites of low polymerization stress and shrinkage, high in strength, and have low toxicity. METHODS: Glass fillers of special composition and particle size distribution were prepared to obtain radiopacity and high packing densities. The glasses were then chemically surface-modified to attach methacrylic, glycidyl, and 3,4-epoxycyclohexyl functional groups via efficient alkoxysilane ligand reactions. The surface modification of fillers was confirmed by FTIR spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyses. Toxicity tests of the modified fillers and composites were also performed to check suitability. BisGMA-TEGDMA (control) and Silmix (®3M-ESPE) based photo-curable dental composites were formulated using the modified fillers to study the surface layer composition effects on particle dispersion, composite cohesion, and cure performance of the fillers. RESULTS: Dispersion and cohesion were found to be improved for select surface-polymer systems. CONCLUSIONS: Surface modification improved the composite filler dispersion and cohesion, without affecting cure or increasing toxicity. This work was supported in part by NIH-NIDCR grant R-21DEO18336.


1102 (118234)

Effect of APF Minute-Foam on Surface Roughness, Hardness of Nano-composites. H. KRAJEWSKI1, C. WIGGINS1, C.E. GARCIA-GODOY1, F. GARCIA-GODOY1, and P.C. HARDIGAN2, 1Nova Southeastern University, Fort Lauderdale, FL, 2Nova Southeastern University, Davie, FL

Objective: to evaluate the changes on the surface roughness, hardness and micromorphology of nano composites after 1 minute APF foam application. Methods: Three nano composites were tested (Filtek Supreme, 3M; Simile, Pentron and Premise, Kerr. Fifteen samples were made for each composite. Samples were prepared using a Teflon mold and light cured by a conventional halogen light following manufactures instructions. The specimens were allowed to set for 15 minutes at room temperature and then stored for 48 hours in artificial saliva at 37º. Profilometry and microhardness measurements were obtained of the untreated specimens (baseline).  The specimens were then rinsed with water, gently air-dried and treated with 1.23% APF Minute-Foam for 1 minute with a brush. Samples were gently dried and measured for hardness and roughness again. Statistical analysis was performed using two way ANOVA with interaction. The main effects were nano composites and condition, we also examined the interaction of nano composites by condition. Multiple comparison test were conducted using Tukey's HSD.

Results:

Roughness

 

Level

 

 

 

 

 

 

 

Least Sq Mean

Simile,Without Fluoride

A

 

 

 

 

0.17800667

Simile,With Fluoride

 

B

 

 

 

0.12208889

Filtek Supreme,Without Fluoride

 

B

C

 

 

0.10168889

Filtek Supreme,With Fluoride

 

 

C

D

 

0.08477778

Premise,With Fluoride

 

 

 

D

E

0.05742222

Premise,Without Fluoride

 

 

 

 

E

0.03177778

Levels not connected by same letter are significantly different.

 

                                                       Hardness

Level

Least Sq Mean

Filtek Supreme,With Fluoride

A

 

50.90

Simile,With Fluoride

A

 

50.10

Filtek Supreme,Without Fluoride

A

 

48.98

Premise,Without Fluoride

A

 

48.57

Premise,With Fluoride

A

 

48.16

Simile,Without Fluoride

 

B

43.32

Levels not connected by same letter are significantly different.

 

                                                                                     

Conclusions: After 1.23% APF Minute-Foam treatment, results showed that Simile presented changes on surface roughness (became smoother) compared to Filtek and Premise that showed no significant difference. Simile also improved surface hardness after 1.23% APF Minute-Foam application compared to Filtek and Premise.


1103 (121422)

Ions released from S-PRG filler and their acid buffer capacity. A. NAGAFUJI, K. SHINNO, T. NAKATSUKA, M. DEGUCHI, and N. NEGORO, SHOFU INC, Kyoto, Japan

Objective: As we previously reported (#2774, IADR2007), S-PRG filler has the acid buffer capacity, which releases 6 elements (analyzed by inductively coupled plasma (ICP) and fluoride electrode (FE)) by coming in contact with water, resulting in the change of the pH in the surrounding environment to a weak alkaline range. The purpose of this study is to investigate the ionic state of each element released from S-PRG filler in the solution.

