0001 (111115)

An investigation of impression techniques used for maxillary fibrous ridges. L. KWASNICKI, T.P. HYDE, and P. BRUNTON, University of Leeds, United Kingdom

Objectives:

To compare the dental casts of maxillary fibrous ridges made from the Watson (1970) ‘window' technique with casts made from a new technique advocated by Lynch and Allen (2006).

Methods:

Two impressions where taken of two different patients'; one impression using the Watson technique, the other the Lynch/Allen method. For each patient a palatal locating device was used to orientate the two casts in an identical 3D position, relative to a precision diamond saw. Each cast was sectioned laterally at four identical predetermined distances. The sectioned casts were placed into a custom built photographic jig with the camera set at a predetermined distance. One to one images of the cut surfaces were produced. The images were imported into Adobe photo shop and converted into a line graphic. For each patient the images taken at corresponding points on the two different casts where assigned different colours and overlaid producing the final image.

Results:

The photographs and line diagrams show the differential movement of the fibrous ridge between the two impression techniques. In this study the incisive papillae of the casts from the Lynch technique are displaced more posteriorly.

Conclusion:

Within the confines of this study the two impression techniques produced distinctly different casts; with the maxillary fibrous ridges displaced in a consistent but different manner. Further studies with greater numbers are required to confirm the consistency of these results and to enquire into the clinical success of dentures made from the 2 impression techniques.


0002 (111077)

Assessing Manual Dexterity in the BDS Curriculum. A. AKRAM1, R. ULLAH1, M.T. BASHIR2, A. SARWAR1, M. DICKSON1, and P.J. HODGE1, 1University of Glasgow, United Kingdom, 2Dundee Dental Hospital, United Kingdom

Objectives: This study follows on from an earlier study investigating the role of manual dexterity testing in the Bachelor of Dental Surgery admissions process. The aim was to investigate the effect of:

a) clinical exposure and training on the development of manual dexterity

b) the implementation of the Post-2004 Bachelor of Dental Surgery degree curriculum on manual dexterity.

Methods: In total 246 students from the first, second, third (post-2004) and fourth (pre-2004) years of a five-year undergraduate dental degree took part in the study. The student cohort in the fourth year had previously been tested under the same protocol three years previously thereby providing a basis for the longitudinal assessment. In the Post-2004 BDS curriculum, clinical exposure began in the first trimester of the second year of the curriculum whereas in the Pre-2004 BDS curriculum this commenced later, in the last trimester of the third year. Manual dexterity was assessed using two simple exercises; a needle threading test and a buzzer test.

Results: A statistically significant relationship showing that manual dexterity improves with increased clinical exposure and training was seen in the fourth year cohort in both the needle threading test (P = 0.0000) and the buzzer test (P = 0.0001). With reference to the implementation of the Post-2004 BDS curriculum, a statistically significant increase in dexterity was exhibited in the buzzer test when Post-2004 curriculum third-year students were compared to Pre-2004 curriculum third-year students (P =0.0003), however the increase was not significant for the needle threading test (P = 0.45).

Conclusion: Manual dexterity improves with increased clinical exposure and training. However, further studies should be undertaken to determine the impact of changes in the undergraduate dental curriculum on the manual dexterity of students.


0003 (111104)

Cost-Effectiveness of Supportive Periodontal Care. F. GAUNT, M. DEVINE, M. PENNINGTON, and C. VERNAZZA, Newcastle University, Newcastle Upon Tyne, United Kingdom

The long-term stability of successfully treated periodontitis demands compliance with supportive periodontal care (SPC).

Objectives: to construct a model to evaluate the cost-effectiveness of SPC when delivered in specialist or general dental practice (private or NHS-based) with 30-minute and 20-minute appointments respectively.

Methods: The model was constructed from the perspective of a single patient over 30 years. The primary outcomes were tooth years lost and clinical attachment level .The clinical data for the model were extrapolated from a systematic review undertaken by the authors (Gaunt et al. 2008; in press).

Results: Over 30 years, difference in costs incurred by the patient when SPC was provided in specialist compared to private general practice was €4466; difference in costs between specialist and general (NHS) practice SPC provision was €5938. In terms of discounted tooth loss, an extra 20.59 tooth years were lost for generalist compared to specialist SPC and an extra 3.95mm of discounted clinical attachment loss. Using private, generalist SPC as baseline, the incremental cost-effectiveness ratios (ICERs) for SPC delivered in specialist care were €217 for 1 extra tooth year and an additional €1130 for 1mm less attachment loss. Using NHS generalist SPC provision as the baseline, the ICERs were an extra Euros288 for 1 extra tooth year or an extra €1503 per 1mm less loss of attachment in specialist care. A sensitivity analysis was undertaken to vary appointment times: for example, by increasing specialist appointments to 60-minutes and maintaining generalist appointments at 20-minutes. The respective ICERs increase to €515 per tooth year and €2683 per mm of attachment.

Conclusion: SPC delivered in specialist compared to generalist dental practice, will be more expensive but will likely result in greater periodontal stability and higher tooth survival rates.


0004 (111337)

Gas, Shh and Holoprosencephaly. M. SEPPALA1, M. DEPEW1, D. MARTINELLI2, C.-M. FAN2, P.T. SHARPE1, and M. COBOURNE1, 1King's College London, United Kingdom, 2Carnegie Institution of Washington, Baltimore, MD, USA

Introduction:

Growth arrest-specific gene 1 (Gas1) encodes a GPI-linked membrane glycoprotein that has been shown to act as an inhibitor of Sonic hedgehog (Shh) signalling. Shh plays a critical role during craniofacial development. Loss of Shh signalling in mice and humans can lead to holoprosencephaly, a congenital disorder characterized by failure of the embryonic forebrain to subdivide into two telencephalic vesicles and defects in midline development of the face. It also plays an important role in palatal and tooth development.

Objectives and Methods:

Objective of this study was to analyse the craniofacial phenotype of Gas1-/- mice and investigate possible genetic interactions between Gas1 and Shh through generation Gas1-/-Shh+/- mutant mice.

Results:

Anomalies found in Gas1-/- mice predominantly affect the craniofacial midline including cleft palate, premaxillary hypoplasia, single maxillary incisors and pituitary gland malformations. They also have premolar-like supernumerary teeth. Molecular investigation and genetic analysis by utilizing Gas1/Shh mice provided convincing evidence that these molecules positively interact: the loss of a single Shh allele in a Gas1 mutant background produced a more severe defect of the facial midline. Interestingly, they also display a mirror image of the proximal mandible including a presence of ectopic tooth formation.

Conclusions:

Midline defects seen in Gas1 mutant mice are characteristic of mild holoprosencephaly, the most common structural anomaly of the human brain (1:250 embryos, 1:10,000-20,000 births). This study represents GAS1 as a candidate modifier gene for this condition and prompts speculation that Gas1 might, contradictory to its previously known role, facilitate long-range shh signalling. However, presence of supernumerary teeth is suggestive of abundant Shh signalling and Gas1 might differentially regulate Shh signalling in the first branchial arch derivatives in comparison to other facial structures.

Funded by a European Union Early Stage Marie Curie Fellowship, Contract No MEST-CT-2004-50402


0005 (111520)

Muscle-Nerve Interactions in Chimaeric In Vitro 3D Collagen Models. W. HAKIM, A. SMITH, B. KAZMI, B. KALMANN, A. SOLOMON, V. SALIH, L. GREENSMITH, V. MUDERA, and M.P. LEWIS, Eastman Dental Institute for Oral Health Care Sciences, London, England

Objectives: Perturbations and alterations in the pterygomasseteric sling are vital in a whole range of clincial conditions. Adaptation of these muscle is required for a successful response to orthognathic surgery and functional applicance therapy whilst TMJ disorder also has a major muscular component. Engineered functional 3-D neuromuscular constructs would be valuable as in vitro test systems and could extend to future applications in skeletal muscle tissue replacement. Both sensory neuron afferents and motor neuron efferents are required to interface with jaw muscle. Therfore the objectives of this study were to assess the formation of nerve-muscle interactions in 3-D neuromuscular constructs.

Method: 3-D collagen constructs (75x25x15 mm) were seeded with primary muscle precursor cells (MPC) and dorsal root ganglion cells-E7-10 (DRGs) or motor neurons, or a combination of both. Constructs were tethered at either end to develop an endogenous static load and allowing the re-alignment of cells parallel to lines of stress. This promoted formation of syncitial myotubes. Gene expression of myogenin and nAChR-epsilon were quantitated. Sucessful motorneurone isolation allowed us to seed these with MPCs within the the same type of 3-D construct. Immunostaining was used to image samples of the second model.

Results: MPC seeded constructs developed syncitial myotubes. DRG co-cultures demonstrated cell viability and alignment over the culture periods. Gene expression showed overall increases in both myogenin (0.26±0.03 for co-cultures vs. 0.08±0.01 for MPC alone) and nAChR-epsilon (0.85±0.26 for the co-cultures vs. 0.41±0.11 for MPC alone) mRNA expression when compared to single culture only.

Conclusion: Two chimaeric 3-D co-culture systems have been created with a cellular nerve-component.


0006 (111017)

Increased Osteogenic Activity of 45S5 Bioglass by Addition of rhBMP-2. F. MIRVAKILY1, A. RAWLINSON2, P.V. HATTON3, and A. CRAWFORD3, 1University of Shefield, Sheffield, England, Uk, 2University of Sheffield, England, 3University of Sheffield, United Kingdom

Objectives: 45S5 Bioglass is commonly employed to promote bone regeneration in periodontal defects . While the outcome is successful, the degree of bone regeneration is inconsistent. The aim of this study was to investigate whether 45S5 Bioglass loaded with recombinant human bone morphogenic protein-2 (rhBMP-2) could enhance the osteogenic activity of bioglass using an in vitro model.

Materials & Methods: 45S5 Bioglass discs were fabricated (10 mm diameter, 1 mm depth) and loaded for 24 hours with 100 ng of rhBMP-2 in 1ml of PBS/0.01% BSA. Mesenchymal stem cells (MSCs) were cultured from bone marrow taken from 5-6 week old female wistar rats and second passage (P2) cells were used for all experiments. MSCs were transferred to multiwell plates and cultured for two weeks in serum-free media (DMEM/0.1%BSA, ITS+ premix, 50µg/ml L-ascorbic acid, and 10 mM ß-glycerophosphate), in the presence of PTEE inserts containing the rhBMP-2 loaded bioglass or control bioglass discs. Cell proliferation was evaluated using Almar blueTM and cell morphology was examined using SEM. Osteoblast differentiation was investigated by measurement of alkaline phosphatase activity, calcium deposition and immunolocalisation of collagen type I.

Results: An increased rate of cell proliferation was observed at days 4 and 8 in MSCs cultured with rhBMP-2 loaded bioglass compared to control discs. Osteoblastic differentiation was also found to be significantly greater (p < 0.05) in MSC cultures containing the rhBMP-2 loaded bioglass as shown by increased alkaline phosphatase activity, collagen I deposition and bone nodule formation.

Conclusion: Loading 45S5 Bioglass with rhBMP-2 enhanced its ability to promote osteogenic differentiation of MSCs in vitro.


0007 (110490)

Microarray-Analysis of the Odontoblast Transcriptome in Primary and Secondary Dentinogenesis. S.R. SIMON, University of Birmingham / University of Paris 7, United Kingdom, A. SMITH, Birmingham University, United Kingdom, P. LUMLEY, University of Birmingham, England, Uk, A. BERDAL, INSERM, Paris, France, and P.R. COOPER, University of Birmingham, United Kingdom

While dentine secretion occurs throughout life, there are significant rate differences between primary and secondary dentinogenesis.. During primary dentinogenesis, odontoblasts are actively secreting cells and become quiescent during secondary dentinogenesis, although they can be up-regulated again in response to an injurious challenge. In a preliminary study, we showed that differential changes in gene expression occur during primary and secondary dentinogenesis, which indicate probable modifications in transcriptional control. Objective: To investigate genes and potential pathways involved in differential behaviour of odontoblasts during primary and secondary dentinogenesis . Methods: Coronal pulps were removed from immature developing (ES) and mature erupted (LS) bovine teeth from 30month old animals and RNA from odontoblasts was selectively extracted (McLachlan et al – Arch Oral Biol 2003;48:373-83). Microarray analysis (Affymetrix) was used to compare the transcriptomes between the two odontoblast populations. The two samples were analysed in duplicate using Bovine GeneChip microarrays (900561). Bioinformatics analysis was conducted using three software programmes (D-chip, Onto-Express and Pathway express). In parallel, 15 genes (IBSP, DCN, CASR, SSB-2, SPP1, ProteinS100, OSTF1, PROTEIN45a, SOSTDC1, TWIST1, PTPRR, NTRKK2, MAPK13, MKK3, MAP2K1) were compared by RT-PCR using experimental replicate samples of each population of odontoblasts (ES and LS). Results: Of the 24,000 genes analyzed, 764 genes were upregulated and 574 down-regulated in early stage (ES) compared to late stage (LS) odontoblasts (p<0.05). The encoded molecules were involved in various cellular pathways with 6 genes identified from the MAPKinase pathway. RT-PCR data generally confirmed microarray results, with good agreement between biological duplicate samples. Conclusion: The differential changes in gene expression in primary and secondary dentinogenesis indicate modifications in transcriptional control of the cells and highlight the importance of these control mechanisms both in the characterization of cell phenotype and to our understanding of control of cell secretory behaviour during regenerative processes.


0008 (110292)

Expression of BMP and wnt inhibitors by rat periodontal tissues. M.S. GHUMAN, M. AL-MASRI, K. TROCKA, I.J. MCKAY, and F.J. HUGHES, Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives: Bone formation may be controlled by the inhibitory action of superficial connective tissues limiting the regenerative potential of bone in periodontal or implant applications. The aim of this study was to investigate the hypothesis that gingival fibroblasts (GF) inhibit BMP and wnt activity, and to determine expression of their antagonists.

Methods: Constitutive expression of 9 BMP and 5 Wnt inhibitors by gingival fibroblasts (GF) was determined by Taqman real-time RT-PCR and compared to expression from periodontal ligament fibroblasts (PDLF). Effects of BMP-stimulation on inhibitor expression were tested by stimulation of cultures with 100ng/ml rhBMP-2 at 2, 6 and 24hrs. Reactions were normalized to GAPDH and EifA2 expression.

To test total BMP-inhibitory activity of rat GF, conditioned medium (CM) was collected from GF cultures over 48 hours and compared with CM from PDLF. Untreated serum-free media were used as controls. ROS17/2.8 (ROS) cells were stimulated with rhBMP-2 at doses up to 10ng/ml, together with CM or controls. BMP-induced osteoblastic commitment was assessed after 72 hours by measuring total alkaline phosphatase activity spectrophotometrically.

Results: 7 out of 9 BMP inhibitors and all 5 wnt inhibitors tested were constitutively expressed by GF. The inhibitors Gremlin-1(2.52x c.f. controls), DAN(0.64x) and Gremlin-2(0.23x) had particularly high levels of basal expression. BMP-stimulation had little effect on inhibitor expression. SFRP-1 was highly expressed in PDL cells. 10ng/ml BMP-2 increased AlP expression in ROS cells by X 76% (Controls 2.37± 0.25 OD units, BMP-2 4.16 ± 0.37 OD units). CM from gingival cells blocked BMP activity which was equivalent to the activity of 50ng/ml Noggin. In contrast CM from PDL cells stimulated AlP activity.

Conclusions: A wide range of BMP and wnt inhibitors are constitutively expressed in gingival connective tissues. This inhibitory activity may limit the coronal bone regenerative potential in periodontal surgery.

Funded by MRC Grant:G0601408


0009 (111721)

Root-Canal Volume-Changes after Fractured File Removal Assessed by Micro Computerised-Tomography. A. MADARATI, A. QUALTROUGH, and D.C. WATTS, University of Manchester, United Kingdom

 

Objectives:

To study the effect of fractured file removal on tooth structure using micro computerized-tomography

 

Methods:

Fifty three canine roots were cleaned, and weighted using a digital micro-balance. Roots were scanned by a Micro-CT scanner at 19.4μm resolution producing 2D images which were reconstructed using the NRecon software into 3D model. Canal-volume was measured using the CT-Analyzer software. Eight roots served as a control group in which canals were prepared using ProTaper system to F5 size. In the other three groups, 4mm of F5 files were fractured in three root-canal locations; coronal, middle and apical. These were ultrasonically removed, and roots of all groups were re-weighted and re-scanned. Reconstruction and analyzing were carried out to re-measure canal-volume. The differences in root-mass and canal-volume between before and after treatment (fractured-file removal or root-canal preparation) were calculated. Data were analyzed to compare the changes by One-way ANOVA at p≤0.05.  A regression test was used to correlate canal-volume and root-mass changes.

Results:

There were significant differences in root-mass and canal-volume change between the three locations (p<0.05). The highest increase in canal-volume was found when fractured files were removed from the apical part (17.53±1.93 mm3) followed by the middle and coronal sites (10.56±2.82 and 4.2±1.52 mm3 respectively). This trend was also found for root-mass changes, with 45.8±5.3 mg root-mass loss when fractured files removed from the apical part followed by the middle and coronal sites (27.7±9.2 and 13.5±5.2 mg respectively). A positive correlation (r2=0.998) existed between changes in canal-volume and root-mass. No significant differences were found between control and coronal groups.

Conclusions:

Root structure significantly deteriorates when fractured files are removed from deeper locations within the root canal. Removal of fractured files located in the apical part is not recommended. Micro computerised-tomography can reliably determine changes in canal-volume resulting from fractured-file removal.


0010 (111220)

Craniofacial MDPCs could be used in clinical bone regeneration applications. K. CARLQVIST, P. BRETT, and M.P. LEWIS, UCL Eastman Dental Institute, London, United Kingdom

OBJECTIVES:

Much data has emerged recently suggesting that there are multipotent cells present within skeletal muscles (MDPCs). Hence, MDPCs might be used in clinical bone regeneration applications as an alternative to MSCs, which are today the gold standard in tissue engineering applications. However, little is known about the efficiency of differentiation of MDPC compared to MSCs. Therefore, the aim of this study is to investigate the potential of human craniofacial MDPCs to differentiate into adipogenic, osteogenic and myogenic lineages and to compare the differentiation potential of MDPCs with MSCs.

METHODS:

MSCs were obtained from Tulane University (US) and MDPCs were extracted from masseter muscle biopsies taken at the Eastman Dental Hospital. MDPCs were separated from cells expressing the myogenic marker CD56 and characterised by flow cytometry. The expression of lineage specific genes were analysed by qPCR and morphological changes were visualised by staining. Mineralization during bone formation was quantified by Alizarin Red S.

RESULTS:

The flow cytometry results showed that the MDPCs expressed CD105, a cell surface protein known for its regulatory function in osteogenic differentiation. The differentiation study showed that the ability of MDPCs to mineralize was comparable with MSCs, but MDPCs formed lipid droplets to a lower extent than MSCs. The MDPCs formed desmin expressing myosacs in myogenic conditions, but the MSCs appeared not to be able to commit to the myogenic lineage. The qPCR results confirmed the morphological changes.

CONCLUSION:

These data clearly indicate that MDPCs have the potential to become an alternative to MSCs in tissue regeneration strategies. MDPCs are as efficient in osteogenic commitment and have a lower adipogenic capability than MSCs. This is particular important, since fat formation often compromises in vivo applications.


0011 (110519)

Distinct Gene Array Profiles of Calvarial and Limb Osteoblasts. S.C. RAWLINSON, C. WELLMANN, M. GHUMAN, I.J. MCKAY, V.J. KINGSMILL, and F.J. HUGHES, Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives: This work is part of a series testing for differences between bone cells from functionally distinct regions of the skeleton. Here, the gene expression profiles of cultured osteoblasts from skull and limb were determined.

Methods: Parietal and ulna bone from five young adult rats were used to generate matched pairs of osteoblast cell lines representing calvarial (COBS) and limb bone (LOBS) using standard collagenase digestion techniques. Cells were cultured in α-DMEM medium, supplemented with antibiotics at 37°C, 5% CO2. Third passage cells were collected; RNA isolated and concentrated to 1μg RNA/ml dH2O prior to hybridization to the Illumina RatRef 12 beadchip. Gene expression was quantified using BeadStudio software, a diff score either below -65 or above 65 indicated genes expressed at significantly different levels.

Results: 247 genes (from 22,517) were differentially expressed, 128 higher in COBS, and 119 LOBS. Despite this small percentage difference, cluster analysis grouped the samples into their respective site of origin. Most interesting was the finding that regional identity markers were expressed in culture (COBS: Zic2, Zic5, Msx2; LOBS: Tbx3, Hox7a, Hoxa10). Whether all these genes influence bone formation and bone density in the adult is uncertain. Although, expression of genes known to control osteogenesis, bone density and turnover were broadly similar between the two populations, there was a notable exception – significantly higher osteopontin (OPN) expression in LOBS.

Conclusions: These data further demonstrate diversity between osteoblasts derived from distinct locations. High OPN expression in LOBS is consistent with the susceptibility of the limb to osteoporosis: OPN null mice are resistant to ovariectomy-induced osteoporosis (Yoshitake PNAS 1999). Although COBS are routinely used in experiments to study mechano-stimulation and possible treatments for osteoporosis, consideration for the use of site-matched populations must be exercised when undertaking cell culture experiments.

Supported by a DoH Clinician Scientist Fellowship Award (VJK).


0012 (111437)

Bone Tissue Engineering Using Porous Ceramic Scaffolds. R. ACKBAR1, S. FORSTER1, S. MCARTHUR1, K. HURRELL-GILLINGHAM2, A. CRAWFORD1, and P.V. HATTON1, 1University of Sheffield, United Kingdom, 2Centre for Biomaterials and Tissue Engineering, Sheffield, United Kingdom

Objectives: Bone defects may arise through injury, congenital abnormality or disease. Currently there is no one, ideal technique for bone augmentation. Autografts, allografts and synthetic bone graft substitutes all have well known limitations. Bone tissue engineering is a promising alternative and has been suggested for the reconstruction of bone defects in maxillofacial surgery as well as use in implant dentistry. This study investigates the use of porous, calcium phosphate ceramic scaffolds for bone tissue engineering applications. In particular, the effect of a plasma treatment on distribution of matrix tissue throughout the scaffold.

Methods: Hydroxyapatite scaffolds based on Permabone® (Ceramisys Ltd) were plasma cleaned using oxygen and water sources. The effect of plasma treatment on the hydrophilicity of the material was measured by contact angle and dye penetration. Chemical characterisation was investigated by XPS. Finally, the ability of cells to penetrate plasma treated and non-treated materials was compared. Micro-computed tomography (MicroCT) has also been explored as a potential method for quantifying the distribution of mineralised tissue.

Results: Plasma treatment both reduced contact angles and increased the rate of dye penetration. Plasma cleaning did not appear to alter the surface chemistry, and the effects on cell penetration were inconclusive. MicroCT was used successfully to not only quantify mineralisation but more importantly, the distribution of that mineralisation.

Conclusions: Bone tissue engineering is a promising tool for maxillofacial surgery and implant dentistry. A crucial difficulty for the tissue engineer is the seeding of cells throughout the entire scaffold, producing a homogenous distribution of bone matrix. Plasma treatment may increase hydrophilicity of hydroxyapatite scaffolds and therefore presents a promising tool to improve scaffold properties.

Acknowledgements: The Author gratefully acknowledges funding from EPSRC, EXPERTISSUES (EU/FP6_NMP3_CT-2004-500283) and Ceramisys. We are very grateful to Prof. Ralph Müller & Dr.Thomas Kohler for the microCT work.


0013 (111481)

Transforming Growth Factor-β Stimulation in an Ex-Vivo Fractured Mandible Model. E.L. SMITH1, R.J. WADDINGTON2, M. LOCKE2, and A.J. SLOAN2, 1Cardiff University, Wales, 2Cardiff University, United Kingdom

We have developed an ex vivo culture model of fractured rat mandible slices, and have demonstrated successful culture of slices for 21 days, with maintenance of cell/tissue architecture and viability. This system may offer significant advantages to current experimental models of bone regeneration when investigating the influence of specific reparative processes. Objectives: To stimulate the model with TGFβ-1, a growth factor known to be involved in migration and proliferation of osteoprogenitor cells during bone repair. Methods: 2mm transverse slices from 28 day old male Wistar rat mandibles were prepared and fractured. Agarose beads were incubated in 80ng TGFβ-1 in 0.1% BSA/PBS, or 0.1% BSA/PBS as controls. 3 beads were transferred into the fracture site of each mandible slice with sterile needles. Slices were cultured for 7 days in DMEM containing 200mM glutamine, 10% FCS, 0.15mg/ml ascorbic acid, and antibiotics, at 37oC, 5% CO2 in air. Cellular behaviour adjacent to the fracture site and 100μm2 area either side of the fracture was assessed by histomorphometry, and immunohistochemistry for proliferation and bone matrix markers (PCNA, OPN). Results: Fractured mandible slices stimulated with TGFβ-1 exhibited a significant increase in cell number (p<0.05) within the PDL directly adjacent to the fracture site compared with control cultures. Similar increases in cell number were observed in areas of 100μm2 either side of the fracture. No significant differences in cell numbers were identified on opposite regions of the mandible slice. Cells within, and adjacent to, the site of fracture in TGFβ-1 stimulated cultures were positive for both PCNA and OPN with a decrease in positive cells distant from the fracture site. Conclusions: TGFβ-1 stimulated cell proliferation within the PDL adjacent to the fracture site in cultured mandible slices. This model may be a valuable tool in the study of specific influences of growth factors in bone regeneration.


0014 (110804)

Surface Modification of Titanium Implant by Electrochemical and Nanohydroxyapatite Deposition. L. SARINNAPHAKORN1, X. LI2, J. HUANG2, R. CHIESA3, C. GIORDANO3, M. FENLON1, and L. DI SILVIO1, 1King's College London Dental Institue, United Kingdom, 2University College London, United Kingdom, 3Polytechnic of Milan, Italy

Objectives: Surface Modification of Titanium (Ti) implants, aiming at increasing the osteoconductivity of implant materials, has generated much attention in the research field of dental implantology. Our objective was to evaluate the cellular response of Ti modified surfaces between novel silicon-based anodic spark deposition (ASDSi) and electrohydrodynamic atomisation (EHDA) deposition. The biological activity was assessed using two human cell models; primary osteoblast (HOB) and mesenchymal stem cells (MSCs). Materials and Methods: Two different Ti surfaces were investigated: ASDSi and EHDA. Commercially pure Ti (cpTi) was the non-treated control surface. Test samples were cut into discs (12 mm in diameter and 0.5 mm thickness) and sterilized by γ-irradiation prior to the test. All surfaces were scanned using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and atomic force microscopy (AFM) for topographic and physicochemical characterization. HOB cells and MSCs were cultured in Dulbeco's Modified Eagle Medium with 10% foetal calf serum and seeded at a cell density of 1 x 105 cells/ml, directly onto the test discs (ASDSi, EHDA, and cpTi), as well as on Thermanox®, a negative control (non-toxic material), and polyvinylchloride (PVC), a positive control (toxic material). Test samples were incubated at 37 oC and 5% CO2. At day 1, cells were fixed and processed for SEM to assess morphology. Cell proliferation was assessed using the alamarBlue™ assay for 28-day period. Results: Both treatments altered surface topography, and surface chemistry of Ti implants. SEM images showed abundant cell layers on all surfaces with active cells visible, and cell filopodia extending across surface. All test samples showed comparable proliferation for both cell types compared to controls. Conclusion: This study has demonstrated that both novel modified Ti surfaces had nanotopographic texture, and chemically-treated composition, favouring cell attachment and growth. This property would be beneficial for enhancing osseointegration for dental implants.

 

 


0015 (111222)

Preservation of saliva for diagnostics. R. PRAMANIK, G.H. CARPENTER, N. SILVER, and G.B. PROCTOR, King's College London, United Kingdom

Saliva contains a wide range of proteins, antibodies and nucleic acids, which makes it an important diagnostic fluid in assessing oral and systemic diseases. The collection of saliva is convenient, non-invasive and cost effective. Objective: This study investigates different methods of collecting, preserving, and storing saliva to ensure simple collection and minimise degradation of proteins and nucleic acids. Methods: Unstimulated whole mouth saliva was collected from healthy volunteers into universal tubes either directly on ice or at room temperature. Saliva was divided, one batch was clarified by centrifugation and the other batch remained un-clarified. The saliva samples were then immediately stored under different conditions; (1) overnight storage at room temperature, 4°C or below 0°C; (2) overnight storage in the presence of protease inhibitor cocktail. Protein composition was analysed by SDS-PAGE and visualised with coomassie brilliant blue. Saliva was also treated with a range of different RNA preservatives, used according to the manufacturer's protocol. RNA was isolated using an RNeasy Micro Kit (Qiagen Inc) according to manufacturer's protocol and was quantified using Quant-iT™ Ribogreen® RNA kit (Molecular Probes, Invitrogen). Results: Collecting saliva on ice retained salivary proteins, in particular histatins and other low molecular weight proteins. Storing saliva samples at -20°C appeared to be optimal for preservation of salivary proteins with minimal loss. The use of protease inhibitor cocktail also preserved proteins. The yield of salivary RNA differed for each RNA preservative. RNA isolated from cell free was approximately 1ng/ml whilst un-clarified saliva was approximately 100 fold greater. Conclusions: Collecting saliva on ice and freezing at -20°C is a practical, quick and easy method for preserving saliva samples that can be implemented in a clinical setting. RNA in saliva can be quantified by fluorescence assay, although cell free RNA appears to be very low.


0016 (110954)

Socio-psychological resources and Generalised Aggressive Periodontitis: a case-control study. A. GAMBOA1, F.J. HUGHES2, and W. MARCENES2, 1University of Liverpool, United Kingdom, 2Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives: It is hypothesised that there is a social gradient in generalised aggressive periodontitis (GAP) running from highest to lowest socio-economic position (SEP) and that psychological stress, represented by number of negative life events, is a risk factor to GAP; while positive life events, high social support, high problem-solving confidence, tendency to confront rather than avoid problems, high personal control and high optimism are protective factors against GAP.

Methods: A hospital-based unmatched case-control study was conducted at the Institute of Dentistry at The Royal London Hospital. Patients were recruited from consecutive patients referred for treatment by their general dental practitioners. All participants were 20-40 years old, had a minimum of 24 teeth and no systemic diseases. Cases (n=80) were defined as patients with a minimum of 4 pocket depths greater than 5.5mm involving at least 4 mouth-sextants. Controls (n=153) had pocket depths not greater than 3.5mm. Self-completed validated questionnaires were used to collect socio-economic, socio-psychological and behavioural variables. Ethical approval and consent were obtained. Data analysis included simple and multiple logistic tests.

Results: There was a statistically significant gradient in GAP from lowest to highest SEP (p=0.010). Adjusted results showed that low SEP [OR=3.4 (1.3-8.6)] and negative life events [OR=2.4 (1.2-4.9)] remained as risk factors to GAP, while positive life events [OR=0.4 (0.2-0.9)], high social support [OR=0.5 (0.2-0.9)] and high optimism [OR=0.4 (0.2-0.9)] remained protective. Smoking [OR=1.6 (0.7-3.3)] did not remain significantly associated to GAP in multivariate analysis. Problem-solving-related variables and dental attendance showed p-value greater than 0.200 when associated with GAP in univariate analysis and were excluded from multivariate analysis. Most participants (97%) reported brushing their teeth at least once a day.

Conclusion: The results suggest that positive life events, high social support and high optimism may balance for the harmful effects of low SEP and negative life events.


0017 (110560)

Synthesis and Characterisations of a Novel-Bioactive Dental Restorative Composite. A.S. KHAN1, I.J. MCKAY2, F.S.L. WONG3, and I.U. REHMAN1, 1Queen Mary University of London, United Kingdom, 2Queen Mary, University of London, United Kingdom, 3Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives: It is desirable for a dental restorative material to have bioactive and bonding properties. Hydroxyapatite (HA) has been shown to be osteo-conductive but can only bonds to resin through silane coating. A novel-bioactive composite has been synthesised based on polyurethane (PU) and nano-HA by creating a covalent linkage between them. In this study, its physical and biochemical characteristics were analysed.

Methods: Nano-HA powder was produced from the sol-gel. A novel covalently bonded PU-nano-apatite composite material was chemically prepared by utilising solvent polymerisation. Chemical, thermal, and mechanical properties of the resulting composites were investigated. The resultant composite material was electrospun to form fibre mats. The bio-adhesion with dentine were analysed in distilled water and artificial saliva. Bioactive behaviour was determined in simulate body fluid (SBF). The composites were hydrolytically degraded in distilled water and phosphate buffer saline (PBS) and were analysed. Cell growth and proliferation was measured by MTS assay.

Results: Spectral analyses showed the grafted isocyanate and ether peaks on HA indicating that urethane linkage was established. The thermal and mechanical properties were enhanced by nano-HA (p=0.05). The SEM images of electro-spun nano-fibres revealed no loose HA particles. Bio-adhesion and bioactivity analysis showed the composite adhered firmly on the tooth surface (enamel/dentine or both). Higher nano-HA content composite showed thicker layer of adhesion. These composites had high resistance toward hydrolysis and little degradation and a significant difference was observed (p<0.05). Biocompatibility test of the composite showed that the cells were growing although at a lower rate of growth compared to PU.

Conclusion: Covalent bond between HA and polymer were found in this novel composite with no silane agent. Bio-adhesion was found between this composite and tooth structure. Hence, it has the potential to be a desirable restorative material.


0018 (110497)

Inhibiting Citric Acid-Mediated Hydroxyapatite Dissolution Using Monoalkyl Phosphates. S.B. JONES1, G.D. REES2, R.P. SHELLIS1, and M.E. BARBOUR1, 1University of Bristol, United Kingdom, 2GlaxoSmithKline R&D, Surrey, United Kingdom

Objectives: Recent results have shown that monoalkyl phosphates (MAPs) may inhibit hydroxyapatite (HA) dissolution in vitro. The aim of this study was to quantitatively compare the effects of sodium dodecyl phosphate (SDP) and potassium dodecyl phosphate (PDP) with sodium fluoride (NaF) on HA dissolution rate in citric acid.

Methods: HA disc dissolution was measured in 14 mM citric acid (pH 3.20) over 30 min periods at 36°C using a pH stat. Baseline dissolution rate for each disc was determined from the mean of three initial measurements. Discs were then exposed to (i) 0.10% SDP (ii) 0.10% PDP (iii) 1.00% PDP or (iv) 300 mgL-1 fluoride for 120 s under gentle agitation. Following rinsing with deionised water, the disc dissolution rate was measured again in fresh acid solution over successive 30 min periods until the baseline rate had been recovered.

Results: Fluoride treatment significantly reduced the HA dissolution rate versus baseline by 14% in the first instance (p<0.05), but inhibition did not persist beyond the first post-treatment acid exposure (30 min). Treatment with 0.10% SDP or PDP also resulted in a statistically significant reduction in dissolution rate versus baseline (p<0.05) of 26 and 34% respectively; PDP was significantly more effective than the SDP. The reduction in HA dissolution by 0.10% MAP was persistent to 60 and 120 min post-treatment respectively for SDP and PDP. Treatment with 1.00% PDP resulted in more sustained inhibition of dissolution compared to the other treatments, with statistically significant suppression of dissolution observed for at least 210 min post-treatment (p<0.05). Conclusions: In this pH stat model, a single treatment with 0.10% MAP confers a greater inhibition of HA dissolution than 300 mgL-1 fluoride. Moreover the dissolution inhibition afforded by MAP is more long-lasting than that of fluoride, and for PDP was dose dependent.

Funding provided by GlaxoSmithKline


0019 (109991)

Porphyromonas Gingivalis LPS Up-regulates RANKL via PGE2 in Osteoblastic Cells. D. REDDI, N. BOSTANCI, A. HASHIM, M. CURTIS, F.J. HUGHES, and G.N. BELIBASAKIS, Barts & The London School of Medicine and Dentistry, United Kingdom

Objectives: Receptor activator of nuclear factor-ΚB ligand (RANKL) is a cytokine that triggers osteoclastogenesis and bone resorption, whereas osteoprotegerin (OPG) is its soluble decoy receptor that can effectively block its action. The objective of this study was to investigate the effect of P.gingivalis on RANKL, OPG and prostaglandin E2 (PGE2) production by an osteogenic murine bone marrow cell line.

Methods: Culture supernatants of P.gingivalis W50 were grown anaerobically for 6 days. Ascending bacterial protein concentrations of P.gingivalis culture supernatant up to 5µg/ml were used to challenge W20-17 cell cultures for up to 48h. The levels of RANKL, OPG and PGE2 were analysed by ELISA. The involvement of PGE2 in RANKL and OPG regulation was investigated by treatment of the cells with indomethacin(10-5M). To investigate the involvement of P.gingivalis proteinaceous components, cysteine proteinases, or lipopolysaccharide (LPS), the P.gingivalis culture supernatants were heat-inactivated, TLCK-treated (1mM), or passed through a polymyxin-B column, respectively.

Results: P.gingivalis supernatant increased RANKL protein production and PGE2 secretion, whereas OPG production was decreased, in a concentration dependent manner. Controls vs 5µg/ml P.gingivalis at 48 h; RANKL: 22±14 vs 273±105 ng/ml; PGE2: 776±773 vs 6446±1540 ng/ml; OPG: 97747±35989 vs 17100±4357 ng/ml. Pre-treatment of the cells with indomethacin decreased P.gingivalis-stimulated PGE2 secretion by 97 % and RANKL production by 98%, but did not affect OPG production. Heat- and TLCK-treatment of P.gingivalis had no effects on RANKL and PGE2 production, but polymyxin-B treatment reduced both by 98% and 78% respectively.

Conclusion: Porphyromonas gingivalis up-regulates RANKL and PGE2, but down-regulates OPG in bone marrow stromal cells. The bacterial effects on RANKL induction appear to be mediated through PGE2 stimulation and these events are triggered by a non-proteolytic and non-proteinaceous component of P.gingivalis supernatants, most probably LPS. This activity may contribute to the bone loss characteristic of destructive periodontal disease.


0020 (109958)

Effects of Intermedilysin on brain cells : not simply punching holes. S.M. THOMAS, R.A. WHILEY, and E. HAGI-PAVLI, Barts and The London School of Medicine and Dentistry, United Kingdom

Intermedilysin (ILY) is expressed by the oral bacterium Streptococcus intermedius at highest levels in strains from deep-seated abscesses although ILY function(s) in-vivo are not fully understood.

Objectives: To investigate the susceptibility and responses of human brain target cells to lethal and sublethal ILY concentrations.

Methods: Primary brain endothelial cells (HBMEC), astrocytes (HA) and a neuronal cell line (DAOY) were treated for 1h or 2h with purified ILY (0.000125 - 0.1µg/ml). Cell viability, damage and recovery were assessed using MTT assay, LDH release and AlamarBlue™. Cellular response assays included cytokine release (IL-1α , IL-1β, TNF-α and IL-8) by ELISA, cell cycle quantification and caspase activity by flowcytometry and NF-κB p65 subunit nuclear translocation plus cytoskeletal changes by immuno-fluorescence. ILY-exposed HBMEC supernatants were used in a neutrophil migration assay.

Results: Dose dependant cell viability decrease was observed with all target cells. ILY susceptibility varied between cell types, with astrocytes and neuronal cells 10-fold more susceptible than brain endothelial cells. Maximal IL-8 release was at lowest (0.000125µg/ml) ILY concentration (3000pg/ml from HBMEC). Increasing IL-1α release was directly ILY dose dependant whereas IL-1β and TNF-α release was negligible. Alteration of the cytoskeleton accompanied by NF-κB nuclear translocation was observed. Dose dependant activation of caspases in an apoptotic cell population with Sub-G1 arrest of cells was evident. HBMEC supernatants also caused migration of neutrophils across an endothelial membrane barrier.

Conclusions: These in-vitro data support the hypothesis that sublethal ILY levels may play an important role in brain abscess pathogenesis. NF-κB activation in brain endothelial cells and astrocytes (blood-brain barrier) may cause release of pro-inflammatory cytokines, especially IL-8, and regulation of the immune response at foci of infection in-vivo. Cell death during infection may not result simply as a direct consequence of pore formation on target membranes but also by activation of the apoptotic caspase cascade.


0021 (111142)

Effectiveness of Whitening Toothpastes: A Systematic Review. S. RAJESH, V. MARINHO, and R. CROUCHER, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives:

To determine the effectiveness of toothpastes containing abrasives,chemical,oxidizing or multiple whitening agents in the improvement of tooth-discoloration/removal/prevention of stains;to examine any adverse effects.

Methods:

The Cochrane OHG Trials Register,CENTRAL, MEDLINE, EMBASE, and reference lists were searched for relevant studies; selected authors and manufacturers were contacted.

Randomized/quasi-randomized trials, comparing whitening toothpastes with placebo/standard non-whitening toothpastes, in adults (over 18), and measuring change in tooth color/ removal/prevention of stains for at least 4 weeks were included. Study selection, data extraction and quality assessment were conducted independently by two reviewers. Random effects meta-analyses were performed where data could be pooled;the main effect measure was the mean difference in change from baseline stain/shade rank scores.

Results:

1213 reports were identified,78 obtained; 22 trials included, 17 with results for meta-analysis.The overall pooled estimates of 8 trials (4 trials containing abrasives, 3 with multiple ingredients, 1 with oxidizing agents) for stain composite scores and 10 (4 with abrasives, 5 with chemical and 1 with multiple ingredients) for area and intensity scores, produced weighted mean differences (WMD) of -0.16 (95% CI, -0.26 to -0.07, p=0.0009), -0.34 (95% CI, -0.47 to -0.2, p<0.0001), and -0.32 (95% CI,-0.48 to -0.15, p=0.0002) respectively, all favoring whitening toothpastes. 1 trial with multiple ingredients for shade rank score also favored whitening toothpaste (4.64 (95% CI,4.11 to 5.17, p<0.0001). Only 1 trial with multiple ingredients for stain score by color matching favored non-whitening toothpaste (0.15 (95% CI, 0.03 to 0.27, p=0.01). All trials analyzed assessed removal/prevention of extrinsic stains,except one (shade rank trial) which assessed internalized stains.

Conclusions:

There is evidence showing that whitening toothpastes are effective in removal/prevention of extrinsic stains; evidence for removal of internalized stains is weak. No evidence is available for intrinsic stains. Adverse effects information was scarce.


0022 (110289)

Quality of Life is a Causal Model, not a Concept. E. VERRIPS, J. KIEFFER, and J. HOOGSTRATEN, Academic Centre for Dentistry Amsterdam, Netherlands

Objectives: Developers of instruments measuring oral health-related quality of life (OHRQoL) disagree about the definition of OHRQoL and how it should be measured, given the fact that instruments differ in number and kind of dimensions and scales, and in the number and kind of items per scale. As a consequence, results of studies using different instruments are not comparable. Moreover, Fayers et al. (1997) suggested that in many Quality of Life (QoL) instruments causal indicators of QoL are mixed up with effect indicators. The aim of our study was to evaluate whether such a mix-up holds true for the items of the Oral Health Impact Profile (OHIP). We choose the OHIP for this exercise as it seems to be the most widely used OHRQoL instrument to date.

Methods: We classified the 49 items of the OHIP into either causal indicators or effect indicators, using thought experiments as described by Bollen (1989).

Results: We classified all functional limitation and pain items and some physical disability items as causal indicators; psychological discomfort and disability items as emotional effect indicators, all social disability items as behavioral effect indicators and most handicap items as inconclusive.

Conclusion: Our main result is that the OHIP consists of a mix of causal and effect indicators. We argue that causal indicators (genetics, environment, objective and self-perceived oral health status) are to be distinguished from QoL, conceptually and in measurement. QoL is to be seen as a latent construct which expresses itself in effect indicators such as cognitions, emotions and behavior. We suggest the term OHRQoL be reserved for an empirical research program studying the relationships between causes and effects of QoL. A model comprising such causes and effects is proposed.


0023 (110143)

Conceptual complexity of Oral Health-Related Quality of Life. J.M. KIEFFER, E. VERRIPS, and J. HOOGSTRATEN, Academic Centre for Dentistry Amsterdam (ACTA), Netherlands

Objectives: To contest conventional wisdom regarding the measurement model used in Oral Health-Related Quality of Life (OHRQoL) research and to outline implications. Most techniques for developing and analyzing multi-item scales stem from Classical Test Theory (CTT) and Item Response Theory (IRT). These theories are based on traditional psychometrics, from which follows a reflective measurement model. Psychological constructs are presumed to be latent variables in that they are the unobservable common cause of several observable variables. The underlying assumption is local independence, that is, the latent variable explains why the observed variables are related to each other. The majority of OHRQoL-scales are based on this assumption. However, this entails that the scales constructed consist solely of indicators that reflect OHRQoL. This assumption is untenable, however. Most OHRQoL-scales also contain indicators that describe symptoms or side effects. Clearly these are rather determinants of OHRQoL than reflections and underpin a formative measurement model. Methods: On the basis of an article written by Fayers et al. (1997) the implications of relying on psychometric approaches for the construction and analysis of OHRQoL-scales containing formative indicators were analyzed. Results: Methods used for construct validation, item selection and developing scoring procedures, like Factor Analysis or techniques used for reliability estimates like Cronbach's alpha all rely on a reflective measurement model and all rest on the assumption of local independence. If OHRQoL-scales contain formative indicators, assuming a formative- as well as a reflective-measurement model, the assumption of local independence is violated. This makes results based on above mentioned methods erroneous. Conclusion: Psychometric methods are not to be used on OHRQoL-scales containing formative indicators.


0024 (110153)

Evaluation of Arabic version of short form Child Perceptions Questionnaire. T. DAAS, Z. MARSHMAN, and P. BENSON, University of Sheffield, United Kingdom

OBJECTIVE: To assess the reliability and validity of the Arabic version of the 16-item short form of the Child Perceptions Questionnaire (CPQ SF-16), an oral health related quality of life measure for 11-14 year old children, for use in Saudi Arabia.

METHODS: Six hundred forty nine children between 11 and 14 years of age attending schools in Riyadh (Saudi Arabia) were invited to complete the CPQ SF-16, ratings of oral health, life overall and satisfaction with dental appearance and self-report the Aesthetic Component of IOTN. They were then examined clinically to record both the Dental Health Component and Aesthetic Component of IOTN and specific aspects of the malocclusion such as overjet. No other clinical data were available.

RESULTS: The Cronbach's alpha for the total scale was 0.85 and ranged from 0.52 to 0.85 for the subscales indicating acceptable internal consistency. Intraclass correlation coefficient on repeated application of the measure was 0.86 suggesting almost perfect agreement. Summary measures of CPQ SF-16 correlated with the global oral health rating indicating acceptable criterion validity. Impact on life overall was related to all summary measures of CPQ SF-16. Relationships between total CPQ SF-16 and subscale scores with clinical data were weak.

CONCLUSION: The Arabic version of CPQ SF-16 shows acceptable reliability, criterion and construct validity in relation to life overall. Further testing of the face and content validity of this measure is required.


0025 (109953)

Third Molar Extraction and Oral Health Related Quality of Life. A. VAN WIJK1, J.M. KIEFFER1, and J.A.H. LINDEBOOM2, 1Academic Centre for Dentistry Amsterdam (ACTA), Netherlands, 2Academic Medical Center, Amsterdam, Netherlands

Objectives: To investigate the impact of third molar surgery on oral health related quality of life, related to pain and clinical variables, in the first post-operative week.

Methods: Patients (n=50) referred to the Department of Oral & Maxillofacial Surgery of the Academic Medical Center (AMC), for surgical removal of their impacted third molars, were included in the study. Patients filled out the OHIP-14 (Oral Health Impact Profile, range total score = 14-70) pre- and postoperatively and questions about pain in the postoperative week. Pre- and postoperative complications, as well as number of molars removed (1 or 2, unilateral), were assessed.

Results: A significant increase in mean total (mean increase = 10.6, s.d. = 12.1) and subscale OHIP-14 scores was found (reduced quality of life). The presence of pre- or postoperative complications does amplify the impact on quality of life (relative mean increase of 7.19 and 14.39 respectively). All patients with postoperative complications still experienced pain on day 7 after surgery. No differences in impact on quality of life could be shown between patients having one or two molars extracted. However, a significant time by group interaction was found (repeated measures ANOVA) which showed that the patients who experienced postoperative complications and who had one molar removed, showed a dramatic increase in mean OHIP-14 score relative to their pre-test (mean difference = 28.7, s.d. = 11.1). This resulted in an increased mean score for the group who had one molar removed.

Conclusions: In general, patients are quite anxious for third molar surgery. Given this preoperative period of stress, surgery itself, and the postoperative period in which oral health related quality of life is substantially affected (and strongly enhanced in case of postoperative complications), it is apparent that third molar surgery is a major event for large numbers of patients.


0026 (110599)

Determinants of Oral Health Related Quality of Life in Children. A. MAT1, S.R. BAKER, PhD1, and P.G. ROBINSON2, 1University of Sheffield, England, Uk, 2University of Sheffield, United Kingdom

Oral health can impact on children's functioning and well-being. However, few studies have examined the range of clinical and psychosocial factors which may influence children's Oral Health Related Quality of Life (OHRQoL).

Objectives: To test the relationships between clinical and non-clinical variables hypothesised within Wilson and Cleary's theoretical model of patient outcomes and to examine whether socio-demographic and individual difference factors influence children's OHRQoL and the key relationships hypothesised within the model.

Methods: Prospective longitudinal design incorporating clinical examination (Dental caries, Periodontal status, Malocclusion and Trauma) and self reported questionnaire (self esteem, health locus of control, sense of coherence, oral health beliefs, OHRQoL, general health perceptions and overall QoL) at baseline and 6 month follow-up.

Results: Data were collected from 439 Malaysian 12 year-olds. Dental disease levels were low with mean DMFT=0.41 (SD 0.90). Lagged analysis indicated that individual differences and socio-demographic factors influenced the experience of symptoms (R²=0.180, p<0.05), functional status (R²=0.242, p<0.05), general health perceptions (R²=0.162, p<0.05) and overall quality of life (R²=0.056, p<0.05) whereas variations in clinical status were unrelated to subjective experiences.

Conclusions: The Wilson and Cleary model of patient outcomes was broadly supported. Individual factors influenced oral health more than clinical status in this low disease population.


0027 (110943)

Dental Erosion, Behaviour and Quality of Life in Young Adults. J. NEWTON1, J. FARES1, K. CHIU1, N. AHMAD1, S. SHIRODARIA2, D. BARTLETT1, and B. DALY1, 1King's College London, United Kingdom, 2GlaxoSmithKline Consumer Health Care, Weybridge, Surrey, United Kingdom

Objective: To determine the relationship between tooth wear at the level of dentine, oral health related behaviour and oral health related quality of life in a sample of young adults not attending for treatment.

Method: Clinical survey of 1010 young adults at a large UK teaching institution. Clinical examination included determination of the tooth wear index for enamel and dentine. Questionnaire measure of oral health related behaviour and the OHIP-49.

Results: The mean (SD) of surfaces affected by dentine erosion at levels 2 and above was 2.34 (2.77). The proportion of participants who experienced any erosion at the level of dentine was 61%. The overall mean OHIP score for the sample was 1.29 (SD 2.51). There was no significant correlation between extent of erosion and OHIP scores (rho=0,05). There were no significant relationships between self reported diet, oral hygiene and other health related behaviours previously demonstrated to related to erosion, with the exception of frequency of consumption of beer (Chi-square=6.28, p<0.05).

Conclusions:In this sample of young adults the presence of erosion into dentine on any surface was prevalent, but at a low level. There was no significant association between the presence of erosion at this level and impact on oral health related quality quality of life. There were few associations between self-reported oral health related behaviour and the presence of erosion, with the exception of frequency of consumption of beer. Erosion into the dentine is common but has few consequences for the individual at low levels.