Materials and Methods: After S-PRG filler (3µm) and distilled water (pH=5.9) were mixed for 24H with 1:1 ratio by weight, the liquid was separated and retrieved by the centrifuge. The elements released from S-PRG filler in the liquid were analyzed using ICP and FE, and also measured the variation of pH value using pH meter. Then, ionic states of the 6 elements (Al, B, F, Na, Si, Sr) released in the liquid were analyzed by ion chromatograph (IC).

Results: After 24H mixing, the pH value was changed from 5.9 to 7.8. It was analyzed using ICP and FE that the elements and their amounts released from S-PRG filler to distilled water were Al (86.2ppm), B (1989.1ppm), Na (498.5ppm), Si (52.4ppm), Sr (319.4ppm), and F (201.0ppm). It was also found that ionic states and amounts of the above-mentioned elements in distilled water were BF4-(0.3mg/L), BO33-(5300mg/L), F-(150mg/L), Na+(960mg/L), SiO32-(42mg/L), Sr2+(250mg/L), analyzed by IC. In addition, the peak area of Al3+ was detected but its quantity couldn't be determined because the peak area didn't change depending on the dilution ratio.

Conclusion: It was considered that the acid buffer capacity which S-PRG filler has was associated with Na+ and Sr2+ ions released from S-PRG filler. In the future, we will investigate the influence of various ions released from S-PRG filler on biological effects such as reinforcement of tooth enamel and re-mineralization of dentin.


1104 (118279)

Restorative Material and Occlusal Contact Location Influence Premolar Cuspal Flexure. T. OGANESYAN, USC School of Dentistry, Los Angeles, CA, and P. MAGNE, University of Southern California, Los Angeles, CA

Objectives: Measuring cuspal flexure of intact and MOD-restored maxillary premolars with different restorative materials and occlusal contact locations. Methods: Micro-CT data, stereo-lithography and surface-driven automatic meshing were used to generate premolar finite element models with an MOD cavity preparation and the corresponding restoration. The different tooth parts were then imported in a finite element software package to create 3-dimensional volumetric models. Occlusal loading either in enamel, at restoration margin or in restorative material was simulated by linear contact analysis. Cuspal widening was measured for the different contact locations and restorative conditions (unaltered tooth, MOD porcelain and composite inlay restorations). Results: A linear relationship between load and deformation was observed. For a given material property, contacts in restoration generated the least amount of cuspal deformation (highest cuspal stiffness), followed by the enamel contacts and contacts at restoration margin. Both models of the intact tooth and the ceramic inlay behaved similarly (cuspal widening at 100N ranging from 1.8-3.0 µm and 1.6-2.6 µm respectively). Cuspal flexure was increased in the MOD composite resin restorations (3.4-5.7 µm at 100N of axial force). The least amount of deformation was generated in the ceramic inlay with contacts in restoration only (1.6 µm at 100N) and the largest in the composite inlay with contacts at restoration margins (5.7 µm at 100N). For the composite restoration, antagonist contacts located at restoration margins were noticeably less favorable compared to those located either on enamel or on the restoration itself. Conclusion: A relatively small cuspal deformation was observed in all models, which is a warrant of cusp reinforcement by the adhesive restorative approach. The trends observed in this study are in agreement with existing data showing the increased cusp-stabilizing effect of ceramic inlays compared to composite ones.


1105 (118795)

Image-guided Selective Removal of Occlusal Caries with a CO2 Laser. Y.-C. TAO, University of California - San Francisco, San Francisco, CA, and D. FRIED, UCSF School of Dentistry, San Francisco, CA

Objectives: Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. Last year we successfully demonstrated that near-IR images can be used to guide a CO2 laser ablation system for the selective removal of artificial caries lesions on smooth surfaces. The objective of this study was to test the hypothesis that two-dimensional near-infrared images of natural occlusal caries can be used to guide a CO2 laser for selective removal. Methods: Two-dimensional NIR images were acquired at 1310-nm of extracted human molar teeth with occlusal caries. Polarization sensitive optical coherence tomography (PS-OCT) was also used to acquire depth-resolved images of the lesion areas. An imaging processing module was developed to analyze the NIR imaging output and generate optical maps that were used to guide a CO2 laser to selectively remove the lesions at a uniform depth. Post-ablation NIR images were acquired to verify caries removal. Results: Based on the analysis of the NIR images, caries lesions were selectively removed with a CO2 laser while sound tissues were conserved. However, the removal rate varied markedly with the severity of decay and multiple passes were required for caries removal. Conclusions: These initial results are promising but indicate that the selective removal of natural caries is more challenging than the selective removal of artificial lesions due to varying tooth geometry, the highly variable organic/mineral ratio in natural lesions and more complicated lesion structure.