Supported by Sensodyne, GSK .


0028 (111063)

Correlation between perceived oral and general health. D.R. REIßMANN1, O. SCHIERZ2, A. HINZ2, and M.T. JOHN3, 1University Medical Center Hamburg-Eppendorf, Germany, 2University of Leipzig, Germany, 3University of Minnesota, Minneapolis, USA

Objectives: The concept of health-related quality of life has gained increasing importance to describe how individuals perceive their health status. The perception of oral health can be characterized by oral health-related quality of life. The aim of this study was to determine the relationship between health-related quality of life (HRQoL) and oral health-related quality of life (OHRQoL) in two different populations.

Methods: This cross-sectional study included a random sample of 811 subjects (age: 50.1±16.0 years; 53% women) of the general population of Germany and 311 consecutive prosthodontic patients (age: 61.7±13.7 years; 57% women). HRQoL was assessed using the Health Survey SF-36, and OHRQoL was assessed using the Oral Health Impact Profile (OHIP-49). To determine the correlation between HRQoL and OHRQoL Pearson correlation coefficients and 95% confidence intervals were calculated for the instruments' sum scores as well as for dimensions' scores in both populations.

Results: The correlation between HRQoL and OHRQoL was highly statistically significant in general population subjects (r=.55) as well as in prosthodontic patients (r=.41). This indicates that OHRQoL explained about 30% of the variability of HRQoL in general population subjects and about 16% in prosthodontic patients. Correlation coefficients in age and gender related subgroups did not differ substantially from the overall estimates.

Conclusion: These results indicate a close relationship between perceived oral health and general health.


0029 (111151)

Using ideals to assess response shift: A demonstration project. P.G. ROBINSON, R.R. PATEL, and S.R. BAKER, University of Sheffield, United Kingdom

Changes in individuals' internal standards for subjective assessments are termed ‘response shift'. Response shift may undermine the validity of assessed oral health related quality of life. This study aimed to explore the feasibility of using ‘ideal ratings' to identify response shift.

Objectives: To assess whether participants' ideal status involved no impacts on oral health, whether there were discrepancies between ideal and actual levels of impact and whether there was variation in discrepancies.

Methods: Questionnaire study of consecutive patients awaiting implant treatment. Questions included OHIP-49 and analogous items enquiring about participants' ideal scores for each item. OHIP-49 and ideal scores were compared using the item codes for each item.

Results: Twenty nine patients provided data. Mean OHIP-49 score was 70.2 and mean ideal score was 28.6. Twenty six participants reported impacts that were worse than their ideal. Mean discrepancy between impact and the ideal score was 41.6 (sd 32.7). In exploratory analyses mean discrepancies in men and women were 26.4 (sd 31.9) and 55.7 (sd 27.3) respectively (t test, p < 0.05). Discrepancies were greater with greater age (r = 0.56, p < 0.05).

Conclusion: The use of ideals shows promise in the identification of response shift. The observation that dental patients expect a certain level of impact from oral conditions has implications for provision of health care and assessment or oral health related quality of life.


0030 (110659)

LFpen/ ICDAS II in detecting occlusal caries in primary molars. K.W. NEUHAUS, J.A. RODRIGUES, I. HUG, H. STICH, and A. LUSSI, University of Bern, Switzerland

LFpen/ ICDAS II in detecting occlusal caries in primary molars

Objectives:

The aim of the present study was to compare the performance of different methods (laser fluorescence, visual examination and radiography) in detecting occlusal caries in deciduous molars.

Methods:

Twenty-three primary molars were frozen directly after extraction. After defrosting and professional cleaning, the teeth were investigated with laser fluorescence (DIAGNOdent 2095 and DIAGNOdent pen, KaVo, Biberach, Germany), visual inspection ("traditional" [D0-D4] and ICDAS II) and radiography for occurrence of occlusal caries. Measurements and scoring were independently performed two times by two experienced examiners. The teeth afterwards underwent histological processing with thin sections; these were stained with Fuchsine dye and light green acetate. After taking photomicrographs under a stereo light microscope with two-fold magnification, caries extension (D0-D4) was assessed by two examiners. Outcome parameters were intra-and interexaminer reliability (ICC and Kappa), sensitivity, specificity, and AUC under the ROC curve. Statistics were obtained with SPSS 13.0 for Mac.

Results:

LF

LFpen

visual

ICDAS II

radiography

Sensitivity

D1

0.833

0.833

0.85

0.933

0.517

D3

0.857

1

0.643

0.893

0.75

Specificity

D1

0.875

1

0.562

0.563

0.781

D3

0.844

0.719

0.953

0.859

0.75

AUC

D1

0.885

0.925

0.706

0.748

0.649

D3

0.887

0.901

0.798

0.876

0.75

Intra-examiner reliability (ICC)

0.941; 0.824

0.903; 0.930

0.801; 0.419

0.881; 0.352

0.592; 0.830

Inter-examiner reliability (Kappa)

0.907

0.929

0.168

0.359

0.359

LFpen showed the highest sensitivity at the D3 level in detecting occlusal caries in primary molars. AT the D1 level, highest sensitivity was obtained with ICDAS II. Intra- and interexaminer reliability was substantially higher for LF than for either visual or radiographic examination.

Conclusion:

LFpen is recommendable as an adjunct tool for occlusal caries detection in primary molars. Careful visual caries diagnosis with ICDAS II system is promising regarding early caries detection, although its specificity is comparably low, and the system seems to need thorough training.


0031 (111645)

Development of an Indicator for Specific Detection of Infected Dentin. O. KAPPLER, I. HAEBERLEIN, H. STOEGER, B. SCHMID, and R. GUGGENBERGER, 3M ESPE AG, Seefeld, Germany

In view of the Minimal Invasive Dentistry approach specific differentiation between infected and affected dentin would significantly contribute to prevent over-excavation of caries lesions. Available caries detectors solutions are subject to discussions because of over-staining of dentin in caries lesions. Objective: of the study was to evaluate if the most prominent bacteria found in infected dentin are stained by the new caries indicator solution BV-1 (3M ESPE) Methods: A PubMed literature search was accomplished to identify the bacteria species with highest prevalence in infected dentin. Among them are S.mutans, S.oralis, S.sanguis, L.fermentum, L.rhamnosus, L.casei, L.gasseri, A.neslundi and A.israeli which were purchased from the German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany. A novel developed caries indicator solution BV-1 (3M ESPE) was used to evaluate if all these bacteria cultured on brain-heart-agar, are stained. The staining and reaction times were monitored with a digital camera (Cannon Power shot G5). Results: All investigated bacteria were stained by BV-1 in 10 to 60 sec. A. neaslundi was stained in 5 sec, L.casei and L.fermentum in 10 sec, S.mutans and S.sanguis in 30 sec, L.rhamnosus and S.oralis in 60 sec. The blue-violet signals were easy to see because the surrounding agar was not stained by BV-1. Conclusion: Staining of the caries lesion related bacteria is a promising starting point to improve the differentiation between infected and affected dentin to prevent over-excavation. Further clinical experiments are initiated to explore the diagnostic performance of BV-1.


0032 (111510)

Evaluating Caries Excavation Techniques Using Confocal Micro-endoscopy and SEM. S. KELLOW, R.J. COOK, A. BANERJEE, F. MANNOCCI, and T.F. WATSON, King's College London, England

Introduction: Heavily bacterial infected dentine is soft and wet, and it has been suggested that the removal of such infected dentine may halt the carious process, promoting the reversal of pulpitis and deposition of secondary or reparative dentine beneath the affected zone. Furthermore, it is established that partially softened caries-affected dentine, if it is well isolated from nutrients, can be remineralised.

Methods: 30 recently extracted human molars with occlusal carious lesions extending midway into dentine were collected. A tungsten carbide fissure bur removed enamel to expose the carious lesion and create adequate access for caries excavation. The teeth were randomly divided into 3 groups according to the caries removal method used: mechanical hand excavation, chemomechanical (Carisolv) or enzymatic chemomechanical. 21 teeth were allocated for caries detection using a confocal laser endoscope (MKT, Cellvizio-G1). 10 readings were obtained before and after caries removal from each tooth. 3 teeth from each group were examined with SEM to evaluate surface topography left after caries removal.

Results: Confocal endoscopy revealed highly autofluorescent signals from the base of the carious lesions before caries removal and these signals decreased significantly after caries removal in all groups. The lowest signals were detected after caries removal using hand excavation followed by chemomechanical and then enzymatic chemomechanical removal. SEM examination showed that dentine surfaces after hand excavation appeared to be covered with a smear layer. In contrast, chemomechanical caries removal produced no smear formation. In the case of enzymatic removal, the pictures observed were more complex as some areas showed smearing while other areas were free of smearing.

Conclusions: Hand excavation over-prepared cavities and produced smearing. Chemomechanical excavation was more selective than hand excavation and produced no smearing. Enzymatic chemomechanical excavation tended towards under- prepared cavities with mixed smeared and unsmeared areas.


0033 (111150)

In vitro Models for Anti Erosion Toothpastes. T. POTH, J.C. PESCHKE, R. KLISS, and C. BUCHERT, SusTech GmbH & Co. KG, Darmstadt, Germany

Objectives:

Dentifrices that deposit calcium phosphate onto the enamel surface can inhibit or even reverse dental erosion. The objective of this study was to compare two in vitro models to test the efficacy of depositing toothpastes.

Methods:

For both studies bovine enamel was embedded, polished and taped to generate reference areas. For treatment specimens were brushed in 1:1 slurries of the dentifrices (150g load, 60sec). In between treatments they were stored in artificial saliva at 37°C. The treatments were performed twice daily.

Erode and Restore Model (MER): Specimen received a 30sec etch (5% citric acid) and 5 consecutive treatments (2.5 days).

Protection Model (MP): Sound specimens were submitted to Coke for 20 min and then received 3 treatments. This cycle was repeated 11 times (15 days).

Analysis was performed by 3D profilometry and customized software. For MER, specimens were scanned post etching and post treatment. Surface restoration was calculated in µm by subtraction of the post etching from the post treatment profile. For MP surface loss (Wear) was determined in µm.

Two depositing pastes have been employed. A silica/NaF (1450ppm) paste containing a Hydroxyapatit Protein Composite (HPC) (P1) and a paste containing a bioglass (Oravive® Alachua, FL, USA, P2, MER only). A standard Silica/NaF (1450ppm) paste (PC) served as control.

Results:

MER: The average wear before treatment was: -1.7±0.3µm

Paste

P1

P2

CP

Restoration (µm)

4.2±0.4

2.7±0.2

-0.5±0.4

MP:

Surface loss (µm)

P1

CP

5 cycles

-0.69±1.40

-9.47±0.61

11 cycles

-3.09±1.99

-19.77±1.17

Conclusions:

The models clearly distinguish between depositing pastes P1 and P2 and non depositing paste CP. Both models are appropriate to assess both the efficacy of toothpastes in erosion inhibition (MP) and their ability to restore the enamel surface (MER). For MER, P1 showed a stronger restoration than P2. For MP a steady state equilibrium between erosion and restoration is reached. Therefore the acid resistance of the deposited calcium phosphate is in the range of natural enamel.

 

 


0034 (111175)

In vitro comparison between Fluorinex® method and traditional topical fluoridation. O. ZUABI1, K. KHAWALED2, and E.E. MACHTEI1, 1Rambam Health Care Campus, Haifa, Israel, 2Fluorinex, Yokneam, Israel

Objectives: 1. To determine in vitro the precipitation of fluoride onto human teeth treated with Fluorinex®, a novel iontophoresis device for topical fluoridation, using the Energy Dispersive Spectrometer (EDS) microanalysis method. 2. To compare fluoride surface enamel content between Fluorinex® method, traditional 1.23% Acidulated Phospholated Fluoride (APF) gel application and non-treated enamel.

Methods: 10 freshly extracted, intact molar human teeth were sectioned longitudinally into 3 sections each and subdivided into 3 groups; Fluorinex® method for topical fluoridation group, traditional APF gel application group and non-treated control group. Following topical fluoridation treatment (Fluorinex® and traditional gel application groups), all samples were mounted onto standard holders and were coated with 20 nm thick carbon film to provide electro and thermo conductivities. For each sample five EDS spectra were collected from areas of about 140x120 µm2. All samples were analyzed under uniform, comparable conditions at two acceleration voltages of 10kV and 20kV, both to assure the necessary surface sensitivity and to enable the optimal detection of main components; Ca, P, F, and O in the EDS spectrum.

Results: Significant differences within groups were found. Mean ± SE fluoride atomic % content measured were; 1.78±0.83, 2.12±0.32 and 12.47±3.16, (p=0.0005) and mean fluoride weight % content measured were; 0.87±0.18, 1.84±0.27 and 10.59±2.78, (p=0.0003) for non-treated, traditional gel application and Fluorinex® method, respectively. Comparison between groups, using analysis of variance (ANOVA, &alpha=0.05) test, showed significantly higher fluoride content in the Fluorinex® group compared with traditional gel application and non-treated groups. No significant difference was found between non-treated and traditional gel application groups.

Conclusions: 1. significant amount of fluoride accumulated on the surface layer of human enamel, after topical fluoridation using the Fluorinex® method. 2. Fluorinex® method was 6 times more efficient compared to traditional gel application.


0035 (111019)

The Safety of Fluorinex® topical fluoridation treatment; an In-vivo study. E. MACHTEI1, Y. BENTUR2, K. KHAWALED3, and O. ZUABI1, 1Rambam Health Care Campus, Haifa, Israel, 2Rambam Health care campus, Haifa, Israel, 3Fluorinex, Yokneam, Israel

The Fluorinex® topical fluoridation protocol includes the use of copper chloride (CuCl2) and 1.23% Acidulated Phosphate Fluoride (APF) gel.

Objectives: to evaluate the safety of Fluorinex® treatment using blood, urinary and salivary parameters.

Methods: 10 healthy volunteers were included in the study. Teeth were treated using the Fluorinex® protocol as follows: 1. a protecting gel was applied to the gingival, 2. one minute pretreatment CuCl2 application in a dedicated tray, 3. thorough water wash, 4. a 4 minutes 1.23% APF gel application in a Fluoritray®. Blood and urinary samples were obtained at baseline, 2 and 24 hours following treatment. Fluoride & copper concentrations, creatinine, total protein, hepatic profile, renal profile, complete blood count (CBC) and salivary fluoride concentration were assayed. Participants were asked to report on any acute gastrointestinal symptoms.

Results: No statistically significant differences were recorded in any blood, urinary and salivary parameter. Average blood copper and fluoride concentrations at baseline, 2 and 24 hours were 105, 112.6, 105 µg/dl, p=0.8263 (for blood copper) and 0.036, 0.035, 0.032 µg/dl, p=0.9583 (for blood fluoride), respectively. Average blood total bilirubin (mg/dl), direct bilirubin and creatinine for these time points were 0.57, 0.47, 0.55, p=0.3974, 1.53, 0.11, 0.7, p=0.3357 and 0.80, 0.77, 0.8, p=0.7399 respectively. No adverse event was recorded. There was a low, transient, within normal range, non-toxic and non-significant elevation in blood copper concentration. Treatment did not alter blood, urinary and hepatic profiles. Conclusions: Fluorinex® treatment is a safe procedure for topical fluoridation.


0036 (110856)

Effect of Desensitizing Agents on Root Dentin De- and Remineralization. C.R. GERNHARDT, A. FREUDENBERG, H.-G. SCHALLER, and K. BEKES, Martin-Luther-University Halle-Wittenberg, Germany

Objectives: Former investigations have shown that desensitizing agents can prevent root surface caries. The aim of the present study was to determine the effect of  two different desensitizing agents (Hyposen, VivaSens) on root surfaces de- and remineralization in vitro. Methods: The root surfaces of 40 freshly extracted caries-free human molars were thoroughly cleaned, thereby removing the cementum. The teeth were then coated with acid-resistant nail varnish, exposing two rectangular windows. All specimens were demineralized for 14 days with acidified gel (HEC, pH 4.8, 37 degrees C). Before remineralization using a NaF-containing calcium-phosphate buffer solution one window was covered. The specimens were distributed among two groups: In one group the desensitizer was applied before demineralization was done, in the other subgroup the desensitizer was applied after demineralization. Two desensitizing agents were used: H: Hyposen; V: VivaSens From each tooth, two dentinal slabs were cut. The depth of the demineralized areas was determined using a polarized light microscope. Results: Following lesion depths (in microns) were evaluated:

  Group

  demineralization -

  desensitizer application -

  remineralization

  desensitizer application -

  demineralization -

  remineralization

  Hyposen

  Vivasens

  Hyposen

  Vivasens

  Lesion

 Deminer.

 Reminer.

 Deminer.

 Reminer.

 Deminer.

 Reminer.

 Deminer.

 Reminer.

  Mean

  128.2

  75.87

  123.1

  84.9

  82.1

  62.3

  120.4

  91.6

  +/-

  21.2

  23.28

  28.2

  17.5

  28.4

  23.1

  31.2

  25.9

The comparison between de- and remineralized groups showed a significant reduction of lesion depth in all cases (p<0.05, Tukeys test). Application of the desensitizer Hyposen prior to demineralisation resulted in decreased lesion depths compared to the demineralization lesion depths without desensitizer application (p<0.05, Tukeys test). Conclusions: It can be concluded that the demineralization of the root surface can be hampered by the application of desensitizing agents in vitro.


0037 (110853)

Effect of Irradiation and Desensitizer Application on Demineralization of Dentin. K. BEKES, U. FRANCKE, H.-G. SCHALLER, and C.R. GERNHARDT, Martin-Luther-University Halle-Wittenberg, Germany

Objectives: The aim of the present study was to evaluate the effect of different irradiation doses and desensitizer application on the onset of initial demineralization of human dentin in vitro. Methods: The root surfaces of 45 freshly extracted caries-free human molars were cleaned, thereby removing the cementum. From each tooth two root dentin specimens were prepared. The specimens were distributed among the following experimental groups: control (no irradiation), 0.5 Gy, 1 Gy, 2 Gy, 5 Gy. The irradiation dose was fractionally applied (0.5 Gy/day). One dentin specimen of each group was inserted into both buccal aspects of each intraoral mandibular appliance. On one side the specimens were additionally coated with the desesensitizer Hyposen (H). On the other side, the specimens were left untreated (C). The appliances were worn by nine persons for five weeks day and night. During meals, the appliance was stored in 10% sucrose solution. After the in situ period, slabs (150 microns) were ground and studied using a polarized light microscope. Results: Concerning lesion depths, ANOVA revealed significant differences between specimens treated with different radiation doses and with/without desensitizer. Following lesion (in microns) depths were evaluated:

 

 Group

 Control

 0.5 Gy

 1 Gy

 2 Gy

 5 Gy

 

 C

 H

  C

 H

 C

 H

 C

 H

 C

H

 Mean

 44.48

 29.76

 41.53

 32.12

 52.52

 33.45

 59.02

 39.7

 64.06

 43.39

 +/-

 8.97

 8.2

 9.30

 8.31

 10.72

 15.63

 10.9

 9.88

 8.73

 10.78

 

Pairwise comparison showed that lesion depths in groups treated with Hyposen were significantly decreased. Concerning radiation dose, significant differences were observed between the Control and 5 Gy group (p<0.05, Tukeys test). Conclusions: Within the limitations of this study it can be concluded that the demineralization of the root surface can be hampered by application of desensitizers. Therefore, Hyposen might have a caries-protective effect on exposed irradiated root surfaces.

 


0038 (109955)

Ormocer-matrix composites can exhibit sufficient viscoelastic stability. M. KALEEM, D.C. WATTS, and J.D. SATTERTHWAITE, University of Manchester, United Kingdom

Objectives: To compare the creep behaviour between a series of TEGMA-free Ormocer matrix composites with classical BisGMA/TEGMA matrix composites at different levels of filler-fraction.

Methods: Three Ormocer matrix composites with descending levels of filler-fraction; 86, 79 and 69%w/w were evaluated versus approximately similar filler loading of BisGMA/TEGMA matrix composites. Three cylindrical specimens (4mm x 6mm) per material were prepared using steel moulds with thorough light curing from multiple directions at 600mm/cm2. All specimens were stored for a week in water at 37 ±1oC. A creep measurement apparatus was used to determine the creep-strain and recovery. Constant compressive stress of 36MPa was applied to each specimen for 2 h followed by load-removal, for 2 h of strain-recovery. Axial-strain measurements were obtained continuously over the total of 4 h. One-way ANOVA and an independent T-test were applied.

Results:

Maximum creep-strain (%)

Resin System & Filler-Load w/w

69%

79 %

86 %

Ormocer matrix composite

Mean(S.D)

5.44 (0.07)

4.08 (0.57)

1.96 (0.27)

BisGMA/TEGMA matrix composite

Mean(S.D)

3.63 (0.10)

2.07 (0.14)

1.59 (0.26)

.

.

.

.

.

At lower filler-fractions Ormocer matrix composites showed greater maximum creep-strain (%) compared to the control BisGMA/TEGMA matrix composites (p<0.05). However there was no significant difference between these resin systems at the higher filler fraction (p> 0.05).

 

Conclusion: Grandio materials showed lower maximum creep-strain than Ormocer materials. Both materials showed an increase in creep resistance when filler-fraction was increased.


0039 (110447)

Improved Polish, Wear-Resistance and Esthetics of a Nanoiomer Restorative Material. J.D. OXMAN, A. FALSAFI, S. MITRA, T.T. TON, V.J. MADSEN, and H.T. BUI, 3M ESPE Dental Products, Saint Paul, MN, USA

 

 

Objective:  The goal of this study was to compare the polish, wear properties and esthetics of Ketac Nano, a nano-hybrid resin modified glass ionomer (NHRMGI), with two resin-modified glass ionomers (RMGI) and a nanohybrid composite (NHC) restorative products and .  The restoratives evaluated included three RMGI materials: Ketac Nano (KN, 3M ESPE), Fuji II LC (FIILC, GC), Fuji Filling LC (FFLC, GC), and a NHC: Tetric Evo Ceram (TEC, Ivoclar Vivadent). Method:  All materials were mixed and light-cured per manufacturers' recommendation. Samples were polished per a clinically relevant protocol using commercial finishing/polishing systems.  The gloss of multiple samples was measured immediately after polishing using a gloss meter at 60 degrees.  Three-body wear depth was measured after 80,000 cycles according to ACTA Protocol.  Multiple specimens of each material per test protocol were prepared and immersed in 37C deionized water for 24 h before testing.  Results: The mean values including their standard deviations in the parentheses are summarized in the following table:

Restorative

Chemistry

FillerType(s)

Wear Depth 80k cycles, micron

Initial Polish Number

Ketac Nano

(KN)

NHRMGI

Fluoroaluminosilicate, Nanomers, Nanoclusters

    21.8(1.3)

    36.5(1.3)

Fuji II LC

(FIILC)

RMGI

Fluoroaluminosilicate

    32.6(0.8)

3.4(0.6)

Fuji Filling LC

(FFLC)

RMGI

Fluoroaluminosilicate

    52.7(1.2)

    2.4(0.4)

Tetric Evo Ceram (TEC)

NHC

Macro, micro and nano fillers

    6.8(0.4)

64.2(11.1)

Conclusions:  ANOVA with Tukey's comparison was performed at p < 0.05.  Ketac Nano paste/paste nano-ionomeric restorative (KN) showed significantly higher gloss compared to other RMGIs, closer to that of a hybrid composite.  Ketac Nano paste/paste nano-ionomer (KN) had significantly lower wear rate compared to other RMGIs. Clinical photographs along with Atomic Force(AFM) and Scanning Electron(SEM) micrographs will be presented.


0040 (110935)

Innovative Composites for Dental Restoration. H. WOLTER1, W. STORCH1, N. SOMCHITH1, R. MALETZ2, T. NEUMANN2, and M. DANEBROCK2, 1Fraunhofer-Institut für Silicatforschung ISC, Würzburg, Germany, 2VOCO GmbH, Cuxhaven, Germany

Innovative Composites for Dental Restoration

H. WOLTERa, W. STORCHa,  S. NIQUEa, R. MALETZb, T. NEUMANNb, M. DANEBROCKb, aFraunhofer-ISC, Würzburg, Germany; bVOCO GmbH, Cuxhaven, Germany

 

Objectives: For a longevity restoration, dental composites with low polymerization shrinkage and tooth-like thermo-mechanical properties are desirable. Taking these requirements into account, the objective of this investigation was to compare dental filling materials based on the nano-hybrid technology (ORMOCER®-based matrices) with the Silorane technology (epoxy-based matrix).

Methods: The composites characterized were FiltekTM Silorane (I, 3M-Espe) with an epoxy-based ring-opening polymerizable matrix and four experimental nanohybrid composites with different monomer-free ORMOCER®-matrices (IIa – IId, Fraunhofer ISC/VOCO). The materialxs polymerization shrinkage and their Youngs modulus were determined according to DIN 13907 and ISO 4049, respectively. The coefficient of thermal expansion α was measured in the temperature range of 5 – 50 °C.

Results:

 

                                              Composites

       I

      IIa

        IIb

     IIc

        IId

 

   Filler content   [wt.-%/vol.-%]

   76*/n. a.

   84.0/70.8

   86,0/73,8

   86.5/74.5

   85.0/70.0

Volume shrinkage          [%]

  1.2 (± 0.1)

  1.7 (± 0.1)

  1.3 (± 0.2)

  1.6 (± 0.1)

  1.4 (± 0.0)

 Youngs modulus           [GPa]

  9.8 (± 0.3)

  12.8 (± 0.4)

  12.3 (± 0.4)

 15.2 (± 0.4)

  11.9 (± 0.4)

     α [10-1K-1]           5 – 50 °C

  30.4 (± 0.1)

  22.8 (± 0.1)

      n. d.

 20.8 (± 0.1)

  24.8 (± 0.4)

*3M-ESPE product brochure

 

The Youngs modulus of composite I is comparably low, while the α-value is comparably high. Due to the polymerization by a ring-opening mechanism a very low shrinkage is observed in spite of the low filler content. In comparison, the experimental composites IIa – IId show higher Youngs moduli (11.9 – 15.2 GPa), lower α-values (20.8 – 24.8·10-1K-1) and only slightly higher shrinkage values (1.3 – 1.7 %) caused by functionalized structure of oligomers within the ORMOCER®-resins and high filler contents.

Conclusion:

Taking the low shrinkage and the more tooth-like Youngs moduli and α-values into account, the monomer-free ORMOCER®-based nano-hybrid composites are examples of a promising alternative class of dental material.

 

This work was supported by the BMBF under the contract 03N400bA3.

 

 


0041 (111157)

Physical properties of a new maxillofacial-silicone elastomer after Accelerated light-aging. M.M. HATAMLEH, and D.C. WATTS, University of Manchester, United Kingdom

Objective: To investigate the physical properties of tensile strength and modulus, elongation, tear strength, hardness, colour change and light transmittance, of a new maxillofacial-silicone elastomer after accelerated light-aging.

 

Methods: For each property (tensile strength, tear strength, hardness and colour change) 16 specimens were fabricated of TechSil 25 silicone-elastomer. Half of the specimens served as control (Group1) and the remaining were aged in environmental chamber (Group2), exposing them to filtered Xenon light of 150 klx, and irradiance of 475 W/m2 under controlled moisture conditions for 360 h.

 

Tensile and tear tests were conducted according to ISO specifications no. 37 and 34 respectively, in a Zwick testing machine. Shore A hardness measurements were run according to ASTM D 2240. Colour change was determined in the CIE LAB system using a Minolta chromameter, and light transmittance was determined using Ocean Optics USB 4000 Fibre optic spectrometer operated by SpectraSuite software.

 

Statistical t-test for independent data was used to analyse significant differences (p<0.05) between both groups (1 and 2) in tensile strength, tensile modulus, elongation, tear strength, hardness, and light transmittance. Colour change (ΔE) greater than 3 was considered visually perceivable.

 

Results: Mean (SD) values of all measurements of both groups are presented in the following table.

 

Properties

Measurements obtained

Groups

Control

Light-Aged

Tensile

Tensile strength (MPa)

4.88 (0.34)

4.64 (0.78)

Tensile modulus (MPa)

1.29 (0.13)

1.13 (0.31)

Elongation percentage (%)

940 (95)

997 (127)

Tear

Tear strength (kN/m)

6.64 (1.61)

6.12 (0.89)

Hardness

Shore A hardness

26.9 (0.20)

27.6 (1.40)

Aesthetic

Light transmittance (%)

1.57 (1.07)

1.65 (1.12)

Colour change (ΔE)

8.26 (0.95)

 

 
 

 

 

 

 

 

 

 

 

 

 
No statistically-significant differences were present between groups (p>0.05) in the analysed properties. However, high colour change was evident.

 

Conclusions: Silicone specimens light-aged for 360 h, which simulate 6-12 months of clinical service, showed no changes with respect to the properties studied. However, colour change was significant and perceivable necessitating replacement of such prosthesis within that period of service.   

 

 

 


0042 (111273)

Microtomographic Measurements of Attenuation of a Novel Radio-Opaque Fissure Sealant. A.A. KHAN, M. PATEL, M. BRADEN, G.R. DAVIS, and P. ANDERSON, Barts and the London School of Medicine and Dentistry, United Kingdom

Objectives: X-ray opacity can be achieved by blending radio-opaque metallic salts with polymer powders before polymerization. A novel approach is to use polymers in which the X-ray opaque element is chemically incorporated within the monomer unit. The aim was to measure the X-ray attenuation of polymerized tin methacrylate materials in which the weight percentage (wt-%) of monomer was increased up to 95 %.

Methods: Solutions of methacryloxytri-n-butyl tin (MBT) were prepared containing 50, 75, 85 and 95 wt-% MBT and poured into 1 x 1 cm cuvettes. The MBT solutions were light cured for 30s using a CU-100r halogen lamp. The filled cuvettes were mounted onto X-ray microtomography (XMT) apparatus and 3D images obtained. The linear attenuation coefficients (LACs) of the polymerized material were obtained from the distributions of LACs in each 3D data set and compared.

Results: The XMT images showed that X-ray attenuation was homogenous throughout the materials for all compositions. The peaks of the LAC distributions increased linearly with weight percentage of MBT monomer. The LACs at 40keV were 2.92, 3.64, 4.36 and 4.76 cm-1 at 50, 75, 85 and 95 wt-% of MBT respectively. The LAC of enamel at 40keV is 3.0 cm-1.

Conclusions: Polymerized MBT monomers with weight percentage compositions of up to 95% produce materials of uniform high X-ray opacity. Such high X-ray opacity materials may have applications as radio-opaque dental materials, for example, fissure sealants.


0043 (111588)

Post-Gel Polymerization Shrinkage of Silorane versus Methacrylate Composites. C. THALACKER, C. ACHELWILM, K. DEDE, O. KAPPLER, A. SYREK, R. GUGGENBERGER, and W. WEINMANN, 3M ESPE AG, Seefeld, Germany

Objectives: Post-gel polymerization shrinkage is the phase of the overall volumetric shrinkage of a resin composite during which significant stresses are exerted on the surrounding tooth structure. Aim of this study was to compare the post-gel polymerization shrinkage of FiltekTM Silorane with a volumetric polymerization shrinkage of <1% to conventional methacrylate-based composites.

 

Methods: Samples (approx. 45mg) of TPH3 (TPH3, Dentsply), Grandio (GRA, VOCO), FiltekTM P60 (P60, 3M ESPE), ELS (ELS, Saremco), Tetric EvoCeram (TEC, Ivoclar-Vivadent), QuiXfil (QXF, Dentsply), Premise (PRE, Kerr), and FiltekTM Silorane (SIL, 3M ESPE) were placed on a biaxial strain gauge (CEA-06-032WT-120, Vishay Measurement Systems) and photopolymerized for 40s with a 3M XL 3000 curing light (650mW/cm2). The induced shrinkage strain was monitored for 10min (n=3).

 

Results: The following table shows the absolute value of post-gel shrinkage strain after 10min in microstrain (µm/m). The standard deviations (SD) are given in parentheses. All data were analyzed by ANOVA and multiple comparisons using the Tukey test (p<0.05). Means with the same letters are statistically the same.

 

Material

TPH3

GRA

P60

ELS

TEC

QXF

PRE

SIL

µstrain

(SD)

2739.5

(33.8)a

2388.1

(131.2)b

2159.7

(45.7)bcd

2158.4

(58.5)bcd

2054.7

(76.1)cde

1951.3

(80.0)de

1927.1

(94.3)e

1111.7

(82.5)f

 

Conclusion: Multiple statistically significant differences were found. FiltekTM Silorane had the lowest post-gel shrinkage strain of all investigated materials.

 

 

 


0044 (111602)

Effect of Additives on Novel Tissue Conditioner Formulations. S. PARKER, M. HASSAN, M. BRADEN, and M. PATEL, Barts and the London School of Medicine and Dentistry, United Kingdom

Objectives:  Dental tissue conditioners have been used to deliver various antimiocrobial/antibacterial agents to treat intraoral Candidal infections. The objective of this study was to investigate the effect of such additives on the gelation time and water uptake characteristics of two tissue conditioner formulations.

Methods:  The formulations comprised a polymer powder (polyethyl methacrylate, PEMA, from Lucite International) with a 95% plasticiser 5% ethanol mix. Two plasticisers were used, acetyl tributyl citrate (ATBC) and butyl phthalyl butyl glycollate (BPBG) from Morflex Inc., USA. Powder liquid ratio used was 5g to 3ml. Additives were clorhexidine diacetate (CHD) and sodium fluoride (NaF) from BDH Chemicals, UK. Formulations were tested with no additives (control) and with 1% CHD and 1% CHD/0.5% NaF mix. Gelation time at 37ºC was determined (using 60% trace reduction method) for all formulations (n=6) with an oscillating rheometer. Water uptake was measured gravimetrically using specimens (n=4) 40 x 10 x 1mm immersed in 100mls of distilled water at 37ºC.  Weight change with time was recorded for 14 days after which specimens were removed, desorbed and solubility calculated.

Results: 

 

ATBC

ATBC/CHD

ATBC/

CHD/NaF

BPBG

BPBG/CHD

BPBG/

CHD/NaF

Gel time min (SD)

36.9 (3.8)

25.0 (4.3)

26.0 (2.7)

17.4 (3.2)

14.1 (2.5)

9.2 (1.5)

% weight change (SD)

2.1 (0.2)

7.6 (0.6)

32.6 (1.8)

3.1 (0.2)

4.8 (0.4)

31.0 (1.6)

% solubility (SD)

0.97 (0.06)

1.37 (0.02)

1.85 (0.11)

1.42 (0.07)

1.73 (0.06)

2.45 (0.06)

The additives reduced the gelation time for both plasticiser formulations. CHD/NaF combination had the most effect on water uptake and solubility. Further analysis of data showed a change in kinetics from Fickean to Fickean plus Case II when CHD/NaF was added.

Conclusions:  The additives affected both gelation time and water uptake characteristics, this needs to be taken into consideration when using these systems for drug delivery


0045 (112354)

Potential for Healing of White Spot Lesions With Novel Product. A.K. BURWELL1, A.H. STONE1, and A. GIBSON2, 1NovaMin Technology, Inc, Alachua, FL, USA, 2Biofilm Ltd, Glasgow, Scotland

OBJECTIVES: To establish an in vitro model to evaluate healing of enamel white spot lesions (WSL) and use the model to assess the potential of a novel NovaMin® (calcium sodium phosphosilicate)-containing resorbable polymer strip to heal WSL.

METHODS: Bovine crowns were epoxy-mounted and ground/polished to expose the sound enamel layer. Surfaces were taped to leave only 5x5mm windows exposed. Artificial WSL were pre-formed on the enamel via 72-hour immersion in demineralization solution (pH=4.52, 37°C).

Samples were subjected to a 10-day pH cycling protocol that consisted of twice-daily 30-minute soaks in demineralization solution (pH=4.52, 37°C) followed by five-minute treatment periods (test product placed on WSL, 0.50mL DI water placed on product, undisturbed for 5 minutes, rinsed to remove visible product). Samples were soaked in artificial saliva (pH=7.00, 37°C) between the two demineralization/treatment periods.

Test groups/products were: A) WSL (72-hour lesion formation only), B) resorbable polymer strip (hydroxypropyl methylcellulose, HPMC), C) NovaMin®-containing polymer strip (HPMC+16% NovaMin®), D) SootheRx dentifrice (7.5% NovaMin®), and E) MI Paste (10% Recaldent™). Surface microhardness (Knoop, KHN) was measured on all samples using a load of 100 grams for 15 seconds.

RESULTS: Data were analyzed using one-way ANOVA and Student-Newman-Keuls statistical methods. All KHN data are mean±S.E.M. with n=15. Results were: A) 2.09±0.35, B) 2.41±0.17, C) 9.84±1.14, D) 7.71±0.56, and E) 2.32±0.16 with C = D > A = B = E (p<0.01). Enamel surfaces were drastically softened during WSL formation. Treatment with NovaMin®-containing resorbable strip significantly hardened artificial WSL compared to polymer-only resorbable strip.

CONCLUSIONS: The WSL formation used in this model was aggressive and needs to be adjusted in future studies. Within the limitations of this model, however, a novel NovaMin®-containing resorbable polymer strip shows potential for treatment and healing of enamel white spot lesions. Clinical confirmation of results and evaluation of product efficacy is planned.


0046 (110126)

Bonding of auto-adhesive luting materials to enamel after surface treatments. J. PISANI-PROENCA1, R.D.C. SALMERÓN1, R. AMARAL2, E.P. PROCHNOW3, M.A. BOTTINO4, L.F. VALANDRO3, and M.C.G. ERHARDT1, 1University of Granada, Spain, 2Sao Paulo State University (Unesp/SJC), Sao Jose dos Campos, Brazil, 3Federal University of Santa Maria, Brazil, 4Paulista State University, São José dos Campos, Brazil

Objectives: To assess the effects of different mechanisms of enamel conditioning on the bonding performance of auto-adhesive luting cements to enamel. Methods: Flat enamel surfaces from forty-eight human molars were divided in four treatment groups: 1) no treatment (control); 2) etching with 36% H3PO4 for 15s; 3) etching with 0.1M EDTA for 60s; and 4) etching with Clearfil SE Bond Primer for 20s. Composite blocks (Tetric Ceram/Ivoclar Vivadent) were cemented to the treated enamel surfaces with the self-adhesive resin cements RelyX Unicem (3M ESPE), Maxcem (Kerr) and Multilink Sprint (Ivoclar), according to the manufacturer's instructions. Bonded specimens were sectioned into beams of 1.0 mm2 cross-sectional area for microtensile bond strength (µTBS) evaluation. Beams were stressed in tension at 0.5 mm/min. Data were analyzed by 2-way ANOVA and Tukey test (α=0.05). Results: Mean µTBS and standard deviations are listed (MPa). Within the same row, identical letters indicate no differences (P<0.05).

 

Control

H3PO4

EDTA

SE Bond Primer

TOTAL

RelyX Unicem

5.7 (1.8) ef

22.4 (6.3) b

12.3 (2.4) de

11.1 (2.0) de

12.8 B

Maxcem

8.0 (1.0) def

28.1 (4.9) a

1.5 (0.3) f

17.9 (3.1) c

13.8 AB

Multilink

14.8 (1.3) cd

22.7 (2.8) b

9.8 (1.4) def

14.5 (1.7) cd

15.5 A

TOTAL

9.5 C

24.4 A

7.8 C

14.5 B

 

Resin-enamel bonds were affected by both cement (P=.0169) and conditioning methods (P=.0000). The highest µTBS were attained after H3PO4 and SE Bond Primer conditioning. Statistically lower µTBS were attained when luting with RelyX Unicem, while Multilink provided statistically higher resin-enamel bond strengths. Conclusions: When using auto-adhesive resin cements, the best bonding effectiveness was obtained by selectively acid-etching enamel prior to luting.

0047 (110137)

Bonding of auto-adhesive cements to discolored dentin after amalgam removal. J. PISANI-PROENCA1, M.C.G. ERHARDT1, L.F. VALANDRO2, R.D.C. SALMERÓN1, S. GONZÁLEZ-LÓPEZ1, and M.V. BOLAÑOS-CARMONA1, 1University of Granada, Spain, 2Federal University of Santa Maria, Brazil

Objectives: To evaluate the bond strengths of a conventional and an auto-adhesive resin cement to discolored dentin beneath amalgam restorations. Methods: Twenty amalgam-filled extracted human teeth were used. After the removals of amalgam, flat surfaces of discolored dentin surrounded by sound dentin were bonded with a conventional (Panavia F / Kuraray) or with an auto adhesive (RelyX Unicem / 3M ESPE) resin cement according to the manufacturer's instructions. Trimmed resin-dentin bonded interfaces (1 mm2) were stored in distilled water for 24 h and subjected to microtensile bond strength (µTBS) evaluation. Specimens stressed in tension at 0.5 mm/min. Data were analyzed by 2-way ANOVA and Tukey test (α=0.05). Results: Mean µTBS and standard deviations are listed (MPa). Within the same column, identical letters indicate no differences (P<0.05).

 

Sound dentin

Discolored dentin

Panavia F

17.8 (7.8) A

14.5 (6.7) A

RelyX Unicem

11.0 (4.5) B

9.9 (3.7) B

The resin bond to dentin was not affected by the type of dentin (P=.171) but was affected by the cement (P<.001). µTBS of Panavia F was significantly higher than that to RelyX Unicem for both dentin types. Irrespective the luting agent used, no differences were found between bond strengths to sound and discolored dentin. Conclusions: As compared to sound dentin, there were not remarkable differences in interfacial bond strength to discolored dentin when luting with resin-based cements. The conventional resin cement remains as a standard in terms of resin-dentin bonds quality.

0048 (110284)

SEM characterization of Filtek Silorane Adhesive-Dentine Interface. A. SANTINI1, V.J. MILETIC1, R. IBBETSON1, and V. IVANOVIC2, 1The University of Edinburgh, Scotland, 2University of Belgrade, Serbia and Montenegro

Objectives: To study the morphological characteristics and the thickness of the hybrid layer (HL) of the adhesive-dentine interface formed by Filtek Silorane adhesive system versus self-etch and etch-and-rinse systems, using scanning electron microscopy (SEM).

Methods: Twelve extracted human, intact third molars were used. A flat dentine surface was exposed by sectioning the tooth in the coronal one third of the crown perpendicular to the long axis. A smear layer was produced using 600- and 1000-grit silicone carbide discs under water. Teeth were allocated to four groups: I Filtek Silorane adhesive system, II AdheSE One (1-step self-etch), III AdheSE (2-step self-etch), IV Excite (etch-and-rinse). Adhesives were applied according to manufacturers' instructions and cured for 10 s with an LED unit. From each tooth, four 1 mm thick sections were cut, polished, subjected to acid-base pre-treatment, critically point dried, gold sputtered and examined at x3000-x10000 magnification using SEM. Statistical analysis was done using one-way analysis of variance (ANOVA).

Results: Filtek Silorane and Excite adhesive systems showed similar dense, thick, cone-shaped resin tags with numerous lateral branches. AdheSE showed numerous longer and thinner resin tags with a few thin lateral branches. AdheSE One showed resin tags with similar morphological characteristics to AdheSE though less numerous. Significant differences in the HL thickness are indicated with the same superscripts: Filtek SiloraneA,B 1.9±0.7 μm, AdheSE OneA,B 0.9±0.3 μm, AdheSEA 3.7±1.0 μm, ExciteB 5.1±1.3 μm (p<0.05, one-way ANOVA).

Conclusions: Filtek Silorane adhesive system showed morphological characteristics of the adhesive-dentine interface similar to the etch-and-rinse system.


0049 (111428)

Strength of aged repairs made by silorane- and methacrylate-based composites. S. MOSER, Dental College, Munich, Germany, R. HICKEL, Ludwig-Maximilians-University, Munich, Germany, and N. ILIE, Ludwig-Maximilians University Munich, Germany

Objectives: to determine the effect of aging on the shear-bond-strength of repaired fillings made by silorane- and methacrylate-based composites.

Methods: Fillings were prepared by polymerizing the composites - TetricEvoCeram/Ivoclar-Vivadent and Filtek Silorane/3MEspe - for 20s with the LED curing-unit Bluephase/Ivoclar-Vivadent in a shaped cavity (depth=2mm, diameter =6mm) of an acrylic cylinder. Following parameters were varied: Filling (S=Silorane; M=Methacrylate-composite), Repair (S=Silorane; M=Methacrylate-composite), Bonding-agent (SB=Siloranebond/3MEspe; HB=Heliobond/IvoclarVivadent; NB=none) and Aging of Filling and repaired samples (no aging; 1Week storage in aqua dest. at 37°C, and 1Month storage with additionally thermocycling with 5000cycles:5°C/55°C). Prior to bonding the filling was roughened (400-grit silicon carbide paper), cleaned (37% phosphoric acid), rinsed with water and air dried. The cylindrical repair (diameter=3mm) was applied in two 2mm thick increments, cured like the filling.

Specimens (n=10) were loaded in a universal testing machine (MCE2000ST, Quicktest PrüfpartnerGmbH, Germany) at a constant crosshead speed of 0.5mm/min.

Results: Data were analyzed by ANOVA, Tukey-HSD(α=0.05).

 

Filling

Repair

Bond

Aging-Filling

Aging-Repair

Strength/[MPa]

S

S

SB

1Week

no

4.1a(2.1)

S

S

SB

1Month

no

7.5ab(1.6)

S

S

SB

no

no

8.0ab(0.8)

S

S

NB

no

no

8.4abc(1.9)

M

M

NB

no

no

10.2abcd(2.4)

M

M

HB

1Month

no

12.9abcde(4.7)

M

M

HB

1Week

no

14.1bcdef(2.9)

M

M

HB

no

no

17.5cdefg(2.7)

S

S

SB

1Week

1Week

19.4defgh(5.8)

S

S

SB

1Month

1Week

19.9efgh(8.8)

M

M

HB

1Month

1Week

22.7fghi(6.0)

S

S

SB

1Month

1Month

24.3ghi(4.8)

M

M

HB

1Month

1Month

24.7ghi(6.0)

M

M

HB

1Week

1Week

26.7ghi(8.8)

S

S

SB

1Week

1Month

26.7ghi(5.7)

M

M

HB

no

1Month

28.0hi(9.6)

S

S

SB

no

1Week

29.8i(7.2)

M

M

HB

1Week

1Month

30.2i(3.6)

S

S

SB

no

1Month

31.8i(7.0)

M

M

HB

no

1Week

31.9i(10.7)

 

            Conclusion: Despite differences in the groups tested immediately after repair, the study exhibited no significant difference between Silorane and Methacrylate-groups after aging.


0050 (111434)

Bonding Strength of Silorane–Based composite to Er-YAG laser prepared dentin. E. KOLINIOTOU-KOUMPIA, L. ZAFIRIADIS, P. KOUROS, D. DIONYSOPOULOS, and V. KARAGIANNIS, Aristotle University of Thessaloniki, Greece

Objectives:

The aim of this study was to evaluate the bonding strength of a silorane–based composite when two different types of equipment was used for preparation of dentin (Er-YAG laser and carbide bur)

Materials and Methods:

Sixteen decay-free human molars sectioned in mesio-distal aspect. Dentin specimens were treated either with carbide bur or with an Erbium:YAG laser. Silorane System Adhesive and Single Bond were applied, according to manufacturer's instructions. In order to eliminate the bonded surface, a cylindrical teflon mould (3 x 4 mm) was placed over the bonded area. The composite were used, combined for each one of the adhesive systems (Filtek silorane and Z-250). The specimens stored in water at 370 C, for 24h and then stressed at a rate of 0.05 mm/min until failure. Failure patterns were analyzed at stereomicroscope and SEM.

A 2-way ANOVA was conducted. Pairwise comparisons, the Bonferoni test were used.

Results:

The main effect of Material, Z-250 and Silorane was not significant p=0.457. The main effect of Treatment bur cut and laser irradiation was not significant p=0.457. Also the interaction effect between Material and Treatment was found to be not significant p=0.974. Particularly there was not any significant difference between the mean values of Z-250 and Silorane when carbide bur cut was used p=0.582. There was no significant difference between the mean values of Z-250 and Silorane when laser irradiation was used p=0.614. In addition, there was no significant difference between the mean values of bur and laser when material Z-250 was used, p=0.614 and there was no significant difference between the mean values of bur and laser when material Silorane was used p=0.582.

Conclusions:

Adhesion of a silorane–based composite bonded to the Er-YAG laser-irradiated dentin using its adhesive appeared equal to those obtained for a bur-cutting dentin.


0051 (111461)

Effects of aging conditions on repair strength of resin composites. M. RINASTITI, University of Medical Center Groningen and University of Groningen, Netherlands, M. ÖZCAN, University of Medical Center Groningen, Netherlands, W. SISWOMIHARDJO, Gadjah Mada University, Yogyakarta, Indonesia, and H.J. BUSSCHER, University Medical Center Groningen and University of Groningen, Netherlands

Objectives:The objectives of this study were to compare 1-the repair bond strength of aged composites after aging, 2-to evaluate the failure types and 3-to study the surface wettening properties of the intermediate adhesive layers (IMR). Methods: One commercial microhybrid (Anterior Shine™), and 3 nanohybrid composites (Grandio™, Tetric EvoCeram™ and Filtek Supreme XT™) (N=240, n=10 per group) were polymerized in the undercut cavities in polyethylene rings under myllar stripes. They were then randomly assigned to the following conditioning methods: (1) Application of the corresponding IMR of each composite (Quadrant Unibond™, Solobond Plus™, Multilink™, Adper Scotchbond 1XT™), (2) Chairside tribochemical silica-coating (30 µm CoJet)+MPS silane coupling agent (ESPE-Sil)+Visiobond™ (SC). Substrate composites were aged either in thermocycling (5-55°C, 5000x cycles), immersion in distilled water at 37°C for 6 months or in the citric acid for 1 week. The substrate-adherend combinations involved the same composite. Specimens were then subjected to shear force at the bonded adhesive interface (universal testing machine, 1mm/min). Failure types were evaluated under the light microscope. Contact angle measurements were performed for each IMR and water as the control. Results: Significant effect of the composite type (p<0.05) and conditioning method was observed (p<0.05) (2-way ANOVA, LSD tests). Thermocyling showed the most aging effect for all composites with lower results (MPa) than other aging methods tested in groups repaired with IMRs (2.8±1 - 12.5± 3.1) with 5.7% cohesive failures. SC enhanced the results (10.5±3.5 – 23±8) and showed 71.4% cohesive failures. The contact angle of silane was 0° and IMRs presented values between 0°- 38.5°. Conclusions: Either SC or IMR can be used to repair the aged composite but it should be taken into account that conditioning with SC resulted in more cohesive failures. Surface wettening properties of IMRs were better after SC for both non-aged and aged composites.


0052 (111718)

Evaluation of a new self-adhesive resin cement. G.J.P. FLEMING, and R. JENKINSON, Dublin Dental School & Hospital, Ireland

Objectives: The potential of two experimental self-adhesive resin cements were evaluated against two commercially available self-adhesive resin cements in dark and light cured modes. Methods: Disc-shaped specimens (11 mm diameter, 1 mm thickness) were tested in bi-axial flexure to determine the strength at short- (0.5, 1, 4, 24 and 48 h) and medium-term (1, 4 and 12 w) time points. In addition, water sorption, water solubility, diffusion coefficients and Vickers hardness measurements were determined following the short- and medium-term water immersion on the disc-shaped specimens. One- and two-way analyses of variance (ANOVA) were made in software (SPSS, V 12.0.1, Chicago, IL, USA) using a critical significance level of P=0.05, guided as necessary by Tukeys correction in multiple partial analyses of the mean strength, water sorption, water solubility, diffusion coefficients and Vickers hardness measurements for the time points investigated in dark and light cured modes. Results: No significant differences in the strength, water sorption, water solubility and Vickers hardness measurements were evident between the self-adhesive resin cements examined. Differences occurred between the mode of curing (either dark or light cured). Conclusions: The current study shows the experimental materials have similar performance in terms of flexure strength, water uptake and hardness with commercially available self-adhesive resin cements.


0053 (111753)

Microtensile bond strength of dual cure resin cements to dentin. D.B. SERIN, E.C. SAY, M. ERSOY, and M. SOYMAN, Yeditepe University, Istanbul, Turkey

Objectives: The aim of this study was to evaluate the effect of cure mode of the adhesive and seating pressure technique on the microtensile bond strength of dual cure resin cements to perfused dentin.

Methods: Occlusal enamel of 32 extracted human third molars were removed using 180 grit SiC paper and smear layer on the mid coronal dentin was standardized using 600 SiC. Teeth were randomly divided into 2 groups according to the resin cement-adhesive combination (AdheSe-Variolink II, Ivoclar/Vivadent; Protect Bond-Clearfil Esthetic Cement, Kuraray). Each group was further subdivided into 4 groups according to the type of the curing mode of the adhesive (cured; uncured) and according to the seating pressure technique (40N/30 sec; 40 N/110 sec). Composite onleys (Filtek Z 250; 3M ESPE) 3mm in thickness and 9 mm in diameter were luted with the dual cure resin cements adhesive combinations to 15 cm/H2O perfused dentin. After storage in distilled water at 37oC for 24 h, microtensile bond strength (MPa) was evaluated using Bencor Multi Testing device attached to a universal testing machine (Instron). Data were analyzed using Mann-Whitney-U test.

Results: Different superscript letters in the same column and different capital superscript letters in the same row indicate significant differences (p<0.05).

Cure mode

Pressure technique

AdheSe-Variolink II

Protect Bond-Clearfil Esthetic Cement

n

uncured

40 N/30 sec

36,69±8,39 a,b,A

20,64±8,52 a,B

22

cured

40 N/30 sec

29,84±12,55 a,b,A

32,63±9,76 b,A

22

uncured

40 N/110 sec

27,53±8,86 a,A

24,47±10,59 a,c,A

22

cured

40 N/110 sec

35,25±14,95 b,A

29,17±9,4 b,c,A

22

Conclusions: Curing of the adhesive may improve the microtensile bond strength to dentin of Clearfil Esthetic Cement in combination with Protect Bond and Variolink II with AdheSe. Pressure technique (30 versus 110 sec) did not affect bonding of both resin cements to dentin in between the cured and uncured groups.


0054 (109987)

Effect of Cavity Configuration on Adhesion of a Silorane Composite. A. VAN ENDE, J. DE MUNCK, A. MINE, P. LAMBRECHTS, and B. VAN MEERBEEK, Leuven BIOMAT Research Cluster, Catholic University of Leuven, Belgium

Objectives: Polymerization shrinkage of a composite in a high configuration factor (C-factor) cavity leads to high polymerization stress. In this study, the effect of C-factor (flat vs. cavity) and composite shrinkage (high- vs. low-shrinking) on the micro-tensile bond strength (µTBS) to dentin was investigated.

Methods: A conventional methacrylate-based composite (Z100, 3M ESPE) and a low-shrinking silorane-based composite (Filtek Silorane, 3M ESPE) were applied to standardized occlusal class-I cavities (4x4x2.5 mm) and flat surfaces using the Silorane System Adhesive (3M ESPE). After one week of water storage, the teeth were sectioned to 1x1 mm sticks by an automated, water-cooled diamond saw (Accutom, Struers). For each group, at least 5 teeth were used, and from each tooth, the 4 central sticks were selected for µTBS-testing.

Results:

Z100

Filtek Silorane

Flat

Cavity Bulk1

Flat

Cavity Bulk1

Cavity Layers2

Cavity Flowable3

Cavity Warm4

Mean ± SD

ptf/n

30.2A,B ± 11.1

0/22

26.6A,B ± 17.3

0/19

33.4A ± 11.2

0/20

13.2C,D ± 9.2

2/18

21.5B,C ± 10.1

0/18

23.7A,B ± 7.9

0/20

4.2D ± 6.8

16/25

Means with the same superscript are not significantly different from each other (ANOVA and Tukey-Kramer tests; p<0.05); n = total number of specimens; ptf = pre-testing failures and were recorded as 0MPa. 1Cavity filled and cured in bulk. 2Composite was applied and cured in three layers. 3Before composite application, a thin layer of flowable composite (Experimental Silorane Flow, 3M-ESPE) was applied and cured. 4Composite was heated to 54°C.

Conclusions: Using Silorane System Adhesive, Z100 as well as Filtek Silorane were equally well bonded to dentin. Bulk-filling of the cavities with Filtek Silorane decreased the µTBS. This was primarily caused by poor adaptation between the adhesive and composite, as evidenced by failure analysis using scanning electron microscopy (Fe-SEM). This decreased strength could partially be restored by application in layers or prior application of a flowable resin.


0055 (109571)

Double coating effect of self-etch primers on bond strength. M. MOUSAVINASAB, University of Isfahan, Iran, and K. KHOSRAVI, Medical sciences of Esfahan University,Dental school, NC, Iran

Objectives:Low acidity in acidic primers compared to phosphoric acid, may be insufficient to achieve essential bond strength. On the other hand, application of these weak acidic primers on dentin with thick smear layer may result in low penetration of resin through smear layer to underlying dentin. This study, aimed to evaluate the effect of double coating of two self-etch primers on micro-shear bond strength to both enamel and dentin.

Materials and Method:104 intact premolar teeth were used to evaluate the etching pattern and microshear bond strength. They were divided in two groups: 52 teeth for enamel studies and 52 teeth for dentin studies. mid-coronal region of buccal aspect of the teeth were prepared for our study.two self–etch primers,clearfil SE Bond and clearfil S3 Bond were applied in one and two coats,respectively,on enamel and dentin surfaces,forming our eight study groups.One specimen of each group was selected for SEM evaluation and other specimens were used to be bonded with composite beams for micro-shear bond strength measurement with Instron universal testing machine.Then data were analyzed with ANOVA.

Results:There were no significant differences in micro – shear bond strength values of two self-etch primers in one or two coats application on both enamel and dentin.

The mean of micro–shear bond strength values of specimens treated using self-etch primer,Clearfil SE Bond,was significantly higher than values of specimens treated with self–etch adhesive,Clearfil S3 Bond, in dentin but there was no difference for enamel samples.

Conclusion:By application of two–step self etch adhesive, Clearfil SE Bond, the sufficient bond strength can be achieved in short time periods even in one layer and double application of primer does not affect the bond strength.The most important question about self-etch adhesive is the bond effectiveness of these adhesives in long time periods.


0056 (109874)

Bonding effectiveness of self-adhesive cements to perfused dentin. C. MAZZITELLI1, F. MONTICELLI2, A. CASUCCI1, M. TOLEDANO3, R. OSORIO3, and M. FERRARI1, 1University of Siena, Italy, 2University of Zaragoza, Huesca, Spain, 3University of Granada, Spain

Objectives: The study aimed to determine the bonding effectiveness of different self-adhesive resin cements to dentin with/out simulated intrapulpal pressure (PP). Methods: Three self-adhesive cements [1.Multilink Sprint (Ivoclar-Vivadent); 2. Max-Cem (Kerr); 3. SAC-A (Kuraray)] were used in dual-curing mode for luting eighteen composite overlays [(AElite All Purpose (Bisco)] to flat mid-coronal dentin surfaces under a PP of zero or 15 cm H2O. After 1 month (37°C; 100% relative humidity), microtensile beams (1 mm2) were cut and stressed to failure under tension. The fracture pattern was evaluated under SEM. Data were statistically analysed with Kruskal-Wallis on ranks (p<0.05) and Mann-Whitney tests (p<0.001) including premature failures. Results: Mean bond strength values (MPa) and SD of the tested cements are summarized in the Table. No significant differences were highlighted with or without PP. SAC-A performed better than Multilink Sprint and Max-Cem. No differences were recorded between the latters in the same experimental conditions. Conclusions: The tested resin cements exhibit a similar behavior when applying or not a PP. The SAC-A cement showed the higher bond strength data.

 

 

 

Letters in each column and numbers in each row indicate significant differences.

Experimental groups

Pulpal Pressure

No Pulpal Pressure

Mean (SD)

Mean (SD)

Multilink Sprint

2.3 (4.4) b1

4.5 (6.4) b1

Max-Cem

2.8  (9.0) b1

4.2 (11.1) b1

SAC-A

7.27(22.14)a1

7.34(9.09)a1


0057 (110749)

May surface pre-treatments improve self-adhesive cements bonding to dentin?. M. TOLEDANO1, C. MAZZITELLI2, F. MONTICELLI3, M. FERRARI2, and R. OSORIO1, 1University of Granada, Spain, 2University of Siena, Italy, 3University of Zaragoza, Huesca, Spain

Acid pre-treatment of dentin has been suggested as an alternative when bonding with self-adhesives resin cements. Objective: To evaluate the bonding effectiveness of self-adhesive resin cements applied on hydrated dentin after different surface pre-treatments. Methods: Three self-adhesive cements (Rely X Unicem, Bis-Cem and G-Cem) were used to lute twenty-seven composite overlays (Aelite All Purpose Body) to deep coronal dentin. Three groups were formed (n=9) according to the following surface pre-treatments: 1) 0.1 M EDTA demineralization; 2) 10% polyacrylic acid (PPA) etching; 3) No treatment of dentin. Luting procedures were performed under a simulated pulpal pressure (PP) of 15 cm H2O. Bonded specimens were stored for 1 month (at 37oC and 100% humidity) maintaining PP, then sectioned into microtensile beams (0.9x0.9 mm) and loaded in tension at a crosshead speed of 1.0 mm/min until failure. Data were statistically analysed with Kruskal-Wallis on ranks (p<0.05) and Mann-Whitney tests (p<0.001) including premature failures (PF). Representative fractured sticks were evaluated under SEM. Results: Mean bond strength (MPa) and standard deviations are presented in the table. Letters in each column and numbers in each row indicates significant differences. G-Cem performed better when luted to PAA conditioned dentin. Bond strength of Bis-Cem fell significantly after EDTA and PAA treatments. No significant differences were recorded for Rely X Unicem. Conclusions: Tested resin self-adhesive cements exhibit a differential behaviour after dentin pre-treatments. PPA conditioning of dentin may be beneficial when using G-Cem for cementation procedures. Acknowledgements:CICYT/FEDER-MAT2004-06872-C03-02.

 

 

Resin Cements

Polyacrilic acid

EDTA

No treatment

PF

Mean (SD)

PF

Mean (SD)

PF

Mean (SD)

Bis-Cem

60%

 6.36 (9.4) A1

84%

7.47 (8.4) AC1

35%

12.29 (11.1) AC2

Rely X Unicem

41%

14.87 (15.5) B1

31%

12.4 (9.9) B1

24%

16.73 (12.5) BC1

G-Cem

31%

13.47 (11.5) B1

32%

10.30 (8.4) BC12

42%

8.03 (8.2) A2

 


0058 (110865)

Adhesion quality of new monomer system in self-etching adhesives. D. NEGOVETIC VRANIC, K. GORSETA, D. GLAVINA, and I. SKRINJARIC, University of Zagreb, Croatia

Objective:. The aim of this study was to evaluate adhesive strength of a new monomer adhesive system coupled with composite and compomer restaurations.

Methods: New monomer system introduced in Adhese One Vivapen (Ivoclar/Vivadent, Lot K10655) adhesive system was compared with other self etch systems: AdheSe (Ivoclar/Vivadent, Lot G2718), Clearfil SE Bond (Kuraray Dental, Lot 4194), Clearfil S3 Bond (Kuraray Dental, Lot 41120), Unifil Bond (GC, Lot 0406021), Futura Bond NR (Voco, Lot 581031), Adper Prompt-L-Pop (3M Espe, Lot 223261) and etch and rinse systems: Single Bond (3M Espe, Lot 6FN) and Excite (Ivoclar/ Vivadent, Lot J14884) in combination with compomer Dyract (Dentsply, LOT 0304001162) and composite Tetric (Ivoclar/Vivadent, Lot E 46159) restaurations. Samples in the shape of cilinders were prepared in the teflon molds (3mm X 4mm). Cilinders were adhered to the tooth surface before testing. Testing of shear bond strenght was performed using Universal testing machine (Lrx Testing machine, AMATEK Lloyd Instruments Ltd). The type of fracture was assesed (adhesive, cohesive or mixed). Statistical analysis was performed using one way ANOVA and Tukey HSD test.

Results: There was no statistical difference between adhesive values of the tested adhesive systems and materials. The highest values of the shear bond test exhibited Clearfil S3 Bond (18,86 Mpa) and the lowest was assesed for the Adhese (15,97 Mpa). The differences between the values of different fracture types were not statistically significant.

Conclusion: Adhesion quality of new monomer formulation self etch adhesives is comparable to that of classical adhesive systems. Further laboratory evaluations are required to test adhesion quality of new monomer systems.


0059 (110964)

Sealant bond strength with self-etching systems in contaminated conditions. F. CHASQUEIRA, J. PORTUGAL, S.S.A. OLIVEIRA, and L.P. LOPES, University of Lisbon School of Dentistry, Portugal

Objectives: To evaluate the influence of the light curing moment of two self-etching adhesive systems in the shear bond strength of a sealant to enamel, in salivary contamination conditions. Methods: Dental sealant (Delton, Dentsply) was applied to sixty human incisors vestibular enamel with Xeno III (Dentsply) or Prompt-L-Pop (3M/Espe). After the application of the adhesive system and before the application of the sealant, all specimens were submitted to saliva contamination. The light curing moment determined the further division of the specimens. Thus, four experimental groups were created according to all possible combinations between the two variables (n=15). In one group, the adhesive system was cured with the sealant (co-polymerization), and in the other, light cured independently (independent polymerization). Shear bond strength tests were done with an universal testing machine. Data was analyzed with a two-way ANOVA. Results: There were no statistical differences (p=0,267) between the two adhesive systems tested (Xeno III - 29,7+/-7,4MPa; Prompt-L-Pop - 31,8+/-8,2MPa). The co-polymerization groups (33,3+/-9,4MPa) yielded statistically (p=0,01) higher shear bond strength values than the independent polymerization groups (28,2+/-4,7MPa). Conclusions: In saliva contamination conditions, the co-polymerization of the adhesive systems and the sealant yielded higher bond strength values to enamel than the isolated polymerization of the components. Even with saliva contamination, the self-etching adhesive systems used yielded high shear bond strength values. (Study performed at UICOB, FCT R&D unit 4062).


0060 (111263)

Simulated pulpal pressure influences self-etch adhesives bonding to dentin. F. MONTICELLI1, R. OSORIO2, M. TOLEDANO2, C. MAZZITELLI3, F. PAPACCHINI3, and M. FERRARI3, 1University of Zaragoza, Huesca, Spain, 2University of Granada, Spain, 3University of Siena, Italy

Objective: The study aimed to assess whether the application of simulated hydrostatic pulpal pressure (PP) may influence the bonding efficacy of self-etch adhesives to dentin. Methods: Flat coronal human dentin surfaces were bonded using four self-etch adhesives systems (1. Clearfil SE Bond; 2. Bond Force; 3. Adper Scotchbond SE; 4. G Bond). Adhesives were applied onto a deep dentin substrate with or without applying hydrostatic PP of 15cm H2O. A hybrid resin composite was selected for coronal build-up (AElite All Purposes). Bonded specimens were stored for 24 hours (at 37oC and 100% humidity) with zero pressure and under PP, then sectioned into microtensile beams (0.9x0.9 mm) and loaded in tension at a crosshead speed of 1.0 mm/min until failure. The fracture pattern was evaluated under SEM. Data were statistically analysed with Kruskal-Wallis on ranks (p<0.05) and Mann-Whitney tests (p<0.001) including premature failures. Results: No significant differences for Clearfil SE Bond and Bond Force bonded specimens were recorded regardless the maintenance of simulated PP. Bond strength of Adper Scotchbond SE was significantly reduced under PP. (Table). All specimens failed prematurely when G Bond was applied under PP. Conclusions: Changes in dentin wetness may influence the bonding performance of self-etch adhesive systems. The application of a constant intra-pulpal perfusion should be considered when simulating bonding procedures in vitro.


0061 (111550)

Shear Bond Strength of New Self-etching Adhesives. S.S.A. OLIVEIRA, F. CHASQUEIRA, M.M. LOPES, J. PORTUGAL, and L.P. LOPES, University of Lisbon, School of Dentistry, Lisboa, Portugal

Objectives: To determine the shear bond strength to dentin of new self-etching adhesives. Methods: Proximal enamel of human third molars was removed to obtain dentin samples, which were randomly assigned to the adhesives (n=12): XP Bond (XP, Dentsply Detrey) and Scotchbond  (SB, 3M ESPE), total-etch adhesives bonded to 35% phosphoric acid etched dentin, and Xeno V (XV, Dentsply), Easy Bond (EB, 3M ESPE), Adper Scotchbond SE (ASSE, 3M ESPE), Adper Prompt L-pop (PLP, 3M ESPE), and Clearfil S3(CS, Kuraray), 1-step self-etching adhesives. The adhesives were applied to the dentin, as per manufacturer's instructions. Samples were shear tested to failure at a crosshead speed of 5 mm/min, with a single plane lap shear testing apparatus. Data were analyzed with one-way ANOVA and Tukey-Kramer tests. Failure mode was determined from SEM micrographs of the failed surface at 2 kX. Results: SBS data are shown in table below. Mean values with same superscript were not significantly different (P<0.001). ASSE was the only self-etching system to yield bond strength similar to both total-etch systems. Samples bonded with XV yielded significantly lower SBS values than all other groups. Conclusions: Most 1 step self-etching adhesive systems tested in this in-vitro study, yielded lower bond strength values to dentin than the total etch system and should need further development, to be predictable. Study performed at UICOB, R&D unit nº4062 of FCT. sofiaaol@fmd.ul.pt.

 viewimage

Adhesive system

Mean values+/- St Dev (MPa)

XP Bond (XP,Dentsply Detrey)

23,0 +/- 7,7 MPaa

Scotchbond  (SB, 3M ESPE)

28,4 +/- 8,3 MPaa

Xeno V (XV, Dentsply)

2,0 +/- 1,5 MPac

Easy Bond (EB, 3M ESPE),

15,1 +/- 5,4 MPab

Adper Scotchbond SE (ASSE, 3M ESPE)

21,8 +/- 2,9 MPaa

Adper Prompt L-pop (PLP, 3M ESPE),

11,7 +/- 4,4  MPab

Clearfil S3(CS, Kuraray),

9,2 +/- 5,4 MPab


0062 (109769)

Fracture Performance of Provisional Crown & Bridge Restoration Materials. M. ROSENTRITT, R. LANG, M. BEHR, and G. HANDEL, Regensburg University Medical Center, Germany

Objectives: High strength of modern provisional materials is important for extending the time for clinical application. It was the aim of this study to determine fracture resistance and fracture toughness of different provisional restorative materials including an experimental product.

Methods: In this in-vitro study fracture strength of three-unit bridges of provisional crown & bridge materials was determined. Identical alloy dyes (Biosil F, DeguDent, G) were fixed in resin at a distance of 10 mm simulating a posterior gap. An artificial periodontium was provided with polyether impression material (Impregum, 3M ESPE, USA). All bridges were bonded with RelyX Temp NE (3M ESPE, USA). Ten samples of each group were stored in aqua dist. for 14 days and subsequently submitted to thermal-cycling and mechanical-loading (TCML: 50 N, 480000 loadings; 1200x5°/55° C). Occlusal wear was determined with 3D scanning. Ten samples of each material were stored for 24 hrs in aqua dist. as a control. All specimens were loaded to fracture (Zwick, G; v=1mm/min). Fracture patterns were determined optically. Independently fracture toughness K1c was determined (n=10). Medians and 25%/75% percentiles were calculated. Statistics: Mann-Whitney-U-Test (α=0.05).

Results:

Median (25 %/ 75%)

Materials

Fracture Force [N]

(24hrs H2O storage)

Fracture Force [N]

(14 days H2O storage + TCML)

K1c [MPa*m1/2]

Luxatemp Fluorescence (DMG, G)

1006 (749/1237)

875 (771/1006)

0.89 (0.84/0.95)

Integrity Fluorescence

(Dentsply, G)

897 (630/1159)

798 (718/897)

0.94 (0.80/0.99)

Structur Premium (Voco, G)

946 (858/1130)

820 (621/946)

1.07 (0.98/1.39)

Experimental Protemp (3M Espe, USA)

1133 (909/1310)

920 (852/1133)

2.18 (1.92/2.40)

Acrytemp (Pluradent, USA)

740 (672/787)

(total failure)

1.66 (1.51/1.71)

Conclusion: The tested materials loose about 11-19% of their fracture strength due to TCML. One material even failed completely during aging. Among the surviving materials experimental Protemp showed the highest fracture resistance after TCML as well as highest fracture toughness and may be therefore considered for long-term temporization.


0063 (109881)

Premolars restored with fiber posts; in-vitro load test variables. W.A. FOKKINGA1, J.G.C. WOLKE1, C.M. KREULEN1, and N.H.J. CREUGERS2, 1Radboud University Nijmegen Medical Centre, Netherlands, 2Radboud University Nijmegen, Medical Centre, Netherlands

 

Objective:

To assess the influence of cyclic loading and a simulated periodontal ligament (PDL) on the in-vitro failure behavior of root-filled premolars with direct resin composite crowns and fiber posts.

Method:

Clinical crowns of 40 single-rooted upper premolars were cut horizontally, 1.5mm above the buccal cemento-enamel junction. Rootcanal treatments were performed and canals were obturated with guttapercha (cold lateral condensation method). The palatal canals were prepared with Parapost drills (diameter 1.25mm, depth 8mm). Press-fit fiber posts (Parapost FiberWhite) were cemented with resin cement (Panavia F). All teeth were reconstructed with a composite crown (Clearfil Photo Posterior) using a mould. Restored teeth were randomly assigned to one of four groups (n=10 each), and were embedded in acrylic. Group 1 and 2 were with a simulated PDL (Express® painted on the roots). Teeth of Group 2 and 4 were submitted to cyclic loading (8 Hz, load 180-300 N, 250.000 cycles). All tooth-crown constructions were subjected to static load at the occlusal surface, with the loading angle 30º to the tooth long-axis. A standard loading device (crosshead speed 0.5 mm/min) was used. Loads until fracture were registered and analyzed using one-way ANOVA. They were assessed being favorable or unfavorable and their frequencies were compared (Fisher's Exact Test).

Results:

Group

PDL

Dynamic preload

Mean Failure Load (SD) [N]

Ratio Favorable/Unfavorable Failures

1

Yes

No

1377 (273)

3/7

2

Yes#

Yes

1465 (388)

4/5

3

No

No

1238 (171)

1/9

4

No#

Yes

1429 (189)

3/6

#one sample was excluded because of test failure.

No significant difference exists among the four groups regarding to mean failure load (P=0.30) or failure mode (P=0.44).

Conclusion:

The use of cyclic loading and a simulated PDL might be unnecessary in this kind of in-vitro load tests since it did not influence the failure behavior.


0064 (109947)

Fracture resistance of fiber posts luted at different lengths. R. SCHIAVETTI1, C. MAZZITELLI1, A. CASUCCI1, R. OSORIO2, M. TOLEDANO2, and M. FERRARI1, 1University of Siena, Italy, 2University of Granada, Spain

Objectives: The study aimed to determine the fracture resistance of fiber posts luted at three different lengths in the root canal. Methods: The anatomic crowns of 30 premolars were cut at the CEJ.  The teeth were endodontically treated and divided into 3 groups (n=10) according to the depth in which the post [(ENDO LIGHT post #09 (RTD)] was luted: 1. Five mm; 2. Seven mm; 3. Nine mm.  The free post length was standardized at 4.8 mm. The post cementation was performed with Fluorocore2 (Dentsply DeTrey) and its adhesive [XP Bond (Dentsply)]. After 24 h, the posts were stressed to fracture under compression on the outer end (45°, crosshead speed: 0.75 mm/min). Data were statistically analysed with One Way ANOVA (p<0.05). Results: Mean strength values (N) and SD are shown in the table. Cementation length did not affect fracture resistance of fiber posts. Conclusions: Over preparation of the post-space should be avoided as varying post length has no significant effect on the fracture resistance of dowels.

Post Length

Mean (SD)

N° specimens

5 mm

40.52(3.14)

10

7 mm

41.68(5.31)

10

9 mm

44.88(6.77)

10


0065 (110154)

Stress Distribution at Tooth/Implant-Supported Prosthesis with Different Connector Designs. D. ENHOS, Ö. INAN, and O. ERASLAN, Selcuk Universitesi, Konya, Turkey

Objectives: The aim of this study is to evaluate the effect of rigid/semi-rigid attachments in implant-tooth and implant-implant supported fixed partial dentures on the supporting bone with two different stress analysis methods.

Methods: 3 Straumann implants with 4,1mm in diameter, 12mm in lenght, solid, screw type and newly extracted caries free right upper second premolar tooth was used. Natural tooth was prepared in shoulder margin design with the angle of º6 at the top. The root surface was coated with silicone impression material 0,20-0,30 mm in thickness.

Implants and natural tooth were placed in acrylic blocks 45mmx10mmx50mm and abutments with 5,5mm in height were fixed on implants. ‘T' type precise attachment was used at connector areas in metal ceramic FPD's. In photoelastic stress analysis method PL-2 epoxy resin was used. In order to see stress areas, white light and polariscope and for loading universal test device was used. The 300N was applied vertically in the centre of occlusal table for each sample and results were screened with digital camera.

For FEM models, enamel, dentine, pulp, periodontal ligament, bone, implant were created as actual sizes regarding elasticity modulus and poisson rates and SAP2000 software was used. Models were sectioned by two milimeters. All structures were assumed as homogen, linear elastic and isotropic. The samples were loaded and results were evaluated with von Misses scale.

Results: The results of two different methods were evaluated comperatively and seperately. The results of, FE and photoelastic stress analysis were parallel and the lowest stress values were located in implant-implant supported models, the highest stress values were located in tooth-implant supported, semirigid attachments.

Conclusions: Rigid connected tooth-implant supported models showed similar results when compared to implant-implant supported models. When implant-implant supported FPD's could not be used, tooth-implant supported FPD's with rigid attachment could be an alternative.


0066 (110229)

Simulation of tooth mobility for load-to-fracture tests: A pilot study. G. STERZENBACH, S. KALBERLAH, A. SCHULZ, and M. NAUMANN, Charité-Universitätsmedizin Berlin, Germany

Objectives: The simulation of the tooth mobility with or without reduced bone support is an aspect of particular interest for in-vitro tests with regard to a clinical perspective. To elucidate the adequate simulation of the periodontal ligament in terms of tooth mobility three materials were tested.

Methods: Human lower sound premolares were selected and divided into 6 groups (n=5), and stored at 37°C in a 0.5%-chloramine solution. To simulate the periodontal ligament the roots were covered with a thin layer of three types of material: (i) polyurethane elastomeric material, (ii) polyether impression material, and (iii) a A-polysiloxane soft cushion material. The teeth were embedded in an acrylic resin block (Techovit 4004, Heraeus Kulzer, Germany) simulating no and 50% bone loss, respectively. The specimens were statically subjected up to a maximum load of 30N perpendicular to the tooth axis (crosshead speed=1mm/min) in a universal material testing machine. The load-deflexion curves and periotest values were recorded. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (p= 0.05). The Pearson's correlation coefficient between the deflexion and the periotest values was calculated.

Results: The median (mm) horizontal deflexion values of the premolar crowns with no bone loss were significant higher for polyether (ii= 0.33; p= 0.008) and polysiloxane (iii= 0.15; p= 0.008) compared to polyurethan (i= 0.02). For 50% bone loss a significant higher tooth deflexion was found for specimens of group (iii) (1.08) as for group (i) (0.03; p= 0.008). All specimens with reduced bone support layered with polyether were dislocated. This deflexion displayed a significant positive correlation with the periotest values (p= 0.01).

Conclusion: It is possible to simulate physiologic tooth mobility by means of an A-polysiloxane material. Specimens are safely retented, even when reduced bone support is simulated.


0067 (110628)

Fracture-resistance of unilayered versus bilayered lithium-disilicate ceramic crowns. N. EREIFEJ, N. SILIKAS, and D.C. WATTS, University of Manchester, United Kingdom

Objective: To compare the fracture strength and behaviour of two types of ceramic crowns by the detection of acoustic signals during compressive loading.

Methods: First-molar teeth were prepared and used for crown construction in two groups (n = 18); unilayered IPS e.max CAD (CADLT), fabricated using a staining technique, and bilayered IPS e.max Ceram/ IPS e.max CAD (Ceram/CAD) fabricated using a layering technique, (Ivoclar-Vivadent, Schaan, Lichtenstein). All samples were loaded in compression with a Universal Testing Machine (Z020, Zwick GmbH & Co. KG, Ulm, Germany) via a Co/Cr maxillary first molar tooth at 0.2 mm/min. Released acoustic signals were collected and analysed. Failed samples were examined fractographically with optical and scanning electron microscopes.15 crowns per group were loaded to final failure, and load-values (Newtons) at initial and final fracture were compared, while 3 samples per group were loaded until fracture initiation and were then examined under the optical microscope.

Results: Although initial fracture values of the two groups did not differ significantly (p > 0.05), CADLT: 881.3 N (227.1) and Ceram/CAD: 808.8 N (259.2); the mean final fracture value of CADLT 2425.5 N (367.3) was significantly higher than that of Ceram/CAD 1469.0 N (290.6). All crowns observed at initial fracture had microscopic signs of initial failure. However, fewer acoustic signals were generally detected during fracture propagation of CADLT samples than with Ceram/CAD samples. Fractographic examination of crowns loaded to final fracture revealed different failure patterns between the two groups.

Conclusions: Uni-layered CADLT crowns showed superior performance under loading than bilayered porcelain veneered samples. Analysis of acoustic signals released during fracture testing, and fractographic examination of failed ceramic crowns revealed essential information regarding their fracture behaviour and modes of failure.


0068 (110638)

The Effect of Load on High-Speed Dental Handpiece Vibrations. R.L. POOLE, S.C. LEA, A.C.C. SHORTALL, and A.D. WALMSLEY, University of Birmingham, United Kingdom

High-speed dental handpieces may potentially propagate cracks within tooth enamel as a result of the vibrations produced during the cutting process.

Objectives: To measure in vitro vibration displacement amplitudes of high-speed dental handpieces using a Scanning Laser Vibrometer (SLV), whilst cutting extracted teeth under various loads.

Methods: Extracted molar teeth were mounted on a laboratory pan-balance so that the tooth crown contacted the cutting instrument at a known load. A Polytec SLV (PSV-300) measured vibrations at the head and angle whilst handpieces were clamped in a fixed position. Repeated measurements were taken using a new diamond rotary cutting instrument (Ash HiDi 541) both unloaded and with increasing loads of 0.5 to 2.0 N. Drive air pressures fell within ranges recommended by the manufacturers. Handpieces were operated at maximum speeds with a coolant water spray. Results were investigated using analysis of variance (ANOVA).

Results: Vibration displacement amplitudes of handpieces were not significantly greater under loading compared to the unloaded situation (p > 0.05); increases in loading did not correspond with increases in displacement of the handpiece. Vibration activity at the head was greater than at the angle of the handpiece.

Conclusion: Contrary to expectations, increasing the loading of rotary cutting instruments did not result in increased vibration displacement amplitudes. However the data was consistent with our earlier work in that greater activity was found at the head, and the levels of vibration remained low (< 5 µm).

This work is supported by an EPSRC project grant (EP/D500834/1).


0069 (110685)

In Vitro Failure of Two Types of CAD/CAM Crown. T. DONNELLY, W. PALIN, S.E. FISHER, and T. BURKE, University of Birrmingham, Birmingham, United Kingdom

Objectives: This in vitro study investigated the fracture resistance of teeth restored with zirconia-based crowns (Lava™indirect CAD/CAM)(L) and Cerec® (C) directly-produced CAD/CAM Vita® Mark II Vitablocs® feldspathic porcelain crowns, each luted with a self adhesive luting material (RelyX™ Unicem Clicker™).

Methods: Standardized preparations were carried out on two groups of ten sound, unrestored, maxillary premolar teeth of similar size. Ceramic crowns were constructed to have a midline fissure thickness of 2mm. A standard C crown morphology database was selected and duplicated for the veneering on the L coping. The fit surfaces of the C crowns were treated with hydrofluoric acid and Sil™silane bond enhancer while the L crowns were treated with CoJet™, Sil™ before luting.

Compressive fracture resistance was determined for each restored tooth using a Universal Testing Machine with a crosshead speed of 1 mm/min transmitted via a 4mm diameter steel bar. Failure modes were examined visually and designated according to a specially designed scale.

Results: Mean fracture resistance of 746 (SD:147)N and 1630 (175)N were recorded for the C and L groups respectively. Statistical analysis by t-test: Paired Two Sample for Means indicated statistically significant differences in the mean fracture resistance of the restored teeth between the groups (p<0.001). The failure modes were different, with the C crowns displaying less destructive modes of failure than the L crowns.

Conclusions: The compressive fracture resistance of teeth restored with Cerec® (C) directly- produced CAD/CAM crowns formed from Vita® Mark II Vitablocs® is significantly less than teeth restored with Lava™ indirect CAD/CAM-produced crowns (p<0.001, and their mode of fracture is different.


0070 (110746)

Biomechanical behavior of cavity configuration on micropush-out test: A finite-element-study. I. CEKIC-NAGAS1, A. SHINYA2, G. ERGUN1, P. VALLITTU2, and L.V. LASSILA2, 1Gazi Universitesi, Ankara, Turkey, 2University of Turku, Finland

Objectives: The objective of this study was to simulate the micropush-out bond strength test from a biomechanical point of view. For this purpose, stress analysis using finite element (FE) method was performed.

Methods: Three different occlusal cavity shapes were simulated in disc specimens (Model A: 2 mm occlusal, 1.5 mm cervical diameter; Model B: 1.75 mm occlusal, 1.5 mm cervical diameter; Model C: 1.5 mm occlusal, 1.5 mm cervical diameter). Quarter sizes of 3D FE specimen models of 4.0×4.0×1.25 mm3 were constructed. In order to avoid quantitative differences in the stress value in the models, models were derived from a single mapping mesh pattern that generated 47, 182 element and 66,853 nodes. Used materials were composite (Filtek Z250, 3M ESPE), bonding agent (Adper Scotchbond Multi-Purpose, 3M ESPE) and dentin as an isotropic material. Load conditions consisted of subjecting a press of 4 MPa to the top of composite disc. The postprocessing files allowed the calculation of the maximum principal stress, minimum principal stress and displacement within the disc specimens and stresses at the bonding layer. FE model construction and analysis were performed on PC workstation (Precision Work Station 670, Dell Inc.) using FE analysis program (ANSYS 10 Sp, ANSYS Inc.).

Results: Compressive stress concentrations were located equally in the bottom interface edge of dentin. Tensile stress was located top area of dentin and at the half of lower side of composite under the loading point in all of FE models. However, the range of stress distribution and stress values were different. Compressive and tensile stress of model A was the highest. Displacement of model A was the highest of the tested design. By increasing the slope, the maximum displacement was also increased.

Conclusions: The FE model revealed differences in displacement and stress between different cavity shaped disc specimens.


0071 (110757)

Vertical Discrepancies Caused by Interocclusal Records. Influence of Loading Forces. M. GHAZAL, and M. KERN, School of Dentistry, Christian-Albrechts University at Kiel, Germany

Objectives: The aim of this study was to evaluate the ability of different materials to reproduce accurate vertical interocclusal relationships when defined compressive forces were applied to stabilize the casts.

Methods: A custom-made apparatus which consisted of two parts and posterior denture teeth was used to simulate the maxilla and mandible. The mandibular teeth 45-47 were prepared. Then eight interocclusal records were made between the prepared teeth and their antagonists in each of the following groups: G1: aluminum wax (Aluwax, Aluwax dental products co., Michigan, USA), G2: hydrocarbon wax compound (Beauty Pink, Miltex, Inc. York, USA), G3-G5: vinyl polysiloxane (Futar D, Futar D Fast, Futar Scan, Kettenbach, Eschenburg, Germany), G6: polyether (Ramitec, 3M ESPE, Seefeld, Germany). The vertical discrepancies were measured by an inductive displacement transducer connected to a carrier frequency amplifier after storage of the records for 1 hour at the room temperature. Different compressive loading forces up to 1 kg were applied onto the upper part to evaluate the influence on the vertical discrepancies of the records. Two-way ANOVA was used for statistical analysis.

Results: All tested recording materials produced vertical discrepancies. However, the compressive loading force had a statistically significant influence on the vertical discrepancies (p<0.01), i.e. higher forces reduced the vertical discrepancies. When a compressive force of 1 kg was applied onto the upper part of the apparatus, the mean vertical discrepancies for G1 (11±3µm) and G2 (12±3µm) were statistically significantly higher than in the other groups G3 (1±1µm), G4 (2±1µm), G5 (0±1µm) and for G6 (-2±2µm).

Conclusion: A compressive force of 1 kg could be used to stabilize the cast during mounting procedures in an articulator using interocclusal records made of vinyl polysiloxane without changing the interocclusal relationships vertically.


0072 (110905)

Evaluations of residual tension states in laser welded CoCrMo alloys. C. BORTUN1, A. CERNESCU2, N. FAUR2, L. SANDU1, and S. POROJAN1, 1Victor Babes University of Medicine and Pharmacy Timisoara, University School of Dentistry, Romania, 2Politehnica University Timisoara, Romania

OBJECTIVES: The study was focused on stress areas evaluation, induced in RPD laser welded frameworks, on the purpose of determining the durability of prosthesis rehabilitations.

METHODS: For testing, there were used 2 types of laser welding with filling material for CoCrMo alloys (WIRONIT-BEGO, "C" VASKUT KFT)in RPD technology. In order to realize a thermal analysis with finite elements and reveal the welding residual stress, a specific software(Solid Works 2007) was used. This analysis serves to welding procedure simulation, in which temperature, heat flux distribution and static analysis of stress state, resulting from welding, were under observation. The following thermal parameters resulted for evaluation: coefficient of linear expansion-β=3,36•105 W/mm2•ºC, coefficient of heat conductivity–λ=6,05•10-2W/mm•ºC; specific heat–C=434 J/Kg•ºC,.

Results: The study results reveal that around the fusion zone there is a stress gradient, and this is the one that forms cracks in the fusion zone in the alloy. The thermal calculation applied in the rib is analyzed in connection with temperatures distribution during welding and cooling. This consists in temperature field's distribution on a period of 1-5s. The highest temperature is obtained in the first second. Analyzing the stress field of a longitudinal section, the high values of stress from the heat affected zone and their orientation towards the welding exterior surface, where cracks usually appear, can be observed.

Conclusion: The study with finite elements has the advantage of being non-invasive and of permitting a correct prognosis of cracks appearance zones in the heat affected zone.

Welding is a useful method for metallic prostheses repairs and for the control of welding heat input, contributing to the decrease of welding stress and to the avoidance of cracks. (CNCSIS 744)


0073 (111153)

Rotational fatigue-resistance of resin-based composites. F. KEULEMANS, A. VAN DALEN, C.J. KLEVERLAAN, and A.J. FEILZER, ACTA, University of Amsterdam and VU University Amsterdam, Netherlands

Objectives: The aim of this study was to evaluate in vitro the influence of fibre-reinforcement on the cantilever beam strength and rotational fatigue resistance of resin-based composites.

Methods: One hundred rectangular bar-shaped specimens (2 x 2 x 25 mm) made of resin-based composite were prepared in a stainless steel split-mould: (i) thirty specimens of particulate filler composite (PFC) (Filtek Z100, 3M ESPE, St Paul, MN, USA), (ii) thirty specimens of fibre reinforced composite (FRC) (Everstick C&B, Sticktech Ltd, Turku, Finland) and (iii) forty specimens of PFC and FRC combined in two longitudinal layers of equal thickness. Each specimen was trimmed into a cylindrical hourglass shape. The fracture resistance (cantilever beam test, n = 10) and the rotational fatigue resistance (rotating cantilever beam test; staircase method: 104 cycles, 1.2 Hz, n = 20) were determined. The cantilever beam strength, the elastic modulus, and the work-of-fracture were calculated. The fracture surface of failed specimens were analysed with SEM.

Results: The results and the statistical analysis are summarized in the table. ANOVA revealed that fibre-reinforcement had significant effect (P<0.001) on cantilever beam strength, rotational fatigue resistance, and work-of-fracture. Student t-test showed significant differences (P<0.001) in rotational fatigue resistance compared to cantilever beam strength.

Group

Cantilever beam strength

(MPa)

Rotational fatigue resistance

(MPa)

Elastic Modulus

(GPa)

Work of Fracture

(kJm-2)

PFC

164.9a (29.7)

51.5e (32.3)

24.6g (3.1)

0.55h (0.19)

PFC-FRC tension tested

711.2b (46.4)

104.4d (9.2)

28.1g (5.3)

14.20i (2.21)

PFC-FRC compression tested

109.2ad (33.1)

24.8g (5.1)

0.21h(0.13)

FRC

936.1c (218.5)

231.9f (2.9)

27.9g (2.9)

27.90j (14.17)

 

Conclusion: Within the limitations of this study, the following conclusions can be drawn (i) the rotational fatigue resistance of resin-based composites is lower than their cantilever beam strength and (ii) FRC are more fatigue resistant than PFC or combinations of FRC and PFC.


0074 (111261)

3D teeth modeling for finite element analyses of prosthetic restorations. L. SANDU1, F. TOPALA1, N. FAUR2, S. POROJAN1, and C. BORTUN1, 1Victor Babes University of Medicine and Pharmacy Timisoara, University School of Dentistry, Romania, 2Politehnica University Timisoara, Romania

Objectives: The aim of the study was to achieve 3D teeth models in order to develop applications for basic research use.

Methods: Enlarged plaster teeth (scale 10:1) were scanned rotary and from a single plane using LPX-1200 Picza Laser Scanner. Resulted files were imported in LeiosMesh, where the point clouds from the teeth surfaces were cleaned and assembled. These points were used to extrapolate the shape of the objects, in order to create continuous surfaces by reconstruction. The collected data were used to construct three dimensional models using Rhinoceros NURBS modeling program. The models were reduced to the natural size in order to obtain a normal size of the teeth. Surfaces and solids were generated. These solids were used as a support for further modeling of prosthetic restorations. Resulted objects were exported in ANSYS finite element analysis software, to be used for structural simulations.

Results: Generated stresses were calculated numerically and plotted graphically. Results were displayed as colored stress contour plots to identify regions of different stress concentrations.

Conclusions: Three-dimensional reconstructions after 3D scanings, in order to obtain accurate models, can be used for numerical simulations of the teeth and dental restorations. (ID_1264)


0075 (111295)

Minimal preparations with the use of a CAD/CAM system. E. TSITROU1, M. HELVATJOGLU-ANTONIADES2, K. PAHINIS1, and R. VAN NOORT1, 1University of Sheffield, United Kingdom, 2Aristotle University of Thessaloniki, Greece

Objectives: The advantages of minimally invasive dentistry are well established, especially for direct restorations. However, when it comes to indirect restorations traditional tooth preparation designs are still advised by most manufacturers. The purpose of the study was to investigate the ability of a CAD/CAM machine (CEREC) to produce minimal preparation designs and identify limiting parameters

Method: Minimal inlay and crown preparations were proposed. Phantom teeth were used. Gauged burs (Intensiv SA; Meissinger Germany) were used to standardise preparations. CEREC Scan/CEREC 3D was used for scanning and designing. Different milling modes were tested (1.6 cylinder, 1.2 cylinder, Endo). The materials tested were ProCAD (Vivadent-Ivoclar) VITA Mark II (VITA) and Paradigm MZ100 (3M ESPE). The morphology, marginal integrity and materials' integrity were examined.

Results: SEM and optical microscopy showed that Paradigm MZ100 produced acceptable crowns with intact margins for the most conservative design (0.4 mm chamfer, 0.6 mm occlusal reduction). VITA Mark II produced acceptable crowns for 0.6mm chamfer margins and 1.2 mm occlusal reduction, whereas ProCAD needed a wider preparation design (0.8mm chamfer margins, and 1.2 mm occlusal reduction). The Endo setting proved most effective for the crown restorations. Transillumination and dye penetration showed no signs of cracks for all materials for these preparation depths. For the inlay preparation it was found that all materials were able to produce the initially proposed minimal design (1.0mm occlusal reduction, 1.0mm proximal box width, U-shaped box, parallel walls).

Conclusions: Within the limits of this study the following conclusions were drawn:

-With regard to the crown preparation only with composite material a more conservative tooth reduction can be achieved

-With ceramic materials minimal preparations can still be applied but less conservative when compared to the composite material

-For the inlay preparation all materials produced the proposed minimal preparation design.


0076 (111616)

Influence of immediate load on implant osteointegration. T. MOURÃO, and A.V. TAVARES, University of Lisbon School of Dentistry, Portugal

Objective: To characterize the bone-implant interface comparing the implant submitted to immediate loading with a control free loading implant.

Methods: The four inferior premolar of six beagle dogs were extracted. After a 20 week healing period, 24 implants were inserted. In the following day the implants of the 4th quadrant were placed in function. The implants of the opposite quadrant, used as control, were left free of loading. Animal euthanasia was carried out in three phases: 9, 17 and 31 days after the load application. A radiographic and histological analysis of the bone-implant interface was carried out to understand the dynamics of bone restructuring.

Results: The radiographical results obtained during implant insertion, in the step of application of fixed bridges and before euthanasia for all implants did not show marginal bone resorption at the level of the bone crest, from implant application until the end of the experiment and the kind of load on the implants does not seem to have influenced the behaviour of the marginal bone remodelling. No significant changes were observed between immediate load and control, although there seems to be higher activity in the primary bone formation process close to the interface of implants placed under immediate load. Same differences were found between the vestibular and lingual sides, with a higher amount of bone tissue contacting the vestibular implant side. In both groups there was not observed encapsulated fibrosis. Bone-implant contact showed a slight percentage increase in the implants under immediate load (52,13%) as compared to control (47,6%).

Conclusions: All implants were osteointegrated, since all of them remained clinically stable until euthanasia. Histologically it was verified that there was osteogenic activity at their interface. Immediate load did not affect the implant osteointegration (Study performed at UICOB, FCT R&D unit 4062).


0077 (111633)

Fracture Strength of Indirect Composite Laminates Cemented on Existing Restorations. M. ÖZCAN, University of Medical Center Groningen, Netherlands, and A. MESE, Dicle University, School of Dentistry, Diyarbakýr, Turkey

Objectives: This study evaluated fracture strength and failure types of indirect laminates adhered to teeth with aged composite restorations. Methods: Preparations were made on intact human maxillary central incisors (N=60). Laminates using a highly-filled polymeric material (Estenia) were produced. Thickness of laminates in the original form of teeth was achieved using impression moulds made before tooth preparation. Class III cavities (3×3 mm) were opened and filled with composite (Quadrant Anterior Shine). The unrestored teeth served as a control group (Group 6). All restored teeth (n=50) were aged in thermocycling and subjected to one of the following protocols: (1) Air-particle abrasion with alumina particles coated with silica (30 µm CoJet) + silanization, (2) Air-particle abrasion with alumina particles (50 µm, Al2O3) + silanization, (3) 9.5% hydrofluoric acid for 90 s (Ultradent) + silanization, (4) Protocol of Clearfil Repair Kit, (5) Adhesive resin (Quadrant Unibond Sealer). A three-step bonding procedure and resin cement (Panavia F 2.0) were employed. The cementation surfaces of laminates were conditioned (CoJet®-Sand, 30 µm SiO2) and silanized (ESPE-Sil). All specimens were cemented ultrasonically (Amdent). The specimens were stored in water for one month prior to fracture test. Failure types were classified as; a) Complete adhesive failure between tooth and laminate (Type A); b) Cohesive failure within laminate (Type B), c) Mixed failure (Type C). Data were analyzed using 1-way ANOVA and Tukey's test. Results: Significant effect of conditioning was observed (p=0.0261). The only significant difference was between Group 2 (299±103 N) and Group 3 (471±126 N) (p=0.0239). The majority of experienced failures were Type C (35/60) followed by Type B (21/60). Conclusions: Fracture strength of laminates did not show significant difference when they were adhered either to existing, aged Class III restorations or to intact teeth but the failure types varied between groups.


0078 (111690)

Influence of Restoration Technique on Cusp-deflection of Molars:A Pilot Study. M. AKMAN, S. AKMAN, T. USTUNTAS, and S. BELLI, University of Selcuk, Konya, Turkey

Objectives: The aim of this pilot study was to test the effect of restoration techniques on cuspal deflection in root-filled molar teeth with MOD cavity using digital-photogrammetric technique.

Methods: Initial reference points were randomly marked on four molar teeth with similar dimensions. Digital images were taken in a stainless-steel model with 16 points whose three dimension coordinates were determined as control. Further digital images were taken under 150N loading at the beginning, after MOD cavity preparation, after access cavity preparation, after restoring the pulp chamber with a resin cement (SuperBond C&B, Parkell) and after the following restoration techniques:1) Direct composite restoration (Clearfil SE Bond and AP-X composite-resin, Kuraray, Japan); 2) A flowable resin (Panavia F, Kuraray, Japan) lined before direct composite resin restoration and a polyethylene fiber (Ribbond, Ribbond Inc. Seattle WA) was embedded into the bed of flowable resin before direct composite resin restoration; 3) Fiber was inserted from buccal to lingual direction on the occlusal surface of the finished composite resin restoration; 4) Fiber was inserted circumferentially before composite resin restoration. The images were analyzed using a three dimensional photogrammetric technique (TOPCON Image Surveying Station PI-3000). The final coordinates were compared with initial coordinates and the movement of cusps were recorded as micron.

Results: Inserting the fiber under the composite resin increased the inter-cuspal distance (47 micron). When the fiber was inserted from buccal to lingual direction, inter-cuspal distance was reduced 1 micron (16micron) when compared to direct composite restoration (17 micron). Using the fiber circumferentially showed a cuspal distance change of 20 micron.

Conclusion: Digital photogrammetric technique used in this pilot study is an appropriate method for the measurement of cusp movement. Fiber use did not give an advantage in terms of cuspal deflection. Further research is needed for the accuracy of these results.


0079 (111802)

Testing of crowns retention to various abutments utilizing different cements. K. LIZENBOIM, B. ZALSMAN, I. SUVOROV, and A. SUVOROV, BJM Laboratories Ltd, Or Yehuda, Israel

Objective: To design series of tests to evaluate the retention of crowns to the various types of abutments utilizing different cements.  

The tests simulated the clinical retention instead of the routinely measuring indirect physical parameters like Shear Bond Strength, compressive strength, etc.

Methods: 4 types of abutments, precisely prepared special die cut crowns and 6 different commercially available resin based cements, comprising permanent, short and long term temporary cements were evaluated in this study.

Abutments were mounted in the stainless steel cylinders. Tested cement was syringed into each crown after which the crown was firmly seated and either holds in place until final polymerization occurred. The specimens were stored in distilled water at 37 oC for 24 hours prior to testing. Bond strength was measured in accordance with ISO/TS11405:2003 utilizing Lloyd material testing machine equipped with a load cell of 10N and specially designed testing device as a tensile test apparatus. The experimental results were statistically analyzed (N=10) by ANOVA (p<0.05).

Results: Significant differences in bond strength were found between the tested cements groups. Short- term temporary cements exhibited the lowest bond strength, which is critical in order to guarantee their retrievability.