1106 (118862)

Optical Coherence Tomography for In-vivo Assessment of Class-III Composite Restoration. A. SADR, Dental Materials Department, School of Dentistry, Shahid Beheshti University MC, Tehran, Iran, J. TAGAMI, Cariology and Operative Dentistry, Department of Restorative Sciences, Tokyo Medical and Dental University; GCOE Program at TMDU, Tokyo, Japan, Y. SHIMADA, Cariology and Operative Dentistry, Department of Restorative Sciences, Tokyo Medical and Dental University, Tokyo, Japan, and Y. SUMI, National Center for Geriatrics and Gerontology, Aichi, Japan

Optical coherence tomography (OCT) is a non-invasive technique that can produce cross-sectional images of substructures in biological systems at a high-resolution.

Objectives: The objective of this study was to utilize a novel OCT system to assess a class-III composite restoration clinically.

Methods: A class-III composite restoration in the distal of a lower left canine of a patient recalled 14 years after the treatment was imaged using a hand-held in-vivo scanning probe attached to a newly developed swept-source optical coherence tomography (SS-OCT) system (OCT-2000, Santec, Japan). The light source repetitively sweeps the wavelength from 1260 nm to 1360 nm at a 20-kHz sweep rate. The imaging depth of the system is about 3 mm; the axial resolution in air is 11 µm, and the lateral resolution of 37 µm is determined by the objective lens at the probe. A series of two-dimensional cross section images of the restoration were obtained in mesial-to-distal and incisal-to-cervical scans.

Results: In the visual examination, the restoration showed mildly discolored margins and the patient had no symptoms. OCT provided clear images of the restoration and the surrounding tissues. Cross-sectional OCT images showed that while enamel margins were sealed, there were some defects within the composite material and a loss of enamel and dentin up to 1 mm in depth was detected beneath the restoration.

Conclusions: OCT can non-invasively present valuable information on the structural soundness of the resin composite, marginal quality, secondary caries and hard tissue conditions beneath the restorations, presently not obtainable by any other means such as radiographic examinations. Chair-side imaging of composite restorations by OCT will open new horizons into non-invasive diagnosis and can be helpful in the selection of the most appropriate treatments and preventive measures. This study was supported by the G-COE program at TMDU.


1107 (119374)

Are Dentists Required to Perform Screenings?. A. DYKUN1, D. BROTHWELL1, and P.C. LEKIC2, 1University of Manitoba, Winnipeg, MB, Canada, 2University of Manitoba, Winnipeg, Canada

The University of Manitoba Variety Children's Dental Outreach Program utilizes general dentists (GP) to screen children in inner-city schools to identify children in need of treatment in order to generate a patient pool for the Faculty. This study investigated whether non-dentists could conduct these screenings.

Objective: The objectives of this ethically approved study are to determine the reliability of screening results when compared to two different gold-standards (G): (a) screening results obtained by a GP, and, (b) treatment needs as determined by subsequent treatment-plan.

Methods: 90 children were screened twice in the school environment, once by a non-dentist and once by a GP. The results were used to categorize the children into one of three groups; group 1 requiring urgent treatment, group 2 requiring less urgent treatment, and group 3 not requiring treatment. Groups 1 and 2 were seen at the Faculty and had a treatment-plan completed.

Results: Results for objective (a) are: sensitivity= 0.9259, specificity= 0.5556 and Ks= 0.4382. For objective (b), 17 of the original 90 children presented for comprehensive treatment plans at the Faculty with results for the non-dentist group as follows: sensitivity=0.8000, specificity=0.8571, Ks=0.5556; with 1 false positive and 3 false negatives. For the GP, results are: sensitivity=0.9000, specificity=0.8571, Ks=0.4767; there were no false positives and four false negatives. For the comparison of the results of brief screenings, Kappa value indicated only moderate agreement above chance.

Conclusion: These results give early indication that non-dentists may be able to reliably screen children according to criteria set out by the Faculty. However, further calibration of non-dentists may be necessary. It is important to note that these results should be interpreted with caution, as further investigation is necessary.