Conclusions: The designed tests simulated the clinical retention and correlate with the findings previously reported by the group. The retention of crowns to the various types of abutments utilizing different cements was defined as a tensile bond strength.


0080 (111821)

Effects of glass ionomer's overlap on the cavosurface angle. M. OLIVEIRA, M.G.A.M. CHAVES, H.D.M. CHAVES FILHO, J.C.B. FARIA, and A.M.R. CARMO, Universidade Federal De Juiz De For a, Juiz de Fora, Brazil

Objectives: The objective of this study was to evaluate the effect of the glass ionomer in the dental enamel. Methods:40 fresh bovine teeth was selected. The apex of each tooth was cut off and the pulp was removed. The cervical portion of each specimen was prepared with 3053 drill and restored with glass ionomer. Two groups were obtained: group 1- the glass ionomer was accomodated until the cavosurface angle limit ;group 2 the glass ionomer was accomodated overshooting the cavosurface angle (1-2mm on the enamel). The specimens were submitted to a hight cariogenic level, using the Streptococcus mutans culture in a kiln (37 Celsius degrees) for a 7 and 15 days period. After cleaned, the specimens . The Labcut machine were to cut off, in a Labcut Machine, in slices which were placed in glass laminae for polishmentin Politriz Machine. Cover glasses were used to orient the samples thickness. The laminae were submitted to a polarized light microscopy analysis. Results: the group 1 specimens had different results varying from the absence of carious to enamel injuries in the interface cavosurface angle/restoration. The group 2 had absence of caries on the enamel subjacent to the ionomer glass. The lesions occurred after the restoration's limits with variations of intensity. Conclusions: the overlap of the ionomer glass protects the enamel when it is submitted to a cariogenic environment; therefore the ionomer glass can be used in cervical restorations. The gap formed between resin and enamel, on the cavosurface region can cause microleakage and alterations on the dental structures.


0081 (109495)

In-vitro optimisation of electronic working length measure, using difference criterion. E. VACHEY1, G. LEMAGNEN2, D. LARROUTURE2, and L. GRISLAIN2, 1Université Victor Segalen Bordeaux 2, Bordeaux Cedex, France, 2Université Victor Segalen Bordeaux 2, France

Objectives: During catheterism, evolution of endodontic impedance depends on Apical Constriction Diameter (ACD) (IADR06). Electronic Apex Locators (EAL) working with difference criterion use 1kHz and 5kHz as signal frequencies (IADR98). The aim of this in-vitro study was to determine the frequencies allowing Working Length (WL) measure, using difference criterion, insensitive to ACD.

Methods: 6 resin models, (ACD from 15/100e to 40/100e, 5/100e step), inserted in CuSO4 gel, were catheterized from 2mm above Apical Constriction (AC), down to 1mm beyond (5/10e step), using a 10/100e K-file conducted by a micrometric displacement table. Calculation of difference criterion are performed using a reference value (C(-2mm): conductance measured 2mm above AC). 936 differences Dij were computed at -0,5mm, AC and +0,5mm with Dij=[Cj-Ci]–[Cj(-2mm)–Ci(-2mm)]; i: reference frequency from 20Hz to 100kHz; j: working frequency from i+1 to 100kHz; Ci=mean of 3 measured conductances. Specificity of WL measure needs: Max(D-0,5mm)<Min(DAC) and Max(DAC)<Min(D+0,5mm). Its sensibility needs the largest differences (DAC-D-0,5mm) and (D+0,5mm-DAC).

Results: About specificity, both conditions are never verified simultaneously; only the first one works with two associations of frequencies: 5-100kHz and 10-100kHz. About sensitivity, the largest results are obtained for both differences with the couple: 5-100kHz. It appears, using 5 and 100kHz, according to Kruskal-Wallis test, that there was significant difference between, D0,5mm, DAC and D+0,5mm (p=0,0008). These results allow us to recommend these two frequencies in case of using difference criterion. Moreover, D0,5mm, DAC and D+0,5mm are linearly correlated to catheterism from -0.5 to +0.5 (r²=0.97), do not depend on ACD (from 15 up to 40/100e) and allow catheterism information.

Conclusion: In-vitro, best results using difference method are obtained with 5 and 100kHz, whatever AC diameter (15/100e to 40/100e). This association of frequencies is not actually used by EAL and is not equal to the one recommended for ratio criterion (IADR07).

0082 (110149)

In vitro pulse measurements in human teeth. K.-A. HILLER, S. LOEFFLER, A. NIKLAS, C. ERMER, J. PUTZGER, and G. SCHMALZ, University of Regensburg, Germany

Objectives: Several methods are available to indirectly measure the vitality of the human tooth pulp tissue in vivo. Pulse signals detected directly from the pulp might be considered reliable for an objective assessment of pulp vitality. The purpose of the present study was to design an in vitro model for measurements of blood pulsing through a human tooth.

Methods: A cylindrical hole was cut in occlusal-apical direction into the center of a human molar crown. A silicon tube (outer/inner diameter: 2.0/1.0 mm) was placed through the hole and connected to a flexible-tube pump (Multifix). An individually designed sensor (infrared light emitter: SFH409, 950nm, Osram, Germany; detector: SFH229FA Photodiode, 880nm, Siemens, Germany) was applied lingual-buccaly to the crown. Air, tap-water, algae (Chlorella 1000µg/l, 685nm), and human erythrocyte-concentrate were pulsed through the tube in two frequencies (F1:3/sec; F2:5/sec) and detected by an individually designed dual channel photopletysmograph. Signals were recorded using an oscillograph (Tektronix TDS2022B, Tektronix Inc., Beaverton, USA), and test parameters Signal-Intensity [Volt] and Signal Duration [ms] were derived. Reference measurements were taken from the tube without surrounding tooth structure. Five samples per experimental group were statistically treated applying non-parametric procedures (a=0.05). 

Results: At all reference measurements F1 and F2 frequencies were detected. Air and tap-water were not detected. Signal duration of algae and erythrocyte-concentrate was for F1 330ms-350ms and for F2 160ms-180ms. Results of the Signal-Intensity measurements (Medians with 25-75% Percentiles) were as follows:

Signal-Intensity, F1 [Volt]

Signal-Intensity, F2 [Volt]

Algae

9.0(9.0-9.5)

7.0(7.0-7.2)

erythrocyte-concentrate undiluted

11.0(11.0-11.0)

9.5(9.5-9.5)

erythrocyte-concentrate 1:10 diluted

12.5(12.5-12.8)

8.0(8.0-8.0)

erythrocyte-concentrate 1:100 diluted

12.0(11.8-12.0)

6.500(6.5-7.0)

 

The  decrease of Signal-Intensity with increasing dilution of erythrocyte-concentrate at F2 was statistically significant, as well as the Signal-Intensity at F1 compared to F2.

Conclusions: This in vitro system turned out to be suitable to detect pulsing blood through tooth structure.


0083 (110609)

Ozone Influence on the Microbial Flora in the Root Canal. B. JANKOVIC, V. NEGOVETIC MANDIC, K. PRSKALO, J. MATIJEVIC, I. CIGLAR, and Z. TARLE, School of Dental Medicine, University of Zagreb, Croatia

Objective: Purpose of this in vivo study was to determine the decrease in the number of root canal colonies after classic chemomechanic treatment and following additional dis-infection of the root canal with ozone.

Methods: Swabs were taken on three occasions from 23 patients with visible periapical process within 5mm diameter. The paper points were inserted into transport media for anaerobs WMGA. After rubber dam placement the first swab was taken after which hand instrumentation was performed up to number 25 with much drainage with 2,5% sodium hypochlorite and root canals were additionaly instrumented with EndoEze technique. After completion of instrumentation a second swab was taken from the root canals and then they were treated with HealOzone for 40 seconds and third swab was taken. After microbial analysis, information obtained was statistically processed with SPSS computer program.

Results: From the analysis of median number of aerob and anaerob bacterial colonies for all three measurements the largest decrease in the number of colonies was observed between first and second measurements for both aerobs and anaerobs. There is also a decrease between second and third but it was somewhat milder for both types of bacteria. Kruskal-Wallis test showed statistically significant difference between number of colonies of aerobes (X2=40,483; df=2;P<0.01) and anaerobes (X2=26,303; df=2;P<0.01). Mann-Whiney test showed a statistically significant difference between the number of colonies of both aerobe and anaerobe bacteria between the first and the third measurement (p<0.01). There was no statistically significant decrease in the number of colonies between the first and second measurement.

Conclusion: After classic chemomechanic treatment of the root canal a certain amount of bacterial colonies always remains, additional disinfection of the root canal is needed for which treatment with HealOzone is very efficient.

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


0084 (110784)

Influence of Head Posture on Tooth Contacts During Lateral Excursion. A. VAN 'T SPIJKER, C.M. KREULEN, and E.M. BRONKHORST, Radboud University Nijmegen Medical Centre, Netherlands

Objective:

The aim of this study was to assess the influence of head posture while seated in a dental chair on contacts during lateral excursion

Method:

Lateral excursions in 22 volunteers (aged 26 to 64 years), all with complete dental arches, were studied while sitting in a dent chair. Subjects were asked to perform a lateral excursion from maximal occlusion to cusp-to-cusp position. Working side tooth contacts during the initial and the advanced part of the excursions were registered (yes / no) per tooth using occlusion strips (Hanel 8 µm). Head postures were altered by tilting the back of the chair in different angles. In position 1, the back was most up-right, and subjects' Frankfurter plane was horizontal. In position 2, both back and Frankfurter plane had a 45 degrees angle to the floor. In position 3, the back was horizontal, and subjects' Frankfurter planes were vertical. The head was supported by the head-rest in all three positions. Changes were recorded for both initial and advanced parts of the excursion within patients.

Results:

Changes in head posture resulted in different tooth contacts during lateral excursion in more than 75% of the subjects (Table 1). Differences ranged from 1 to 7 altered tooth contacts per subject. Only two subjects showed unchanged tooth contacts during excursions in all three positions.

Table 1

Changes in tooth contacts

Position 1 vs. 2

Position 2 vs. 3

Position 1 vs. 3

All positions

n

%

n

%

n

%

n

%

No

3

13,6

5

22,7

3

13,6

2

9,1

Yes

19

86,4

17

77,3

19

86,4

20

90,9

Total

22

100

22

100

22

100

22

100

Conclusion:

Head posture influences the number of contacts during lateral excursions.


0085 (111134)

Analysis of forces acting during hard and soft bolus processing. L. HIMMLOVÁ, Charles University, Prague, Czech Republic, and T. GOLDMANN, Czech Technical University in Prague, Czech Republic

Objectives: The magnitude of masticatory force acting on each single tooth is likely very individual and dependent on extensive number of variables varying during the life (number of occluding teeth, size of contact surface, type of the food). Therefore it is very important to determine not only masticatory force but especially its direction. These factors can be responsible for possible overloading of teeth, abutments or implants and for fractures of fillings or veneers of bridgeworks. The project was aimed to the experimental strain measurements and subsequent computation of chewing forces magnitude and direction.

Method: Measurements were performed using individually custom-built crowns of first lower molar. Three measuring and one compensating strain gauges were placed in the central part of the crownwork made from LC composite material. Subjects were asked to bite with maximal force on working side only, to change balancing and working side, to bite via plastic spacer and to chew with ordinary chewing force pastry and nuts. The magnitude and direction of loading force was computed from strain gauges records, location of occlusion and from known crownwork profile. Chewing force components for each single occlusal contact are in percents of general force computed from evaluated strain values for the same occlusal contact.

Results: The main component of chewing force acting caudally and represents 70-90% of general force. In the horizontal plane the most important are forces acting in oro-vestibular direction (30 – 70 %); in mesio-distal direction acts forces of minor extent (up to 40 %).

Conclusion: The experiment design complies with the planned measurement. The horizontal portion of chewing forces makes important part (more than one half) of general acting force, therefore cannot be omitted during treatment planning or in mathematical models.

This work was funded by MSM 6840770012 and by the GACR 106/06/0849 projects.


0086 (111359)

Chewing Pattern Modulation in Partial Denture Wearers. S. SIOVAS, V. ANASTASSIADOU, and N. KAFANTARIS, Aristotle University of Thessaloniki, Greece

Background: The use of commercially available chewing gums within a range of perceived hardness for studying the modulation of chewing pattern as an alternative to custom made test foods is well documented. Transcriptors of chewing pattern such as chewing time and amplitude of the opening phase have been successfully used in healthy dentate subjects.

Objectives: To explore the alteration of the masticatory pattern in partial denture wearers and correlate this with the equivalent in healthy dentate subjects, using commercially available chewing gums as the test food.

Method: Five healthy elderly and asymptomatic class I partial denture wearers and five healthy and asymptomatic fully dentate subjects took part in the study and chewed three replicas of five commercially available chewing gums for 30 strokes. Mandibular movement was recorded by Sirognathograph, Siemens.

Results: Transcriptors such as chewing time, amplitude of the opening phase and frequency were analyzed. Statistically significant differences were found for all the transcriptors between the two groups and within subjects in each group.

Conclusion: The results of the present study indicated that despite the prosthetic treatment, the differences recorded between the two groups were attributed to the weakness of the removable restoration to reach the effectiveness of natural dentition. Chewing gums provide a useful and objective diagnostic tool, applicable in clinical studies of the physiology of mastication for deteriorated dental arches


0087 (111360)

Tooth Mobility, Movement and Symptoms Following Crown Cementation. O. GERASIMIDOU1, B. MILLAR1, and T.F. WATSON2, 1King's College London, United Kingdom, 2King's College London Dental Institute, United Kingdom

Objective: When a fixed prosthesis is constructed for a tooth the natural morphology of the occlusal surface cannot be reproduced exactly. Therefore the new occlusal surface introduces minor changes that cannot always be identified. The aim of this study was to monitor single crown restorations and the behaviour of the teeth involved over a four-month period in order to identify changes in tooth mobility and position after cementation. Methods: Single tooth crowns, with and without intentional occlusal interferences, were cemented in 17 patients. Ethical approval and consent was obtained. Tooth mobility was recorded using the Periotest device and silicone impressions were obtained to record tooth position. Casts were analyzed using a surface contact scanner to produce 3D images. Recordings for tooth mobility and tooth movement were obtained immediately after cementation as well as one month and four months later. Results: 15 of the 17 patients reported lack of pain but a slight discomfort the first 3-4 days, while all patients reported a return to normal within less than two weeks. An increase in tooth mobility was observed only immediately following the cementation, with normal values recorded one month and four months later. Tooth movement occurred to teeth which had received high occlusion crowns. Conclusions: Occlusal forces following the cementation of high crowns have no long-term effect on the mobility of posterior teeth. Tooth movement occurred between cementation and one month later. Discomfort was transient and mild.


0088 (111485)

Do Masticatory Functional Changes Influence Masseter Muscle of Adult Rats?. A.M. ÖDMAN, Institute of Odontology, Gothenburg, Sweden, N.P. HUNT, UCL Eastman Dental Institute, London, United Kingdom, S. KILIARIDIS, University of Geneva, Switzerland, H.A. MATLOUB MOAWAD, UCL Eastman Dental Intitute, London, United Kingdom, and M.P. LEWIS, Eastman Dental Institute, London

Objectives: This study aimed to investigate the effect of masticatory functional changes on the deep masseter muscle of adult rats.

Methods: Thirty-six 21-day-old male Sprague-Dawley rats were divided into two groups. Twelve received ordinary (hard) food during the whole experimental period [normal group]. The remaining twenty-four received a soft diet to develop a hypofunctional masticatory system. These were divided after 21 weeks into two groups: one continued on a soft diet [hypofunctional group], and the other changed to an ordinary (hard) diet with the aim of functionally rehabilitating their masticatory system [rehabilitation group]. After 6 weeks all animals were sacrificed and biopsies from deep masseter muscle were taken. The levels of expression of the myosin heavy chain isoform genes MYH 1+2 (fast), 3 (embryonic) and 7 (slow) were compared using quantitative reverse transcriptase polymerase chain reaction analysis.

Results: The results showed that the gene expression of MYH 3 were significantly higher in the rehabilitation group compared to the normal group (P=0,008). There were no significant differences in the comparison of the three groups regarding the gene expression of MYH 1+2, but the levels were after six weeks the same for the normal and rehabilitation group.

The analysis showed that there were distinct differences in gene expression of MYH 7 between the rehabilitation and normal group (P=0,000), rehabilitation and hypofunctional group (P=0,001), where the levels were highest in the rehabilitation group and lowest in the normal group.

Conclusion: A six weeks period of masticatory function rehabilitation in deep masseter muscle of adult rats made it possible for the fast (MYH 1+2) isoforms to normalize and the slow (MYH 7) isoform levels to increase; an adaptation of the increased mechanical load. The increased level of embryonic (MYH 3) isoform can be due to the need of creation of new MYH isoforms.


0089 (111538)

Measurement of Electromyographical Signals from the Genioglossus Muscle. S. LANGRAN1, C.M. O'CONNOR2, M.J. O'MALLEY2, and M. O'SULLIVAN1, 1Dublin Dental School & Hospital, Ireland, 2University College Dublin, Ireland

The genioglossus muscles are primary protruders of the tongue and abnormalities of these muscles play a key role in obstructive sleep apnoea syndrome. Electromyography is an important tool in observing muscle activity. Problems have been reported previously in measuring genioglossus electrical activity due to difficulties accurately positioning and stabilising probes. Aims: (1) To design an oral appliance to measure electromyographic signals from the genioglossus muscle; (2) To determine inter-appliance reproducibility; (3) To determine optimal electrode positioning. Materials and Methods: Dental impressions were made and casts obtained. Acrylic resin appliances were designed with a row of five electrodes along the genioglossus muscle, 3 mm from the central fraenum. A number of prototype appliances were fabricated and tested until a definitive design was produced. Five appliances were constructed from separate casts for one patient to determine inter-appliance variability. A further three appliances were constructed to investigate varying electrode positions with one control row, and a second row at distances of 3/6/9 mm laterally. Electromyographical recordings were completed in a sound proof recording room. The subject bit gently on a bite block and placed variable tongue pressure on a customised force transducer. The signals were filtered and amplified and displayed on a PC and analysed using Matlab programs. Results: The definitive appliance design provided good signals from genioglossus. Inter-appliance reproducibility results showed similar trends in EMG signals, amplitude and conduction velocity. The varied electrode position recordings showed decreasing signal quality as the electrode distance was moved further from the control position. Amplitude values were lower on anterior electrodes. Conduction velocity values were higher on anterior electrodes and decreased towards the middle section of the muscle. Conclusions: All appliances successfully recorded EMG signals from the genioglossus muscle. Reproducibility between appliances was observed. Electrodes moved further from the midline produced EMG signals of lesser quality.


0090 (111557)

Signs and Symptoms of TMD in Postmenopausal Women. A. NEKORA-AZAK, G. EVLIOGLU, A. CEYHAN, H. KESKIN, S. BERKMAN, and H. ISSEVER, University of Istanbul, Turkey

Objectives:The prevalence of temporomandibular disorders (TMD) is about 2-5 times higher in women than in men in the community. Data for the higher prevalence of TMD in women and prevalence rates peak during the reproductive years and decrease after menopause. This indicated that female sex hormones may play a role in the aetiology or maintenance of TMD.

Methods:The aim of this study was to investigate the relationship between postmenopausal hormone use and TMD in Turkish postmenopausal women. One hundred eighty postmenopausal women, aged 42-72 years, were examined both clinically and by questionnaire with regard to the signs and symptoms of temporomandibular disorders, general health's status and use of postmenopausal hormonal replacement therapy in preceding one year. Ninety one postmenopausal women (50, 6%) were having hormonal replacement therapy. The remaining 89 (49, 4%) postmenopausal women were not having hormonal replacement therapy.

Conclusion:The signs and symptoms of TMD were not different in postmenopausal women using and not using postmenopausal hormones.

Results:There was no association between the use of postmenopausal hormones and the signs and symptoms of TMD in this study.

Key words: Temporomandibular disorders, postmenopausal hormone replacement threapy.


0091 (111565)

Developing an outcome measure for endodontic treatment. T. RASHEED, A.N. DONALDSON, J.E. GALLAGHER, and S. DUNNE, King's College London Dental Institute, United Kingdom

Background: The rise in evidence-based health care has led to a demand for patient-based outcome measures of health status & quality of life.

Objectives: To create and validate an instrument for measuring health outcomes associated with restorative procedures (focusing on endodontic therapy).

Methods: Initially, 58 items were selected based on an extensive literature review of currently used measures, outlining their strengths & weaknesses. These items were applied to evaluate outcome of endodontic therapy in 101 adults presenting at King's College London Dental Institute. Patients self-completed the proposed outcome measures at baseline, at completion and at the one-month follow up visit. Factor analysis (ML extraction with Varimax rotation), followed by multiple linear regressions of the total scores and an expert-based approach were undertaken to select statistically and clinically significant and independent items. Validity, reliability, responsiveness and interpretability of the final instrument is being tested for the endodontic therapy in an external sample of 30 adults presenting at the same site.

Results: In the factor analysis stage, 22 items were identified and in the modeling stage this was reduced to 15 items. These items, their effects and 95% confidence intervals and statistical significance were: painful mouth: 2.0 (0.62,3.5)**; Sensitive teeth 2.3 (1.0,3.7)**; unable brush: 1.4 (0.09,2.7)*; avoid eating 3.0 (1.5,4.5)**; troubled pronunciation: 2.5 (1.0,4.1)**; taste worsened: 4.0 (2.4,5.5)**; food catching:2.0 (0.8,3.3)**; sore-jaw 2.6 (1.3,3.8)**; toothache 2.4 (0.8,4.1)**; sleep: 2.6 (1.1,4.0)**; depressed: 4.0 (2.5,5.6)**; embarrassed: 5.7 (4.3,7.1)**; untolerant of partner/family 4.5 (2.5,6.5)**; general-health 3.6 (1.9,5.3)**; unable-to-work: 4.5 (2.8,6.3)**. An extra item was added to the questionnaire using expert-based approach by consultation with the clinicians.

Conclusion: The final questionnaire consists of only 16 items grouped in seven conceptually distinct subscales: functional limitations, physical pain, psychological discomfort, physical disability, psychological disability, social disability and handicap.


0092 (111797)

Gutta-Percha Removal with Different Techniques in Roots Filled with BeeFill2in1. S.P. KARAPINAR, Z. YILMAZ, B. OZCELIK, and Z.C. CEHRELI, Hacettepe University, Ankara, Turkey

Objectives: To evaluate the efficacy of hand and two rotary instruments in the removal of gutta-percha (GP) filled with BeeFill 2in1(VDW,Munich,Germany) warm vertical compaction technique.

Methods: 42 extracted single-rooted human teeth were prepared with Mtwo nickel titanium rotary instruments to instrument size 35/.04 .The prepared canals were obturated by using BeeFill 2in1 with warm, vertical compaction technique. The obturated teeth were randomly divided into 3 groups (n=14) to remove the gutta-percha and sealer using different techniques, as follows; group 1: GP removal with hand instrumentation with Hedström files (VDW Antaeos, Munich, Germany), group 2: GP removal with Protaper Universal files (Dentsplay, Maillefer, Switzerland), group 3: GP removal with Mtwo files (VDW, Munich, Germany).The time required for retreatment was recorded. Then, the teeth were split longitudinally and each half of the roots were photographed. The areas of remaining obturation material were measured using image analysis program (Image-Pro Plus 4.5; Media Cybernetics, Silver Spring, MD). The results of the analysis of residual root filling material analysed with Kruskal -Wallis test and working time was analysed with Welch ANOVA test.

Results: Statistical analyzes demonstrated that there were there were no significant differences between three groups (p>0, 05). The retreatment time with protaper instruments was significantly shorter than Mtwo and hedström instruments (p<0,001).

Conclusion: Under the condition of the present study there were no statistically significant difference among three groups, however Mtwo retreatment instruments were more efficient than the others in removing filling materials.


0093 (110023)

Reducing the Noise from Dental Handpieces with Adaptive Filtering. B.J. MILLAR, King's College London, United Kingdom, E. KAYMAK, Brunel University, London, K.R.G. ROTTER, London South Bank University, and M.A. ATHERTON, Brunel University, London, United Kingdom

Objective: To develop a system to reduce the patient's discomfort and provide hearing protection for the clinical team from the noise from dental handpieces. The specific aim of this part of the study was to reduce the handpiece noise in the frequency range from 2.5kHz to 11kHz by at least 6 dB. This would mean that the power of the noise would be reduced to only a quarter of its original value so the frequency would then be barely audible against background sound.

Method: Five sound recordings were made of five dental air turbine handpieces in use with different amounts of loading: no load, 1N, 2N and 2.5N according to BS EN ISO 7785-1. The sound recordings were analysed using FFT power spectral density plots in the Matlab Signal Processing Tool (SPT). A Normalised Least Mean Square (NLMS) adaptive filter algorithm was applied to the recordings. Comparisons were made between the original recordings and the filtered recordings.

Results: Five air turbine handpieces were tested and sound recordings at the four different loads were recorded and analysed. The application of adaptive filtering brought about noise reduction in each case with a maximum noise reduction of the sound peak of 27dB. For each test the noise reduction was always greater than 6dB and was statistically significant (p<0.001) for each handpiece at each loading condition.

Conclusions: Adaptive filtering can be used to specifically reduce the unpleasant noise from dental air turbine handpieces without removing other background sounds. Supported by W&H.


0094 (111266)

Pulpal and Gingival Blood Flow in Diabetic Type I Patients. E. KRSLJAK1, V. MILETIC2, D. GRGA1, J. ROGANOVIC1, and D. STOJIC1, 1Faculty of Stomatology, University of Belgrade, Serbia and Montenegro, 2The University of Edinburgh, Scotland

Objectives: We used a laser Doppler blood flowmeter to evaluate the impact of diabetes type I on blood flow through gingival and pulp tissue.

Methods: Recordings were made from upper central and lateral incisors as well as from surrounding gingiva in healthy volunteers (n=30) and type I diabetic patients (n=10) using a laser Doppler flowmeter (Periflux PF5001 masters; Perimed Jarfalla, Sweden).

Results: The average blood flow signal recorded from central incisors in healthy subjects was 12.92 ± 5.9 while in diabetic patients was 6.50±2.2 (p<0.05). Recorded blood flow from lateral incisors in healthy patients was 19.13 ±5.2 and in diabetic patients 10.24±3.1 (p<0.05). The blood flow signal obtained from gingiva surrounding incisors in healthy patients was 33.07±4.8 and in diabetic patients 13.28±1.1 (p<0.05).

Conclusions: The results suggest that in type I diabetic patients, blood flow through pulpal and gingival tissue was significantly reduced compared to healthy subjects.

The work was supported from the Ministry of Science and Environmental Protection- Serbia ( grant No 1450).


0095 (109530)

SRP with various rinsing solutions – Clinical and microbiological results. H.F.R. JENTSCH1, R. PURSCHWITZ1, G.U. KNÖFLER1, W. PFISTER2, T. KRÜCK1, and S. EICK2, 1University Leipzig, Germany, 2University Hospital of Jena, Germany

Aim: The aim of this study was to compare the influence of three different rinsing solutions during SRP on clinical and microbiological results in a prospective clinical controlled trial.

Material and Methods: 51 adult volunteers with generalized moderate chronic periodontitis were treated by full mouth SRP using either 0.9% sodium chloride (group A, n=18), 0.12% chlorhexidine digluconate (group B, n=17) or povidone iodine (group C, n=16) for rinsing during SRP. At baseline (0), after 3(1) and 12(2) months PD, BOP and CAL were recorded in a 6-point measurement. Gingival crevicular fluid was collected at 4 teeth with PD=4-6mm for quantitative real time PCR analysis of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola. Nonparametric tests were used for statistical analysis.

Results: The results were as follows: PD A0-3.03±0.43mm 1-2.85±0.57 2-2.67±0.33, B0-2.98±0.42 1-2.46±0.53 2-2.59±0.40, C0-2.98±0.34 1-2.60±0.23 2-2.54±0.33; BOP A0-33±17% 1-17±13 2-17±13, B0-30±20 1-14±13 2-13±10, C0-43±19 1-22±18 2-18±15; CAL A0-3.32±0.73 1-3.09±0.71 2-3.11±0.67, B0-3.39±0.56 1-3.02±0.69 2-3.17±0.71, C0-3.26±0.40 1-2.87±0.38 2-2.88±0.57. PD was significantly reduced in all groups (p<0.001 – p=0.002), group 2 was better than group 1 after 3 month (p=0.041). BOP was significantly better in all groups (p<0.001 – p=0.002) but without significant differences between the groups. CAL was significantly better in all groups after 3 months, in group B and C also after 12 months (p<0.001, p=0.044) but without significant difference between the groups. Porphyromonas gingivalis was significantly reduced in group C after 12 months (positive samples 95 % vs. 35 %, p=0.023). Tannerella forsythia was significantly reduced in group C after 3 months (76 % vs. 53 %, p=0.019).

Conclusions: Within the limits of the study one may conclude that there are no important differences between the applied solutions regarding the influence on clinical variables. Povidone iodine seems to reduce the studied microbiological species in a higher degree.


0096 (111482)

Evaluation of dental alginates impression materials in dental students. P. FONTANA1, B. CROVATO2, D. DALESSANDRI3, L. LAFFRANCHI3, F. ZOTTI4, and S. BONETTI4, 1Faculty of Dentistry, University of Brescia, Italy, 2University of Brescia, Italy, 3Università degli studi di Torino - Dipartimento di scienze biomediche e oncologia umana, Italy, 4Università di Brescia, Italy

Objectives: the aim of this study was to compare 5 alginates products used for orthodontic impressions.

Method: The materials investigated were Alginplus Tropical “A”; Alginmax “B”; Alginmajor “C”; Alginkid Orthodontic “D” and Alginplus Fast “E”(Major Dental, Moncalieri-To, Italy, ww.majordental.com). Fifty dental students were recruited from the University. Two operators, one orthodontist was assigned to mixing and the second assigned to setting. Each subject had two impressions, giving a total of 100 impressions (20 impressions for each alginate). The manufacturer's instruction were followed and impressions taken at 23°C whilst the models were poured with water at 4°C. Each alginate was evaluated by five features: Mixing; Water absorption; Consistency; Processing time; Curing time at final evaluation. For each feature we considered two degrees of quality: POSITIVE, favourable for working time; NEGATIVE, not favourable for working time.

Results: the comparison showed no significant clinical differences between the alginates. Mixing: positive; Water absorption: positive; Consistency: positive; Processing time: positive; Curing time: positive, the best for alginate “D” (1'50'').Total final evaluation: positive.

Conclusion: the differences between the materials were not significant.


0097 (110929)

Impression Pressure and the Distance to a Tray Perforation. T.P. HYDE, H.L. CRADDOCK, and P.A. BRUNTON, University of Leeds, United Kingdom

Objectives: The research literature differs on the importance of special tray perforations in reducing impression pressure. One in vitro study reported that perforations in special trays reduce pressure; however another found that perforations in special trays have little effect on pressure. The aim of the study is to investigate the pressure of an impression when a perforation in the ‘tray' is at different, set distances.

Method: Vinyl polysiloxane impression material (express 3M) was placed between 2 approximating discs on a universal testing machine and the pressure generated at the centre of the upper disc was recorded. The lower disc was perforated at the centre and at 3, 6, 9, 12, 15, 18, 21, & 24mm from the centre with 2mm perforations. The perforations were sealed. Each perforation, in turn, was unsealed and the impression pressure as the discs were approximated was recorded for 5 approximations. Data was analyzed by ANOVA with post hoc multiple comparisons (Tukey-B) at the 0.05 level of significance.

Results: The peak pressure means (S.D.) were 76.88(8.34), 176.8(10.79), 214.83(9.13), 256.80(9.13), 289.91(7.58), 316.23(7.78), 340.71(5.03), 357.46(11.09), 378.83(11.50), and 378.02(26.57)KPas. There was a significant difference between the groups (p<0.00001). The Tukey-B showed significant difference for each of the holes up to and including the hole 15mm from the centre (alpha=0.05). The holes at 18 and 21mm and the holes at 21, 24mm & ‘no hole' formed homogenous subsets.

Conclusion: In this in vitro experiment, perforations have a decreasing effect on impression pressure as they become more distant from the sensor. At distances greater than 21mm the effect of the perforation is not statistically different from no perforations.


0098 (110345)

Effect of Crown Retrieval Method on Internal Threads of Implants. M. DASHTI, D.J. SETCHELL, C.J. TREDWIN, and D.R. MOLES, UCL Eastman Dental Institute, London, United Kingdom

Objective: The purpose of this study is to investigate the presence of damage to internal threads when retrieval of cement-retained restorations is attempted with a conventional and novel removal technique.

Methods: Forty implant fixtures of different lengths were allocated to two treatment groups. Group 1 included implants with tight abutment screws and group 2 included loosened abutment screws. All specimens were sectioned using a standardised cutting procedure. The internal geometry of all fixtures was replicated with an impression material. All specimens were uniquely marked then prepared ready for examination under scanning electron microscopy. The same procedure was repeated after crown retrieval. Retrieval was undertaken using a conventional and novel technique.

Results: For each treatment group there were obvious signs of damage to the internal threads after crown retrieval. No correlation was found between the extent of damage and the number of attempts to remove each crown. Non-parametric statistical tests revealed no significant difference in damage to internal threads between the conventional and novel retrieval methods. The same insignificant outcome was found when comparing damage when retrieving crowns of loosened abutment screw versus tight abutment screws. Comparison of all treatment groups showed no correlation.

Conclusion: Retrieval of cement-retained restorations using a conventional or a novel technique resulted in minimal damage to the internal threads of the implants tested. The effect of the looseness of the screw did not seem to have an effect on damage to the internal threads.


0099 (111298)

Prevalence: Hyperplasia around dental implants in Head Neck Cancer Patients. F. QAYYUM, King's College London, United Kingdom, and M.R. FENLON, GKT Dental Institute, King's College London, England, Uk

Objectives:

To clinically evaluate hyperplasia around dental implants placed at the grafted site after tumour resection and secondary irradiation.

Methods:

Forty cancer patients had tumour ressected and reconstructed with free vascularised flaps. One hundred and fifty- three implants were placed and examined in Deep Circumflex Iliac Artery free vascularised, Radial Forearm Flap or Fibula Grafts. Data was collected for presence of peri-implant soft tissue hyperplasia around the dental implants after irradiation.

Results:

Peri-implant hyperplasia was observed in 15 patients with no irradiation and 14 patients had no hyperplasia. In irradiation 9 had no hyperplasia and 2 had hyperplasia.

Fifty-nine implants in non irradiated site had no hyperplasia and 47 implants sites had hyperplasia.

Conclusions:

Peri-implant hyperplasia was found to be a common finding around implants in vascularised flaps used for post cancer reconstruction. This effect was lost in therapeutic radiation fields.


0100 (111048)

Aesthetics of implant-supported single crowns in the anterior maxilla. V.H. VILHJÁLMSSON1, K. KLOCK1, K. STØRKSEN2, and A. BÅRDSEN1, 1University of Bergen, Norway, 2Haukeland University Hospital, Bergen, Norway

Objectives: To evaluate the aesthetics of implant-supported single crown in the anterior maxilla.

Methods: Fifty patients (mean age: 31.3 years; range:18-56 years. Gender:46.4 females/ 53.6 male) having implant-supported single crowns replacing teeth absent due to trauma or aplasia in the anterior maxilla were included. The patients were treated at the Implant Clinic,University of Bergen (n=15) or at the Haukeland University Hospital, Bergen (n=35). Evaluation was carried out one year after placement of the crown by the use of the Pink Esthetic Score (PES) and the Implant Crown Aesthetics Index (ICAI). The patients rated their satisfaction of crown and adjacent soft tissue.

Results: The median sum score for PES was 8 (range: 3-13). For the ICAI the median sum score was 9 (range: 2-28). When the ICAI was dichotomised with the first 5 items related to the crown and the following 4 items related to the adjacent mucosa, the mucosa score had a median value of 6, while the crown score had a median value of 3. Regarding the form and colour of the crown, 87.5% and 83.3% of the patients were satisfied while 70.8% were satisfied with the adjacent mucosa. A significant bivariate correlation was found between the PES and the ICAI (rs -0.71, p < 0.01). The PES also correlated with the patient satisfaction related to the adjacent mucosa (rs -0.30, p < 0.05). The ICAI correlated with the patient satisfaction related to colour of the crown (rs 0.35, p < 0.05), however, the mucosa score of the ICAI also correlated to the sum of the questions related to the form and colour of the tooth (rs 0.29, p < 0.05).

Conclusion: All though most patients were satisfied, the objective evaluation shows that the peri-implant mucosa is the main challenge for the aesthetics outcome of single implants.


0101 (109484)

Implant-to-natural-tooth fixed partial denture by 3D-FEA. L. PIERRISNARD, and A. NAVEAU, Paris Descartes University, Montrouge, France

Objectives: numerous problems have been reported following therapies used to attach natural teeth to implants beneath a fixed prosthesis. The aim of the study was to show the mechanical behavior of implant and tooth-supported prosthesis.

Methods: this study was performed using 3D finite element analysis. Twelve models were compared using three different lengths (12, 10 and 8mm) and two different diameters of implants in titanium (4 and 5 mm). Each of the 6 implants carried an abutment in titanium and was connected to a tooth by a ceramic prosthesis. Two prosthetics configurations were considered: two connected crowns and a 3 unit Fixed Partial Denture. The implant and the tooth were seated in a supporting structure of cancellous bone. A vertical occlusal load of 100 newtons is applied in the middle of the prosthesis.

Results: Whatever the shape of the implant, it acted like the fulcrum of a device that induces the intrusion of the tooth. Bone stresses appear around the neck of the implant. In implants and abutments, stresses are meaningfully less intense when the diameter was 5 mm and when the distance between the tooth and the implant decreases. Implant length is a less influencing parameter.

Conclusion: If implant abutments and natural teeth are involved to support a prosthetic restoration, the use of wide-bodied implants in selected cases of short-span fixed partial dentures is recommended. Nevertheless, bone quality and methods of connection are important parameters that must be studied and taken into account


0102 (110503)

Bio-social Influences on Psychological Constitutions of Patients with Removable Dentures. J. PISTORIUS, A. PISTORIUS, J. HORN, and J. KRAFT, Johannes Gutenberg University, Mainz, Germany

Objectives: In view of the increasing prevalence of psycho-depressive illnesses especially in older patients, psychological aspects gain importance also in dentistry. Therefore we tried to verify influences on the psychological constitution of patients and a potential correlation to their oral rehabilitation.

Methods: 129 men and 114 women (mean age 63 ± 11.3 years) with removable dentures were clinically examined. Oral hygiene status and the form of prosthodontic rehabilitation were ascertained. A questionnaire gave information about social contacts, marital and social status, syndromes, oral hygiene habits, frequency of undergoing dental service and contendedness with dentures. Psychological constitution was measured with the Geriatric Depression Scale (GDS from Sheik and Yesavage 1986). The statistical evaluation was made by Fisher`s-Exact-Test, Chi-Square-Test with independant variables, Wilcoxon- and Kruskal-Wallis-Test: p<0.05. Results: 17.9% of all patients suffered from a light or medium depression (GDS value: 5≤10) and 0.8% from a heavy one (GDS value: >10), 22.7% of those were men and 14.3% women. These patients had worse oral hygiene than the healthy ones (p=0.019). Higher GDS values were correlated with age (p=0.33), missing partners(p=0.005), rare social contacts (p=0.000), worse state of health (p=0.002), lower income (p=0.005), discontent with dentures (p=0.009), fewer remaining teeth (p=0.000) and a worse estimation of their oreal health related quality of life (p=0.003).

Conclusions: The results showed numerous correlations between GDS and bio-social factors. These potential risk factors should be tried to be ascertained by an extensive case history. Since patients with light or medium depression showed worse oral hygiene and a higher discontent with their dentures than healthy ones (29.8% to 13%), dentists should give more attention to these patients and carefully explain therapy and dentures before starting treatment.


0103 (110828)

The Prevalence of Xerostomia in Patients With Removable Prostheses. F. NIKOLOPOULOU1, T. TASOPOULOS2, and R. JAGGER2, 1Dental School, University of Athens, Greece, 2Department of Oral Dental Science, University of Bristol, United Kingdom

ABSTRACT

Objectives: The aims of this study were to determine the prevalence of xerostomia among patients attending an undergraduate clinic for provision of dentures and to investigate the relationship between xerostomia and oral hygiene.

Methods: One hundred and eighty denture wearers (80 male and 100 female, age 42-80, mean age 65 years) attending the clinic of Prosthodontics, in the Dental School of the University of Athens completed a questionnaire asking questions related to xerostomia and related medical conditions. Patients were examined and cleanliness of teeth was determinedusing a modified Debris Index. Cleanliness of complete dentures was determined using the same index.

The relationship between xerostomia and plaque deposits on natural teeth and complete dentures was determined using odds ratio.

Results: The total number of patients with xerostomia was 120. Fifty two had idiopathic xerostomia (no related systemic diseases) and 68 xerostomia with related systemic diseases.

There was a correlation between xerostomia and plaque deposits in partial denture wearers (odds ratio 1.65). There was also a correlation between xerostomia and hygiene of complete dentures (odds ratio 1.42).

Conclusion: There was a high prevalence of xerostomia in the patient population. There was a correlation between xerostomia and oral hygiene.


0104 (111183)

Clinical Evaluation of Injectable Ceramic Restorations After Maximum 75 Months. T. ABE, and Y. ITO, Aichigakuin University, Nagoya, Japan

Objectives: The advantages of all ceramic restoration materials are unparalleled aesthetics, good biocompatibility and lack of cytotoxicity compared to metal ceramic restorations. However, castable ceramic crowns may fracture. The purpose of this study was to evaluate the clinical strength of an injectable dental ceramic system based on Diopside (CERAESTE, Tokuyama Dental Co. Ltd., Japan) restorations.

Methods: Injectable ceramic restorations were made according to lost wax process, each ingot being heated at 900°C and pressed into a mold for 15 to 25 min. After pressing, the crystallization process was accomplished automatically during the cooling down process of the casting ring to room temperature. 115 injectable ceramic restorations were placed on 34 patients, from a period of December 7th, 2001 up to February 4th, 2005 at Aichi-Gakuin University dental hospital. These restorations were investigated at the time of dental treatment by dentists. Statistical method of survival analysis according to the Kaplan-Meier was applied to investigate the effects of fractures. Not only observed fractures but also those demonstrating cracking or chipping were considered to be fractured.

Results: Observed fractures were 17 out of the 115 (14.8%) of the restorations. The longest survival time until now has been 75 months. The Kaplan-Meier survival probability calculated for these restorations were 0.97 anterior teeth region and 0.82 posterior teeth region after a time interval of 24 months, and giving a survival probability of 0.97 anterior teeth region and 0.81 posterior teeth region after a time interval of 60 months. There were significant differences (P=.022, log-rank test) in the survival between the two region.

Conclusion: It was thus concluded that injectable ceramic restorations are suitable for clinical use, although not totally without problem, especially attention is necessary for use in the molar region for long-term use.


0105 (109483)

Effects of vertical interarch space and abutment design by 3D-FEA. A. NAVEAU, and L. PIERRISNARD, Paris Descartes University, Montrouge, France

Objectives: This 3D Finite Element Analysis (FEA) study aimed to determine stress levels and distributions in all-ceramic crown restored implants as a function of three different extents of interarch space versus different abutment designs for sealed or screwed crowns.

Methods: Nine 3D-FEA models were constructed with identical implants (diameter 4.1 mm and length 10 mm): the first three models have the same vertical interarch space with different abutment lengths (4, 5.5, and 7 mm) ; models 4 to 6 have three different extents of interarch space with corresponding abutment lengths ; models 7 to 9 represent implants with identical abutments (2.5 mm) with screwed crowns and different extents of interarch space. The implants were placed in the center of a bony structure. Crowns were loaded with a defined force of 30 N inclined 30° chosen arbitrarily.

Results: Within the implant and bone, the most intense stresses appeared in the cervical area. Highest stresses occurred within the implants first at their neck, and progressively decreased towards the bone, the abutment, in the threaded part and the cervical area of the crown. Stress levels increased with the vertical interarch space, which is the dominating factor. Abutment height adaptation to the vertical interarch space is an important parameter.

Conclusions: In this mechanical context, the comparison allows preference to abutments designed for cemented crowns. Moreover, implant initial stability seems easier with short vertical interarch spaces.


0106 (111041)

Elderly Receiving Home Care Nursing Risk Factors for Dental Caries. T. WILLUMSEN1, B. FJAERA2, and H. EIDE2, 1University of Oslo, Norway, 2Oslo University College, N/a, Norway

Objectives: In dentistry the oral health of elderly is a growing concern. Elderly receiving home care nursing in Norway have rights for free dental treatment in community dental services. However, professional secrecy prevents the dental professionals to identify them. Home care nurses have general responsibility of the patient's need for health services and need for assistance in general and oral hygiene. Oral health has a history of little attention from nursing staff. To highlight oral health among nurses, the present study was planned. The aim was to explore risk factors for dental caries among elderly in home care nursing, knowledge of their rights for free dental services and self-reported problems with- and need for assistance in performing dental cleaning.

Method: Cross sectional, descriptive study, 137 patients in Oslo, Norway receiving home care nursing were questioned by nurse students.

Results: Mean age 80.8 years (sd 10.0), mean 38.1 month (sd 40.0) in home care nursing, 85.5 % natural teeth., 54% xerostomia, 61% more than 5 medications daily.

64% reported more than 6 months since dental treatment. 38% had been informed about their rights for free use of- and 19% used community dental clinics , Although 76% reported poor eyesight and 50% reported paresis in hands or fingers, only 16% reported problems with proper tooth brushing and only 7.3% wanted assistance with oral hygiene. Only 4.4% received assistance.

Conclusion: The majority of patients have objective risk factors for dental caries; they were not properly informed about their rights for dental services and there was a divergence between reduced physical function (paresis is arm/ fingers, eyesight) and the subjective need for assistance with tooth cleaning. To identify risk factors of dental caries and implement proper prophylactic plans, increased focus and cooperation among dental staff, nursing staff and elderly themselves is essential


0107 (110942)

Erosion potential and saliva stimulation efficacy of two acidic lozenges. J.M.L. SILVEIRA1, D.N.S. MARQUES1, J.R.O.F. MARQUES1, E.T.M.C. FELINO2, N.F.R.P.M. GUILHERME2, and A.D.S.P. MATA1, 1Faculdade de Medicina Dentária da Universidade de Lisboa, Portugal, 2Instituto Superior de Ciências da Saúde Egas Moniz, Caparica, Portugal

Objectives: This was a double parallel arm randomized clinical trial on the dental erosion (DE) potential and saliva stimulation efficacy (SSE) of two different acidic lozenges used for stimulation of salivary flow. The rationale was to study if Xerodent (Alpharma, Sweden) a recently marketed acidic lozenge containing weaker malic acid, fluoride and xylitol (NAL) produced a different DE potential and SSE when compared with SST (Sinclair, UK) a traditionally citric acid based one (C).

Methods: 120 patients, attending a Portuguese University dental clinic were recruited for this study and randomized to one of two groups and then administered either a NAL or a C lozenge. Saliva collection was obtained by established methods at different times ranging from 0 till 20 minutes. Salivary secretion rate (SSR) was expressed as mean +- SD of the difference between lozenge stimulated and basal salivary flow in ml.min-1. The salivary pH of the samples was determined with a pH meter and a microelectrode. Erosive potential was defined as the mean ± SD time interval (in minutes) of salivary pH below 5.5. The 95 % confidence intervals (CI) for absolute risk reduction (ARR) and number needed to treat (NNT) were obtained in order to better quantify erosive potential differences between the two groups. Paired or unpaired Student t test were employed for testing of mean differences as appropriate, significance level was set at 5%. This study was approved by the local ethical committee.

Results: SSR for group NAL and C was 0.904 ± 0.434 and 0.968 ± 0.459 ml.min-1 respectively. The ARR for patients in the NAL group was 78% ± 11 and the NNT 1 for 95% CI.

Conclusions: In this study both lozenges presented similar salivary stimulation rates while the NAL presented a significant reduction in dental erosion potential when compared to C.


0108 (111642)

Confocal microscopy evaluation of post-resin-dentine interfaces. S. DI RENZO1, S. SAURO2, N.M. GRANDE1, G. PLOTINO1, F. SOMMA1, T.F. WATSON2, and F. MANNOCCI2, 1Catholic University of Sacred Heart, Roma, Italy, 2King's College London, England

Objectives: The objectives of this study were to compare the number of voids and the cement thickness in post-resin-dentine interfaces of teeth restored with conventional and anatomically modified glass fibre posts. Methods: 48 single-rooted mandibular premolars were selected. After removing the crowns at the cemento-enamel junction the coronal portions of the root canals were prepared using Gates Glidden drills and instrumented to a size 40 master apical file. The apical portions of the roots were obturated with vertically condensed gutta-percha. The roots were divided into 2 groups. The teeth in group 1 were restored with standard fibre posts (Easypost Lux) and the teeth in group 2 were restored with anatomically modified glass-fibre posts (Periodent). The posts were cemented using a dentine bonding system (Sealbond Ultima) and composite cement (Corecem). The bonding agent was labelled with Rhodamine B, applied on the root dentine and on the surface of each post and light cured for 60s. Each tooth was sectioned along the long axis in a mesio-distal direction and sections were randomly selected for the study, 24 independent specimens were therefore included in each group. Confocal microscopy was used to assess the presence of voids between cement and fibre post (G1) between dentine and adhesive (G2) and between cement and adhesive (G3) at six sites for each specimen (two coronal, two middle, and two apical).The thickness of the cement was also evaluated at the same sites. All data were statistically analyzed using Pearson's X2 Results: The presence of voids in Group 1 was significantly greater than in group 2. No significant differences were found between the cement thicknesses of the two groups. Conclusions: Anatomically modified glass fibre posts produced a post-resin-dentine interface of better quality than conventional posts.


0109 (110711)

6-year Results of a Controlled Trial in Class 2 cavities. G. DONDI DALL'OROLOGIO, R. LORENZI, and F. FAZZI, University of Bologna, Italy

Objectives: The aim of the study was to test a new ormocer in class 2, using or not a flowable as liner. Methods: A CT was scheduled on 100 patients, 41 males and 59 females, between 22 and 61, with 3 class II cavities with floor and cervical margins in dentin for each one. The materials selected were Admira and Admira Bond (AB), AB+ flow (ABV) (Voco), P60 and SB1(PS), PS+flow(PSM) (3M-Espe), Solitaire and Confort Bond (SC), SC +flow (SCH) (Heraeus-Kulzer), Definite and Etch&Prime 3.0 (DD) (Degussa).There were five groups of patients, with 20 subjects for any group, for a total of 100 restorations for any Voco group and 100 for all the controls.The procedures were done according with manufacturer's instructions with the same clinical protocol by three expert operators. The restorations were evaluated by one independent examiner with an intra-agreement > 80%, with a loop (4.5x) according with USPHS modified criteria at baseline, 6,12,24,36,72 months. A statistical analysis with Mann-Whitney non parametric test was performed (p=.05).Results: After 6 years 70 patients and 210 restorations were assessed;there were 7 failures in group AB and 5 failures in ABF without any significant difference between the groups;the control groups had 70 restorations with 41 failures, without any statistical difference using or not a flow liner. Conclusions: Within the limits of this clinical trial the new ormocer worked at the same level with or without a flowable liner, the control groups showed catastrophic results.


0110 (109681)

Monomers detected in saliva after treatment with composite fillings. V.B. MICHELSEN1, G. MOE1, H.B.M. KOPPERUD2, I.S. KLEVEN2, G.B. LYGRE3, J. SVAHN3, M.B. STRØM4, L. BJORKMAN1, E. JENSEN4, and H. LYGRE1, 1University of Bergen, Norway, 2NIOM, Haslum, Norway, 3University of Bergen/UNIFOB AS, Norway, 4University of Tromsø, Norway

Objectives: Substances and particles are released from dental restorative materials into saliva by elution and/or degradation. The aim of the study was to investigate in vivo the amount of monomers in human saliva after restorative therapy with etch-bond technique and composite fillings.

Methods: Ten healthy individuals each had one premolar cavity restored with composite filling material (Z250, 3M Espe). Etching and adhesive procedure with Scotchbond (3M Espe) was performed according to the manufacturer's instructions. Non-stimulated saliva was collected for 15 minutes, before treatment (controls), and 10 minutes, 24 hours, and 7 days after the placement of the filling. Samples were analysed with GC-MS (Thermo Quest Trace GC with Finnigan MD 800 quadrupole MS) and LC-MS/MS (Agilent 1100 Series LC/MSD IonTrap). Tailor-made internal standards were used for quantification.

Results: In samples collected before restorative therapy (controls) no monomers from composite filling materials were found. The monomers HEMA, TEGDMA, UDMA and Bis-GMA were detected in saliva samples after restorative therapy. HEMA was found in all samples collected 10 minutes after treatment in quantities from 0.015 to 0.185 µg/ml saliva. The amount of UDMA and Bis-GMA was quantified in the samples taken 10 minutes after treatment and were from 0.01 to 1.78 µg/ml for UDMA and from 0.03 to 18.93 µg/ml for Bis-GMA. TEGDMA was detected in 4 samples taken after 10 minutes, but the amounts were below quantification limit. No monomers were detected in the saliva samples collected after 24 h and 7 d, except in one of the samples taken after 24 hours, where detectable amounts of HEMA were found.

Conclusion: These results show that monomers (HEMA, UDMA, TEGDMA and Bis-GMA) from the investigated composite filling material and adhesive system was found in saliva shortly after treatment. One week after the treatment the amounts of monomers were below detectable concentrations (S/N<3).


0111 (111817)

Contact angle measurement of dentin surface with different EDTA solutions. Z. YILMAZ, T.T. DEMIRTAS, H. DOGAN BUZOGLU, and M. GÜMÜSDERELIOGLU, Hacettepe University, Ankara, Turkey

Objectives: To detect the effect of combined and single use of EDTA, EDTA-T, REDTA and NaOCl to the wettability of root canal dentine.

Methods: Forty-two extracted human anterior teeth were used. Mid-root portion were bisected longitudinally. The specimens were randomly assigned to seven experimental groups (n=6). The flat dentin surface was prepared with carborundum paper. Surface roughness of each dentin surface was measured with a contact profilometer (Mitutoyo SJ-400). The value of surface roughness was accepted 0.60 µm. One-half of each root samples were kept for control measurement. The experimental group were treated as follows: groups 1: 17 % EDTA, group 2: 17% EDTA followed by 2.5 % NaOCl, groups 3: REDTA, group 4: REDTA followed by 2,5 % NaOCl, group 5: EDTA-T, group 6: EDTA-T followed by 2.5 % NaOCl. Group 7: 2,5 % NaOCl. Then all samples surfaces were submerged in deionized water before contact angle measurement. Drop shape analyses system DSA 100 (Krüss, Germany) was used to measure the contact angles from top-view images of sessile drop. Statistical analysis was performed using Kruskal-Wallis test (p<0.05).

Results: There was significant difference between all groups (p<0.05). Compared to the control group; combined and single use of EDTA significantly decreased the contact angle of dentine surface. Contact angle levels were between 39,9±17,7 and -4,5±14,9.

Conclusion: Use of low surface tensioned EDTA compounds alone or in combination with NaOCl increased the wettability of root canal dentine.


0112 (110595)

Wnt signalling in tooth development. M. LOHI, King's College, London, United Kingdom, and P.T. SHARPE, King's College London, United Kingdom

Objectives: To investigate canonical Wnt signalling in tooth development and establish its roles in tooth formation and dental stem cell regulation.

Methods: Axin2-lacZ reporter mice were used ranging from embryonic day 10.5-16.5, to identify the sites of canonical Wnt activity in tooth development. Dental pulp cells from Axin2-lacZ mice were extracted and cultured for up to 4 weeks and then stained with X-gal.

Results: At the thickening stage of tooth development Axin2 expression can be found in epithelium and mesenchyme in the outer layer of the developing mandible. At the bud stage expression can be identified in the developing enamel knots of the incisors and the molar tooth buds. At the cap stage expression can be seen in the dental epithelium of the incisors and it is clearly visible in the developing enamel knots of the molars.

Wnt positive cells were cultured from dental pulp and the number of cells were found to increase with time in culture and with the age of the teeth.

Conclusion: Canonical Wnt signalling is evident at different staging of tooth development, suggesting it plays multiple roles in tooth development. Wnt signalling is identified in cultured dental pulp cells, as changes with tooth age revealed. The role of Wnt activity in responses to tooth damage is under investigation.


0113 (111453)

Ultrasound Induction of Wnt Signalling Pathway in Odontoblast-like Cells. J. MAN, C.E. JONES, G.M. CALDWELL, P.R. COOPER, R.M. SHELTON, and B.A. SCHEVEN, University of Birmingham, United Kingdom

Objectives:

Little is known about Wnt signalling in dental tissues. Wnt-signalling has been suggested to play an important role in tooth development and the regulation of the dentine-pulp complex. In bone, Wnt signalling is upregulated in cells after mechanical loading. We hypothesised that ultrasound may exert biological effects on dental tissues that could involve the Wnt signalling pathway. In this study, the effects of ultrasound on Wnt/beta-catenin signalling were investigated using an odontoblastic cell line, MDPC-23.

Methods:

MDPC-23 cells in suspension were treated for 1 minute using incremental ultrasonic powers (P0, P3, P5 and P7) at 30 kHz ultrasound transmitted via a dental scaler probe (EMS, Nyon, Switzerland). Treated cells were then cultured in DMEM/10%FBS for 4 or 24 hours. Viability and numbers of adherent cells were measured using WST-1 assay (Roche). Immunocytochemical localisation of beta-catenin was carried out after fixing the cultured cells with an acetone:methanol mixture. In addition, the expression of the Wnt target gene, nkd1, was analysed by real-time PCR.

Results:

MDPC-23 cells showed a non-linear response to ultrasound inducing approximately 40% cell death at the highest ultrasound dose P7. MDPC-23 cells exhibited no significant beta-catenin staining at 4H after ultrasound treatment; however a dose-related response was evident in the 24h treated cells, which was characterised by the accumulation of beta-catenin within cell nuclei. Real-time PCR data showed a 1.9 fold and 2.8 fold increase in expression of nkd-1 at P3 and P5 respectively 24h after treatment relative to 4h cultures. At P7, nkd-1 expression was decreased.

Conclusion:

Data indicate that ultrasound may induce the Wnt signalling pathway in odontoblast-like cells. Further work is warranted to elucidate the mechanisms by which ultrasound may affect cellular Wnt signalling in cells of the dentine-pulp complex.


0114 (111155)

Identification of Pericytes as Potential Dental Stem Cells. J. FENG1, A. MANTESSO2, and P.T. SHARPE1, 1King's College London, United Kingdom, 2Universidade de Sao Paulo, Sao Paulo/SP, Brazil

Objective:

The developmental lineage origins of dental stem cells and their locations are not known. This is largely because most studies have utilised non-specific protein markers with cultures of human cells. Previous studies have however implied highly vascularised sites as potential stem cell niches, and perivascular / pericyte associated markers were among those found to be present on dental stem cell populations. The aim of this study is to use a mouse genetics approach to determine if pericytes are the source of dental stem cells.

Methods:

We used a transgenic mouse line expressing nuclear LacZ in pericytes to trace the distribution and molecular marker expression profile of these cells during tooth formation. In addition, tooth damage was generated to understand the response and involvement of pericytes to injury.

Results:

From bell stage onwards, LacZ-positive pericytes start to appear associated with blood vessels close to the tooth germ and also inside the dental papilla mesenchyme. Pericyte markers such as alpha smooth muscle actin (αSMA) and neuro-glial proteoglycan 2 (NG2) as well as mesencyme stem cells marker such as low-affinity nerve growth factor receptor (p75NGFR) were found co-expressed with some of the LacZ positive pericytes. Following injury to 5-day old pericyte LacZ mice teeth, pericytes were accumulated in the damaged area. Phosphohistone 3 staining showed some of these pericytes were undergoing cell proliferation.

Conclusion:

The results imply that single pericytes, not associated with vessels are found in the mesenchyme of developing teeth. In response to damage of the pulp and odontoblasts, these pericytes proliferate. Pericytes are thus closely associated with the niche created following damage. Experiments to determine if these pericytes differentiate into odontoblasts in the niche are ongoing.


0115 (110302)

Expression of Scube genes during murine tooth development. G.M. XAVIER, K. HAWORTH, M. SEPPALA, M. ZOUPA, P.T. SHARPE, and M.T. COBOURNE, King's College London, United Kingdom

Objectives: Teeth are organs that form in the embryo from a series of interactions between oral epithelium and neural crest-derived ectomesenchyme of the early jaws. Scube (Signal peptide-CUB-EGF domain-containing protein) genes encode a three-family group of secreted plasma membrane-associated proteins. Members of this family share a conserved protein domain organization of at least five recognizable motifs: an N-terminal signal peptide sequence, multiple EGF domains, a large spacer region followed by three repeated stretches of 6-cysteine residues and a C-terminal CUB domain. This study was conducted to evaluate the expression pattern of Scube1 and Scube3 during mouse tooth development. Methods: Radioactive section in situ hybridization using 35S-UTP radio-labelled riboprobes. Results: Scube1 and -3 demonstrate distinct and reciprocal expression patterns in the developing tooth. Scube1 expression is restricted to the mesenchymal component of the tooth from the early bud stage of development, with transcripts localizing to the dental papilla during the cap and bell stages of development. In contrast, Scube3 expression is restricted to the epithelial component of the developing tooth germ and is present throughout the primary thickening during initiation and inferior regions of the tooth bud. During the cap stage, transcripts are restricted to the internal and external enamel epithelium in peripheral regions of the tooth germ, but absent from the stellate reticulum internally. Conclusion: Scube1 and Scube3 expression patterns are highly restricted and reciprocal during murine tooth development. These patterns of expression suggest that Scube-family genes may play an important role during tooth development. Supported by the Programme Alâan, the European Union Programme of High Level Scholarships for Latin America (E07D400355BR).


0116 (111841)

Palatally Impacted Canines- Analysis of Cementum. J. HOGAN, and F. MCDONALD, King's College London, United Kingdom

Objectives: Palatal canine ectopia is frequently seen in patients referred for orthodontic treatment. There is considerable evidence to support the view that genetic factors are the primary origin of such displacement, and Runx2 has been proposed as a candidate gene. Mutation of Runx2 in patients with cleidocranial dysplasia causes delayed and ectopic eruption of permanent teeth and also cementum abnormalities. The aim of this study was to evaluate any differences in the distribution of cementum on the roots of palatally displaced canines, extracted from non-syndromic patients, compared to canines which erupted normally.

Methods: A sample of 12 extracted canines, which had been palatally displaced, was compared to an age-matched control group of 5 canines. Sections were prepared from cervical, middle and apical root thirds, perpendicular to the long axis of each tooth. Cementum area was calculated using image analysis software.

Results: Median cementum area of the cervical root sections was greater in the impacted canine group (3.535 mm2) than the control group (3.03 mm2). The middle root thirds also showed increased cementum area in the ectopic group (4.14 mm2) compared to controls (3.94 mm2). The apical root section measurements showed a reduced cementum area in the impacted canine group (8.44 mm2) compared to the control canines (10.5 mm2). However, differences in the median values were not sufficient to exclude the possibility that these variations were due to random sampling variability. Conclusion: The results indicated that there was no statistically significant difference between the cementum distribution on palatally impacted canines and maxillary canines which erupted normally (p>0.05).


0117 (110813)

Folic Acid Deficiency and Cleft Palate Appearance in Mice. E. MALDONADO, Y. LÓPEZ, C. MAESTRO, M.C. BARRIO, A. DEL RÍO, J. MURILLO, E. MARTÍNEZ-SANZ, I. CASADO, I. PARADAS, C. MARTÍNEZ-ÁLVAREZ, and J. PÉREZ-MIGUELSANZ, UNIVERSIDAD COMPLUTENSE DE MADRID, Madrid, Spain

Introduction: A deficit of dietary folic acid (FA) has been considered an aetiological factor in the appearance of cleft palate (CP) in humans. However, the reasons why this cleft palate is produced have been poorly investigated. Objective: Our aim was to determine the effects of the absence of FA in the palate of the progeny of mouse females under a FA deficient diet. Methods: C57 mouse females received either a control (2 mg FA/kg diet -control group-) or FA deficient (0 mg FA/kg diet + 1% succinyl sulfathiazole -experimental group-) diets for 2, 4, 6, 8, 10, 12, 14 or 16 weeks. Phoetuses (n=39) were extracted at embryonic day 13.5 (E13.5) and their palatal shelves were cultured for 18 or 36 hours. Other phoetuses were extracted at E17 (n=205) and were examined externally to check the presence of CP. Both cultures and heads were embedded in paraffin, sectioned and haematoxilin and eosin stained. 18 hour palatal shelf cultures were TUNEL stained and TUNEL positive cells were counted. In 36 hour cultures, opposing medial edge epithelia (MEE) adhesion and disappearance were measured. E17 mouse heads were microscopically analysed looking for CP. Results: Palate cultures from embryos progeny of 2 week experimental females showed a significant reduction of MEE cell death, palatal shelf adhesion and fusion. Alteration of palatal ossification was observed in phoetuses from 4 week experimental females onwards. Partial or complete CP was observed in 4% of the whole experimental group phoetuses, starting in the progeny from 2 week FA deficient diet mouse females. Conclusion: Even acting during a short time, FA deficiency alters palate development, affecting both the medial edge epithelium and the mesenchyme.

This work has been supported by grants FIS (PI06/0184) and UCM-CM to the Complutense Research Group 920202, 2006.


0118 (111105)

The Role of Edaradd in Embryonic Salivary Gland Development. K.L. WELLS, and A.S. TUCKER, King's College London, United Kingdom

Objectives:

Hypohidrotic ectodermal dysplasia is a syndrome characterized by defective development of ectodermal structures. In humans and mice the disorder is caused by mutations in the Eda pathway. Defects in Eda (the ligand) and Edar (the receptor) in the mouse lead to hypoplasia and dysplasia of developing salivary glands. However the role of Edaradd (the intracellular component) has not been investigated. The objective of this study was to describe the embryonic Submandibular gland (SMG) phenotype of Edaradd mutant mice and to determine the expression pattern of Edaradd in wild type SMGs.

Methods:

Edaradd mutant and wildtype mice were paraffin sectioned, and analysed for insitu hybridization and histology of submandibular gland development.

Results:

The SMGs of Edaradd mutant mice are hypoplastic in comparison to the wild type and exhibit disorganised epithelium with reduced branching and histodifferentiation. Edaradd was expressed in the epithelium of the wild type SMG from E13.5 onwards. Expression of Shh in the SMGs was downregulated in the Edaradd mutant in comparison to the wild type, while the expression of E-cad was unaffected.

Conclusion:

The SMG phenotype of Edaradd mutant mice is similar to that seen in Eda mutants, and the expression of Edaradd in the wild type mirrors that of Edar. This suggests that Edaradd is an essential component of the Eda pathway, interacting with Edar to regulate epithelial branching and differentiation in the SMGs. The downregulation of Shh in the SMGs of Edaradd mutants suggests that the Eda pathway acts through Shh to regulate SMG development.

This is the first work to characterize the SMG phenotype of Edaradd mutant mice and to examine the expression pattern of Edaradd in the SMGs.

This work is funded by the NFED and the MRC.


0119 (110797)

Parotid enlargement elicited by soya feeding – mechanism of action. T. ZELLES, G. VARGA, E. SZõKE, E. FEHÉR, and I. BOROS, Semmelweis University, Budapest, Hungary

Objectives: Soya feeding stimulates pancreatic growth. This action is due to the cholecystokinin releasing effect of active trypsin inhibitors in soya bean. Previously we have shown that soya feeding induces marked parotid enlargement in rats as well. The present study was designed to investigate the possibility of the same mechanism in the two exocrine glands.

Methods: Groups of female adult Wistar rats were fed with either standard rat chow or soya bean ad libitum for 7 days. Devazepide, a CCK antagonist (1mg/kg s.c. twice daily), Camostate, a trypsin inhibitor (200 mg/kg, i.g.) or propranolol, a β-adrenerg blocking agent (14mg/100ml drinking water) was used in combination with soya feeding. At the end of the experiments, animals were sacrificed, their pancreata as well as the parotid and submandibular glands were excised. Tissue weight, DNA content and at the propranolol treatment caspase 3/7 activity were determined. Values are given as mean ± S.D.

Results: Soya feeding resulted in increases of both pancreatic and parotid tissue weight and DNA content indicating that this treatment induces hypertrophy as well as hyperplasia in these glands. There was no changes in the submandibular gland. Devazepide blocked the pancreatic effect of soya but it did not inhibit the trophic action of soya feeding on the parotid gland. Camostate treatment increased pancreatic weight and DNA content but did not affect these values in the parotid glands. Propranolol treatment was without effect on pancreatic growth but inhibited parotid enlargement by 60%.

Conclusion: Our results suggest that endogenous CCK release has no determinant effect on the parotid hypertrophy/hyperplasia unlike on the pancreas. β-adrenergic effects play important roles in the parotid enlargement elicited by soya feeding.

Supported by: OTKA T-046511, ETT 247/2003-5


0120 (110812)

Electrophoretic analysis of parotid tissue and saliva of soya-fed rats. E. SZõKE, I. BOROS, and T. ZELLES, Semmelweis University, Budapest, Hungary

Objectives: We previously reported that soya feeding (SF) leads to significant enlargement of the parotid gland, as also occurs in the pancreas; we have now examined changes in salivary protein composition.

Methods: Changes in the protein profiles of the enlarged parotid tissue and saliva produced by the gland were monitored by microchip technique using the Agilent 2100 Bioanalyzer (Germany) and its Protein 230 Kit. Data analyses were performed automatically by 2100 Expert Software of the system.

Results: In addition to the native controls, rats with isoproterenol-induced parotid gland hypertrophia/hyperplasia (IPR) were also included to make further comparisons between the data. Compared to the controls, significant alterations in the parotid tissue proteins of SF animals were detected. However, nearly the same polypeptide patterns were seen when the data of SF and IPR-treated animals were compared. In the SF group the relative amount of the 89.5kDa protein fraction was markedly increased (from 3.0% to 13.9%), while the rate of the 44.6kDa was significatly decreased (from 16.6% to 3.7%). The rate of 53.9kDa protein (amylase) was only slightly decreased (from 43.1% to 38.0%). New major bands at 62.6kDa and 109.1kDa (15.2% and 23.9%) respectively have appeared in the SF samples. In addition, the quantity of proteins at 179.7, 84.7, 63, 19.4, 21.9 and 17.4kDa were decreased below 2% or the detection limit. Changes in protein composition and distribution of parotid saliva were also evident. The rate of 170.4, 85.2, 72.8, 60.1, and 44.6kDa proteins were below 2% or undetectable. The amount of amylase was increased from 22.2% to 38.3%. A new fraction was detected at 62.9kDa (20.5%).

Conclusion:The similarities between marked changes in tissue and saliva protein distribution caused by either SF or IPR treatment strongly suggest a common role of the β-adrenergic mechanisms in these models.

Supported by ETT-247/2003-5, OTKA T-046511


0121 (111813)

Long-term effects of removable denture wearing on salivation. G. SCHMIDEGH, P. KIVOVICS, M. MADLENA, G. NAGY, and K. MARTON, Semmelweis University of Medicine, Budapest, Hungary

Objective: To assess the influence of removable dentures on the palatal, labial and unstimulated whole saliva(UWS) flow rate. A further aim was to assess possible differences between two methods (weighing method and PERIOTRON® method) used to determine the flow rates of the minor salivary glands.

Methods: 29 patients (15 denture-wearers,14 controls) were included (mean age:67.4±4.02; and 66,3±5.2 years, respectively). UWS was collected with the “spitting” method. Patients were asked to refrain from smoking, eating, and drinking for 2 hours prior to the test session. Palatal and labial saliva flow rates were measured separately, by filter paper discs of previously measured weight, placed bilaterally in the region of the maxillary first molars, 15 mm from the edentulous ridge and in the middle of the lower labial mucosa, 15 mm from the vestibular sulcus. Collection was carried out for 30 seconds. Measuring vessels and paper discs were weighed before and after each collection with an electronic scale. Separate saliva samples from the same mucosal sites were determined by the PERIOTRON® method.

Results: Weighing method: removable-denture-wearers: palatal-right side: 2.4±3.3 µl/min/cm2, palatal-left side: 1.0±3.8 µl/min/cm2, labial: 1.4±2.6 µl/min/cm2; controls: palatal-right side: 3.7±5.2 µl/min/cm2, palatal-left side 1.4±2.5 µl/min/cm2, labial: 1.8±3.9 µl/min/cm2; UWS flow rates: 0.32±0.26 ml/min and 0.29±0.24 ml/min respectively. Results of the PERIOTRON® method: denture-wearers: palatal-right side:4.0±4.6µl/min/cm2, palatal-left side:3.5±3.6µl/min/cm2, labial:0.9±0.6 µl/min/cm2; controls: palatal-right side:2.2±3.1µl/min/cm2, palatal left-side:1.8±1.8 µl/min/cm2; labial:1.9±3 µl/min/cm2. None of the results differed significantly by the paired Student's t-test between the two groups or methods.

Conclusions: This study revealed that neither UWS nor the minor salivary gland (palatal/labial) flow rate was significantly influenced by long term removable denture wearing. There was no difference between the weighing method and the PERIOTRON® method employed in the measurement of the minor salivary gland flow rates.


0122 (109488)

Caries Prevalence in Dutch Juveniles Between 1999 and 2005. J. POORTERMAN, ACTA, Amsterdam, Netherlands, and A.A. SCHULLER, TNO, Leiden, Netherlands

In 1985, a new dental insurance scheme for juveniles from 0-18 years, was introduced in the Netherlands. Possible effects were evaluated in six phases between 1987 and 2005. Meanwhile, in 1995, Health Insurance Funds changed the rules for reimbursement for persons of 18 years and older. Objectives: To evaluate possible changes in caries prevalence between 1999 and 2005. Methods: In 2005, juveniles insured by a Health Insurance Fund, aged 5, 11, 17 or 23 years, were invited to participate in a clinical study. Data from a comparable study in 1999, with participants of the same age, was used as a reference. Dental caries experience was registered clinically in all age groups. Bitewing radiographs were not used. Inter observer agreement was determined by duplicate measurement and was found to be satisfactory. Unfortunately, over the years the response rate for participating in such epidemiological studies is gradually dropping. Results: In 2005, the DMFS score for 23-year-olds was significantly lower (10.8 vs 12.8), mainly due to a lower FS component. For the other age groups, the DMFS and DMFT score did not change significantly. The percentage of caries free 17-year-olds increased, but decreased for 5-year-olds. The number of sealed surfaces increased significantly: from 2.4 to 2.9 for the 11-year-olds and from 1.8 to 2.5 for the 23-year-olds. Conclusions: Between 1999 and 2005 the caries prevalence of 23-year-olds decreased, while for the other age groups these scores remained stable. More occlusal surfaces were sealed in 11- and 23-year-olds.


0123 (110054)

Dentists' Estimates of the Longevity of Dental Restorations in Finland. U. PALOTIE, and M.M. VEHKALAHTI, University of Helsinki, Finland

Objectives: To evaluate Finnish dentists' perceptions of the longevity of direct dental restorations, and to assess the possible impact of gender and working sector on these perceptions.

Methods: The sample consisted of 592 general practitioners selected by systematic sampling from the membership list of Finnish Dental Association in spring 2004. The self-administered questionnaire asked dentists: ”In general, what is your estimate for the mean age of restoration in permanent teeth?”, separately for five types of restorations: amalgam Class II and MOD in a posterior tooth, composite Class III in an incisor, and composite Class II and MOD in a posterior tooth. Statistical evaluation was performed by ANOVA.

Results: A total of 328 (55%) dentists responded. The mean of their estimates for all types of composite restorations was 9 years (95%CI 8.6-9.3) and 18.7 years for amalgam (95%CI 18.0-19.5). Mean estimate for composite MOD was 8.6 years and for amalgam MOD 18.3 years. For Class III (composite only), the mean estimate was 10.7 years (95%CI 10.1-11.3). Compared with female dentists, male dentists gave longer estimates for posterior composites (Class II, p=0.04 and MOD, p=0.04), but shorter estimates for amalgams (Class II, p=0.002 and MOD, p<0.001). According to working sector, private dentists gave longer estimates for posterior composites (Class II, p=0.002, and MOD, p=0.001) than did the public dentists. Similar difference appeared among female dentists: the private dentists gave longer estimates than did the public dentists (Class II, p=0.008 and MOD, p=0.01). Among male dentists, this difference was only seen for composite MOD (p=0.04).

Conclusion: Perception of the composite longevity is significantly longer among male and private sector dentists than among female and public sector dentists in Finland.

Grants to UP by the Finnish Dental Society Apollonia and the City of Helsinki Health Centre are gratefully acknowledged.


0124 (110085)

The Distribution of Caries Prevalence and Treatment Needs, Turkey-2004. S. GOKALP, and B. GUCIZ DOGAN, Hacettepe University, Ankara, Turkey

"Objective: To assess the dental caries status and treatment needs of Turkish people in WHO index age groups.", "Methods: A cross-sectional survey using proportional stratified cluster sampling was conducted. The investigation was performed on a total sample of 7833 individuals belonging to urban and rural areas. All subjects were clinically examined by trained 27 examiners according to WHO (1997) guidelines. Khi square test was performed to test the significance of the differences in bivariate analysis.", "Results: More than half of the individuals had caries. Five year old males had more caries and missing teeth while 65-74 year old females had more (p<0.05). Filled teeth prevalence was higher in urban areas among all ages (p<0.05). The situation of teeth was worse in rural areas than urban for all ages. The prevalence of 0 dmft was 29.0% among 5 year olds, 33.9% in 12 years and 30.0% in 15 years. Oppositely, having 7 and more DMFT was 7.1% among 15 year-olds and gradually increased to 70.7% among 35-44 year-olds, reached 96.2% in 65-74 year-olds. In the age groups of 5, 12, 15, 35-44 and 65-74 years, restorative treatment needs were 68.7%, 61.8%, 61.8%, 81.5% and 96.2%, respectively. At age 5, most frequent need was one (35.6%) or multiple surface fillings (37.6%). In the older age groups, the greatest need was for preventive, caries arresting care. Need for dental extraction increased from 10.3% in 5 year-olds to 25.7% in 35-44 year-olds.", "Conclusions: The caries prevalence for all age groups was high. The need for dental treatment was great. Effective oral health promotion strategies were needed to improve oral health in Turkey."

This study was supported by Hacettepe Univ. Research Center and the Ministry of Health.


0125 (110524)

Bibliometric description of dental research literature using various ranking parameters. C. ROBERT1, C.S. WILSON2, S. CHERBI1, J.-F. GAUDY1, and C.-D. ARRETO1, 1Université Paris Descartes, Montrouge, France, 2University of New South Wales, Sydney, Australia

Objectives: This study describes the scientific dental literature using different bibliometric parameters to rank the research performance of countries.

Methods: The 2006 Clinical Medicine and Life Sciences collections of Current Contents (CC) from the Thomson Scientific database identified 4,222 journal papers on dental research which were analyzed using bibliometric measures.

Results: About 60% of the papers (2,570) were from journals indexed in the Dentistry, Oral Surgery and Medicine (CC-Dentistry) discipline; the rest (1,652) were distributed principally among four CC-Life Sciences disciplines: Medical Research, Organs & Systems (283), Multidisciplinary (126), Medical Research, Diagnosis & Treatment (103), and Microbiology (103); and three CC-Clinical Medicine disciplines: General and Internal Medicine (81), Research/Laboratory Medicine & Medical Technique (79), and Radiology, Nuclear Medicine & Medical Technique (60). Among the top-20 most productive countries in dental research, only France and Japan published more in other medical and experimental fields of research (69% for France, and 56% for Japan) than in CC-Dentistry. For numbers of publications, the ranking of the top-20 countries in dental research differed from the overall country-ranking in all biomedical research. Brazil, Turkey and the Nordic countries were ranked higher in dental research while China, Italy, France, Spain and South Korea ranked higher in all biomedical research; however, three countries (USA, Japan, and the UK) were consistently the top-three in both rankings. Although the 20 top-ranking countries for CC-Dentistry (2,570 papers) were globally similar to those for all dental research papers (4,222), rankings by the journal impact factor, a measure of the impact of research in a discipline, gave quite different country rankings.

Conclusion: This study highlights the importance of bibliometric parameters chosen when describing the field of dental research. The results of the rankings from various parameters would be useful for researchers in providing journal lists for reading, citing and publishing.


0126 (110546)

Changing experiences of dental care among Polish schoolchildren. M. GANOWICZ1, F. SZATKO2, I. STRUZYCKA1, E. IWANICKA-GRZEGOREK1, and M. WIERZBICKA1, 1Medical University of Warsaw, Poland, 2Medical University of Lodz, Poland

Objective: To investigate children’s experiences of dental care. Methods: A survey was undertaken to investigate experiences of dental care among Polish schoolchildren. Stratified random sampling was used to identify 2275 12-year-olds from 7 regions of Poland. Children completed a questionnaire investigating their experiences of dental care. Results were compared with data obtained in 1999 and 2003. Results: Over 33% of children responding in 2007 had experienced pulpal pain during the past year, while 20% had observed a new cavity and 32% had experienced dental pain during eating. The proportion of children who had visited a dentist within the last 6 months decreased from 60.8% in 1999 to 56.7% in 2007, while the proportion that had been within the past year fell from 83.5% to 77.8% during this period. The proportion of children who had attended a school dental office fell dramatically from 30.6% in 1999 to 12.2% in 2003, remaining at this level in 2007. The proportion who had attended a regional public dental office also decreased substantially from 28.2% in 1999 to 16.8% in 2007, while the proportion who had sought private dental treatment increased from 33.0% to 44.7% during this period. The proportion of children declaring that they had their own permanent dentist increased during this time by over 15%. A relatively low proportion of children had received oral health education from their dentist; this figure fell from 34.1% (1999) to 28.5% (2007) for children receiving instruction in tooth brushing, and from 19.8% to 16.0% for children receiving dietary advice. However, an increasing proportion received instruction in flossing (increase from 8.6% to 12.8%) and advice as to which toothpaste to use (increase from 17.5% to 21.2%). Conclusion: An important issue which needs addressing is the decreasing access to affordable dental care for children within the public sector.


0127 (110548)

Trends in dental caries among Polish schoolchildren. I. STRUZYCKA, M. GANOWICZ, E. DYBIżBAńSKA, M. ZAWADZIńSKI, and M. WIERZBICKA, Medical University of Warsaw, Poland

Objectives: To investigate trends in dental caries over a 12-year period. Methods: An epidemiological study was carried out in 2007 to investigate oral health among Polish 12-year-olds. 2275 children from 7 regions of the country were selected by stratified random sampling, and underwent an oral examination by trained dental epidemiologists. Additionally, children were asked about participation in school-based programmes of fluoride prophylaxis. Results were compared with earlier data from 1995, 2000 and 2005 to determine trends in oral health. Results: During the period 1995-2007, a gradual decline was observed in both prevalence of dental caries (from 90.5% of children in 1995 to 80.7% in 2007), and in its severity (from mean DMFT=4.3 to mean DMFT=3.07). The decline in caries prevalence was most noticable in rural areas, where the percentage of children free of caries more than doubled. Changes were also seen in DMFT components, with DT decreasing by more than half from 2.7 in 1995 to 1.15 in 2007, and MT decreasing by nearly half (0.1 in 1995; 0.06 in 2007), while FT increased moderately from 1.5 in 1995 to 1.87 in 2007. The proportion of children with MT1 nearly halved from 7.5% in 1995 to 3.9% in 2007. Marked regional variation was observed in oral health improvement, particularly with regard to the decrease in the proportion of children with severe caries (DMFT4) and the increase in the treatment index. Overall, regional variation had a greater effect on oral health than did gender or localization (urban/rural). Moreover, access to school-based fluoride prophylaxis was not significantly associated with an improvement in oral health. Conclusion: Despite a gradual decline since 1995, dental caries is still a significant problem in Polish schoolchildren. Results do not confirm efficacy of currently functioning programmes of fluoride prophylaxis.


0128 (110761)

A National Biobank of Human Primary Teeth in Norway. H.M. TVINNEREIM1, R. EIDE1, G.B. LYGRE2, K. KLOCK1, K. HAUG1, and P. SCHREUDER3, 1University of Bergen, Norway, 2University of Bergen/UNIFOB AS, Norway, 3The Norwegian Institute of Public Health, Bergen, Norway

Introduction: Primary teeth can be used as biomarkers of environmental exposures. The Norwegian Mother and Child Cohort Study (MoBa) is a national study comprising 100 000 pregnancies. Mother, father and child are included and there is no limitation for follow-up. Data is collected using questionnaires and biological samples. Specific aetiological hypotheses may be tested by estimating the association between exposure and disease.

Objectives: To increase the scientific value of the MoBa Study by including a biobank of exfoliated primary teeth (MoBaTann).

Methods: The project is a co-operation between the University of Bergen and the Norwegian Institute of Public Health, running the MoBa Study. The project is approved by all relevant Authorities. Invitations to donate teeth will be sent to all participating mothers during 2008 - 15, when the child is about seven years (Table 1).

 

Year

2008

2009

2010

2011

2012

2013

2014

2015

Children (n)

6171

8438

12299

13382

15417

17336

16500

16500

 

The invitation contains information about the biobank and an informed consent form to be signed by the parent and returned with the tooth/teeth. The teeth are stored in the biobank with the same identification code as the data in the MoBa database.

Perspectives and Results: We mailed the first 80 invitations in February 2008, and 46 teeth were received by March 31. The database includes all results and is available for other researchers. Relevant projects may apply for analyses of subgroups of teeth. Primary teeth are well suited for documenting long-term exposure. With modern methods pin-pointing approximate times of exposure is possible, by taking samples across the growth lines. Information from the biobank can thus supplement the information within MoBa.

Conclusion: Results from MoBaTann combined with information from the MoBa Study will give invaluable information about the association between exposure and disease.

 


0129 (110891)

Caries Prevalence and Oral Health Awareness Among Pregnant Women. E. MALKIEWICZ, College of Finances and Management in Siedlce, Poland, and K. MALKIEWICZ, Medical University of Warsaw, Warszawa, Poland

Objectives:

The aim of the study was to investigate the level of caries frequency and the health awareness among young mothers and pregnant women living in both urban and rural area in the central part of Poland.

Material and methods:

The study was performed on 160 women aged 15-44 years, from six randomly chosen antenatal classes at the Siedlce (urban) and Przysucha (rural) regions situated in the Mazowieckie province.

The dental examination was performed in the health centers according to WHO standards. Data was recorded on clinical cards and the results were subjected to statistical analysis.

Results:

Analysis of the results showed that the mean DMFT value was 13,71 among women living in the city and 12,70 among these living at rural areas. The 74,7% of investigated women living in the city declared attending dental office during last year comparing to 68,8% investigated inhabitants of villages.

Conclusion:

In the light of the results presented, it is evident that preventive and promotional measures are necessary to improve the oral health status of young mothers. This confirms the need to pay greater attention to oral health care in this social group.


0130 (110900)

Consumption of sugary snacks among the dentate adults in Finland. M.M. VEHKALAHTI1, A.L. SUOMINEN-TAIPALE2, and B. TSEVEENJAV1, 1University of Helsinki, Finland, 2National Public Health Institute (KTL), Helsinki, Finland

Objectives: To investigate consumption of sugary snacks among the dentate Finnish population aged 30-64.

Methods: The present study is part of a nationwide comprehensive Health 2000 Survey. The sample size was 8028; 79% participated in the clinical oral health examination. The present study included dentate subjects aged 30-64 who responded the questions on the frequency of the consumption of sugary snacks (n=4505). The questions inquired how often the respondent usually consumed coffee or tea with sugar, other sweet beverages, chocolate or filled biscuits, toffee or liquorice or dried fruit, and lozenges or chewing gum (without xylitol). The five response options (with their later given frequency scores in parentheses) were: 3+ times a day (3.5), 1-2 times a day (1.5), 2-5 times a week (0.7), less often (0.3) and never (0). The sum of these scores indicated the frequency of a subject's overall consumption of sugary snacks. According to its distribution, this frequency score (theoretical range, 0-21) was categorized into very low (0-2), low (3-4), moderate (5-6), and high (7+) consumption categories. Subject's age and gender served as background information. Statistical evaluation was by chi-square test.

Results: Frequency of the consumption of sugary snacks was very low for 40%, low for 31%, moderate for 21%, and high for 8% of all. Of women, 49%, and of men, 29%, belonged to the very low consumption category (p<0.001), the corresponding percentages for belonging to the high consumption category were 5% and 12%, respectively. Differences between the age groups were obvious: the younger the subjects the fewer belonged to the very low consumption category (p<0.001). Of men, 21% of those aged 30-34 belonged to the high category.

Conclusion: Oral health education should be targeted to the younger men, in particular.

Grants and details of the Health 2000 Survey at: http:\\www.ktl.fi/health2000


0131 (110922)

Tap Water: Impact on Fluoride Intake and Excretion in Gaza. L.M.A. ABU-HALOOB, A. MAGUIRE, and P. MOYNIHAN, Newcastle University, Newcastle upon Tyne, United Kingdom

Background: There is a high prevalence of dental fluorosis in Gaza Strip (GS). This study hypothesised that fluoride (F) concentration in home tap water significantly impacts on Total Fluoride Intake (TFI).

Objectives: to compare TFI of 4-year-old children exposed to low, moderate or high F in tap water (<0.7, 0.7-1.2, >1.2 ppm F respectively) in GS; to compare the relative contribution of different sources of F to TFI; to investigate the relationship between TFI and 24-hour urinary F.

Methods: Dietary information (3 day food diary), tap water and a 24-hour urine samples were collected from 216 children with low (n=81), moderate (n=72) and high (n=63) F in tap water. Statistical analyses used ANOVA, Tukey's test and Pearson's Correlation.

Results: Mean (±SD) F concentrations in tap water in low, moderate and high F groups were 0.21(±0.15), 0.91(±0.13) and 1.71(±0.35) ppm F respectively. Mean TFI was 0.02, 0.04 and 0.05 mg F/kg body-weight/day for the three groups respectively (P<0.0001). Food made the largest contribution to TFI (63.8%), other beverages (22%), drinking water (13.5%) and toothpaste (0.7%). Although urinary F differed between groups, only a weak positive correlation existed between TFI and 24-hour urinary F (r2= 0.28, P<0.0001), suggesting that 24-hour urinary F is not a strong indicator of TFI. TFI was similar to recommended levels for young children. The relatively low TFI of moderate and high F groups may be explained by a trend towards drinking filtered water. However, as home tap water is used to prepare foods, food was the primary source of F. Conclusion: Home tap water significantly impacts on TFI but TFI values in this study suggest the children are not at risk of fluorosis. If fluorosis in GS persists food preparation using filtered water should be advised.

Funded by: ORSAS and Newcastle University.


0132 (110975)

Analysis of Saliva and Caries Susceptibility in Sportsmen. M. BARRANQUERO, A. GARCIA, J. GOIRIENA, and M. VITORIA, University of the Basque Country, Leioa, Spain

Objectives: To assess the oral health in sportsmen and the prevalence of microorganisms associated with caries risk.

Methods: Sample of 340 young people between 14-16 years, 170 sportsmen and 170 sedentary. Epidemiological survey: hygienic habits, brushing, dental floss, mouthwash, sweets, tobacco, alcohol, care mouth reasons, etc.° Determination rates of S.mutans, Lactobacillus, buffer capacity at the beginning of the study and 12 months later and determination of new decay to be related to the rate of cariogenic microorganisms.

Results: The general parameters are similar in both groups. Sportsmen without brushing 5.8% and 6.5% sedentary. 70.6% men do not use dental floss and 54.4% women. 33% males do not eat sweets and 30.9% women. Reasons care mouth, male: 25.6% clean mouth, aesthetics 25.1%, 24.1% avoid pain, keep teeth 14.1%,female: 45.6% clean mouth, aesthetics 31.5%, avoid pain 11 , 4%, keep teeth 10.2%. Sports: S. mutans 10.2x106/mL, Lactobacillus 0.1x105/mL, non sports: S. mutans10.6x106/mL,Lactobacillus 0.1x105/mL. After 12 months the relation between new caries and level of microorganism was 0 caries: S. mutans 6,6x106, Lactobacillus 0,1x106. <2 caries : S. mutans 10,4x106, Lactobacillus 0,1x106. ≥2 caries: S. mutans 19,5x106, Lactobacillus 5,3x105. The relation between new caries and levels of S.mutans. Lactobacillus was statistically significant in booth groups. (p>0,05). Caries non sport/sport O.R. 1.15 (95% CI=0,72-1,83). Caries non sport >2 caries O.R. 1.47 (95% CI =0,78-2,77)

Discussion: There are low levels of use of dental floss and high consumption of sweets. Aesthetic component stands out in women and in males to avoid the pain. There are statistically significant relationship between sedentary and decay rates and high rates of S. mutans and new decay.

Conclusion: There are statistically significant association between sedentary and decay and high levels of S. mutans and new decay.


0133 (111040)

Internet access and adolescent dental neglect in a deprived environment. G. SARRI1, S. STANSFELD2, G. TSAKOS3, and W. MARCENES1, 1Institute of Dentistry, Barts and The London School of Medicine and Dentistry, United Kingdom, 2Barts and the London, Queen Mary's School of Medicine & Dentistry, United Kingdom, 3University College London, United Kingdom

Aim: To assess the role of internet access as protective factor for dental neglect among adolescents in a deprived environment.

Methods: This cross-sectional Research with East London Adolescents; Community Health Survey (RELACHS) collected data in 2005 in a representative sample of 15-16 years old schoolchildren. This is a longitudinal secondary school based epidemiological study that followed up pupils aged 11-12 years in 2001 and 13-14 years in 2003. Data collection included dental clinical examinations and answers to questionnaires completed individually by pupils in a classroom setting. Dental clinical examinations were conducted by two calibrated dentists following WHO criteria (1997). Experience of dental neglect was assessed by presence of at least one untreated dental condition (untreated dental caries, missing teeth due to caries, untreated traumatic dental injuries) and/ or experience of dental pain. Explanatory variables were gender, ethnicity, refugee's status, age of coming in UK, eligibility status for free school meals, house and car ownership and internet access. Data analysis included simple and multivariable logistic regressions.

Results: 975 out of 1451 adolescents (67.2%) participated in the study. This analysis was restricted to 397 adolescents with dental conditions in 2005. The prevalence of dental neglect was 45.1%. Adolescents without internet access at home were 1.7 (1.03, 2.62) times more likely to experience dental neglect compared to their counterparts with internet access, after adjusting for car ownership and age of coming in UK. Adolescents coming in UK at the age of 5 years old or younger were less likely to experience dental neglect compared to adolescents who lived all their lives in UK (P=0.015), adjusted by car ownership. No other explanatory variable was associated to dental neglect in the univariate analysis.

Conclusions: Internet access was a protective factor for adolescent dental neglect, after controlling for socioeconomic differences and age of coming in UK.


0134 (111047)

Lifestyle and Oral Health in Pregnant Women. M.ª.T. DEL HIERRO, M. BARRANQUERO, R. MANZANARO, M. LOPEZ VALVERDE, and J. GOIRIENA, The University of the Basque Country, Leioa, Spain

Objectives: To assess the habits of pregnant women in relation with oral health.

Methods: A random sample of 170 pregnant women is taken to carry out an epidemiologic questionnaire: tobacco consumption, alcohol drinking, sweets, hygienic habits, sanitary attention, knowledge about health, drugs, visit to the dentist, etc… alterations such as: dry mouth, halitosis, caries exploration, periodontal pathology, etc…

Results: Tobacco consumption before pregnancy >10 cigarettes 45,9%, during pregnancy 5,3%, O.R. consumers >10 cigarettes before pregnancy–pregnancy 11,93 (95% CI=5,71-24,95). The 52,4% thinks that tobacco does not damage her oral health. Alcohol consumption before pregnancy 29,4%, during pregnancy 11,2%. O.R. consumers alcohol before pregnancy-pregnancy 5,17 (95% CI=2,93-9,12). The 48,2 % thinks that alcohol does not damage her oral health. 92,9 % believes that alcohol harms pregnancy. Sweets consumption: 15,3 % does not consume, 29,4 % consumes >6 times per week. Absence of tooth brushing 7,1%, visit to dentist last year 28,2%, reason: revision 25,3%, filling 24,7%, profilaxis 22,4%. Bleeding during brushing before pregnancy: 61,7%, during pregnancy: 72%. O.R. 1,67 (95% CI=1,06-2,64). Halitosis always 32,9%. Dry Mouth always, O.R. 1,47 (95% CI=0,87-2,47). Exploration: upper crowding 5,3%, lower crowding 8,8%, upper/lower 12,9%. Plaque index 1,74 ± 1,01 in 5º sextant. Gingival index varies from 1,41 ± 0,80 in 5º sextant to 1,22 ± 0,83 in 2º sextant. Epulis 1,2%. O.R. gingivitis 1,30 (95% CI=0,85-2,01).

Discussion: Decrease of toxic habits in pregnancy, low frequency dentist visits, near 50% prophylaxis and review. Prevalence of periodontal health goes down. O.R. positive between pregnancy- bleeding gums, dry mouth, gingivitis, in spite of the decrease of tobacco consumption.

Conclusions: Decrease of negative lifestyles in pregnancy, positive association with dry mouth, bleeding and gingivitis.


0135 (111091)

Perceptions of school life and adolescent dental caries experience. P. EVANS1, G. SARRI1, W. MARCENES1, and S. STANSFELD2, 1Institute of Dentistry, Barts and The London School of Medicine and Dentistry, United Kingdom, 2Wolfson Institute of Preventive Medicine, Barts and the London Queen Mary's School of Medicine and Dentistry

Objectives: To assess the role of adolescents' perceptions of school life on dental caries experience.

Method: This cross-sectional Research with East London Adolescents; Community Health Survey (RELACHS) collected data in 2005 in a representative sample of 15-16 years old schoolchildren. This is a longitudinal secondary school based epidemiological study that followed up pupils aged 11-12 years in 2001 and 13-14 years in 2003. Data collection included dental clinical examinations and answers to questionnaires completed individually by pupils in a classroom setting. Dental clinical examinations were conducted by two trained dentists following WHO criteria (1997). The outcome of interest was presence of second molar caries experience. Data analysis included multivariable logistic regressions.

Results: 975 out of 1451 adolescents (67.2%) participated in the study. This analysis was restricted to 864 adolescents with complete clinical data. Prevalence of caries experience in the second molar was 18.8%. Results of univariate analysis showed adolescents who reported not liking school at all were 2.07(95%CI 1.12, 3.8, p=0.02) times more likely to experience caries in second molars compared to adolescents who reported liking school a lot. This result was of marginal significance (p=0.06) after adjusting for ethnicity. Results of multivariable analysis confirmed that being male (OR=0.61,95%CI 0.42;0.89), having only mothers employed (OR=0.32,95%CI 0.15;0.67), and being Asian (OR=0.31,95%CI0.15;0.64), Black Caribbean (OR=0.32,95%CI 0.16;0.65), and African (OR=0.16,95%CI0.04;0.63), were protective of second molars caries experience. Borough of residence, refugee status, free school meal eligibility, house and car ownership, teacher and student support, school connectedness and perception of teacher's opinion were not significantly related to second molar caries experience (p>0.05).

Conclusion: Enjoyment of school seems to be significantly correlated to caries experience. Further data analysis should assess the interaction between ethnicity and enjoyment of school.


0136 (111097)

The role of socioeconomic position in ethnic differences in health. W. SABBAH1, G. TSAKOS2, A. SHEIHAM2, and R. WATT2, 1UCL, London, United Kingdom, 2University College London, United Kingdom

Socioeconomic position was suggested to have a role in ethnic differences in general health. However, this role has not been adequately addressed in relation to oral health.

Objectives:

(1) To examine the role of education and income in ethnic differences in subjective and clinical oral health. (2) To compare the role of socioeconomic position in ethnic differences in oral health to its respective role in general health.

Methods:

Data were obtained from the Third National Health and Nutrition Examination Survey (USA, 1988-1994). Oral health was indicated by perceived oral health, moderate periodontitis, gingival bleeding and tooth loss. General health was indicated by perceived general health and ischaemic heart disease. For each health outcome, regression models adjusting for ethnicity (White, African, Hispanic Americans and other ethnicities), sex, age, smoking, and medical/ dental insurance, were compared to models additionally adjusting for education and income. The contribution of socioeconomic position to ethnic differences in health was assessed by calculating the percentage reduction in the odds ratios for each ethnic group before and after adjusting for education and income.

Results:

The probabilities of poorer general and oral health were higher among ethnic minorities compared to White Americans. For African Americans, adjusting for income and education resulted in a risk reduction for ischaemic heart disease (90%), poorer perceived general health (52%), poorer perceived oral health (43%), gingival bleeding (60%), tooth loss (30%) and periodontitis (30%). Similar risk reductions were observed among Hispanic Americans.

Conclusion:

Education and income play an important and similar role in ethnic differences in both oral and general health. Despite the major impact of socioeconomic position, the results imply that there are additional causes of ethnic differences in oral and general health.


0137 (111126)

Family life is associated with current toothache in adolescents. A. PAU1, G. SARRI1, S. STANSFELD2, and W. MARCENES1, 1Institute of Dentistry, Barts and The London School of Medicine and Dentistry, United Kingdom, 2Wolfson Institute of Preventive Medicine, Barts and the London Queen Mary's School of Medicine and Dentistry

Objectives: To assess the role of family structure and adolescents' relationships with their parents in adolescents' toothache experience

Methods: Data were collected through the Research with East London Adolescents: Community Health Survey (RELACHS) in 2005 from a representative sample of 15-16 year-old schoolchildren. This is a longitudinal secondary school based epidemiological study that followed schoolchildren aged 11-12 years in 2001 and 13-14 years in 2003. Data collection included dental clinical examinations and answers to questionnaires completed individually by pupils in a classroom setting. Dental clinical examinations were conducted by two trained dentists following WHO criteria (1997). Questionnaire data were collected on current toothache experience as the outcome variable, and gender, ethnicity, refugee's status, years lived in the UK, eligibility status for free school meals, house and car ownership, family structure and adolescent/parent relationships as explanatory variables. Simple and multivariable logistic regression analyses were performed.

Results: 975 out of 1451 adolescents (67.2%) participated in the study, of whom 964 responded to the question on toothache. The prevalence of current toothache was 7.3%. Adjusted odds ratios for those more likely to report current toothache were 2.76 (95% CI 1.12-6.79, p=0.027) for those living in reconstituted families, 2.56 (95% CI 1.39-4.72, p=0.003) for those who indicated that their mothers or female carers had low understanding of their problems or worries, and 1.82 (95% CI 1.09-3.03, p=0.024) for those who indicated that their mothers or female carers were more harsh with their punishment.

Conclusions: Family structure and adolescents' relationships with mothers' or female carers were statistically significantly associated with current toothache experience in school-going adolescents in inner East London.


0138 (111338)

Oral Health Status of Employees of Mashhad Dental School(Iran). M. MEHRABKHANI, B. AJAMI, and S. GHORBANZADEH, Mashhad University of Medical Science,Faculty of Dentistry, Iran

Objectives:

The aim of this study was to assess the oral health situation of the employees of Mashhad dental school in Iran.