1108 (119708)

DIAGNOdent-pen: sensitivity and specificity in primary molars. C. FINKE, R. ERMLER, and P.-G. JOST-BRINKMANN, Charité - Universitätsmedizin Berlin, CC3, Berlin, Germany

Objectives: Due to the anatomy of deciduous molars, proximal caries cannot be detected at an early stage in crowded teeth by simply using mirror and probe. Therefore, additional methods to find early proximal caries have to be used.

Methods: Proximal surfaces between first and second deciduous molars of 31 children (4-9 years of age) were examined. 231 ²seemingly² healthy areas were examined from buccal and lingual/palatinal aspect using the DIAGNOdent-pen [KaVo, Biberach/Germany] with the commercial measuring probe and a thinner experimental probe. The classification proposed by Lussi (2006) for proximal caries in the permanent dentition was used. The results were compared with those obtained from bitewing radiographs and visual inspection after separation with elastic separators. The clinically determined actual lesion depth was then compared with the values obtained using the DIAGNOdent-pen. Sensitivity and specificity were calculated in order to compare the frequency of true positive and negative diagnoses of the DIAGNOdent-pen with that of the clinical/radiological diagnosis in addition a Receiver Operating Curve (ROC) analysis was carried out.

Results: Sensitivity and specificity refer only to those measured values distinguishing between absence of caries and presence of enamel caries. Cumulative effects caused by adjacent teeth affected by caries could not be demonstrated. The sensitivity in detecting a closed proximal area was: experimental probe (67%), original probe 78%, in opened proximal areas: 75% and 89%, respectively. Both probes deliver results that are superior to the level achieved by radiological examination (63.5%). The ROC analysis showed that the specificity and sensitivity for absence of caries was highest with a measured value of £7.

Conclusions: Laser fluorescence does not render any of the existing diagnostic approaches obsolete; however, it represents a valuable supplement. In future, the classification proposed by Lussi (2006) should be adjusted for deciduous molars.


1111 (120581)

Computer-Assisted Diagnosis of Interproxmial Caries on Bite-wing Radiographs. T.-S. KIM, University Hospital of Heidelberg, Department of Operative Dentistry, Section of Periodontology, Heidelberg, Germany, A. SCHULTE, University of Heidelberg, Heidelberg, Germany, and P. EICKHOLZ, JWG-University of Frankfurt, Frankfurt, Germany

Objectives: Radiographical diagnosis of interproximal caries is difficult in terms of reproducibility. Thus, improvement of diagnostic methods is still a goal of clinical research. The aim of this study was to compare the diagnosis of interproximal carious lesions on standardized bitewing radiographs both directly by analyzing conventional films with a loupe and with the help of a special computer program after digitalization of these conventional radiographs. Methods: 78 patients underwent standardized conventional bitewing radiographs for detection of interproximal carious lesions. In total n=625 interproximal surfaces were evaluated on conventional films with a magnification aid (LOUPE) and on a monitor after scanning the conventional films and subsequent digitalization (COMP) by an experienced examiner on a scale from C0-C4. Agreement between both methods was calculated both with weighted kappa (kw) and prevalence-and-bias-adjusted kappa statistics (PABAK) for different thresholds of therapeutic intervention. Results: Agreement between both methods was moderate (kw=0.547, sE=0.032). 133 lesions (21.3 %) were diagnosed with both methods, 80 lesions (12.8 %) were only diagnosed with LOUPE, 41 lesions (6.7 %) were exclusively diagnosed with COMP. PABAK-statistics depending on hypothetic thresholds for therapeutic interventions were: 0.613 (95 % CI: 0.551-0.675) for C1, 0.722 (95 % CI: 0.667-0.776) for C2, and 0.920 (95 % CI: 0.889-0.951) for C3. Conclusions: Digitalization and the use of a computer software can lead to changes in the interpretation of the size of interproximal carious lesions and thus alter therapeutic decisions.