Methods:

A total 156 individuals were clinically examined according to the WHO basic criteria's. DMFT index and Dental treatment Needs index (based on WHO Criteria's) used for dental status and PDI index used for periodontal health status. A questionnaire (investigating demographic and oral health behavior data) was filled. Findings analyzed using Chi - Square, kruscal-wallis and Mann - Whitney tests .

Results:

The mean DMFT value was 10.4 ± 5.2 that the filling (F)component was the highest within the DMFT. The rate of caries free patients was 2.5% (males 1.2%, females 4.1%)

Dental treatment needs in this survey was 79.9% (males 85% , females 73%) , the most common treatment need was restorative treatment.

The mean PDI scores was 1.81 ± 1.26 and it was shown that 24/9% of individuals had healthy periodontia , and 56.75% had gingivitis and 18.13% had periodontitis

Conclusion:

Our result confirm a high caries prevalence and also a need for treatment. Also , results of oral health behaviors was not statisfactory . So an effective oral health promotion progamme in this population should be provided .


0139 (111364)

Self-assessed dental treatment need among insured adults in Tehran, Iran. F. BAYAT, M. VEHKALAHTI, and H. TALA, University of Helsinki, Finland

Objectives: To evaluate factors related to self-assessed need of dental treatment (NDT) among dentate adults having insurance, based on subsidized dental services.

Methods: Four trained interviewers collected cross-sectional data by phone. Of 1531 subjects answering the phone call, 224 were too young (<18 years), 221 refused to participate, 327 had no insurance, and 15 were edentate and were excluded, leaving 744 subjects. Of the subjects, 59% were women, and 61% were under 35 years (range 18-75, mean=32.6). The question about NDT offered four options, later dichotomized as High (very high-high) or Low (low-no need). The interview also covered respondents' self-reported oral health (excellent-very good, reasonable, poor-very poor), frequency of tooth brushing (twice a day, less than twice a day) and numbers of filled and extracted teeth. Age, gender and level of education served as background information. Data analysis included the Chi-square test and logistic regression.

Results: Of the subjects, 41% assessed their NDT as high with no gender difference. In the youngest age group (18-24 yr), 28% reported high NDT (25% of men, 31% of women) for all other age groups the figures were clearly higher (41%-51%). A high NDT dominated among those who assessed their oral health as poor (p<0.001), had a low level of education (p=0.01) or reported having one or more fillings or three or more extracted teeth (p<0.001). According to the logistic regression model, those who assessed their oral health as poor (OR=2.6) or reported having more than three extractions (OR=2.3) were more likely to assess their NDT as high. In the model, age, gender, level of education and frequency of brushing showed no impact on the assessments of NDT.

Conclusion: Among insured adults, self-assessment of NDT and oral health correlated directly, despite their background information.


0140 (111409)

Trends in Prevalence of Traumatic Dental Injuries in Newham, London. W. MARCENES, and S. MURRAY, Barts and the London School of Medicine and Dentistry, United Kingdom

Objective: This study aimed to assess the prevalence of Traumatic Dental Injuries (TDI) in 14-year-old schoolchildren in Newham in 2002-03, to compare the results with data from 1995-96 and 1998-99, and confirm correlates of TDI. Methods: A cross-sectional survey design was adopted. The same protocol was used, and one dentist (SM) carried out all dental examinations using the same criteria for identification of TDI in all three surveys. Only upper and lower permanent incisors were examined for signs of TDI. The examiner recorded the type of damage sustained, any treatment carried out and the treatment need. Results: 609 out of 861 14-year-old schoolchildren in Newham in 2002-03 participated in the study (Response rate 70.7%). The prevalence of TDI was 26.9% in 2002-03, compared to 23.7% in 1995-96 and 43.8% in 1998-99. Boys (30%) sustained more TDI than girls (23.9%), but the difference was not statistically significantly (P=0.086). Ethnicity and socio-economic position measured by eligibility to free school meals were not related to TDI (P>0.05). Biological predisposing factors such as overjet larger than 5 mm (P<0.001) and inadequate lip coverage (P=0.007). Conclusions: Similarly to the national data in the UK there was not a clear trend in the prevalence of TDI in Newham, and the prevalence remained higher than the overall prevalence in the UK, 26.9% compared to 13%.


0141 (111418)

Oral Health KAP of Students in a Primary School, Turkey. B. GUCIZ DOGAN, and S. GOKALP, Hacettepe University, Ankara, Turkey

Objective: To determine the oral health related knowledge, attitudes and practices (KAP) of 5th-8th grade Turkish students in a primary school.

Methods: In this descriptive study, the data was gathered in a primary school in Ankara via a self-administered questionnaire. It was aimed to reach all of the students of 5th-8th grade; 227 students out of 234 were covered. Khi square test was performed to test the significance of the differences in bivariate analysis.

Results: Half of the students were male and the distribution to grades was similar. They were between the ages of 10 to 16, mean age was 12.7±1.2. One-fourth of fathers had lycée or higher education while 10.5% of mothers. Among the students, 8.4% had tried smoking and 3.5% drinking alcohol once, and 0.4% was current smoker. Of the students, 77.5% had ever visited a dentist; the age at first visit was between 3 and 14. Only 12.5% of them visit the dentist regularly. Ninety-six point five percent had toothbrush; 43.1% of them was brushing their teeth at least twice a day (no significance by sex and grade), 99.5% use toothpaste. Among the students, 46.3% considered their dental health moderate, 38.8% good. Only 44.9% was happy with the appearance of their teeth. They stated that the healthiness of teeth is important for general health (90.3%), and regular visit to dentist (82.4%) and regular brushing could protect dental problems (88.1%), caries ruin the appearance (86.8%), and eating sweet foods produces caries (88.5%). Of the students, 48.9% had no idea whether the toothpastes consisted of caries protecting substance; however, girls had significantly more knowledge (p<0.05).

Conclusions: Although 5th-8th grade students have rather good knowledge, the oral health practices are not good. Effective intervention oral health strategies are needed to improve oral health among students in Turkey.


0142 (111498)

Oral Epidemiology in General Dental Practice. G.V.A. TOPPING, University of Dundee, Scotland, Uk, and N. PITTS, University of Dundee, United Kingdom

Objectives: To assess in General Dental Practice: time taken, ease and attitudes towards recording 4 clinical measures after an e-learning based training and standardisation exercise.

Methods: A convenience sample of 7 GDPs were trained to record: caries (D1 threshold), periodontal disease (CPI/Loss of attachment); fluorosis (Dean's index) and oral premalignancies (WHO) using an interactive e-learning package. Each dentist was asked to complete standard forms provided by the European Global Oral Health Indicators Development for 10 patients; to record the time taken for each measure and complete a form after each patient to evaluate ease of: following clinical instructions, applying codes and charting. These were assessed on a 7-point Likert scale with low scores indicating greater ease.

Results: All 7 GDPs returned completed forms, this ranged from 2-10 patients per dentist, 46 patients were assessed. For each measure the following is shown in the table below: time taken (mins); ease of following clinical instructions, applying the codes and completing a chart.

Measure N Time Instr Codes Chart

Caries 35 11.2(6.3) 2.5 (2.1) 4.6 (1.8) 3.9 (2.1)

Fluor 7 0.9 (0.6) 1.1 (0.3) 1.3 (0.7) 1.0 (0)

Perio 24 4.8 (4.6) 1.4 (0.7) 1.6 (1.0) 2.3 (1.8)

Cancer 33 0.8 (0.6) 1.2 (0.6) 1.3 (0.8) 1.2 (0.7)

The GDPs reported that the charting of caries and periodontal disease was “time consuming” and “tedious”.

Conclusion: Barriers to recording oral epidemiological information in the GDS included the time taken to chart caries and periodontal disease in particular.


0143 (111786)

Socioeconomic status and tooth loss in working age adults. T. MUNDT1, I. POLZER1, S.A. SAMIETZ2, T. KOCHER2, R. BIFFAR1, and C. SCHWAHN2, 1Greifswald University, Germany, 2University of Greifswald, Germany

Objectives: It has been reported that tooth loss is more frequent among persons of low socioeconomic status (SES) than among people of higher SES. The aims of this study were to investigate (1) the individual impact of each key SES indicator (i.e., income, education, and occupation) on incident tooth loss in working aged people and (2) the role of gender in this association.

Methods: Between 1997 and 2001 4,310 residents aged 20-81 years, participated in a representative baseline examination in West Pomerania, Germany. Out of those 3,300 persons were available for the follow-up between 2002 and 2006. For this study 1,971 dentate participants (1,062 women, 909 men) aged between 25-59 years at baseline were selected. The relative rate (RR) and its 95% confidence interval (CI) were calculated for each SES indicator (education, occupational prestige, income) by negative binomial regression analyses with Stata/SE software. The models were gender-stratified and adjusted for age, marital status, and the other two SES variables.

Results: The tooth loss for men was higher than for women (RR=1.25; 95%CI=1.03-1.51). Occupational prestige showed no association with tooth loss, whereas low educational level and low household income were determinants of incident tooth loss in both women (RR= 1.67 and 1.69, 95%CI= 1.03-2.72 and 1.15-2.47, respectively) and men (RR= 1.94 and 1.64, 95%CI= 1.15-3.30 and 1.12-2.40, respectively).

Conclusion: The higher tooth loss rate in men could be explained by the poorer health behaviour compared with women. The effect magnitude of the SES indicators did only show slight gender-differences. Strategies to prevent tooth loss should aim to enhance school education and paid employments in order to support an entire population shift in terms of improved health behaviour.


0144 (109528)

Physicians' knowledge about the association between Diabetes and Oral health. R.A. AL HABASHNEH, Jordan University of Science and Technology, Irbid, Jordan, and H. ALWAELI, JUST, Irbid, Jordan

Back ground: The interaction between oral and systemic health has long been of interest.

Objectives: The study was designed to assess the views and knowledge of health care providers in general medicine and other specialties on the association between diabetes and oral health.

Materials and Methods: Cross-sectional data were collected from 400 physicians practicing in northern Jordan using

a structured questionnaire. Chi-squared test and regression analyses will be carried out for revealing factors influencing the awareness, perception, and knowledge regarding diabetes and oral health.

Results: from the preliminary result we got so far the overall response rate expected to be around 70%. Less than half of the respondents had heard about the possible association between diabetes and oral health. The majority of the physicians agreed that Diabetes increase the tendency to have gingival inflammation. However, few advised their diabetic patients to consult their dentist when complaining about oral changes. Only about a third agreed that getting oral health under control might help in controlling diabetes level. Factors may be significantly associated with reporting positive association between diabetes and oral health will be:(1) Specialty level; (2) years of practice; (3) being female; and (4) rating of oral health as good. Television and internet were the main source of knowledge with the rate of 50%. Physicians do not routinely advise their diabetic patient to seek dental care. General practitioners were less informed about oral health practices among diabetic patient. Issues on training need to be addressed. A public health campaign is required to educate health care providers to encourage diabetic patients on the need for a regular dental check ups.

Conclusion: There is probably limited knowledge of the possible relationships between oral health and diabetes. Therefore, there is a need to educate health-care personnel further about oral health and diabetes


0145 (110614)

Problem Cases for PBL in Dentistry: An Example of Pedodontics. S. ATAMER-SIMSEK, Marmara University, Istanbul, Turkey, and Y. GUVEN, University of Istanbul, Turkey

Objectives:Interactive teaching methods are more beneficial to student learning in medical and dental education than traditional methods, preventing passive learning and memorization by students.In this study it was aimed to assess the advantages of this teaching method.

Methods: Simulated case examples were created to present real life dental cases to students using this method. Psychodrama a simulation technique was used for simulation of these cases. By this purpose students randomly grouped to simulate these problem cases. Than each student had a chance to dramatize of these cases. And also each student took place as an audience in during sessions.They worked on their roles and played the role the clinician and the patient. One of the simulated case represents “Delayed Tooth Eruption Due to Parasitic Infection” as an example of a multidisciplinary approach to the patient in dentistry. This case was discussed, along with requested laboratory tests, their interpretations and the benefits of consultation during diagnosis.

Results:It is found that this method increased both the success ratio (from 64.0 to % 92.27 P 0.001) of the sudents and borrowing books from library during preparation of case-plays (from % 5 to% 62).PBL students rated this method at a mean 4.68 on a Likert-type scale of 1 (not helpful) to 5(outstanding).

Conclusions: It is concluded that this teaching method provides for the development of a competency-based programme which increases the reflection of their knowledge in the behavioral attitudes of the students. This method both increased reading needs and also facilitated learning.

A multidisciplinary approach to the dental patient is essential in solution of both oral and dental problems as well as systemic conditions. The creation of additional case examples for this technique is continuing in order to encourage more discussion of the medical and dental aspects of medically compromised patients in our faculties.


0146 (109585)

Changes in Health Complaints after Removal of Dental Amalgam Restorations. T.T. SJURSEN1, L. BJÖRKMAN2, K. DALEN1, G.B. LYGRE2, and V. HELLAND2, 1University of Bergen, Norway, 2University of Bergen/UNIFOB AS, Norway

There is some concern in the public that mercury leaking from dental amalgam may cause ill health. Objectives: The aim of this study was to investigate changes in health complaints after removal of dental amalgam restorations in patients referred with adverse reactions allegedly related to dental amalgam. Methods: Forty patients previously examined at the Norwegian Dental Biomaterials Adverse Reaction Unit, were included and randomized into a treatment group (n = 20) and a reference group (n = 20). No causal relationship was established between participants' complaints and dental amalgam at the initial examination. The treatment group had all their dental amalgam restorations replaced with other restorative materials. Results from follow-up at 12 months after removal are presented here. There was no intervention in the reference group. Health complaints were measured by visual analogue scales (VAS) in both groups. Index scores for intraoral, orofacial and general health complaints were calculated and given as mean per cent of maximum possible value for the respective indices. Paired t-tests were used to test changes in health complaints. Analysis of covariance, with gender, age and complaint intensity at inclusion as covariates, was used to compare the reduction of complaints in the two groups. Results: In the treatment group, 12 month results showed significant reductions (p < .05) of mean index scores. The intraoral index was reduced from 13.9 to 7.7, orofacial index from 14.0 to 4.5, and general index from 34.6 to 26.3. The treatment group showed significantly (p < .05) greater reductions of intraoral and orofacial complaints as compared with the reference group. The reduction of general health complaints was not significantly different in the two groups. Conclusion: Data support that removal of dental amalgam reduces local complaints, but not general health complaints. Acknowledgement: The project is funded by the Norwegian Ministry of Health.


0147 (110631)

A Problem–oriented Approach To Dental Education, An Example: Xerostomia. Y. GUVEN, University of Istanbul, Turkey, and S. ATAMER-SIMSEK, Marmara University, Istanbul, Turkey

Objectives: The goal of this study was to improve students integration of knowledge acquired in basic dental sciences in to competent clinical skills.

Methods: In this study a course was conducted to evaluate the effectiveness of problem – oriented learning ( POL ) method on the common problem of xerostomia using a multidisciplinary approach in the dental curriculum. A hypothetical scenario of a 62 year old patient with taste disorder and dry mouth complaints in need of a partial denture was created.Ten students were attended to this course for 2 hours a week for a total of 3 sessions under the supervision of a tutor. The students found solutions to the problems of a simulated xerostomic patient by examining the data from, possible anamnesis, intra – and extraoral examination, laboratory and radiographic findings provided by the tutor. They formulated the optimal diagnosis and treatment plan based on these simulated results.

Results:The assessment of students' performance conducted at the end of course . Results of tutorial evaluation of the students' performance in the view of critical appraisal skills, self- directed learning, group participation and humanistic attitudes and skills was found 90%.Success ratio of the students in the final exam was also evaluated and it was 82%

Conclusions:It is concluded that if courses are taught in an integrated multidisciplinary form, students may acquire broad clinical knowledge on xerostomia in a short time period due to their active role in the POL process. Use of this method encouraged students to develop autonomous learning and interactive skills, as well as a more critical approach to diagnosis and treatment than would traditional dental education. Small group interactive teaching encouraged problem-oriented learning. This was perceived to be beneficial in helping students relate theory to practice and in encouraging an active and enquiring approach to clinical evidence.


0148 (110715)

National Reporting of Adverse Reactions to Dental Materials. L. BJÖRKMAN1, N.R. GJERDET2, V. HELLAND1, G.B. LYGRE1, and J. SVAHN1, 1University of Bergen/UNIFOB AS, Norway, 2University of Bergen, Norway

The number and complexity of materials for dental use has increased considerably during the last decade. Dental materials, being classified as medical devices according to the European Directive 93/42/EEC, are subject to the mandatory general vigilance reporting procedure for severe adverse reactions or adverse events linked to the use. This reporting procedure is, however, not designed to record subtle adverse reactions. In Norway, the Dental Biomaterials Adverse Reaction Unit is responsible for the operation of a national reporting procedure concerning adverse reactions seen with dental biomaterials. The procedure is based on spontaneous and voluntary reporting from dentists, physicians, and dental hygienists. Objectives: To gain knowledge about material associated adverse reactions, and to study changes over time. Methods: Adverse reaction reports were recorded in a database and analyzed with regard to the materials involved using multiple response analysis on a yearly basis. Results: From 1993 to the end of 2007 a total of 1705 reports were received. The proportion of reports involving dental amalgam decreased from a peak of 89 % of the reports in 1994 to 54 % in 2007. Reactions involving composites and cements did not increase, being below 25 % in 2007, even though the use of such materials has increased substantially in Norway. Reactions associated with fixed prostheses increased during the registration period; in 2007 the proportion of reports involving cast alloys was 37.5 %. Conclusion: Voluntary reporting of adverse reactions or adverse events in the form of a dedicated reporting procedure can reveal changes in adverse reaction patterns and serve as a signal-generating tool. It can be used to complement the general vigilance reporting procedure and post-marketing surveillance by the manufacturers.

Acknowledgement: The Norwegian Dental Biomaterials Adverse Reaction Unit is funded by the Norwegian Ministry of Health.


0149 (111367)

Examination of Patients Referred for Adverse Reactions to Dental materials. G.B. LYGRE, L. BJÖRKMAN, V. HELLAND, J. SVAHN, B.F. LUNDEKVAM, and T.-L.L. BERGE, University of Bergen/UNIFOB AS, Norway

The Dental Biomaterials Adverse Reaction Unit in Bergen, Norway is a national Unit for medical and dental examination of patients referred for health complaints allegedly related to dental biomaterials. Objectives: The aim of this study was to gain knowledge on change over time in intensity of health complaints related to dental treatment after the examination at the Unit. Methods: During the period 1993-2005, a total of 630 patients (72% women and 28% men) were examined at the Dental Biomaterials Adverse Reaction Unit. Of these 398 patients were referred to dermatologists and patch tests were performed with dental series of test substances. During 2000 to 2007 a follow-up questionnaire dealing with subjective health complaints was sent to all examined patients. Changes of health complaint intensity were calculated for patients examined 1999 to 2005. Results: More than half of the patients who were patch tested had positive reactions to one or more test substances. 81 patients with a positive patch test, but without clinical signs of contact allergy, were recommended to avoid dental materials containing the relevant components in future dental treatment. Removal of dental materials was recommended in 48 patients with clinical relevant allergy to substances in dental materials and in 31 patients with contact lesions adjacent to dental materials. Patients who had removed dental materials at follow-up had larger reduction of intraoral and general symptom index at follow-up compared with patients who did not remove materials (ANOVA; p=0.009 and p=0.031). The reduction was slightly larger in patients who were recommended to remove materials compared with patients who removed materials without recommendation (not significant). Conclusion: Removal of dental materials may be followed by a reduction of health complaints. Several mechanisms may be involved. Acknowledgement: The Norwegian Dental Biomaterials Adverse Reaction Unit is funded by the Norwegian Ministry of Health.


0150 (109916)

Factors Affecting Research in Primary Care Dentistry – the Dentists' View. L. HOPPER1, L. MORRIS2, F.A. BLINKHORN3, and M. TICKLE2, 1Salford Primary Care Trust, United Kingdom, 2University of Manchester, United Kingdom, 3Northern Sydney Central Coast Health, Australia

Objectives:

To understand the attitudes and views of primary care dentists (PCDs) towards research in primary care.

Methods:

Focus group and semi-structured, face-to-face interviews were used. Focus group was used to explore experiences of PCDs and academic researchers in undertaking research in primary care. Findings were used to develop an interview topic guide, which was expanded and developed as the interviews with the PCDs progressed. Interviews were undertaken using an iterative approach: purposive, staged sampling of non-specialist dentists who had been, were involved in, or had not been involved in primary care research, including PCDs who were not interested in research. Interviews were undertaken until saturation. Data was analysed using constant comparison.

Results:

Research was seen as a way of improving patient care and practice of dentists. Some thought that research lagged behind clinical practice, and was constantly trying to provide an evidence base for what was already being undertaken. Hands-on courses, advice of colleagues and experimentation were preferred ways of improving clinical practice. Research findings were viewed with caution, with PCDs preferring evidence based journals and review papers.

The majority of dentists were keen to undertake research, but wanted whole team involvement. Understanding of modern research governance, and where to seek advice was poor. Lack of time, relevance of research, and support were seen as barriers to involvement in primary care research. Pressure of practice was main cause of refusals. Long-term trials were viewed unfavourably. Training for staff, working with the practice and use of a research facilitator were seen as beneficial. Patient well-being was central to PCDs, and concerns were raised about harm to patients by undertaking research.

Conclusion:

PCDs were willing to be involved in research of short duration that was relevant and beneficial to their patients. Support is required and a research facilitator was viewed favourably.


0151 (109993)

MG-CFA of the s-FDPQ in Dutch and English samples. J. HOOGSTRATEN1, A.J. VAN WIJK1, C. HO2, and H. BUCHANAN2, 1Academic Centre for Dentistry Amsterdam (ACTA), Netherlands, 2University of Nottingham, United Kingdom

Objectives: To test the equivalence of the English and Dutch version of the s-FDPQ (short Fear of Dental Pain Questionnaire).

Methods: A sample of Dutch psychology freshmen (N = 204) and a sample of UK psychology freshmen (N = 293) filled out the s-FDPQ. Multi-Group Confirmatory Factor Analysis (MG-CFA) was applied to test for factorial (or measurement) invariance. Put simply, when factorial invariance holds, any differences in observed score then reflect proportional differences with respect to the latent variable the instrument is supposed to measure. Lisrel 8.10 was used to perform the MG-CFA. Given non-normal distribution of the data, and the categorical nature of the items, the Satorra-Bentler X2 was used based on the ‘normal' covariance matrix and on a polychoric correlation matrix. A one-factor model was tested in both samples separately and combined. Next, factorial invariance was tested using increasingly restrictive models in which the Chi2 likelihood ratio test was used to test the hypotheses necessary to establish factor invariance. The first model tests for metric invariance (equal factor loadings), the second model tests for strong invariance (equal error terms) while the last model tests strict invariance (equal intercepts).

Results: The one-factor model gave an excellent fit in both the Dutch and the UK sample separately and combined. Both approaches (covariance and polychoric matrix) showed that factorial invariance holds. Only for the covariance approach, one factor loading (first item) could not be restrained to be equal since this resulted in a misfit of the model.

Conclusions: Since the translated s-FDPQ behaved as expected (one-factor structure) and showed factorial invariance, it is concluded that the English and Dutch version of the s-FDPQ are equivalent. The clinical implication is that the s-FDPQ can be used in cross-cultural studies, allowing unbiased comparison with respect to the latent concept Fear of Dental Pain.


0152 (110201)

The Persian Version of the Oral Health Impact Profile (OHIP-14). V. RAVAGHI, Queen Mary University of the London, United Kingdom, N. FARRAHI-AVVAL, University of Toronto, Toronto, Ontario, Canada, D. LOCKER, University of Toronto, Canada, and M. UNDERWOOD, Queen Mary University of London, United Kingdom

Background: The Oral Health Impact Profile (OHIP) is an instrument that investigates oral health related quality of life and popular for measuring subjective oral health status. Objective: To validate and adapt the shortened 14 item OHIP for native Persian (Farsi) speakers and to test it for validity and reliability. Methods: The OHIP-14 was translated to Persian (OHIP-P), followed by back-translation into English, after which the Persian version was modified. The questionnaire was administered to native Persian speaking clients at a university-based dental clinic in Tehran, Iran (n = 240, 123 female and 117 male, mean age 38.6 ± 15.04). Convergent validity was examined by analyzing the association of OHIP-P with both self-rated general and oral health. Discriminative validity of OHIP was tested by analysing its association with the experience of pain and satisfaction with oral health. Test-retest reliability was evaluated by administering the instrument to 37 patients a second time. The internal consistency and reliability were analyzed using Interclass Correlation Coefficients (ICC) and the Cronbach's reliability coefficient respectively. Results: The associations between both subscales of self-reported general (rho 0.38-0.52) and oral health (rho 0.25-0.45) and additive OHIP-P subscale confirmed convergent validity. Discriminative validity was confirmed through the significance relationship between the experience of pain and the response to OHIP-P (P < 0.001). The instruments' responsiveness, test-retest reliability (intraclass correlation coefficients: 0.75-0.88), and internal consistency (Cronbach's á: 0.45-0.73 and Cronbach's á if item deleted: 0.88-0.85) were satisfactory, thereby confirming the reliability of OHIP-P. Conclusion: The Persian version of OHIP-14 was found to be valid and reliable and appropriate to be used among native Persian speakers.


0153 (110334)

Oral Self-Care in Elderly Lithuanians According to Professional Prevention Received. S. VYSNIAUSKAITE, and M.M. VEHKALAHTI, University of Helsinki, Finland

Objectives: To investigate the association between intensities of self-reported oral self-care and professional prevention received as reported by dentate elderly patients in Lithuania. Methods: The cross-sectional questionnaire-based data were collected from two public dental offices in Kėdainiai, Lithuania. A total of 174 dentate patients 60 years and older responded; mean age 69.2 years, 53% men. Intensity score for oral self-care covered tooth brushing at least twice daily, using fluoridated toothpaste always, going to dental check-ups, and not using sugar in coffee or tee; each aspect, when true, made one point, otherwise zero, resulting in a score range of 0─4. Intensity score for professional prevention covered having received any chair-side preventive measures during the most previous treatment course, and having ever in a dentist's office received advice on tooth brushing, interdental cleaning, use of fluoride, diet, and recalls; each of these six aspects, when true, made one point, resulting in a score range of 0─6. Age, gender and level of education served as background information. Statistical evaluation was by chi-square test, ANOVA, and Pearson's correlation. Results: For oral self-care, mean intensity score was 1.43 (women, 1.73, men, 1.16; p=0.003). Of all, 21% obtained scores 3─4 and 32%, the score zero; women obtained higher scores (p=0.01). For professional prevention received, mean intensity score was 1.47 with no gender difference. Of all, 33% reported as having received no professional prevention or counselling, for 13% the score was 4─6. Intensity score for oral self-care was the higher, the higher the score for the intensity of professional prevention (r=0.46). Subjects' level of education positively correlated with the intensities of oral self-care (r=0.47) and professional prevention received (p=0.25). Conclusion: Professional prevention should be more widely employed to improve oral self-care among the elderly. Acknowledgements: Grant by the Finnish Dental Society Apollonia.


0154 (110382)

Influence of pregnancy on the utilisation of oral health-care services. J.-N. VERGNES1, P. POISSON2, C. NABET3, and M. SIXOU1, 1Faculte de Chirurgie Dentaire, Toulouse, France, 2Faculte de Chirurgie Dentaire, Bordeaux, France, 3Faculte de Chirurgie Dentaire - INSERM U149, Montrouge, France

Objectives:

Pregnancy is characterised by complex physiological changes that can adversely affect oral health. There is emerging evidence of a relationship between periodontal infection and adverse pregnancy outcomes. Pregnancy is also an opportune time to inform women about preventing dental caries in young children. On the other hand, oral health screening is not consistently included in prenatal care, and many dental surgeons still hesitate to treat pregnant women. The aim of this study was to observe whether pregnancy modifies the calls women make upon oral health-care services, by using a matched-pair study design.

Methods:

The population studied was affiliated to the Mutualité Sociale Agricole (a French special medical insurance) of the Aquitaine and Midi-Pyrénées regions of south-western France. The consumption of oral care during pregnancy and during the nine months after delivery was noted for all women declaring a pregnancy between January 01 and June 30, 2005. Each of the 816 selected women was paired with one non-pregnant woman, matched according to age, profession, department of residence and follow-up dates. The primary outcome was the binary variable "at least one visit to the dentist". Statistical analysis was performed using a conditional logistic regression model.

Results:

Pregnancy did not appear to modify the utilisation of oral health-care services among expectant mothers in comparison with non-pregnant women (OR=1.18; 95%CI=[0.92,1.51]). In contrast, the utilisation of oral health-care services was significantly higher during the nine months after delivery (OR=1.34; 95%CI=[1.08,1.67]).

Conclusion:

This study shows that, outside specific prevention campaigns, there is a lack of prevention awareness among pregnant women, which is confirmed by a trend to defer care until after delivery. As it is now accepted that oral care is generally safe and effective during pregnancy, it seems necessary to encourage well-targeted prevention campaigns in the population, before and during pregnancy.


0155 (110512)

Caretakers' Perception of Infant's Oral Health in Uganda. M. WANDERA1, J. KAYONDO1, I. ENGEBRETSEN1, I. OKULLO2, and A.N. ÅSTROM1, 1University of Bergen, Norway, 2Makerere University, Kampala, Uganda

Objective: Focusing on Ugandan infants 6-36 months of age, this study examined the degree to which clinical- and psycho-social factors relating to child oral health associate with parents' evaluation of the child health and oral health status.

Methods: Eight hundred and sixteen caretaker/children pairs attending MCH clinics in Makindye (n=541) and Nakawa (n=275) divisions for immunization-and weight monitoring purposes were surveyed in 2007. A calibrated dentist (JK) examined the children for dental caries. Children were also measured for height and weight. A structured questionnaire was completed by caregivers in face to face interviews. Guided by the conceptual framework of Wilson and Cleary (1995), data analysis was carried out by unconditional-and stepwise logistic regression analysis.

Results: Seven hundred and twenty five caretaker/child pairs where children having ≥1 tooth were included in the analysis. 25.4% of Makindye- and 24.4% of Nakawa caretakers reported poor child oral health status. Corresponding figures for perceived poor child general health status were 34.0% and 32.9 %. Perception of child oral health and general health status was positively and statistically significantly associated (p<0.001). Stepwise multiple regression revealed that, poorest family wealth, (OR=1.9), rural place of residence of parent (OR=0.5), no symptoms during tooth eruption (OR=0.3) and distressed family activities due to child's oral problems (OR=2.3) were significantly associated with parental perception of poor child oral health. Corresponding determinants for perceived poor child general health were poorest family wealth (OR=1.7), no stunting (OR=0.5) and perceived poor child oral health status (OR=2.8)

Conclusion: Socio-demographic factors and psycho-social factors related to child oral health was directly associated with caretaker's overall response to children's oral health- and general health status. The results support a growing recognition of oral health as an important mediator of health and wellbeing in early childhood.


0156 (110674)

The public's perspective of dental services in Wales. I.G. CHESTNUTT1, D.R. THOMAS2, M. JONES1, and D. CHANNING1, 1Cardiff University, United Kingdom, 2National Public Health Service, Pontypool, United Kingdom

The provision of NHS General Dental Services in Wales is now based on a system of local contracting. No rigorous examination of the public's experience and expectations of dental services in Wales had been undertaken, information that is key to developing a locally user focused service. Objectives: This study sought to determine: expectations of a publicly funded dental service, the impact of cost on care and preferences in terms of care and service utilisation. Methods: Data were collected by a self-complete postal questionnaire of a random national sample, stratified to account for social deprivation, geographic location, urban/rural environment and dental caries prevalence. Results: Of the 1141 survey participants, 658 (57.7%) indicated their preference was to visit the dentist every 6 months – only 15.3% indicating they wished to attend at a frequency based on personal risk. 989 (86.7%) wished to attend a practice to which they were “registered” and see a known dentist. The commonest reasons for wishing to visit the dentist were “to catch things before they go wrong” (740/64.9%) and “It's something I have been brought up to do” (418/36.6%). Cost stopped 5.3% going to the dentist at all, while 20.4% claimed cost stopped them attending as frequently as they would like and 12% claimed cost a barrier to the treatment they “want”. Conclusions: The public's perspectives are at variance with recent service developments. They do not appreciate the current guidance on risk-based frequency of dental attendance. The importance of the dentist-patient relationship is highlighted as is the preventive mindset of the majority, in attending the dentist. Cost, while not a major barrier to dental attendance, limits treatments that patients can afford. These data are of use to commissioning authorities in contracting for and designing primary dental care services.


0157 (110695)

Referral Pattern to an Oral Medicine Unit in Southwest Ireland. R.M. NI RIORDAIN, and C. MCCREARY, National University of Ireland - Cork, Ireland

Background: The oral medicine unit of Cork University Dental School and Hospital was established in late 2002 and is one of two such units in the Republic of Ireland. Objective: The aim of this study was to examine the factors influencing the referral of patients to this oral medicine unit. Methods: A retrospective analysis of all clinical records and referral letters to the oral medicine unit for the calendar year 2007 was undertaken. Patient demographics and referral information for all new referrals to the department were collected and data were entered on a standard proforma. Results: The average age of the patients referred was 46.7 ± 18.2 years and the majority of patients referred were female (65.6%). Almost equal numbers of patients were referred from Cork city (34.6%) and County Cork (37%). 23.8% of patents were referred from contiguous counties and the remaining patients from distant counties (4.5%). 73.8% of referrals came from dental practitioners and 26.3% from medical practitioners. The most common reason for referral was a white lesion (20%) and the most common site mentioned was the tongue (43.3%). Conclusion: This oral medicine unit provides a referral base for a wide geographic area. There is a considerable demand for the service dealing with lesions and conditions that general practitioners prefer to refer.


0158 (110751)

Development of a Dental Assessment Tool for use in Prisons. K. BUCHANAN1, K.M. MILSOM2, A. PAU3, L. ZOITOPOULOS4, and M. TICKLE1, 1University of Manchester, United Kingdom, 2Halton & St Helens PCT, Runcorn, United Kingdom, 3Institute of Dentistry, Barts and The London School of Medicine and Dentistry, United Kingdom, 4King's College London, United Kingdom

Objective:

To compare the performance of a questionnaire based assessment of dental pain delivered by non-dental prison nursing staff against a clinical examination performed by an experienced prison dentist (Gold Standard).

Setting:

The research fieldwork took place in the Healthcare Department at HMP Brixton located in South London.

Methods:

The cohort were those who had complained of dental / facial pain to the prison authorities and were therefore placed on the waiting list for emergency dental care. Subjects were asked to complete the screening test and were then clinically examined a trained and calibrated dentist. The screening test was in the form of a 12-item questionnaire designed to categorise a population reporting dental pain into one of three groups. The screening test results were compared with the diagnosis of a clinical examination.

Results:

Ninety-six subjects were recruited during the 16-week study period. Of the 96 prisoners recruited 27 of those failed to complete the screening test and / or the diagnostic examination even though they had reported pain previously. When sensitivity and specificity values were calculated for the 96 prisoners recruited the sensitivity was fairly high (81%) and the sensitivity was poor (33%). However, when these values were calculated for the sub–population, those that completed both the screening test and diagnostic examination (N=69), the sensitivity did not improve particularly (83%) but the specificity value reduced dramatically to 13 percent.

Conclusions:

This study highlighted the problems of conducting research in the prison environment for example, increased security preventing researchers from gaining access into the prison and general pressures on prison staff. Additionally, the study demonstrated that screening is not effective in local prison with a high turnover of prisoners


0159 (110756)

Trigeminal Neuralgia: Patients Attributes' Relationship with Preferred Health Outcomes. E.J. KAY, Peninsula College of Medicine and Dentistry, Plymouth, England, S. CREANOR, University of Plymouth, United Kingdom, and J. ZAKRZEWSKA, Eastman Dental Hospital, London, United Kingdom

Objective: The aim of this study was to examine the effect of various patient attributes on the utility gained from treatment for trigeminal neuralgia (TN).

Methods: One hundred and fifty four previously diagnosed TN patients completed a time-trade-off utility measurement questionnaire, to ascertain how they valued the potential outcomes from various surgical and medical treatments. Each of twelve outcomes was dichotomised at its threshold value. Individual and multiple variable logistic regression models were used to identify whether previous surgery or levels of anxiety, depression or pain were associated with patients' treatment preferences.

Results: Basic decision analysis showed that microvascular decompression (MVD) surgery was the treatment which attracted the maximum expected utility i.e. offered patients the best chance of improved quality of life. However this result was highly sensitive to the patients' utility value.

Preference for treatments other than MVD was associated with individuals' levels of anxiety (p = 0.018) and whether they had had previous surgery (p = 0.032). Preference for MVD with subsequent relief of pain was significantly associated with the patients' current pain score (p = 0.016).

Conclusions: Levels of pain, anxiety and previous experience of surgery of any kind, but particularly partial rhizotomy, affect how patients value health outcomes. In particular, patients' evaluation of the side effects of medicine are influenced by their past experiences of surgery and their levels of anxiety. There was, however, little evidence that depression influenced utility values sufficiently to alter which treatment attracted the maximum expected utility.


0160 (110778)

The Restorative Care Index in Children. Childrens' factors. A.A. SCHULLER1, J. BRUERS2, B. VAN DAM2, J. POORTERMAN3, V. GERARDU1, and G.J. TRUIN4, 1TNO, Leiden, Netherlands, 2Dutch Dental Association, Nieuwegein, Netherlands, 3ACTA, Amsterdam, Netherlands, 4Radboud University NIjmegen Medical Center, Nijmegen, Netherlands

In The Netherlands, the restorative care index (RCI) in 5-years old children is estimated at 17% (primary dentition) and 51% in 11-yr-olds (permanent dentition). Both childrens' factors and dentists' factors could play a role in the level of the RCI.

Objectives:

The aim of this study was to analyze factors concerning the child that play a role in the level of restorative care in children.

Methods:

Secondary data-analyses were performed on data from the TJZ-study and from the JTV study. Both studies were carried out in 2005.

TJZ study: 386 5-yrs-old and 492 11-yrs-old children recruited from 4 different sick fund insurances, participated in the clinical examination.

JTV study: 579 5-yr-olds and 549 11-yr–olds recruited from the organised Youth Dental Care Organisation, participated in the clinical examination.

Results:

44% of the 5-yrs old and 53% of the 11 yrs old TJZ-children and respectively 41% and 62% of the JTV-children were caries free (dmf or DMF = 0). Factors as socio-economic status and oral care are determinants for probability of the occurrence for being caries-free. Furthermore, the ‘type of dentist' (general practitioner or dentist working at an institution for organized Child Dental Care) is a determinant for the probability of curative treatment (in the case of carious lesions).

Conclusions:

Child factors as socio-economic status and oral care play an important role in the occurrence for being caries-free. In children that are not caries free, the level of restorative care (RCI) is mainly determined by the ‘type of dentist'.


0161 (111102)

Antibiotic prophylaxis practices amongst dental practitioners in Iran. S. SOHEILIPOUR1, J.T. NEWTON2, and S. DUNNE1, 1King's College London, United Kingdom, 2King's College London Dental Institute

Objectives: This study aimed to determine: the knowledge and application of current expert recommendations on antibiotic prophylaxis to prevent infective endocarditis in at-risk patients; the most common sources of information on this topic amongst dentists in Iran. Methods: Postal questionnaire survey.The questionnaire was designed in 3 sections: Part A demographic data, Part B antimicrobial prophylaxis prescribing habits for adults treated under local analgesia, Part C sources of information about recommended schedules and changes in dentists' prophylaxis regimens. Results: Responses were received from 200 dentists (33% response rate). 99% of dentists organized the prophylaxis themselves. Over 80% of dentists would refer patients to his/her cardiologist for further advice about prophylaxis if they were unsure of the indications. 72% of respondents mentioned AHA as preferred guideline to follow for antibiotic prophylaxis. A significant proportion of practitioners prescribed the correct antibiotic for patients non-llergic to penicillin but their decision-making with regard to choice of prophylaxis for patients allergic to penicillin was poor. Although dentists were familiar with the dental procedures that could place their patients at risk, they were less informed about current recommendations in terms of familiarity with high-risk cardiac conditions and considered antibiotic prophylaxis for patients with the medical history not known to be at risk from dental procedures. About 94% of dentist would like to attend further courses about this topic. Conclusion: The results from this study show an inappropriate level of knowledge of antibiotic prophylaxis among Iranian dentists. Further regular education is required for the development of guidelines for dentists on the appropriate prophylactic use of antibiotics to promote the health of patients.


0162 (111167)

Role of dentists in providing alcohol advice; preliminary interview findings. S. SHEPHERD1, L. YOUNG2, D. BONETTI3, J. CLARKSON3, and G. OGDEN3, 1Dundee Dental School, United Kingdom, 2NHS Education for Scotland, Dundee, United Kingdom, 3University of Dundee, United Kingdom

Background: Alcohol misuse has social, economic and health costs. Trends towards increased consumption and availability manifest with increased alcohol related harm. Little is known about the beliefs or behaviour of General Dental Practitioners (GDPs) relating to communicating alcohol as a risk factor for oral cancer to patients in primary care.

Objectives: To investigate the core beliefs, attitudes and behaviours of GDPs in Scotland, and to investigate barriers and facilitators to providing alcohol related advice in general dental practice.

Methods: Semi-structured interviews conducted with a convenience sample of GDPs in order to inform the development of a questionnaire for distribution to a random sample of GDPs in Scotland.

Results: Interviews were conducted with a convenience sample of 12 GDPs from the Highland region consisting of 10 salaried general dental practitioners and 2 private practitioners of varying age groups and years since qualification.

Overall, attitudes to providing alcohol advice were negative. Many barriers were cited including disrupting patient-clinician relationships, patient embarrassment and patients deeming it irrelevant. Despite GDPs accepting alcohol as a risk factor they believed that delivering alcohol related advice not relevant to daily practice and outside their remit. GDPs exhibited low confidence in discussing alcohol but would undertake this if clinically indicated by the presence of suspicious lesions. Knowledge about recommended safe drinking guidelines was also low and indicative of further training needs.

Conclusions: Semi-structured interviews identified barriers to providing alcohol advice in general dental practice, the most prevalent of which were adverse behavioural outcomes and disruption of the patient-clinician relationship. The results are informing the design of a larger postal survey in Scotland, to further understand the relative importance of the barriers related by this small sample. The overall aim is inform the development of an intervention to enable GDPs to better communicate oral health risk to patients.


0163 (111196)

Arabic Oral Health Impact Profile (OHIP 14) in Saudi population. N. AL-HAZMI1, K.A. AL-JOHANI2, M.A. AWAD3, M. AL-ZAHRANI1, M. ALHUTHALI1, and S. BUKHARY1, 1King Abdulaziz University, Jeddah, Saudi Arabia, 2UCL Eastman Dental Institute, London, United Kingdom, 3University of Sharjah, United Arab Emirates

Introduction:

The vast majority of oral conditions present as established disease entities that greatly impact the quality of life (QoL) of the patients. Oral conditions are as yet far from being totally preventable and therefore the clinical evaluation of their impact and their treatments is still widely used as the most important evaluation tool.

The OHIP has recently been translated into the Arabic language by Al-Jundi et al. We have extracted the shorter version of the questionnaire, OHIP-14, comprising the seven sub-sets and have randomly sampled it on patients being treated in several governmental hospitals in Jeddah, Saudi Arabia

Material & Methods:

The questionnaire was administered randomly to both male and female patients in government hospitals by general dentists. Patient's age, gender and nationality were noted and patient identity was kept confidential. Only Saudi nationals were included in the study.

Results:

Female participants (n=77, mean age:30.6, s.d:9.5) were significantly younger than males (n=88, mean age 35.65, s.d 14.4). Overall, participants experienced the most oral health related quality of life (OHRQL) problems in the functional limitation domain (mean: 2.97 (s.d: 1.7). The least OHRQL problems were in the physical pain domain (mean: 5.1, s.d: 2.3). Furthermore, using the summary OHIP-A-14 score as the dependent variable, females experiences significantly less oral health related quality of life problems compared to males (means: 30.82 Vs 24.77, respectively, p=0.003). This association was persistent after adjustment for age and level of education.

Discussion & conclusion:

Our results indicate a significant difference between females and males in this study. This difference could indicate the fact that women take better care of their oral health or could be an actual perception of better health. Further studies are essential in this part of the world and when paired with clinical examination will help reach more assertive conclusions.


0164 (111206)

Dental hygienists' willingness to perform treatment and barriers they encounter. B. TSEVEENJAV1, J.I. VIRTANEN1, N.J. WANG2, and E. WIDSTRÖM3, 1University of Helsinki, Finland, 2University of Oslo, Norway, 3National Research and Development Centre of Welfare and Health, Helsinki, Finland

Background: In the Nordic countries, discussion on the redistribution of clinical tasks between dentists and dental hygienists continues. Objectives: To study Nordic dental hygienists' willingness to perform specific clinical treatment measures as well as barriers to carrying them out. Methods: A questionnaire survey was conducted among dental hygienists in Finland and Norway (n = 1 733) in 2004. The questionnaires assessed the dental hygienists' willingness to perform specific clinical treatment measures in future as well as their perceived barriers to carrying out these measures. In addition, we collected information on the hygienists' backgrounds. The response rate was 56%. Results: The dental hygienists worked predominantly in the public sector in both countries. A clear majority of the working dental hygienists (67%) agreed that they fully use their professional skills in their current clinical work. In addition to their daily activities, the dental hygienists reported their willingness to carry out “more often than now” different treatments such as procedures related to orthodontics (59%), local anaesthesia (59%), clinical photographing (58%), glass-ionomer filling (57%), composite filling (51%), and tooth bleaching (47%). The most important barrier reported was the dental hygienists' perceived competency (39%). In addition, the dental hygienists identified the homogeneity of their current patient group (32%), comprised mostly either children or adults, and the traditional way of delegating tasks in their work places (31%) as important barriers to carrying out clinical treatment measures. Conclusion: Our study indicates that further redistribution of tasks between dentists and dental hygienists requires changes in dental hygienists' training programmes that aim to provide them with sufficient skills and confidence to carry out a wider variety of clinical treatment measures.


0165 (111267)

Analysis of primary qualification for dentists in an urban PCT. D.A. WHITE1, A. MORRIS2, L. BURGESS2, and R. HAMBURGER3, 1University of Birmingham, England, 2University of Birmingham, England, Uk, 3Birmingham Public Health Network, England

Objective:

To analyse the primary care dental workforce in an urban Primary Care Trust (PCT) as part of a wider workforce review.

Methods:

Analysis of lists of dentists working in the area in 2005 and PCT dental performers list data in 2008. Data were cross-referenced with General Dental Council on-line registration data for verification and subsequently analysed.

Results:

Analysis of pre-2006 lists was problematic as these were difficult to update and verify. Performers list arrangements, introduced in 2004 and 2005, simplified the process greatly as dentists could only appear on one PCT performers list and systems for administering this, through a shared services agency across 4 PCTs, were robust. There were 125 dental performers on the PCT list as at 1/4/08. Fifty-seven (45.6%) had obtained their primary qualification in the previous ten years. Of these, only 4 were vocational trainees. Twenty (16.0%) had obtained their primary qualification over 30 years previously. Forty-nine (39.2%) had qualified from the local dental school in Birmingham and 15 (12.0%) from a London dental school. The remaining UK-trained dentists were from a range of dental schools. Seven (5.6%) had a registrable overseas qualification and 17 (13.6%) had the GDC statutory qualification. The majority of those having trained overseas (20/24; 83.3%) were in the youngest group of dentists. The numbers were relatively small and other PCTs' lists are now being analysed.

Conclusions:

Modern dental performers lists provide a useful resource for workforce analysis. This urban PCT had a high proportion of younger dentists with overseas qualifications. The picture is complex and requires further investigation. It is difficult to infer trends in workforce composition from such data.


0166 (111422)

Apex Locator Use by General Dental Practitioners in Merseyside. L.E. MOLYNEUX, C. MCCULLOUGH, A.J. PRESTON, and F.D. JARAD, University of Liverpool, United Kingdom

Objectives: The aim of this study was to investigate the use of apex locators by general dental practitioners in the Merseyside region, and the use of supplemental techniques for root canal length determination. Methods: A structured questionnaire was developed and distributed to dental practices across Merseyside. A total of 780 questionnaires were sent out as a supplement to the Mersey Deanery monthly newsletter.  Results: Of the questionnaires distributed, 321 were returned, giving a response rate of 41%. From those questionnaires returned, 44.5% of general dental practitioners do use apex locators for endodontic treatment, compared with 55.5% who do not. Of those using apex locators, confirmatory working length radiographs were always taken by 29.1% of these practitioners, most of the time by 22.7%, occasionally by 34%, and never  by 14.2% of respondents. Practitioners were also asked to indicate their use of other root canal length determination techniques, with the results as follows:

Technique

% of total sample

Uses apex locator %

Does not use apex locator %

1

Tactile

15.0

23.9

8.1

2

Paralleling radiograph

25.7

25.4

26.0

3

Bisecting angle radiograph

22.8

19.4

25.4

4

Others

4.6

5.2

4.0

1 & 2

13.4

13.4

13.3

1&3

11.4

4.5

16.8

1,2 & 3

2.9

3.7

2.3

1,2,3 and 4

0.7

1.5

0.0

2&3

3.3

2.2

4.0

1,3 & 4

0.3

0.7

0.0

Conclusion: This study shows that apex locators are not widely used amongst general dental practitioners in the Merseyside region, and that many practitioners still rely on other length determination techniques, most commonly radiographs and tactile sensation. Amongst those practitioners using apex locators there appear to be wide differences of opinion regarding the need for confirmatory working length radiographs.


0167 (111489)

Increasing functionality in problem-based learning groups. J. PEPPERELL, J. MCHARG, and L. KAY, Peninsula Dental School, Plymouth, United Kingdom

In a problem-based learning (PBL) curriculum, students sometimes complain that their PBL group is dysfunctional because of the group dynamic. This can lead to at best non-enjoyment of the group sessions and at worst poorer learning.

Objectives: The objective of this study was to evaluate the effect of constructing PBL groups by allocating individuals according to Belbin team roles in a new graduate entry dental programme. The functionality of the groups in terms of group engagement and performance was assessed.

Method: Prior to commencing the programme, students took an online Belbin test from which they were classified into one of nine team roles. Half of the PBL groups were constructed such that they were balanced in their representation of each team role, whilst the remaining students were allocated randomly to their groups. After 18 and 31 weeks of the programme the PBL facilitators scored group members according to MacGowan's groupwork engagement measure (GEM). GEM scores of individuals and groups were compared depending on whether they belonged to Belbin or non-Belbin groups. GEM scores of individuals in each group were also correlated with performance on a test of applied dental knowledge.

Results: Initial findings show no correlation between functionality of the group and whether the group was a Belbin group or not. Nor does there appear to be any correlation between individual performance on a test of applied dental knowledge and belonging to a Belbin PBL group. Sum of individual GEM scores for each group and group functionality do however have a positive correlation. Further results will be presented at the meeting.

Conclusion: PBL groups would appear to differ significantly from business teams for Belbin grouping PBL groups to have no effect.


0168 (111499)

Evaluation of a primary care minor oral surgery service. T.A. DYER, University of Sheffield, England, Uk

Objectives: To evaluate a pilot specialist primary care minor oral surgery service.

Methods: Data collected as part of the pilot monitoring process were analysed to evaluate service activity, waiting times and patient outcomes. Patient satisfaction was assessed by a postal satisfaction survey of 100 consecutive patients using a global satisfaction measure and a modified version of the Dental Visit Satisfaction Scale.

Results: 470 patients referred by 49 different dentists were offered treatment appointments. Of the 542 treatment appointments offered, 14.2% were not attended and no treatment was provided in a further 12.9%. The mean waiting time from receipt of referral to first treatment appointment was 6.9 weeks. Treatment provided included: surgical removal of third molars; surgical removal of non-third molars and surgical endodontics (27.4%, 60.1% and 5.5% of cases respectively). Antibiotics were prescribed in15.6% of all treatment cases and only 3.5% of treatment cases required unscheduled review appointments for post-operative complications.

Eighty completed satisfaction questionnaires were received after 3 mailings. 100% of participants reported overall satisfaction with care received. Following consultation and treatment, 100% strongly agreed or agreed that: they knew what their treatment would involve; they knew what to expect after treatment; they felt understood by the oral surgeon; the oral surgeon accepted them as a person and knew they were worried about the possibility of pain; the oral surgeon seemed to know what he was doing and was thorough doing the procedure. 77.5% were seen on time and 22.5% within 15 minutes of their appointment. Overall, 76.3% felt the standard of service was better than they would expect from a hospital and none felt it was worse.

Conclusion: The findings of the evaluation suggest that specialist oral surgery can be successfully provided in primary care and is acceptable to patients.


0169 (111531)

Compensation for Endodontic Treatment Injuries in Finland: a Pilot Study. J.I. VIRTANEN1, O. SWANLJUNG2, S. PÖYRY2, V. LILJA2, and H. MURTOMAA1, 1University of Helsinki, Finland, 2Patient Insurance Centre, Helsinki, Finland

The legal Patient Injuries Act has been in force for two decades in Finland. Based on this legislation, compensation is paid to patients for treatment injuries and infections taking into account severity criteria. Objectives: To investigate endodontic treatment injury claims for compensation filed at the Finnish Patient Insurance Centre. Methods: All applications and decisions related to endodontic treatment cases at the Patient Insurance Centre in 2002 were analysed. Two specialist dentists examined all the treated cases for which decisions were given (n = 83), including patient claims, dentists' reports and accessible radiographs, and analysed their grounds. Specifically, endodontic treatment, restorations, ICD-10 diagnoses and root anatomy were explored. Background variables included age, degree and working sector of the dentist, as well as patients' age, education and area of residence. Results: In total, compensation was paid to the patient in 48% of the cases. In 30% of the cases no patient injury was observed, while the injury was not avoidable or of a minor nature in 22%. A majority of the injured teeth were restored (84%) and vital (66%) at the initial phase of the treatment. The most frequently endodontically treated teeth were the first permanent molars (42%). Manual root canal preparation (90%), calcium hydroxide medication (71%) and gutta-percha (45%) were the most common treatment methods. A majority of the cases were treated in the private sector (58%). A statistically significant (p<0.05) association between young patients (<35 years) and compensated endodontic treatment injuries was observed. Conclusion: About half of the patients with claims related to endodontic treatment filed at the Finnish Patient Insurance Centre were compensated. The relatively high number of young patients with endodontic problems that were compensated for calls for more attention among dentists.


0170 (111546)

Oral-Health-Related Quality of Life of Patients on Hemodialysis. E. GUZELDEMIR1, H. USLU TOYGAR1, D. TORUN2, and A.C. YAZICI3, 1Baskent University, Faculty of Dentistry, Department of Periodontology, Ankara, Turkey, 2Baskent University, Faculty of Medicine, Department of Nephrology, Adana, Turkey, 3Baskent University, Faculty of Medicine, Department of Biostatistics, Ankara, Turkey

Objectives: Chronic renal failure (CRF) defined as a progressive decline in renal function associated with a reduced glomerular filtration rate. The one of the treatments of CRF is hemodialysis. The aim of this study was to assess hemodialysis patients' self-perceived oral health and Oral-Health-Related-Quality of Life(OHRQoL) outcomes.

Methods: Forty-seven hemodialysis patients were evaluated. Age, gender, education levels, socio-economic variables, the duration of hhemodialysis therapy, the length of time since participants were diagnosed, other medical diseases, oral hygiene habits were recorded. General Oral Health Assessment Index(GOHAI) and Oral Health Impact Profile(OHIP) were used in the assessment of the OHRQoL. Perceived oral health was measured by a question “How would you describe the health of your teeth and gums?”

Results: The age range was 17-75 years (46.48±15.10; 49% female, 51% male). CRF diagnosis length was as a ranged from 1 to 25 years(7.82±5.64) and the participants were undergoing hemodialysis ranged from 9 to 208 months(71.04±51.16). Forty-seven percent of patients had no brushing habit. The patients reported that they were uncomfortable when eating (63%) and swallowing (58%), having trouble when pronouncing (%62) and having hot/cold sensitivity in their gums and teeth (70%). They had sense of taste worse (91%) and painful aching in mouth (72%). The patients described their oral health as “mediocre-poor” (53%). OHIP and GOHAI scores were significantly higher in uneducated patients and the patients had lower-income(p<0.5).

Conclusions: The most of the hemodialysis patients have functional limitations, pain and discomfort. Patients on hemodialysis in lower socio-economic levels reported a higher impact on their OHRQoL. Understanding the consequences of oral diseases by these patients are essential due to nutrition, preventing from inflammation and other systemic diseases. The patients should be motivated for oral hygiene and regular dental visits as a part of their CRF treatment for to improve their quality of life.


0171 (111618)

DPwSI Oral Surgery Scheme Evaluation. S. DIU1, S. NANJAPPA2, and A. PAU1, 1Institute of Dentistry, Barts and The London School of Medicine and Dentistry, United Kingdom, 2St. Bartholomew's & The Royal London, United Kingdom

Objective: To evaluate a Dental Practitioner with Special Interest in Oral Surgery (DPwSI-OS) Scheme in Havering PCT.

Methods: Telephone questionnaire interviews with patients, postal questionnaire survey of referring dentist, telephone interviews with the DPwSI-OS, and analysis of management information data for the initial three-month pilot period were carried out.

Results: 45 (50%) dentists responded and 40 knew about the scheme, although not all reported using the scheme. Those who knew about the scheme reported that it was helpful and satisfactory. The DPwSIs who participated in the scheme reported that the majority of referrals made to them were appropriate. Of the 83 referrals received by the Clinical Assessment Service during the trial period, 66 were referred to a DPwSI. Of these, 46 patients were treated, 5 received consultation only and 15 could not be contacted or failed to attend. Nearly 90% of patients rated the service as good or excellent. The cost of treating 46 patients requiring extractions of wisdom teeth or teeth of special difficulty by DPwSIs was about one sixth of the cost when treated in hospital. The average waiting time between the referral date and the treatment date was 36 days, with 75% of those referred seen within 43 days, or just over six weeks.

Conclusions: It is concluded that the Havering PCT DPwSI scheme is well received by both patients and dentists, it provides an efficient and value for money service to the local community. It is recommended that the scheme be continued and expanded to include other areas of minor oral surgery such as frenectomy, removal of simple cysts, and apicectomy, and the referral form be modified to improve the both the appropriateness of referrals and the accuracy of information requested.


0172 (111630)

Audit of Referral Patterns and Treatment for Periodontitis Patients. L.M. DUNPHY, School of Dental Science, Dublin 2, Ireland, and D.J. MACCARTHY, University of Dublin, Trinity College, Ireland

Objectives: In this audit of patients referred to Dublin Dental School & Hospital, we examined (a) length of time between referral and assessment, (b) source of referral, (c) treatment required, (d) treatment completed. Methods: Charts and computer records of 143 patients were analysed to gather necessary information. Results: 79% of patients attended for baseline assessment, 15% did not attend and 6% of charts not located. Average time from referral to assessment was 10 weeks. 59% were referred from GDP/specialist practice, 13% from HSE, 5% from general hospitals/hospice, 3% were self referred/unknown, 20% internal to DDS&H. Assessment revealed a main diagnosis of gingivitis (12%), gingival hyperplasia (7%), gingival recession (18%), mild/moderate periodontitis (18%), severe periodontitis (31%), perio-ortho-rest (11%), epulides (2%) and miscellaneous (1%). 84% of patients had some form of relevant medical history and 30% were smokers (11% past smokers). Patients were assigned for treatment as follows: undergraduates (15%), postgraduates (38%), consultant (23%), SHO/JHO/Staff dental hygienist (24%). Letters were sent to the GDP for 70% of patients assessed. Chart audit revealed the current treatment status: undergraduates (16%), postgraduates (17%), consultant (4%), SHO/JHO/staff dental hygienist (11%), referral to other departments (12%), discharged (39%). Treatment provided was: OHI (100%), scaling (46%), debridement (39%), surgical debridement (5%), mucogingival (6%); extraction (7%), implants (4%). Discussion: This audit shows that patients are assessed within the NICE time guidelines. A significant number of patients did not attend for assessment. The majority of referrals were from GDP and patients were referred for management of moderate to severe periodontitis. Treatment provided was usually OHI and debridement. Senior staff appear to discharge patients back to GDP following treatment, undergraduates have longer treatment times. Not many patients are receiving supportive periodontal therapy. Conclusions: Follow-up for patients who did not attend and establish SPT for the patients with more severe disease.


0173 (111766)

Dentistry Networks for Women and Part-time Dentists-Users Experiences. K.A. THORNLEY1, D.A. WHITE1, J. DAVIES-SLOWIK2, R. HAMBURGER3, and L. BURGESS1, 1University of Birmingham, United Kingdom, 2West Midlands Deanery, Birmingham, United Kingdom, 3Birmingham Public Health Network, United Kingdom

Objective: To investigate the experiences of women and part-time dentists participating in specially designed continuing professional development (CPD) courses. These formed part of a Dentistry Networks initiative established by West Midlands Deanery in 2005.

Method: Before and after-event questionnaires were designed, piloted and used to ascertain attendees' views and experiences of six CPD events over a 2-year period. Data analysis was carried out using SPSS v15.

Results: Six CPD events tailored to the needs of women and part-time dentists and including crèche provision were organised between 2005-7 in the West Midlands. 125 participants, mainly women (93%), booked and attended the events. A total of 251 before and after event questionnaires were completed and analysed including those from participants who hadn't booked. Of the dentists, 65 (83%) worked in general dental practice. 51 attendees (39%) were not dentists but dental care professionals. Factors that were reported as attracting participants to the course were course content (99%), crèche facilities (30%) and school hours (33%). Almost 2 out of 3 of the women dentists preferred to meet in a group with women to some extent whilst this was 1 out of 3 of the dental care professionals. The majority of participants (86%) reported that they found the course to be a very valuable learning experience.

Conclusions: Provision of tailored CPD courses proved attractive to women dentists and dental care professionals who might have difficulty in attending more traditional CPD events.

Supported by Department of Health


0174 (111827)

Dental Services in the Family Health Strategy in Brazil. P.S.A. GOES, Pernambuco Dental School-University of Pernambuco, Recife, Brazil, and R.D.A.C.P.R. ROCHA, Pernambuco Dental School -University of Pernambuco, Recife, Brazil

There are several works in the access area to the health service, therefore there are few researches in order to access the Oral Health Care service, and mainly after the inclusion of the Oral Health Care in the Family Health Strategy. Aim: Assess the factors associated to access to oral health services in, comparing areas covered and not covered by the Family Health Program (FHP). Material and Methods: Quantitative study with a population-based transversal design , n = 827, age ≥ 18 years, of a random representative sample of urban sector populations that include National Health Units, stratified into areas covered and not covered by the Family Health Program, in which previously validated forms were applied. Statistical analysis consisted of a descriptive and analytical phase, in which frequency distributions were verified, for statistical analysis it was used Pearson's chi-square and logistic regression. Results: Individuals living in areas not covered by FHP were 1.5 times more likely to have access (OR = 1.5; CI = 95% = 1.1-1.9; p = 0.004) to oral health services when compared to those living in FHP-covered areas. However, this probability diminished, losing its significance (OR = 1.1; CI 95% = 0.8-1.6; p = 0.337) after being adjusted for sex, age, income, schooling and self-perception of health. Conclusion: Sociodemographic factors were the main predictors of access to oral health services.


0175 (111309)

The experience of local network co-ordinators for women dentists. L. BURGESS1, D.A. WHITE1, A.J. MORRIS1, and R. HAMBURGER2, 1University of Birmingham, England, Uk, 2Birmingham Public Health Network

Objective:

To investigate the experience of six local network coordinators for a pilot women and part-time dental workers support scheme established by West Midlands Deanery in 2006.

Method:

Semi-structured interviews were carried out with all six co-ordinators, using a topic guide that had been developed and piloted. A framework approach to data analysis was utilised.

Results:

The six co-ordinators were all women with children working in primary care dental services and had been qualified for between ten and thirty-one years. Four of the dentists were working as performers in General Dental Practice and two as salaried dentists in Primary Care Trust Dental Services.

Interviewees reported the difficulties of accommodating work and domestic commitments and stressed the importance of personal experience in allowing them to empathise with those using the network for support. As one said ‘something happens after you have children, you're torn, you are split and you find you can't really stretch yourself everywhere'. The importance of childcare for meetings and at events was highlighted and coordinators felt it was preferable to arrange meetings in their home with crèche facilities. The use of multiple methods of recruiting dental workers to the events, particularly the use of personal contacts was seen as key to successful recruitment of network users. Cold advertising, including leaflet mailings to dental practices was not reported as successful. Support from the central network office was viewed as critical, as was the streamlined arrangements for paying speakers. The experience of network users is reported elsewhere.

Conclusions:

It is possible to establish local networks of this kind with good support and careful selection of co-ordinators who are able to use a variety of recruitment methodologies.

Supported by Department of Health


0176 (111842)

Analysis of dentist workforce in a semi-rural PCT. A.J. MORRIS, University of Birmingham, United Kingdom

Objective: To analyse the primary care dental workforce in a semi-rural planning locality within a large Primary Care Trusts (PCT) as part of a wider workforce review.

Methods: Analysis of PCT dental performers list data in 2008 for two former English PCTs, now forming a commissioning locality within a larger PCT. Data were cross-referenced with General Dental Council on-line registration data for verification and subsequently analysed. Dates of birth and contract status data were available.

Results: Data were generally robust. There were 93 dental performers on the list for this locality as at 1/4/08, with an average age of 44 years (range 24-71 years). Nineteen (20.4%) had obtained their primary registrable qualification in the previous ten years, of which one was a vocational trainee. Twenty (21.5%) had obtained their primary qualification over 30 years previously. Forty-two (45.2%) had qualified from the local dental school in Birmingham. The remaining UK-trained dentists were from a range of dental schools. Fifteen (16.1%) had a registrable overseas qualification. The age-difference between UK-trained and overseas dentists was not statistically significant (p>0.05), though the overseas dentists tended to be older at the time of gaining their primary registrable qualification. The former PCTs in the locality had participated in active overseas recruitment mechanisms, but this explained only 2 of the 16 dentists who had trained outside the UK. Nine of the overseas dentists were providers; one provider did not perform services under their contract.

Conclusions: Modern dental performers lists provide a useful resource for workforce analysis. Dates of birth are particularly useful for analysing the workforce comprising dentists with overseas primary qualifications. The majority of overseas dentists had come to the UK through informal routes. The picture is complex and requires further investigation.


0177 (112013)

Socio-economic Conditions and Orthodontic Treatment in France. A. GERMA, INSERM, Villejuif, France, and C. NABET, INSERM - Faculty of Dentistry Paris Descartes University - Charles Foix Hospital, Villejuif, France

Objectives:

Malocclusions are considered as risk factors for dental caries and periodontal diseases through inefficient dental cleaning. The cost of orthodontic treatment remains a barrier for many households. Social disparities in orthodontic care have been poorly explored in France. The aim of the study was to estimate the prevalence of orthodontic treatment by age and to investigate the associations between socio-economic factors and orthodontic treatment among children and adolescents in France.

Methods:

The study was based on the national health survey, which is a transversal study carried out on representative sample of the population living in France, made by INSEE (Institut National de la Statistique et des Etudes Economiques) in 2002-2003. Informations were collected by questionnaire. 5988 individuals aged from 8 to 18 years living with their parent(s) were selected. The variable of interest was having or not an orthodontic treatment. Data provide demographic and socio-economic informations related to the child, the parents and the household. Statistical analysis was carried out using a weighted multivariate logistic regression model.

Results:

Prevalence of orthodontic treatment among subjects aged 8-11, 12-15, 16-18 years was 9%, 23% and 9% respectively.

Multivariate analysis showed that orthodontic treatment is more likely for females, living in a 2-children family, in urban area, whose mother was born in France, in higher socio-economic groups, with private medical insurance (adjusted OR ranged from 1.2 to 1.9).

Conclusion:

There are social disparities in orthodontic care in France. It reinforces the view that current orthodontic treatment coverage should be put into question.


0178 (111661)

Identification of Residual Products from Six Different Resin Cements. S.H. ALTINTAS1, B. BAGIS2, A. YASAR1, and A. USUMEZ3, 1Karadeniz Technical University, Trabzon, Turkey, 2Karadeniz Technical University, Faculty of Dentistry, Trabzon, Turkey, 3Gaziantep University, Turkey

Objectives: The aim of this study was to identify residual acrylates and other products from six different resin cements in order to obtain information about the composition and occurrence of sensitizing acrylates.

Methods: The tested resin cements were Variolink II (Ivoclar), Rely X ARC (3M ESPE), ResiLute (Pulpdent), Nexus 2 (Kerr), Rely X Unicem (3M ESPE) and SuperBond C&B (Sun Medical). Disc shaped specimens (5 mm in diameter, 2mm in height) were polymerized and stored in ethanol/deionized water solution for 3 days. The residual acrylates and products of resin cements in solution were identified by using gas chromatography with mass-selective detection and liquid chromatography with ultraviolet detection. Among components detected were monomers, co-monomers, initiators, stabilizers, decomposition products and contaminants. Identification was confirmed with reference substances, if available.

Results: The identified residual acrylates which are not reported in safety data sheets were Methyl methacrylate (MMA), Bisphenol A diglycidyl ether (BADGE), Bisfenol A for Variolink II, MMA, BADGE, Urethan dimethacrylate (UDMA) for Rely X ARC, MMA, UDMA, BADGE, HEMA, TEGDMA, Bis 2,2-bis-[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]-propane (Bis-GMA) for ResiLute, MMA, UDMA, TEGDMA, HEMA, BADGE, Bisphenol A dimethacrylate (BisDMA), Bis-GMA for Nexus 2, Bis-GMA, UDMA, BADGE, Bisfenol A, Bisfenol A Ethoxylate, HEMA, MMA for Rely X Unicem, HEMA, UDMA, BADGE, Bis-GMA for SuperBond C&B.

Conclusions: The study demonstrated that the tested products contained acrylates which are not reported in the safety data sheets. Safety data sheets need to be improved so that the health risks for patients and dental personnel can be reliably assessed.


0179 (109795)

Mechanical properties of various mixing ratios of a dual-curing resin-cement. B.J. STEMPLINGER, M. BEHR, and G. HANDEL, Regensburg University Medical Care Center, Germany

Objectives: Hand-mixing of dual-curing resin cements using aberrant mixing ratios may alter their mechanical properties. As an example, this study investigated the therapeutical range of dual-curing resin cement Calibra™ (Dentsply, Konstanz, G).

Methods: Starting with the recommended 1:1 base/catalyst ratio, mixings with 30 wt% and 60 wt% too much and too few base/catalyst ratio were carried out. All specimens were light-cured for 40s. Vickers Hardness (VH) (after 24 hours), three-body abrasion and flexural strength (after 24 hours) were evaluated. Difference Scanning Calorimetry (DSC) showed enthalpy changes of the cement setting depending on the ratio. Statistics: Means, standard deviations, ANOVA.

Results:

base/catalyst

VH [MPa]

Wear after 200,000 cycles [µm]

Flexural strength [MPa]

1.6:1

50.3 ± 2

111.3 ± 3

116.8 ± 7

1.3:1

51.6 ± 2

114.6 ± 11

128.5 ± 9

1:1 (regular)

64.9 ± 4

99.8 ± 11

116.5 ± 7

1:1.3

52.8 ± 5

114.7 ± 9

114.3 ± 5

1:1.6

52.4 ± 2

115.7 ± 13

100.4 ± 8

Vickers hardness was statistically significant higher for the regular 1:1 mixing ratio (p<0.001). The flexural strength (p=0.153) and the three-body abrasion (p=0.058) seemed to be not affected by different ratios. DSC showed enthalpy changes even after 24h of light-curing for all ratios.

Conclusions: The investigated dual curing resin cement tolerates a wide range of mixing errors.


0180 (109911)

Evaluation of Two New Veneering Techniques for Zirconia-based FDPs. T. ALBRECHT, F. PERKON, S. HEINTZE, and H. KAPPERT, Ivoclar Vivadent, Schaan, Liechtenstein

Objective: To evaluate the risk of chipping and the fracture strength of two new techniques to veneer zirconia-based FDPs by CAD/CAM technology. Materials and Methods: Forty-eight standardized three-unit zirconia frames (e.max ZirCAD) for FDPs were milled with the Sirona InLab system and veneered with a lithium-disilicate glass ceramic (e.max CAD) which was also milled by CAD/CAM technology (CEREC 3). The anatomical dimensions were equal for all FDPs. Frame and veneer were joined by two different techniques: Group I (n=12): glass soldering material during the cristallization process of e.max CAD; Group II (n=12): luting technique with a self-adhesive composite (Panavia 21; group II) after acid-etching and silanization of the veneer material. Half of the FDPs were luted adhesively (Panavia 21) on PMMA abutments und submitted to a rigid dynamic eccentric loading protocol in a chewing simulator (Willytec) with simultaneous thermocycling (5°C/55°C). The FDPs were loaded on the pontic with a steel stylus (Ø 2.4mm) that moved 2 mm from the central fossa to the buccal cusp. The load was increased after each 100,000 cycles (3kg, 5kg, 9kg). The other half of the FDPs were cemented on standardized steel abutments with a glass ionomer cement and submitted to a fracture load test in a universal testing machine until failure. Results: During dynamic loading chipping has occurred in one FDP of Group I and in two FDPs of Group II. The mean fracture load of the not pre-loaded FDPs was 2179(±648) N for Group I and 1492(±257) N for Group II. One-way ANOVA revealed a statistically significant difference between both groups (p=0.003). Conclusion: The risk of chipping can be regarded as minimal and the mean fracture load was well above 1000 N. Therefore, the new techniques can be evaluated in clinical trials with an adequate safety level.


0181 (110053)

Effects of fluoride on structure,morphology and hardness of plastic brackets. C. TZIAFA1, S. ZINELIS2, T. ELIADES3, and G. ELIADES1, 1University of Athens (EKPA), Greece, 2University of Athens, Greece, 3University of Thessaloniki (AUTH), Greece

Objectives: To investigate the surface morphology, structure, molecular and elemental composition and hardness of plastic brackets exposed to different fluoride solutions.

Materials and methods: Two types of plastic brackets were used (Silicon and Spirit). Both of them were exposed to three fluoride solutions (APF, NaF and SnF2). Each type of bracket was studied before and after cyclic immersion (1 min each time, 10 times) in each F- solution by (a) ATR FTIR spectroscopy; (b) scanning electron microscopy and X-ray energy dispersive microanalysis (SEM/EDS); and (c) Vickers hardness measurements. Hardness data were analyzed with two-way ANOVA and Tukey test at the .05 level of significance with bracket and fluoride solution as predictors.

Results: ATR FTIR showed that both brackets have similar organic phase (polycarbonate). After APF treatment an increased contribution of -OH peaks at 3200 cm-1 (str) and 1640 cm-1 (b) was observed in both brackets. SEM revealed that APF and NaF had prominent effects on the morphology and surface structure of brackets with projections of reinforcing fibers, and surface deterioration. EDS showed evidence of Al, Si, Ca, Mg, K, assigned to reinforcing glass fiber constituents. No difference was found among the three treatments and two bracket type in hardness, which ranged in the order of 20 VHN.

Conclusion: Repeated exposure of plastic aesthetic brackets to fluoride solutions may have a pronounced effect on structure and morphology, however no hardness changes are observed.


0182 (110824)

Porosity evaluation of ormocer- and dimethacrylate-based composites using X-ray micro-tomography. M.M. HAMMAD1, L.M. CAVALCANTE1, L.F.J. SCHNEIDER1, A. QUALTROUGH1, and N. SILIKAS2, 1The University of Manchester, United Kingdom, 2University of Manchester, United Kingdom

Objectives: To evaluate the porosity of two different matrix-types of dental composites with three varying filler content by using X-ray micro-tomography (micro-CT). Methods: A dimethacrylate- Grandio (GRA) and a model pure ormocer-based-matrix ORMOCER (ORM) were used. Each material had three different types according to their filler content (%w/w): composite (87% and 86%), flowable (80% and 79%) and fissure sealer (70% and 69%) for GRA and ORM respectively. The materials were packed into metallic moulds in order to obtain disc specimens (10 mm diameter x 1.0 mm thickness). The materials were then photo-activated for 40 s from top and bottom surface. A total of 36 specimens were prepared, six discs for each material (n=6) and dry-stored for 24 h at 37°C until testing. The specimens were scanned at a resolution of 19.4µm using Skyscan 1072 micro-CT. The machine operated at a voltage of 104 kV and current of 84 ìA. 50 sliced images were obtained horizontally along the length of the specimens. Three-dimensional reconstructions were made, the volume ratio of pores in the specimens were calculated and subsequently changed to percentages. The results were submitted to 2-way ANOVA (factors: matrix and filler content) and Tukey post-hoc statistic test (p=0.05). Results: The type of matrix had no influence on the porosity (p=0.118), while filler content had (p=0.049). The interaction filler*matrix was significant (p=0.042). Filler content affected the porosity only for ORM. Porosity values ranged from 0.04 to 0.06% for GRA and 0.03 to 0.08% for ORM. No significant correlation was detected between filler content and porosity (r2=0.20). Conclusion: Ormocer-based composite with higher filler content produced a less porous material compared to flowable and sealer material. The filler content had no effect on dimethacrylate-based-matrix.


0183 (110831)

Measurement of shore hardness on thin samples. M. BRADEN, A. SIDDIQUI, M. PATEL, and S. PARKER, Barts and the London School of Medicine and Dentistry, United Kingdom

Objectives:  To test a theoretical model which predicts the effect of sample thickness on  Shore Hardness.

ASTM D2240 specifies that samples should be at least 6mm thick, and measurements taken at least 12mm from any edge. However, measurements are often taken on thinner samples

Methods:

The following materials were used:

Extrude Light, Medium, and Heavy Body, MPV, and Extra Putty(Kerr USA), Evatouch Super ( GC Japan ), Oranwash VL (Zhermack, Italy) . These  were mixed according to manufacturers instructions and samples  moulded as plane sheets 1,2,3,& 6mm thick

Shore Durometer Readings were made using  a Congenix Wallace  Hardness tester.

Using the  6mm thick samples as the standard, the theoretical  prediction was based on three equations:

                            i) that, relating the Shore Hardness Reading (s) to the depth of penetration  of the indentor(d) :

                                                 d(cm) =0.254-2.54s                    1)

                               ii) that of Waters, relating the effect of sample thicknes (t) on the classical force- indentation equation for a cylindrical indenter (radius=R)

For  thinner samples, the following equation was found to apply:

                                                      d1/d =f(t/R)                    2)          

where f(t/R) is a function only of the ratio t/R; values for   f   are tabulated in the literature.

 

 Here the value of s for a 6mm sample is used to calculate d

For other values of t, t/R is calculated,  f(tR) found, and d1 calculated from 4)

This is now substituted in 1) to get the  s1 results

 Results:

             Tests of the theory are shown in Table 1., for the hardest(1) and softest(2) materials studied.

 

t(1) mm

Hardness(1)

Exp           Theory

t(2)mm

 

Hardness(2)

Exp             Theory

0.8

66.3          66.5

0.98

80.9            79.7

1.55

45.3          54.3

1.84

72.5            73.93

2.96

37.0          44.1

2.97

71.4            72.5

6

35.0          35.0 

6.07

69.1            69.1


 

Conclusions:

 The proposed theory fits the experimental data adequately. Note the thickness dependence is greatest with the thinnest specimens

 

 

 

 

 

 

.


0184 (110903)

Evaluation of different impression materials by Shark- fin test. K. STEBNER, C. KOLBECK, R. LANG, and G. HANDEL, Regensburg University Medical Center, Germany

Objectives: The aim of this study was to evaluate rheological properties of different impression materials using the Shark-fin test. In addition a new method for evaluation of the shark-fin specimens was introduced.

Methods: 10 samples of each impression material (see table results) were made according to the usual shark-fin examination. The specimen was digitised via Optimas 6.2 on a light-optical microscope. The evaluation was carried out with length and area measurement functions of the Optimas 6.2 software . Medians and 25%/75% percentiles were calculated. Statistics: Mann- Whitney- U Test (α= 0.05)

Results:

Material

Manufacturer

Height [cm] median (25%/75%)

Area [cm²] median (25%/75%)

Permadyne Garant

3M Espe, G

1.39 (1.37/1.42)

26.48 (26.05/27.07)

Impregum Garant Duo Soft

3M Espe, G

1.48 (1.43/1.51)

29.21 (28.47/29.96)

Express Ultra Light

3M Espe, G

1.49 (1.43/1.54)

29.24 (28.08/30.64)

Panasil Contact

Kettenbach, G

1.35 (1.29/1.40)

26.49 (25.72/27.90)

Aquasil Ultra XLV Regular

Dentsply, G

1.34 (1.30/1.37)

27.62 (27.62/28.62)

 

Conclusion: Comparing height with area the same order of materials was found. Nevertheless the digitised evaluation of specimen should be preferred in comparison to the ruler examination.


0185 (110977)

Flexural strengths of self-adhesive resin cements. E. MAGNI, F. PAPACCHINI, I. CONIGLIO, M. SEDDA, and M. FERRARI, University of Siena, Italy

Objectives: To compare the flexural strengths of three self-adhesive resin cements. Methods: Ten specimens measuring 2mm×2mm×20mm were created with each of the following self-adhesive resin cements: 1) A widely investigated self-adhesive cement (RelyXUnicem, 3M ESPE), which served as reference; 2) and 3) Two more recent self-adhesive cements (G-Cem, GC Corp. and Biscem, Bisco Inc.). The specimens were light-cured for 30s from each surface (VIP, Bisco; 600mW/cm2 output) and left undisturbed for 15min before being stored 24h in an environment 100% saturated in humidity at 37°C. A three-point bending test was performed in a universal testing machine (Triax50, Controls)  at crosshead speed of 0.75mm/min. The load at failure was recorded and the flexural strength (σ) was calculated in Megapascals (MPa) using the equation: σ= 3Fl/2bh2,

where F= load at failure (N), l= spam between the supports (mm), b= specimen width (mm), and h= specimen height (mm). The flexural strength data were analyzed with the One-Way ANOVA followed by the Tamhane's test. Results: The One-Way ANOVA revealed statistically significant differences among the groups (p<0.001). Means and SD of the measured flexural strengths are reported in the Table.

Table: Means(SD) of the measured flexural strengths (p<0.05). Different superscript letters indicate statistically significant differences. The number of tested specimens is reported in square brackets.

Self-adhesive cement

Flexural strength(MPa)

RelyXUnicem (reference group)

61.63(24.94)a

[10]

Biscem

29.70(3.37)b

[10]

G-Cem

41.43(10.23)a

[10]

Conclusion: The flexural strength of G-Cem resulted comparable to that of the widely investigated RelyXUnicem. Biscem exhibited a lower flexural strength in comparison to the other two investigated cements.


0186 (111002)

Elastic moduli of resin-composites with silorane, ormocer and dimethacrylate matrices. L.M. CAVALCANTE, L.F. SCHNEIDER, K. MASOURAS, N. SILIKAS, and D. WATTS, The University of Manchester, United Kingdom

Objective: To determine the elastic properties of a silorane- and an experimental ormocer- versus dimethacrylate-based matrix composites. Methods: Two materials of novel matrix chemistry: Filtek Silorane (SIL) and experimental Ormocer (ORM) were compared with two dimethacrylate composites: Grandio (GRA) and ELS - Ceramco (ELS). Cylindrical specimens (5 mm diameter x 6 mm) were prepared in moulds from each material (n=12) by thorough irradiation and stored dry for 24 h. Six specimens were used to measure the Young's modulus (E), allowing free radial expansion under axial-compressive loading at 1mm/min. The other six specimens were radially constricted in a rigid stainless steel ring during compression, from which the bulk modulus (B) was calculated using equations of elasticity. Poisson's ratio (ν) was calculated from the equation ν = 0.5 - (E/6B). The results were submitted to One-way ANOVA (p=0.05). To determine any correlation between elastic moduli and w/w filler content, Pearson's test was applied. Results: The filler content, E, B and ν values are reported in the Table below. Statistically significant differences were found among the materials. A significant correlation was observed between elastic moduli and filler content (r2=0.99). Thus materials with higher filler content, i.e: ORM and GRA, presented higher elastic moduli than SIL and ELS.

Material

SIL

ORM

GRA

ELS

Filler content (% w/w)

76

86

87

74

E (GPa)

4.0 (0.7) B

7.2 (0.7) A

7.9 (0.5) A

3.1 (0.3) B

B (GPa)

14.6 (0.9) C

23.6 (0.9) A

23.1 (1.2) A

16.9 (0.8) B

Poisson's ratio - ν

0.45

0.45

0.44

0.47

Conclusions: Elastic moduli varied linearly with filler-fraction, being maximal for the ormocer and the conventional dimethacrylate. The silorane composite and the ‘ELS' dimethacrylate had lower moduli. These lower moduli may contribute to reduced shrinkage-stress.

0187 (111003)

Microhardness of Flowable Composite Light-cured through Fibre-reinforced Composite. W.M.M. FENNIS1, N. RAY2, C.M. KREULEN1, and N.H.J. CREUGERS1, 1Radboud University Nijmegen Medical Centre, Netherlands, 2National University of Ireland, Cork, Ireland

Objectives: To assess the influence of indirect fibre-reinforced composite (FRC) material on microhardness of light-curing flowable resin composite. Methods: To simulate a placing procedure of indirect restorations, cured slices (thickness 1.5 mm, diameter 8 mm)of resin composite (Clearfil AP-X, Kuraray) (Group 1), FRC (Everstick, StickTech) (Group 2) or air (control) (Group 3) were placed on top of rings (thickness 1.5 mm) filled with uncured flowable resin composite material(Clearfil Majesty Flow, Kuraray). The flowable composite simulated the luting cement or restoration basing. Light-curing tip was placed on the top slice with exposure times of 20, 40 and 60 seconds. For each group 10 specimens were prepared for each exposure time. Top surface Vickers microhardness numbers (VHN) of the flowable composite layers were recorded. Results were analyzed with one-way Anova and post-hoc tests (significance level 5%). Results: Maximum VHNs for Group 1 were reached after 60 seconds, whereas this was 40 seconds for the other groups. For all exposure times VHNs of Group 3 were significantly higher than that of the other groups. Conclusion: Results suggest that the presence of an indirect restoration impairs polymerisation of resin luting or basing composite. The addition of FRC to an indirect resin composite restoration improves hardness of the restoration basing.


0188 (111021)

Influence of storage on the mechanical properties of resin cements. E. MAGNI1, N. ILIE2, R. HICKEL3, and M. FERRARI1, 1University of Siena, Italy, 2Ludwig-Maximilians University Munich, Germany, 3Ludwig-Maximilians-University, Munich, Germany

 

Objectives: To assess the mechanical properties of three resin cements after different storage conditions. Methods: Fifteen 4mm×4mm×2mm specimens were prepared with PanaviaF2.0 (Kuraray Co.), Corecem (RTD) and RelyXUnicem (3M ESPE) and light-polymerized for 30s. Five specimens of each cement were stored at 37°C in one of the following conditions: dry, deionised water or mineral oil. Modulus of elasticity (E), elastic work (We/Wtot), creep (Cr) and Vicker's hardness (VH) of each cement were measured 24h and 1month after storage. The mechanical properties measured 15min after polymerization served as control. Measurements were performed with a microhardness indenter (FischerscopeH100C, Fischer). Data were analyzed with a Multivariate ANOVA and Tukey's test (α=0.05). Results: The cement resulted as a significant factor affecting mechanical properties (p<0.001), time and storage condition affected the properties except of VH (p=0.56) and We/Wtot (p=0.431) respectively. The Table reports the measured mechanical properties. Conclusion: The tested cements exhibited different susceptibility of their mechanical properties to storage conditions over 1month.

Cement

Property

Storage

Control

dry

oil

water

24h

1month

24h

1month

24h

1month

PanaviaF2.0

E(GPa)

4.50(1.19)b

6.57(0.93)de

5.22(1.80)bc

7.57(1.52)ef

6.10(1.48)cd

6.66(0.70)de

2.97(0.75)a

We/Wtot(%)

31.60(2.49)ab

30.29(2.12)a

34.31(4.47)bc

31.05(3.94)a

35.19(5.36)c

28.95(4.74)a

36.57(1.55)c

Cr(%)

4.44(0.31)gh

4.89(0.27)jk

5.07(0.50)k

4.73(0.22)ij

4.61(0.39)hi

4.83(0.49)ijk

4.97(0.41)jk

VH(N/mm2)

13.82(4.81)a

21.00(3.58)b

20.81(4.78)b

25.95(3.58)b

24.79(9.11)b

20.97(5.99)b

10.05(3.94)a

Corecem

 

E(GPa)

9.91(0.39)ij

10.06(0.28)jk

9.75(0.84)ij

9.40(0.42)ghij

8.80(0.93)ghi

8.26(0.43)fg

8.58(0.72)fgh

We/Wtot(%)

50.13(0.91)i

49.82(0.92)hi

51.06(1.14)i

49.31(0.87)ghi

51.09(0.71)i

50.47(1.59)i

51.39(4.02)i

Cr(%)

3.75(0.08)de

3.58(0.06)bcd

3.69(0.16)cde

3.79(0.15)de

3.85(0.20)e

3.90(0.17)e

4.27(0.35)fg

VH(N/mm2)

64.48(5.46)fg

63.25(2.53)efg

65.83(5.63)g

58.84(3.35)def

57.97(5.41)de

54.36(3.65)cd

62.16(13.57)efg

RelyXUnicem

E(GPa)

14.78(1.30)mn

15.61(2.19)n

12.56(1.86)l

14.40(1.00)m

10.23(1.55)jk

11.09(2.38)k

9.48(0.80)hij

We/Wtot(%)

46.83(1.78)efg

46.69(3.20)efg

47.27(3.42)fgh

44.77(1.30)def

46.58(3.80)ef

44.25(3.70)de

42.96(1.66)d

Cr(%)

3.48(0.17)bc

3.18(0.15)a

3.75(0.20)de

3.42(0.18)ab

4.16(0.16)f

3.78(0.17)de

4.61(0.27)hi

VH(N/mm2)

87.85(6.14)i

92.60(6.21)i

79.26(9.34)h

81.43(5.25)h

63.12(4.41)efg

62.30(5.29)efg

50.95(5.59)c

Table: Means(SD) of the mechanical properties. Different superscript letters indicate significant differences(p<0.05).


0189 (111022)

Linear dimensional stability in tissue- conditioners. G. BAYRAKTAR, C. BURAL, D. BIRLER, I. BAYRAMGURLER, and M. TEMIZKAN, University of Istanbul, Turkey

Aim: This study evaluated the linear dimensional stability of tissue conditioners, mixed with increased powder/liquid (P/L) ratio after 2 h of gelation and water storage of 24 and 48 h .

Materials and Method: A total of 24 heat-polymerized acrylic resin discs (3 mm height, 40 mm diameter) were lined with 2 tissue-conditioners mixed with recommended (Va,Fa) or increased P/L ratios (Vb,Fb). Linear dimensional changes were measured after 2 h of gelation and water storage for 24 and 48 h. Data were analysed using one-way ANOVA (p≤ 0.05).

Results: After 2 h of gelation and water storage of 24 h, linear shrinkage were observed in Va (0,92%, 2,82%) and Fa (1,2%, 2,95%) groups, respectively (p>0,05). After 48 h of water storage, linear shrinkage for Va (0,45%) and linear expansion for Fa (0,66%) were determined (p>0,05). When P/L ratios were increased, linear shrinkage were observed in Vb (1,72%, 1,95%) and Fb (2,12%, 2,24%) groups after 2 h of gelation and water storage for 24 h, respectively (p>0,05). After 48 h of water storage, linear expansion in Vb 0,33% and linear shrinkage in Fb groups were measured (p>0,05).

Conclusion: When dentures are lined with tissue conditioners, mixed with recommended or increased P/L ratios, accurate functional impressions can be taken after a period of 24 h.


0190 (111023)

Factors Affect Porosity of Injectable Glass Ionomer Cement. J. LUO, A.J. BUSHBY, and G.J. PEARSON, Queen Mary University of London, United Kingdom

Objective:  To investigate the influence of powder/liquid ratio of two glass ionomer cements using two different bore diameter delivery tubes, on the porosity of injectable glass ionomer pastes.

Method:  Two commercial cements, FUJI IX (GC Dental) [FIX] and Amalgomer (Advanced Healthcare)[AM] were prepared as follows: AM powder was mixed with water as (P+A)/W ratio of 3.575/1 and 2.146/1. FIX liquid contains 50% of water and two combinations of liquid and powder were used as P/A/W= 7.2/1/2.29 [(P+A)/W=3.575/1] and P/A/W=2.575/1/1 [(P+A)/W=3.575/1]. P=glass powder, A= Acid, W= water. The first combination (COM 1) of FIX is the same as AM and the second combination (COM 2) contained more acid.  After hand mixing, the pastes were immediately loaded into a 1 ml plastic syringe connected to a narrow bore needle with either a 1.29mm or 0.89mm diameter. The paste was injected into an epoxy mould containing a spherical cavity of about 3mm diameter. The density of the cements and epoxy moulds was measured using Archimedes Principle. This allowed the theoretical amount of cement required to fill each bubble to be determined.  Having determined the true weight of the mould and injected cement the volume of air incorporated within the cement was determined by subtraction.  5 samples for each variant were measured.

Results: The mean percentage of the air volume was recorded [Table 1].

 

AM L

P/L=3.575/1

AM S

P/L=3.575/1

AM L

P/L=2.146/1

AM S

P/L= 2.146/1

FIX

COM 1

FIX

COM 2

AIR VOLUME (%)

3.29

[sd=1.35]

5.05

[sd=1.14]

3.03

[sd=0.68]

3.9

[sd=1.6]

2.64

[sd=2.6]

7.81

[sd=7.8]

L= 1.29mm needle, S= 0.89mm needle, COM 1= combination 1, COM 2 =combination 2

Statistical analysis was carried out using student"t"Test. There was a significantly greater air void volume when using the smaller bore needle for AM samples [p=0.019] and more acid for FIX samples [p=0.003]

Conclusion: The internal bore of the needle significantly affects the porosity of the glass ionomer pastes. The smaller the needle bore the greater the air void volume. The effect was reduced as the P/L of the paste was reduced. Acid percentage could also affect the porosity of the cement.


0191 (111065)

Nano-dynamic-mechanical Properties of a Nano-composite as Function of Curing Time. N. ILIE, Ludwig-Maximilians University Munich, Germany, and R. HICKEL, Ludwig-Maximilians-University, Munich, Germany

 

Objectives: to analyse the variance of nano-dynamic mechanical properties of a nano-filled dental composite, at clinical relevant depth and by varying the curing procedure. 

Methods: A nano-hybrid composite (Filtek SupremeXT, 3M-ESPE) was polymerised in a mould 2mm high for 5, 10, 20 and 40 seconds with a LED-curing unit (Freelight2, 3M-ESPE, 1241 mW/cm²). The nano-dynamic mechanical parameters (complex, storage and loss modulus, tand) were determined after storing the samples for 24h in distilled water at 37°C (Triboindenter, Hysitron Inc., Minneapolis, USA). The frequency of the sinusoidal force was 110Hz and the dynamic force 5µN. All properties were measured at 2mm depth, at the bottom of the samples.

Results: To differentiate between the individual compounds of the nano-composite, four different zones were selected: Filler, Filler surrounding, Matrix near Filler and Matrix (= Matrix far away from the Filler), and were evaluated statistical (ANOVA/Tukey HSD, α = 0.05 and GLM).

 

Time

Zone

CM

LM

SM

tan

5s

Filler

26.9i(2.4)

0.8a(0.1)

24.4g(3.0)

0.1a(0.0)

Filler surrounding

12.1d(0.6)

1.7b(0.1)

14.3d(0.8)

0.3c(0.0)

Matrix near Filler

8.7b(0.6)

2.1c(0.1)

9.9bc(1.1)

0.4e(0.0)

Matrix

5.7a(0.8)

3.3d(0.9)

5.5a(1.2)

0.5f(0.0)

10s

Filler

26.5i(2.5)

1.0a(0.3)

25.6g(3.2)

0.1a(0.0)

Filler surrounding

18.5g(0.9)

2.3c(0.2)

18.3e(1.0)

0.2b(0.0)

Matrix near Filler

14.4e(0.7)

3.1d(0.2)

14.0d(0.9)

0.3d(0.0)

Matrix

10.5c(0.8)

5.0e(1.8)

9.7b(0.8)

0.4e(0.0)

20s

Filler

27.7i(1.3)

1.1a(0.4)

24.9g(2.8)

0.1a(0.0)

Filler surrounding

21.5h(1.8)

2.4c(0.2)

19.2ef(0.9)

0.2b(0.0)

Matrix near Filler

17.2f(1.0)

3.1d(0.2)

14.6d(0.6)

0.3cd(0.0)

Matrix

12.1d(1.3)

4.5e(0.6)

11.3c(0.9)

0.4e(0.0)

40s

Filler

26.8i(0.8)

1.1a(0.3)

25.0g(1.1)

0.1a(0.0)

Filler surrounding

20.8h(1.4)

2.2c(0.2)

20.7f(1.1)

0.2b(0.0)

Matrix near Filler

16.6f(1.2)

3.0d(0.2)

15.2d(1.0)

0.3cd(0.0)

Matrix

12.0d(1.2)

4.1e(0.4)

11.2bc(3.0)

0.4e(0.0)

 

Conclusion: At 2mm depth, an increase in polymerization time also increased all measured properties. The organic matrix was shown to be inhomogeneous for all curing times, presenting a lowering of the nano-dynamic mechanical properties with the distance to filler. However, for a longer polymerisation time, these differences tended to decrease.


0192 (111085)

Artefacts caused by dental materials in MRI and CT. T. KLINKE, J. WETZEL, and R. BIFFAR, University of Greifswald, Germany

Objectives: The specifications of dental materials for oral applications are well defined and accepted. Less known is their influence on imaging with computed tomography (CT) and magnetic resonance imaging (MRI). The diagnostics of CT or MRI images is complicated by ingredients of filling or restoration materials which cause superposition, erasements and distortions. The aim of this in-vitro research was to characterise artefacts of different restoration materials in CT and MRI.

Methods: Test specimens of metal and non-metal restoration materials were fabricated and embedded with a reference specimen. The samples were placed in a 1.5-teslar MRI and CT (both Siemens, Germany) and evaluated in two dimensions. Artefact size and distortions were measured by using digital image analisis software.

Results: Out of 35 filling materials 6 materials showed no artefacts in CT. All metal based materials and 9 filling materials showed inhomogeneities in MRI. Artefacts which were caused by materials containing titanium and zirconia as well as filling materials consisting of rare earths showed erasements.

Conclusions: Metal based restoration materials had strong influence on CT, but they did not cause any artefacts in MRI images. Rare earths, such as Ytterbiumtrifluorid, as component of dental materials led to effacements in the MRI, but not in the CT. Developments of new dental materials should recognise these findings to reduce artefacts in MRI and CT images.


0193 (111171)

Shrinkage/Expansion Strain of Three Luting Cements During Setting. M. AL-RABAB'AH, and H. DEVLIN, University of Manchester, United Kingdom

Objective: to assess the shrinkage/expansion strain behaviour of three different types of luting cements used commonly with high strength all-ceramic crowns.

Methods: specimens ( 7 per group) were mixed from the following luting cements according to their corresponding manufacturers' instructions ; glass ionomer Ketac Cem (K), Panavia 21 EX adhesive cement (Pa) and RelyXTM Unicem self-adhesive cement®. Each freshly mixed specimen was immediately loaded into a bonded disc apparatus attached to a Linear Variable Displacement Transducer (LVDT). The signals recorded during setting in millivolts (mV) by the LVDT were transformed into displacement (Shrinkage/Expansion) strain measurements in µm based on a known calibration factor. Strain measurements were plotted against time and tested for statistical difference using a Kruskal-Wallis test followed by Mann-Whitney test.

Results: both adhesive cements (Pa&R) showed net shrinkage strains ( Pa= (1.9±0.3) %, R= (2.1±0.2) % while glass ionomer cement (K) almost reached zero net shrinkage (P<0.001). Ketac cem showed greater fluctuation in strain behaviour during setting.

Conclusion: adhesive resin cements have a steady shrinkage strain during setting while glass ionomer cement showed wider range of shrinkage/expansion strain which might lead to cohesive failures in the cement.


0194 (111315)

The Effect of Phosphate Buffered Saline on Mineral Trioxide Aggregate. M. LOTFI1, S. VOSOUGHHOSSEINI2, S. BAKHSHI SHAYAN3, and B. RANJKESH3, 1Department of Endodontics and Research center for pharmaceutical Nanotechnology/Tabriz Univerity of Medical Sciences, Iran, 2Department of Oral Pathology and Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Iran, 3Dental School, Tabriz University of Medical Sciences, Iran

Objectives: The aim of this study was to compare the sealing ability of white and gray mineral trioxide aggregate as root end filling material after immersing in Phosphate Buffered Saline (PBS). Methods: Fifty five single-rooted human anterior teeth were used in this study. Teeth were randomly divided into 2 experimental groups with 20 teeth each and 2 negative and one positive control group each with 5 teeth. The root canals were prepared with the conventional step-back technique and were obturated with gutta percha (VDW, Munich, Germany) without sealer, using a cold lateral compaction technique. The apical 3 mm of the roots was resected. The apical ends of the roots were prepared with the Kis-3D microsurgical ultrasonic instrument (Spartan, Missouri, USA).The apical preparation was filled as follows: group A- WMTA (Tooth colored formula, Dentsply, Tulsa Dental,Tulsa, OK, USA); group B- GMTA (Dentsply, Tulsa Dental, Tulsa, OK, USA).15 teeth were divided randomly into 3 groups of five teeth each as 2 negative and one positive control groups. All teeth were incubated for 4 hours at 37 degrees Celsius in 100% humidity and then immersed in one Liter of PBS for 3 days at 37 degrees Celsius. Linear dye penetration was measured in millimeters. Data was analyzed using the ANOVA test at the 0.05 level of significance. Results: All the preparations in the positive control group demonstrated leakage throughout the entire lengths. The root – ends preparations in the negative control groups that filled with WMTA or GMTA did not display any leakage. The mean dye leakage was 0.5 ± 0.1 mm for WMTA and 0.3 ± 0.1 mm for GMTA group respectively. There was no significant difference in leakage between two experimental groups (p=0.14). Conclusions: This study suggests that both types of MTA can prevent microleakage when suspend in PBS.