1112 (120600)

In-Vitro-Diagnosis of Interproximal Carious Lesions with Micro-CT. N. ZIMMERMANN1, D. JOERSS1, J. SEIDEL1, R. COSGAREA1, U. RIETDORF2, and T.-S. KIM1, 1University Hospital of Heidelberg, Department of Operative Dentistry, Section of Periodontology, Heidelberg, Germany, 2German Cancer Research Institute, Heidelberg, Germany

Objectives: Diagnosis of interproximal carious lesions still is a challenge due to the lack of reproducibility of clinical diagnoses and poor inter-rater agreement in the interpretation of conventional bitewing radiographs. The aim of this study was to evaluate the reproducibility of a micro-computertomographic method (micro- CT) to diagnose the extent of interproximal carious lesions in an in-vitro model. Methods: Artificial carious lesions were generated on the approximal surfaces of 45 extracted teeth with the help of a demineralizing chemical agent. Artificial interproximal spaces were created by incorporating the teeth with the artificial defects into plastic block models. Each model consisted of 5 teeth (canine, first and second premolar, first and second molar) with 8 interproximal surfaces. Two experienced examiners had to diagnose the amount of interproximal caries on 72 surfaces on a scale from C0 to C4 with 3 different methods: Clinical examination, interpretation of standardized bitewing radiographs, interpretation of micro-CTs. The micro-CT made sections of the teeth in 0.1-mm increments in three different sectional planes. Inter-examiner agreement for the 3 different methods was calculated with weighted-kappa statistics. Results: Inter-examiner-agreement was only fair for the clinical examination (kw = 0.321, SE=0.069). The use of bitewing radiographs for quantification of interproximal lesion resulted in a moderate inter-rater agreement (kw=0.600, SE=0.068). With the help of a micro-CT, agreement between the two examiners was very good (kw=0.824, SE=0.054). Conclusions: With the help of a micro-CT, reproducibility of interpromixal caries lesions could be enhanced in comparison to conventional bitewing radiographs in an in-vitro model. Further studies are necessary to evaluate to which extent conventional radiographs can give a realistic picture of demineralized interproximal areas.


1113 (120623)

Leukotoxine Gene in Patients with Severe Forms of Periodontitis. P. FRANK1, S. EICK2, C.-K. KIM3, P. EICKHOLZ4, and T.-S. KIM1, 1University Hospital of Heidelberg, Department of Operative Dentistry, Seciton of Periodontology, Heidelberg, Germany, 2University Hospital of Jena, Jena, Germany, 3Yonsei University College of Dentistry, Seoul, South Korea, 4JWG-University of Frankfurt, Frankfurt, Germany

Objectives: Detection of Aggregatibacter actinomycetemcomitans (A.a.) is important to establish an effective adjunctive antibiotic therapy in patients suffering from severe forms of chronic and aggressive periodontitis. Microbiological tests often exhibit marked differences with regard to their sensitivity and specifity for the detection of A.a. The aim of this study was to compare the results of a commercially available testkit for periodontal pathogens with an individualized realtime PCR in a research laboratory and a specific test to detect the leukotoxine gene of A.a. in subgingival plaque samples from patients with aggressive and severe chronic periodontitis. Methods: Subgingival plaque samples were drawn from 193 patients diagnosed either with severe chronic or aggressive periodontitis. All samples were screened for A.a. with a commercially available testkit for periodontal pathogens and an individualized laboratory realtime PCR to detect A.a.. Furthermore, the presence of leukotoxine gene of A.a. was analyzed in all samples that had been tested positively with the individualized realtime PCR. Results: 47 patients (24.4 %) were tested positive for A.a. with the individualized realtime PCR, 59 with the commercially available testkit (30.6 %). The leukotoxine gene could be detected in samples from 43 out of 47 patients (91.5 %) that had been tested positively for A.a.. Conclusions: The results obtained with different microbiological tests to detect periodontal pathogens – especially A.a. – should be interpreted with care. Further investigations focussing on the detection of leukotoxine gene of A.a. in patients with severe chronic and aggressive periodontitis are necessary.


1114 (121446)

Photostimulable-phosphor digital subtraction radiography using a cross-arch biteplate. R. COUTURE1, C. HILDEBOLT1, N. GARCIA2, and D. DIXON3, 1Washington University, Saint Louis, NE, 2Saint Louis University, St Louis, MO, 3Southern Illinois University, Alton, IL

Objectives: To describe our methods for measuring small changes in alveolar bone, using photostimulable phosphor radiography and a new method for rigid, precise patient alignment; problems encountered are also discussed.

Methods: Subjects were rigidly attached to the X-ray tube by occlusal registration, using a cross-arch bite plate which is attached to the tube head with a vacuum coupling device. The photostimulable phosphor system has an accurate, proportional response to X-rays, which allows subtraction radiography without contrast corrections. A 16-bit gray scale gives