0195 (111326)

Surface Topographic Image of Mineral Trioxide aggregate and Portland Cement. S. VOSOUGH HOSSEINI1, M. LOTFI2, B. RANJKESH3, and S. BAKHSHI SHAYAN3, 1Department of Oral pathology and Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Iran, 2Department of Endodontics and Research Center for Pharmaceutical Nanotechnology, Tabriz Univerity of Medical Sciences, Iran, 3Dental School, Tabriz University of Medical Sciences, Iran

Objectives: Mineral trioxide aggregate (MTA) is a mixture of Portland cement and bismuth oxide. Both MTA and Portland cement are used as bioactive materials in endodontic treatment. Surface topography of biomaterials has an important role in biocompatibility. The purpose of this research was to compare the surface crystallographic pattern of Portland cement and MTA under scanning electron microscope. Methods: White mineral trioxide aggregate (WMTA) and Portland cement were mixed with distilled water separately and mounted in an individual disc. The samples were then allowed to set in an incubator at 37°C for 48 hours without surface touching. After setting, scanning electron microscope was used for imaging and to determine surface topography. All analyses were carried out at 15 kV. Because of the inhomogeneous nature of the samples, final image for each sample was based on the average of 12 analyses. Results: Needle like crystals covered the surface of all WMTA samples. Cubic and hetragonal crystals were shown on the surface of all Portland cement samples. Conclusions: It seems that bismuth oxide that adds to MTA as a radio opaque agent play a role on crystal pattern on the surface of WMTA. Further studies need to reveal the role of these patterns on biocompatibility of MTA.


0196 (111444)

Microhardness of self-adhesive compared to conventional resin cements. R. OSORIO1, R. FULGENCIO2, R.M. CARVALHO3, F.S. AGUILERA1, E. OSORIO1, and M. TOLEDANO1, 1University of Granada, Spain, 2Universidade Gama Filho, Rio de Janeiro, Brazil, 3Bisco, Inc, Schaumburg, IL, USA

Objectives: To evaluate the microhardness of some self-adhesive resin cements (Rely X Unicem – 3M ESPE,  G-Cem – GC, Bis-Cem –Bisco) compared to conventional dual cure resin cements (Calibra – Dentsply, Panavia F2.0 – Kuraray, Multilink Sprint –Ivoclar Vivadent).

Methods: Five specimens of each resin cement were prepared with a disk-shaped (8.0 mm diameter and 2,0mm thickness). Photo-activation was performed (40s@500mW/cm2) using a conventional QTH light-curing unit (Optilux 401).  Specimens were kept for 24 hours at 37oC. Afterward they were attached to a pre-molded resin matrix enclosed in a PVC pipe. Specimens were polished using silicon carbide paper from 500 to 4000 grit-number for a microhardness testing  at an Instron Wolper hardness tester. Five identations for each specimen were performed with a load of 300g during 60 s and Vickers hardness was determined in VHN.  Data were submitted to one-way ANOVA and Student Newman Keuls multiple comparisions (P< 0.05).

Results:

Material

GCem

RelyX Unicem

Multlink Sprint

BisCem

Panavia F 2.0

Calibra

Vickers hardness (VHN)

64.4(16.6) a

49.2(11.3)b

29.3(9.6)d

44.1(8.7)b,c

40.9(15.5)c

38.4(9.4)c

Means (Standard deviation) for each experimental group are listed in the table.  Groups with by the same letter are not significantly different. Differences occurred in microhardness values according to resin cement.

Conclusions: In general, self-adhesive resin cements showed higher microhardness values than conventional luting cements. (Grants number - CAPES# O565-07-5 – CITYT/FEDER:MAT04-06872-C03-02).

 


0197 (111454)

Flexural strength of self-adhesive resin cements. R. FULGENCIO1, A. PINTO2, R.M. CARVALHO3, R. OSORIO4, F.S. AGUILERA4, and M. TOLEDANO4, 1Universidade Gama Filho, Rio de Janeiro, Brazil, 2Instituto superior de ciencias da saude, Monte Caparica, Portugal, 3Bisco, Inc, Schaumburg, IL, USA, 4University of Granada, Spain

Self-adhesive cements contain acidic monomers that may compromise curing and consequently the mechanical properties when compared to traditional non-adhesive cements.

Objectives: This study evaluated the three-point bending flexural strength of self-adhesive resin cements (Rely X Unicem – 3M ESPE, G-Cem – GC, Bis-Cem –Bisco) compared to conventional non-adhesive resin cements (Calibra – Dentsply, Multilink Sprint –Ivoclar Vivadent, Panavia F2.0 – Kuraray).

Methods:

Five rectangular specimens (25×2×2 mm) were prepared from each cement. Light-curing was carried out immediately after mixing and dispensing using a conventional QTH light-curing unit (Optilux 401) with a power density of 500 mW/cm2 and placed in  distilled water at 37 °C for 48 hours. The flexural strength was determined in a Instron universal machine (Model 4411, Instron Corp., Canton, MA) at 0.75 mm/min. Data were submitted to one-way ANOVA and Student Newman Keuls (P< 0.05).

Results:  Mean flexural strength and standard deviation are presented in the table. Same letters indicate no differences between groups

Material

GCem

RelyX Unicem

Multlink Sprint

BisCem

Panavia F 2.0

Calibra

Flexural Strength- Mpa (SD)

47.7 (16.0)c

76.7 (13.0)b

104.9 (8.8)a

88.7 (8.5)a,b

106.6 (21.2)a

91.2 (14.4)a,b

In general, conventional cements presented higher flexural strength than self-adhesive ones. Among the self-adhesive, the weakest material was G-Cem followed by Unicem and BisCem that were not different from one another.

Conclusions: Self-adhesive resin cements presented lower flexural strength than conventional, non- adhesive resin cements. (Grants number - CAPES# O565-07-5 – CITYT/FEDER:MAT04-06872-C03-02).


0198 (111466)

Evaluation of dental alginates impression materials in special needs kids. L. LAFFRANCHI1, B. CROVATO2, D. DALESSANDRI1, F. ZOTTI3, P. FONTANA4, and L. VISCONTI3, 1Università degli studi di Torino - Dipartimento di scienze biomediche e oncologia umana, Italy, 2University of Brescia, Italy, 3Università di Brescia, Italy, 4Faculty of Dentistry, University of Brescia, Italy

Objectives: The aim of this study was to compare 5 different alginates for dental impressions which we used only for orthodontic ones.

Materials: We used 5 alginates (Alginplus Tropical “A”, Alginmax “B”, Alginmajor “C”, Alginkid Orthodontic “D”, Alginplus Fast “E”, Major Dental, Moncalieri-To, Italy, www.majordental.com) for impressions to develop models for orthodontic studies.

Methods: Fifty patients “special-needs kids-down syndrome” took part in our group; there were two operators: one orthodontist was assigned to mixing and the second one was assigned to setting. Each patient had two impressions, for a total of 100 impressions (20 impressions for each alginate). The producer's instruction was to develop impressions at 23°C of atmosphere and defined quantities, which we respected. We decided to use the same temperature for water,4°C.

For each alginate we developed a quality evaluation defined by five features: mixing, water absorption,consistency, processing time, curing time,and a total final evaluation.

For each feature we considered two degrees of quality:POSITIVE, favourable for working time; NEGATIVE, not favourable for working time.

In our clinical practice with special-needs kids we need very short working time.

Results: The comparison shows no significant clinical differences among our alginates.

• Mixing: positive

• Water absorption: positive

• Consistency: positive

• Processing time: positive

• Curing time: positive, the best for alginate “D” (1'50'')

Total final evaluation: positive

Conclusion: The differences are not significant to guide us in a specific choice of one of these alginates. The only one important feature is curing time because of kind of our patients: “special-needs kids”, who have a poor and very short in time collaboration for invasive dental procedures in comparison with normal people.


0199 (111476)

In-vitro characterisation of voids within resin-composite restorations using micro-CT. H. ELBISHARI, N. SILIKAS, and J.D. SATTERTHWAITE, University of Manchester, United Kingdom

Objective: To investigate and quantify the effect of placement techniques of resin-composite on the presence of voids within restorations using micro-CT

Methods: 30 Ivorine teeth (Kavo EWL Model) were used. A standardised MOD cavity preparation was prepared in each one. Teeth were randomly allocated to two groups based on the placement technique (bulk filling or incremental layers) and then restored with a light cure resin-composite (Spectrum TPH universal composite Dentsply UK).

Scanning of all teeth using a micro-CT (Skyscan 1072) was performed followed by 3D reconstruction using NRecon software and analysis using CTAn software. The percentage volume occupied by voids within each restoration was calculated. Data were analysed and compared with a T-test (p< 0.001).

Results: The mean volume of voids within the restoration was greater in the incremental layers group (0.57%) than in the bulk group (0.10%). This difference was statistically significant (p<0.001)

Conclusions: The percentage of voids within a restoration is dependant on technique and is higher with incremental layering. This may have clinical relevant.


0200 (111500)

Rheological characterisation of a commercial glass poly(vinylphosphonate) cement. P. BROOKBANK1, O. GHITA1, M.E. BARBOUR2, and K. EVANS1, 1University of Exeter, United Kingdom, 2University of Bristol, United Kingdom

Objectives: It has been shown that the working and setting properties of traditional glass ionomer cements (GICs) are affected by the cement mixing time. This study (co-funded by Kemdent UK and Great Western Research Initiative) aimed to explore the effects of mixing time on the working and setting time of a glass poly(vinylphosphonate) cement.

Working time is defined as time taken for vibrational displacement, measured using a rheometer, to reach 95% of the initial displacement value. The setting time is when the displacement reaches <5% of the initial value. The "tan delta" represents the phase separation between the applied stress and resultant strain waves and is used to calculate complex viscosity.

Methods: The material used was a restorative cement, Diamond Carve Rapid Set Capsules. Characterization was carried out using an oscillating rheometer. Capsules were mixed using a conventional amalgamator at 3000 rpm for 15, 20 or 25 seconds. Working and setting times were measured using the stated criteria.

Results: Working and setting times decreased as mixing time increased. The material's viscosity showed a similar trend for each mixing time, increasing for the first 5.5 min, after which the viscosity of materials mixed for different times began to deviate. The cement with the shortest mixing time ultimately reached a higher viscosity than that with the longest mixing time. The tan delta decreased with time until 5.5-7.5 min after mixing, at which time an increase was observed.

Conclusions: The decrease in working and setting time with increasing mixing time is in accordance with observations of traditional GICs. The increase in tan delta (decrease in viscosity) may be attributed to the replacement of bivalent strontium and calcium cations with trivalent aluminium cations to form the final cement. That this exchange of cations may cause a decrease in viscosity has not been previously observed.


0201 (111572)

Comparison of the transverse strength of six acrylic denture resin. F. UNALAN, University of Istanbul, Turkey, O. GURBUZ, Private practice, Istanbul, Turkey, and I. DIKBAS, Yeditepe University, Istanbul, Turkey

Objectives:

To evaluate the transverse strength of three kinds of heat cured acrylic resin, namely, Meliodent HC, Acron S, Lucitone 199; one kind of microwave acrylic resin, namely, Acron MC; one kind of visible light curing resin, namely Triad VLC; and one kind of cold cured acrylic resin, namely Meliodent CC.

Methods:

A total of 60 specimens (65mm x 10mm x 3mm) were fabricated, 10 from each material. The specimens were loaded until failure on a three-point bending test machine (AVK, Budapest). For statistical analysis, Kruskal-Wallis test followed by Dunn's multiple comparison test were used.

Results:

The transverse strength values showed statistically significant differences among acrylic denture resin groups (p=0.0001). The mean transverse strength (N/mm2) was as follows: Acron MC 124.30 ± 9.91, Meliodent HC 120.00 ± 9.13, Acron S 113.30 ± 10.88, Lucitone 199 103.40 ± 11.96, Meliodent CC 84.64 ± 12.93, Triad VLC80.22 ± 9.99.

Conclusion:

Within the limitations of this study, Acron MC showed the highest mean transverse strength value among the materials tested.


0202 (111592)

Comparative study of impact strength of six acrylic denture resin. I. DIKBAS, Yeditepe University, Istanbul, Turkey, O. GURBUZ, Private practice, Istanbul, Turkey, and F. UNALAN, University of Istanbul, Turkey

Objectives:

To determine and compare the impact strength of three kinds of heat cured acrylic resin, namely, Meliodent HC, Acron HC, Lucitone 199; one kind of microwave acrylic resin, namely, Acron MC; one kind of visible light curing resin, namely Triad VLC; and one kind of cold cured acrylic resin, namely Meliodent CC.

Methods:

A total of 60 specimens (75mm x 10mm x 3mm) were fabricated, 10 from each material. The impact strength was evaluated using the Charpy method. The test was performed at room temperature in an impact testing machine (Zwick Pendulum Impact tester, Germany) of a capacity of 0-7.5 joule scale; the specimens were fractured. For statistical analysis, Kruskal-Wallis test followed by Dunn's multiple comparison test were used.

Results:

The impact strength values exhibited statistically significant differences among acrylic denture resin groups (p=0.0001). The mean impact strength (Joule) was as follows:

Lucitone 199 0.56 ± 0.063, Acron MC 0.32 ± 0.048, Acron HC 0.31 ± 0.046, Meliodent HC 0.27 ± 0.048, Meliodent CC 0.20 ± 0.055, Triad VLC 0.16 ± 0.042.

Conclusion:

Within the limitations of this study, Lucitone 199 showed the highest mean impact strength value among the materials tested.


0203 (111613)

Light Stability of a Silorane and a Methacrylate Composite. J. BRODESSER, A. SYREK, C. THALACKER, A. STIPPSCHILD, O. KAPPLER, W. WEINMANN, and R. GUGGENBERGER, 3M ESPE, Seefeld, Germany

Objectives: Aim of this study was to compare the light stability of two chemically different curing composites at different illuminations of a dental operatory lamp.

 

Methods: The radically curing Tetric EvoCeram (EVO, Ivoclar-Vivadent) and the cationic ring opening Filtek Silorane (SIL, 3M ESPE) were exposed at four illuminations (4000 lux, 8000 lux, 14000 lux, and 20000 lux) to a dental operatory lamp. The light stability was determined according the procedure of the EN ISO 4049 except the variation of different illuminations. (EN ISO 4049 only considers 8000 lux).

 

Results: The following table shows the light stability of Tetric EvoCeram and Filtek Silorane in seconds:

 

Material

Manufacturer

t@4000 lx

t@8000 lx

t@14000 lx

t@20000 lx

Tetric EvoCeram

Ivoclar-Vivadent

210

110

60

50

Filtek Silorane

3M ESPE

720

360

180

150

 

 

A reciprocal function for t[EVO]=1,07*10^(-6)/Lux[lx] and t[SIL]= 3,53*10^(-6)/Lux[lx] was found. The statistical correlation factor calculates to R²= 0,971 (SIL) and R²=0,974 (EVO). The quotient of the function yields to a higher light stability of Silorane of a factor of 330%.

 

Conclusion: Filtek Silorane exhibits at every illumination a higher light stability than Tetric EvoCeram. In both cases a decrease of the light stability with increasing illumination was observed. For both materials a reciprocal correlation of 1/time~illumination was found.


0204 (111682)

PEEK- a potential dental biomaterial. T. SPINTIG1, W.-D. MUELLER2, and C. ABERT1, 1Humboldt-Universitat, Berlin, Germany, 2Humboldt-Universität, Berlin, Germany

Objectives:

Aim of the study was the verification of the useability of Polyetheretherketone (PEEK) as a biomaterial for dental implants. This first study is concerned with PEEK material parameters and the inflence of configuration and surface modification on them.

Methods:

45 PEEK specimens (2x10x10mm) have been manufactured from 5 PEEK compounds of different configurations, and were polished.

Afterwards two thirds of the specimens were grinded with bioceramics (GB and TCP) of different grain sizes; 15 specimens remained untreated. Following tests included the determination of Vicker's hardness (VH) using different loads, roughness (Ra, Rz and Rmax) and surface wettability. Finally SEM- micrographs, EDX- analysis and statistics were taken.

Results:

The results of Vicker's hardness evaluation were in a range of 27,87kg/mm2 to 38,31kg/mm2. While the average roughness Rz increased with a ratio 1 : 1,34 : 8,33 (untreated : TCP : GB) the wetting angle decreased with a ratio 1 : 0,69 : 0,76.

This implys an improve of surface wettability. EDX- analysis showed that surface manipulation using bioceramics leads to a significant change in surface configuration.

So the primary dependence of roughness and surface wettability from surface configuration could be displayed.

Conclusions:

Surface treatment of PEEK with bioceramics leads to a modification in ist configuration. This is connected with an alteration of roughness and wetting angle which improves the wettability with hydrophile solvents significantly and should have a positive influence on cell- adherency.


0205 (111684)

Effect of delay in layering particulate filler resin composites. A. MESE, Dicle University, School of Dentistry, Diyarbakýr, Turkey, and M. ÖZCAN, University Medical Center Groningen, Netherlands

Objectives: Adhesion of new layer of particulate filler composites (PFC) to the already polymerized ones may be affected when the time between application of subsequent layers is prolonged. The aim of this study was to compare bond strength of two PFCs relayered after four time points. Methods: Disc shaped PFC (PFC1=Sinfony, PFC2=Targis) (N=96) were fabricated and processed according to each manufacturer's instructions. They were randomly assigned to 4 groups. PFC surfaces were conditioned with their corresponding activator (Sinfony, 3M ESPE) or wetting agent (Targis, Ivoclar-Vivadent). Specimens were stored in dark. After time points of 5 minutes, 24 hours, 1 week, a new layer of PFC of same kind with the substrate was adhered to the substrate in polyethylene molds. In control groups, PFCs were adhered to substrate immediately after application of the adhesive resin or wetting agent. Final polymerization was made in polymerization devices assigned for each PFC. Shear force was applied to adhesive interface in a universal testing machine. Data were analyzed with 1-way, 2-way ANOVA, Tukey's tests. Results: Both the PFC types and relayering time points significantly affected the bond strength results. While PFC1-PFC1 adhesion was not affected when relayering was performed at the tested time points (34.5±5.3 - 32.2±4.4 MPa) (P=.939), it affected the results for PFC2 significantly (38.9±6.9 - 25±5.7 MPa) (P=.0008). When compared to 5 minutes, 24 hours (P=.0028), 1 week (P=.0025) delay showed significant decrease in the results for PFC2. Conclusions: Delay in relayering did not affect the PFC1-PFC1 adhesion but PFC2 showed decreased bond strength especially after 1 week. Restorations made of Sinfony can be relayered at delayed time points up to 1 week but Targis should be processed preferably in one day in order not to experience decrease of bond strength between the layers which may induce clinical chipping problem.


0206 (111730)

Storage Stability of Dibenzoylperoxide Derivatives in Different Monomers. A. GIANASMIDIS, A. BROT, F. ZEUNER, P. BURTSCHER, V. RHEINBERGER, and J.-F. ROULET, IvoclarVivadent AG, Liechtenstein, Switzerland

Since more and more self-curing cements are stored at room temperature, their storage stability must be improved to guarantee the claimed properties over the whole storage period. Dibenzoylperoxide, as the most frequently used peroxide for the paste-paste systems, is the benchmark.

Objective: To determine storage stability of alternative halogeno-substituted dibenzoylperoxide-derivatives used in formulations of dental cements and in combination with different methacrylic monomers.

Methods: Fourteen dibenzoylperoxide-derivatives including bis-(2,4-difluorobenzoyl)-peroxide, bis-(3,3'-bromobenzoyl)-peroxide and bis-(4,4'-trifluoromethylbenzoyl)-peroxide etc. were dissolved in different monomers: 2-hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), 1,10-decanedioldimethacrylate (DMA) and ethoxylated-(3)-bisphenol-A-dimethacrylate (EBADM). The corrected molecular weight from each peroxide was allowed in a concentration of 1-1.5%. At intervals of 1-4 weeks measurements were done by a double determination with a validated iodometric redox titration and an absolute accuracy of 0.03%. The solutions were stored at 37°C up to a period of 23 weeks. To prevent the samples from premature polymerization a high amount of stabilizer was added (5000ppm; 3,5-di-tert-butyl-4-hydroxytoluene - BHT).

Results: None of the experimental peroxides reached the benchmark. In average all the monomers in consideration an overall degradation of less than 20% was achieved. Mixtures with hydroxy groups containing monomers were significantly less stable with a degradation of 30 to 90% than in less polar/hydrophilic monomers with 5-30%. The most hydrophobic monomer 1,10-decanedioldimethacrylate was by far the most stable environment for the investigated peroxides with a low degradation degree of only 5-15%. Note that the highest degradation (always above 70%) was observed with the ethoxylated-(3)-bis-phenol-A-dimethacrylate. Only bis-(4,4'-fluorobenzoyl)-peroxide and bis-(2,2'-fluorobenzoyl)-peroxide had a similar stability compared to dibenzoylperoxide.

Conclusion: The polarity of some monomers influenced the stability of the peroxide in a very significant way. The stability was decreasing by DMA < TEGDMA = UDMA << HEMA << EBADM. This result should be considered in future formulations of self-curing systems.


0207 (111761)

Material Properties of Self-adhesive Resin Cements: a Comprehensive Performance Profile. C.A. WIEDIG, R. HECHT, G. RAIA, and M. LUDSTECK, 3M ESPE AG, Seefeld, Germany

Objectives: The purpose of this in vitro investigation was to compare different self-adhesive resin cements regarding their physical and mechanical properties as well as adhesive strength to create a comprehensive performance overview.

 

Methods: Materials tested were Maxcem™ (Kerr), Biscem®  (Bisco), EMBRACE™ WetBond™ (Pulpdent), G-Cem™ (GC Corp.) and universal self-adhesive resin cements RelyX™ Unicem Aplicap  and Clicker™ (3M ESPE). Flexural strength [MPa] and water sorption [µg/mm3] were determined according to ISO4049. Linear swelling [%] was measured on ISO-specimens after 1 month of water storage (36°C). For tensile bond strength (TBS) testing bovine teeth were ground, polished (600 grit sandpaper), water-rinsed and air-dried. A wax mould (Æ=6mm) was attached to the tooth and filled with cement. Cements were light- (lc, 20s) or self-cured (sc, 1h@36°C) and a metal screw for pull-off was attached. After 24h storage (36°C@100% rel.hum.) bond strength was determined using a universal testing machine (Zwick Z010, 1mm/min) and statistically analysed (multiple range). pH-development during and after cement setting was monitored.

 

Results: see table

 

Linear expansion

Water sorption

Flexural strength

TBS

Substrate

curing mode

 

sc

 

lc

 

lc

 

sc

 

lc

Dentin sc

Dentin lc

Enamel sc

Enamel lc

G-Cem

0.5±0.1

0.5±0.1

52±1

22±8

26±4

2.6±0.6

3.4±1.1

4.6±0.3

3.0±0.5

Biccem

1.9±0.1

1.8±0.1

95±5

49±11

39±10

0

0

6.8±1.0

8.6±1.9

Embrace

2.0±0.2

1.8±0.1

107±2

50±8

93±3

0

0

3.3±3.6

7.1±2.7

Maxcem

1.1±0.1

1.1±0.1

65±2

60±2

70±11

1.1±0.5

0

4.5±1.1

3.9±0.6

Unicem-AC

0.5±0.1

0.5±0.1

36±1

64±4

77±5

2.2±1.7

2.6±1.0

5.4±2.0

7.6±2.4

Unicem-Clicker

0.6±0.1

0.6±0.1

30±14

57±11

87±9

1.7±0.6

3.7±1.6

5,0±1.1

6.8±1.1

 

Conclusion: While all other tested materials exhibit weaknesses in one or the other material property, RelyX Unicem self-adhesive resin cement shows good or best performance in all parameters tested. A both well-balanced and good performance profile can be predictive for clinical success and reliability.

 


0208 (111776)

Rheology of Dental Restorative Cements that Includes Fumed Silica Nanoparticles. N. ZALTSMAN, A. VALDMAN, B. ZALSMAN, K. LIZENBOIM, A. KHASKIN, A. SUVOROV, and I. SUVOROV, BJM Laboratories Ltd, Or Yehuda, Israel

 Objective: The purpose of this study is to investigate and characterize the rheological behavior of 60/40 Bis-GMA/TEGDMA blend frequently used in dental materials in presence of the different fumed silica(FS) particles, 6µ-silanized glass powder(GP).

 Methods:  Four different commercially available treated FS particles were tested for their rheological nature within the resin blend: A– (0.2-0.3µ) untreated FS, B- (0.2-0.3µ) FS treated with polysiloxane, C- (0.2-0.3µ) FS with siloxane and D– (0.2-0.5µ) methacrylsilane FS. Viscosity measurements were taken by Brookfield viscometer in two different tests. At first test all of the solids were examined for their rheological nature within the resin blend by measuring viscosity at varying shear rates and comparing within themselves. The second test consist of three continuous stages: determining the yield stress(YS), accelerating the shearing, stopping the shearing but continuing to measure the stress that still occurs. This compare is to simulate the recovery of materials at the end of shearing. At this stage the example consists of 40wt% resin blend, 55wt% glass powder and 5wt% of particular FS for each sample.

 Results: Bis-GMA/TEGDMA blend exhibited Newtonian fluid viscosity of 530 cP at 25˚C. Applying the Hershel-Buckley model to the mixtures of fluid with GP and D showed close to Newtonian behavior with flow index = 1 and low YS. The three other examples of FS dispersed in resin at different concentrations showed pseudoplasticy even at low FS concentrations. The flow indexes are: A: 0.30, B: 0.61, C: 0.50. YS is: A:100 D/cml, B:2500 D/cml, C:1700 D/cml and D:100 D/cml. The torque relaxation is: A:0%, B:21%, C:16%, and D:0%.

  Conclusions: Heavy glass powders with inert surface increase only the consistency but don't change significantly the Newtonian nature of the resin blend. Longer chains treated FS cause greater yield stress and more shear thinning character.


0209 (111930)

Effect of gauge length of single filament tensile strength. L.V.J. LASSILA, and P.K. VALLITTU, University of Turku, Finland

Effect of gauge length of single filament tensile strength

Objective: Fiber reinforced composites (FRC) are increasingly used in various dental applications. Mechanical properties of polymer matrix, reinforcing fiber and adhesion between fiber and matrix has main factor of final strength of FRC. Aim of this study was to evaluate the influence of gauge length on single fiber tensile test.

Methods: E-glass  or bioactive glass   single fiber (n=30/gauge length) were embedded to acrylate resin using gauge length of 5,10,15,20 and 25 mm. Specimens were tensile tested using loading rate of 1.0 mm/min with a material testing device and maximum load was recorded (N). Mean values and standard deviation for tensile strength values (MPa) were calculated and data were analyzed statistically using one-way analysis of variance, followed by the Tukey B rank order test (p=.05). Results: Analysis of variance indicated significant differences between different gauge length (p<0.05) for both fiber type. By increasing gauge length of single filament, the tensile strength values are decreased.

 Conclusion: If tensile strength of single filament fibers is measured, the effect of gauge length should be taken in account.

Fiber type

Gauge length (mm)

Tensile strength (MPa)

SD

 

E-glass

5

1614

241

E-glass

10

1314

285

E-glass

15

1242

396

E-glass

20

1150

416

E-glass

25

1103

379

 

 

 

 

BioFiber

5

660.16

132.65

BioFiber

10

571.40

119.84

BioFiber

15

523.36

126.21

BioFiber

20

548.04

209.41

BioFiber

25

505.62

89.46


0210 (109543)

Apoptosis of odontoblasts in Pulp of Deciduous and Permanent Teeth. A. MAJORANA1, A. SANTORO2, P. FLOCCHINI2, E. BARDELLINI2, and F. FACCHETTI2, 1Università di Brescia I, Italy, 2University of Brescia, Italy

OBJECTIVES: To examine the extent of odontoblastic layer and the apoptosis of odontoblastic cell population in dental pulp tissue in deciduous (DT) and permanent teeth (PT).

MATERIALS AND METHODS: Dental pulp was obtained from twelve DT and twenty-three PT extracted from thirty-five different patients between 2002 and 2003.

All teeth were immediately fixed in 10% formalin. Twenty specimens were successively decalcified in 10% nitric acid for at least 48 hours and embedded in paraffin. To perform immunohistochemistry the remaining twelve DT were differently decalcified in EDTA solution for 12 hours after the removal of enamel with a slow-speed saw under water lubrication.

Histomorphometry was carried out on photomicrographs of the entire section stained from each specimen by means of the olympus BX-60 microscope. The quantification of odontoblastic layer extent was assessed by the odontoblastic index (OI), defined as the ratio of odontoblastic layer length to pulp chamber perimeter x 100.

Dental pulps of six DT and twenty PT were stained for anti-ssDNA, using formalin-fixed tissue sections. The apoptotic index was defined for odontoblastic layer as the ratio of ssDNA-positive odontoblast to all counted odontoblastic cells x 100.

RESULTS: Dental pulps extracted from DT are characterized by absence of odontoblastic layer and occurrence of apoptotic odontoblasts. Odontoblastic index is significantly lower in DT as compared to PT. Pro-apoptotic BAX phenotype expression on odontoblasts correlates with the occurence of numerous activated caspase-3+ odontoblasts in DT.

CONCLUSION: Histomorphometry and immunohistochemistry data confirm the lack of odontoblastic layer in dental pulps of DT in association with higher occurrence of apoptotic odontoblasts as compare to PT. Taken together our results offer a possible explanation for lower success of vital treatments on primary teeth in comparison to PT.


0211 (109622)

Root development and mineralizing capacity of pulp fibroblasts in vitro. N. KORNELI, S. PREUSSKER, U. HEMPEL, R. KOCH, and W. KLIMM, TU Dresden, Germany

Objectives:

The pulpal survival after injury is mediated amongst others by changing of pulp fibroblasts to odontoblast like cells for building and mineralizing new dentin matrix. The aim of this study was to detect a relationship between root development and mineralizing capacity of human pulp fibroblasts in vitro.

Methods:

Single cultured human pulp fibroblasts (D-MEM, 10% FCS, 50µg/ml Gentamycin) were divided in group A – incomplete and group B – complete root development. Stimulation of mineralization in vitro was done by adding calcium hydroxide (1.7g/ml), beta-glycerophosphate (10mM) and ascorbic acid (50µg/ml) individually or combined together. Determination of viability was done at day 1 by using an MTT-test. At day 4, amount of collagen typ I was measured with METRA-CIP EIA Kit and alkaline phosphatase activity was determined by the 4-NPP method at days 1, 4, 8, 11 and 15. Deposition of calcium phosphate by pulp fibroblasts was detected with an X-ray microanalysis.

Results:

Compared to control cells, a significant increase in pulp fibroblasts viability was obtained by adding beta-glycerophosphate and ascorbic acid (p = 0.05). The amount of collagen typ I as well as the deposition of calcium phosphate were significantly influenced with all stimulating agents (p = 0.05), while no significant effect of the stimulating agents was detectable in alkaline phosphatase activity. Root development did not influence any measured parameter.

Conclusion:

Compared to the stimulating agents used, root development had no significant influence on the mineralizing capacity of human pulp fibroblasts in this in-vitro study as shown by viability, alkaline phosphatase activity, collagen typ I amount and deposition of calcium phosphate.


0212 (111071)

Murine Oro-Facial Morphology: a model for human dental anomalies. T.L. COXON, J.H. HIBBARD, A.H. BROOK, and R.N. SMITH, University of Liverpool, United Kingdom

Objectives: To assess the reliability of variable measurement for the objective phenotyping of Wild type CD-1 mice; a model for dental anomalies, using Image Analysis techniques (IA). This methodology will then be applied to provide genotype-phenotype relationships of X-linked Amelogenesis imperfecta (X-AI) using Amelx mutant mice.

Methods: A control population of 20 left and right hemi-mandibles and mandibular incisors were extracted from 20 CD-1 Wild-Type mice at ≤ 22 weeks old at age of death. Calibrated images were captured using established IA consisting of a 13.5 mega-pixel Kodak/ Canon DCS/n SLR digital camera mounted on a Kaiser photographic stand. Standardised conditions of illumination, orientation and magnification were used to obtain images from both buccal and lingual aspects of the hemi-mandibles and lower incisors. Repeat images and measurements were taken after a minimum interval of 1 week and 24 hours respectively, by 2 independent operators. Eight quantitative variables of size, shape curvature and bulk were defined for mandibles, (1) overall-length; (2) ascending-height; (3) basal-length; (4) mandible-angle; (5) coronoid-coronoid; (6) diagonal-length; (7) mandible-area; (8) mandible-perimeter,  and incisors, (L) overall-length; (An) angle-of-curvature; (W) width-at-midpoint; (P) incisor-perimeter and (Ar) incisor-area, using Image Pro Plus 5.1 software.

Results: Intra-Class Correlation Coefficients (ICCC) for intra-operator repeatability's ≥0.79 and inter-operator reproducibility's ≥0.77 represented good reliability for all variables (Tables 1 & 2).

Conclusions: The study validated the IA for measurement of murine mandibles and incisors with good operator reliability. The variables chosen proved practical, providing additional information towards the understanding of the X-AI aetiology.

Table 1. Intra And Inter-Operator Repeatability For Mandible Measurement.

 

INTRA-Operator 1

Aspect

Buccal

Lingual

Variable

1

2

3

4

5

6

7

7

1

2

3

4

5

6

7

8

Left

0.92

0.98

0.84

0.94

0.88

0.85

0.81

0.81

0.99

0.98

0.94

0.99

0.95

0.87

0.98

0.99

Right

0.99

0.82

0.92

0.98

0.96

0.79

0.89

0.91

0.84

0.86

0.80

0.98

0.95

0.86

0.90

0.87

 

INTER-Operator

Left

Right

0.98

0.95

0.92

0.97

0.86

0.91

0.97

0.99

0.98

0.96

0.93

0.97

0.83

0.82

0.90

0.99

0.89

0.83

0.95

0.98

0.84

0.85

0.83

0.91

0.90

0.83

0.87

0.97

0.88

0.84

0.84

0.86

 

Table 2. Intra And Inter-Operator Repeatability For Murine Incisor Measurement

 

 

INTRA-Operator 1

Aspect

Buccal

Lingual

Variable

L

An

W

P

Ar

L

An

W

P

Ar

Left

0.91

0.96

0.99

0.92

0.83

0.95

0.96

0.99

0.97

0.92

Right

0.89

0.83

0.99

0.93

0.88

0.94

0.83

0.99

0.97

0.91

INTER-Operator

Left

0.85

0.91

0.99

0.91

0.82

0.81

0.93

0.99

0.95

0.89

Right

0.90

0.77

0.99

0.93

0.86

0.82

0.82

0.99

0.96

0.91

(Sponsored by the Wellcome Trust; grant number GRO75945MA).  

0213 (111525)

Effect of Glucocorticoids on Different Physiological Parameters of Human Osteoblasts. G. MAZZAGLIA1, O. GARCIA-MARTINEZ2, L. DIAZ RODRIGUEZ3, L. RODRIGUEZ PEREZ3, C. TORO VELASCO3, and C. RUIZ RODRIGUEZ3, 1School of Dentistry, University of Messina, Italy, 2University of granada, Granada, Spain, 3University of Granada, Spain

Glucocorticoids are used widely in a range of medical specialities, like dentistry, but their main limitation is an adverse impact on bone. In dentistry, glucocorticoid as methilprednisolone are used after a bone surgery, generally in a single dose and when the intervention has finished, to minimise the inflammatory process. It is suggested that glucocorticoids induce rapid bone loss and increase the risk for osteoporotic fractures after long periods of treatment.

Objectives:The purpose of the present study was to obtain further insight into the effect of metilprednisolone on human osteoblast-like cells proliferation after 24 and 48 hours and to study the effect of this drug on antigenic phenotype profile of cultured human osteoblast-like cells.

Methods:

Osteoblasts were obtained from samples of human bone sections obtained in the course of third molar surgery. Human osteoblast-like lines were isolated, characterized and cultured with two different concentration of metilprednisolone (10-6M and 10-8M). Osteoblasts proliferation was examined by count of cell number after 24 and 48 hours. Flow cytometer was used to analyze the following molecules: CD10, CD13, CD44, CD54, CD80, CD86 and HLA-DR.

Results:

After 24 and 48 hours the experiments demonstrated a decrease in cell proliferation in cultures incubated with 10-6M and 10-8M concentrations of metilprdnisolone compared with controls (p<0.01 and p<0.0001, respectively). There were no differences in the expression of any antigens between the cells cultured in metilprednisolone and control cells.

Conclusions:

Although many studies had determined that glucocorticoids alter bone proliferation after long periods of treatment, our results suggest that metilprednisolone decreases osteoblasts proliferation in shorter periods of treatment, like 24 and 48 hours, however there isnxt any change in other physiological cell parameters like differentiation and immunological function. It would appear that in oral surgery an alternative anti-inflammatory is preferable where a rapid increase in osteoblast number is important.


0214 (111591)

Effect of Ibuprofen on MG63 Proliferation and Differentiation. L. DIAZ RODRIGUEZ, O. GARCIA MARTINEZ, L. RODRIGUEZ PEREZ, C. TORO VELASCO, M. ARROYO MORALES, and C. RUIZ RODRIGUEZ, University of Granada, Spain

Both the NSAIDs and ibuprofen are generally used in clinical practice to relief pain and inflammation, especially in odontology after surgical interventions wich affect bone, like dental extraction or quistectomy in wich a rapid bone recovering is normally required to its prompt rehabilitation, or after placing dental implants where a rapid bone growth is needed to ensure its osseointegration. Objectives:The objective of this study has been to set, in vitro, the effect of the ibuprofen on the osteoblast proliferation and differentiation in the MG63 human osteosarcome cellular line.

Methods: The study of the effect of the ibuprofen on the cellular proliferation was carried out by using as treatment doses 5, 25 and 75 μM during 24 and 48 hours and the flow cytometry. The effect on the differentiation was determined by quantifying the osteocalcine levels in the culture supernatant by immunoassay radio after the treatment with 25 μM ibuprofen doses during 24 hours. The experiences were carried out fourfold and the t Student analysis was followed for the statistical analysis.

Results: The treatment by using ibuprofen during 48 hours with 5 and 25 μM doses produced significant cellular proliferation increases p<0.05 and p<0.01, respectively, with no change in the treatment during 24 hours. The use of a higher doses approximately 75 μM just in treatments during 24 hours caused a significant proliferation decrease regarding the non-treated cellules p<0.05. We have also observed that the short term treatment (4 hours) of the MG63 line caused a significant osteocalcine synthesis decrease.

Conclusions: The ibuprofen in therapeutic doses in short term treatments could be the choosing NSAID in those clinical situations in wich a rapid bone tissue formation is required, like odonthology treatments.


0215 (111391)

Isolation of dental pulp progenitor cells utilising stem cell markers. C.P. LEE, J.S. REES, R.J. WADDINGTON, and A.J. SLOAN, Cardiff University, United Kingdom

Adult stem cells are found in the dental pulp, remaining quiescent until recruited during reparative dentinogenesis. Isolation and clonal expansion of dental pulp cells demonstrates variable odontogenic potential, suggesting more than one progenitor population exists. Objectives: To establish clonal colonies of progenitor / stem cells from rat dental pulp using two different methods of isolation and examine characteristics relative to stem cell behaviour. Methods: Single cell suspensions were enzymically obtained from dental pulps of male Wistar rats. Neural crest cells are proposed to persist within adult dental pulp. Cells with high expression of low affinity nerve growth factor receptor (p75NGFR) surface protein (p75 cells) were isolated from disintegrated pulps using magnetic column sorting. High levels of ß1 integrin are reported for primitive cells. These progenitor cells were isolated from disintegrated pulps by preferential adherence to a fibronectin for 20 minutes (FNA cells). For both populations, colony forming efficiency (CFE) was recorded and population doublings (PD) were calculated on passaging. Vimentin levels and p75NGRF expression for each progenitor population were examined using immunocytochemistry and RT-PCR. Migration and differentiation of progenitor cells towards collagen gels impregnated with dentine matrix extract was examined using “boyden chambers” and immuo-fluoresence. Results: From 40,000 cells seeded, p75 cells demonstrated a higher CFE, yielding 101 colonies (average), whilst FNA cells produced 23 colonies (average). Following expansion of clonal colonies, both progenitor populations demonstrated high PD. FNA cells had higher expression of vimentin, whilst higher expression of p75NGFR was seen in p75 cells. FNA progenitor cell migrated into collagen gels with chemotactic response demonstrating a positive correlation to DME concentration. Conclusions: Early data suggests the potential presence of more than one population of progenitor cell which vary in terms of their cellular characteristics and behaviour. The differential responses progenitor populations may indicate different roles in tertiary dentinogenesis.


0216 (111417)

Bone Formation around Titanium Implants in Diabetic and Normal Rats. J. UNDERWOOD1, J. OKAZAKI2, J.S. COLOMBO1, A.J. SLOAN1, and R.J. WADDINGTON1, 1Cardiff University, United Kingdom, 2Osaka Dental University, Japan

Diabetes Mellitus is currently recognised as a contraindication for implant treatment due to impaired osseointegration leading to early failure. The reason for the slower bone formation is unclear, but is related to poor glycaemic control in the post operative period. Objectives: To investigate osteoblast cellular activity around implant sites of normal and diabetic rats. Methods: Implants were inserted into both normal Wistar rats and GK diabetic rats immediately following incisor extraction. Rats were sacrificed at 1, 3 or 9 weeks post-operation. Dissected mandibles were fixed in formalin, demineralised in formic acid and paraffin embedded. 5 micron sections were taken from posterior and anterior aspects of the mandible and stained histologically using H&E or Alzarin red (mineral deposition). Immunohistochemistry was performed to investigate the presence of the osteoblast differentiation marker osteopontin, and proliferation marker, PCNA. Results: H&E staining revealed a cell rich granulation tissue around the implant site at 1 week in both animals. At 3 and 9 weeks, bone formation was more advanced in normal rats than diabetic rats, which was evident in both posterior and anterior sections. Alizarin red staining showed greater mineralisation in normal rats compared to diabetic animals. Osteopontin was observed around normal and diabetic implant sockets by 3 weeks. By 9 weeks osteopontin was no longer detected around the normal implant socket, while it persisted around the diabetic implant socket. PCNA expression was observed around normal and diabetic implant sockets at 1 and 3 weeks post-operation. Expression was absent around normal implant socket by 9 weeks but evident around the diabetic implant socket. Similar temporal patterns for bone markers were observed for anterior and posterior sections. Conclusions: Diabetes had a significant effect on cellular proliferation and osteoblast differentiation, which was particularly evident 9 weeks post operation. This had consequential effects on reduced bone formation around implants.


0217 (111467)

Biological Effects of a Restorative Material During Ex-Vivo Culture. R. CARR, R.J. WADDINGTON, A.S.M. GILMOUR, S. YOUDE, and A.J. SLOAN, Cardiff University, United Kingdom

Testing of dental materials has limited investigations on their effects on pulp cell behaviour. Whilst there is greater understanding of the therapeutic mode of action of calcium hydroxide, suggesting a role in mediating tissue repair, there is little biological evidence for similar reparative effects of currently used resin bonding agents in restorative dentistry. Objectives: To investigate effects of a commercially available self etch resin bonding agent on the pulp using an ex-vivo culture system. Methods: Transverse 2mm think sections were prepared from incisor teeth extracted from 28 day old male Wistar rats. Affi blue agarose beads were soaked in commercial bond and either polymerised or left in the unpolymerised phase and applied to the pulpal tissue in the tooth slices. Cultures were maintained for 1 and 5 days prior to histological processing for microscopic analysis. Beads soaked in PBS and slices cultured in the absence of beads served as controls. Scanning electron microscopy (SEM) was used to confirm adhesion of bond to agarose and tissue were examined histological following culture. Results: SEM demonstrated bond coating of beads confirming these as an appropriate material carrier. All control cultures showed maintenance of cell and tissue architecture throughout the culture periods, minimal tissue damage at the site of bead application. In cultures with un-polymerised bond, formation of a fibro-cellular lining around the bead with close bead-cell integration was observed. Polymerised bond appeared to induce a clear space between bead and cells. No clear evidence of cytotoxicity was observed in cultures with beads coated with either phase despite direct pulpal application. Conclusions: These preliminary results demonstrate that a commercially used bonding agent can stimulate tissue responses within the dental pulp following culture, with little cytotoxicity and suggest that direct pulp capping with resin based materials should be investigated further. (Supported by Welsh Assembly Govnt).


0218 (111823)

Functional Adaptation of the Alveolar Bone in the Adult Rat. A. MAVROPOULOS, University of Gothenburg, Sweden, A.M. ÖDMAN, Institute of Odontology, Gothenburg, Sweden, and S. KILIARIDIS, University of Geneva, Switzerland

Objectives: To assess the influence of masticatory function rehabilitation on trabecular micro-architecture and size of the alveolar process in adult rats.

Methods: Forty-four male rats received soft diet for a prolonged period so that they developed masticatory hypofunction. After 21 weeks, when their growth was over, they were divided into two groups: one group continued for six more weeks with soft diet (hypofunction group), while the other changed to ordinary diet with the aim to retrain their masticatory muscles (rehabilitation group). A third group of sixteen male rats (normal group) received ordinary (hard) diet during the whole experimental period and served as control. Bone micro-architecture parameters of the mandibular alveolar bone were calculated at the end of the experiment (27 weeks) using microtomographic histomorphometry (micro-CT). The height and width of the alveolar process were also measured.

Results: The alveolar process trabecular bone volume fraction (BV/TV) was found to be lower for the animals of the hypofunctional group in comparison to the normal (p<0.01) and rehabilitation (p<0.05) groups. Despite the significant improvement observed in the rehabilitation group, BV/TV was still lower than in the normal group (p<0.05) at the end of this experiment. All the other microtomographic parameters followed the same pattern of change; values for the rehabilitation group were between the two other groups, differing significantly from both of them. The alveolar process was significantly shorter in the normal group in comparison to both other groups (p<0.05). Both the normal and rehabilitation groups had a wider alveolar process than the hypofunctional group (p<0.05). Both alveolar height and width were significantly correlated with all histomorphometric parameters under study.

Conclusions: Masticatory function rehabilitation led to an improvement of alveolar bone quantitative and qualitative characteristics in adult rats, although the negative effects of hypofunction were not totally reversed during the period under study.


0219 (110059)

Continuous Force on Rat Molars Increases Osteopontin in Alveolar Bone. L. BONAFE-OLIVEIRA1, N. D'ANDREA-MATEUS1, and V.E. ARANA-CHAVEZ2, 1University of São Paulo, Brazil, 2University of São Paulo, Sao Paulo, Brazil

Objectives: Osteopontin (OPN) is a major noncollagenous bone matrix protein that is believed to play a key role in wound healing and cellular responses to mechanical stress. Orthodontic tooth movement is possible by alveolar bone remodeling, which consists in a sequence of events that results in bone resorption and deposition. We have previously showed the concomitant presence of these two antagonist tissue reactions at the pressure areas of rat alveolar bone in upper first molars submitted to continuous orthodontic force. The aim of the present study was to investigate the presence and distribution of OPN in alveolar bone at the pressure areas when molars were submitted to continuous orthodontic force.

Methods: Ten 2½ months old male Wistar rats were used. Eight rats had their upper first molars moved for 3d (n=4) and 7d (n=4) with a 15cN continuous force, while the remaining two rats had their molars non-moved and were processed as controls. The rat maxillae were dissected out and quickly immersed in 0.1% glutaraldehyde + 4% formaldehyde and fixed under microwave irradiation. Then, specimens were decalcified and processed for high-resolution colloidal gold immunocytochemistry with an anti-OPN antibody.

Results: At both studied times the immunolabeling was present recovering the resorbed alveolar bone surfaces thus forming a lamina limitans. Other regions showed wide strips with intense immunoreactivity for OPN. These regions were detected even when active osteoblasts were absent suggesting the deposition of circulating OPN on these surfaces. Later, when new bone matrix was laid out over these strips, wide cement (reversal) lines strongly labeled for OPN were observed.

Conclusions: This study showed that OPN is overexpressed at alveolar bone surfaces adjacent to rat molars submitted to continuous orthodontic force. Financial support by FAPESP (grant 03/06554-6) and CNPq (Brazil).


0220 (109508)

NPY-Y1 receptors in normal and inflamed dental pulp. S.R. HAUG, B. RAJU, I. FRISTAD, E. BERGGREEN, and K. HEYERAAS, University of Bergen, Norway

Accumulating research has shown interplay between sympathetic nerves and the immune system during inflammation. Neuropeptide Y (NPY) is a neuropeptide found mainly in the sympathetic nervous system. Recent findings show that NPY immunoreactive nerve fibers undergo sprouting during pulpitis, and that NPY is involved in the regulation of immune responses via its Y1 receptor (NPY-Y1R). Objectives: To map out the distribution and location of NPY-Y1R in normal and inflamed rat dental pulp. Methods: A total of 14 adult male Sprague-Dawley rats were used; sham (n=6), experimental (n=6). Sham animals received no treatment, while experimental animals were deeply anesthetized and had large pulp exposures on maxillary first molars. After 7 days the rats were perfused with 4% paraformaldehyde and 0.2% picric acid. Following decalcification in 10% EDTA, serial sections of 30 µm were processed for double labeling immunohistochemistry with primary antibodies for NPY-Y1R and laminin. Two rats were sacrificed with CO2 inhalation and had molar pulp, incisor pulp, gingiva and trigeminal ganglion removed, snap frozen and processed for RT-PCR. Results: In control rats the NPY-Y1R was mainly located in capillaries and small vessels (mean diamater 10µm) beneath and within the odontoblast layer in the coronal dental pulp. Double labeling with laminin confirmed the colocalization of NPY-Y1R within the wall of blood vessels. Immune cells were not NPY-Y1R in the normal dental pulp. During inflammation, larger blood vessels (mean diameter 25 µm) appeared to be NPY-Y1R immunoreactive as well as immune cells localized around the inflammatory site. RT-PCR revealed the presence of NPY-Y1R in the dental pulp, trigeminal ganglion and gingiva. Conclusion: The NPY-Y1R is mainly located to small blood vessels in the dental pulp. During inflammation it is expressed in larger blood vessels and in immune cells.


0221 (110204)

Expression of TRPM8 in Human Tooth Pulp. M.W. BARBER1, F.M. BOISSONADE1, A.R. LOESCHER1, P.P. ROBINSON1, B. MATTHEWS2, and H.D. RODD1, 1University of Sheffield, United Kingdom, 2University of Bristol, United Kingdom

Objectives: Caries-related toothache is frequently initiated or exacerbated by thermal stimuli. The transient receptor potential channel melastatin 8 (TRPM8) has been implicated in the transduction of cold temperature and pain sensation, and has recently been identified in tooth pulp. This study sought to investigate any differences in the pulpal expression of TRPM8 between intact and carious human teeth, and between painful and asymptomatic carious teeth.

Methods: A total of 43 lower mandibular first permanent molars were obtained from children undergoing routine extractions, and the teeth categorised as intact (n=25) or grossly carious (n=18). Grossly carious teeth were sub-grouped as painful or non-painful on the basis of symptoms occurring within 48 hours prior to the extraction. Coronal pulps were removed and processed for indirect immunofluorescence using antibodies raised against TRPM8 and either the neuronal marker, protein gene product 9.5, or alpha smooth muscle actin in conjunction with ulex europaeus agglutinin 1 lectin to fully label the pulp vasculature. The level of expression of TRPM8 was quantified using image analysis.

Results: TRPM8 was expressed in both neuronal and vascular tissue in all teeth examined. There were no significant differences between the level of neuronal or vascular TRPM8 expression in carious and non-carious teeth (p>0.05 independent sample t-test). However, in the mid-coronal pulp region, expression of neuronal TRPM8 was significantly lower in carious painful samples than in carious non-painful samples (p=0.037). There appeared to be higher vascular TRPM8 expression within the pulp horn region of carious painful samples, but this difference was not significant.

Conclusions: The level of pulpal TRPM8 expression appears to be unaffected by the presence of caries. However, there are differences between the expression of neuronal TRPM8 in painful and asymptomatic teeth, suggesting that it may be involved in the initiation or response to pain.


0222 (110300)

Substance P Production by Human Dental Pulp Fibroblasts. S. KILLOUGH, F. LUNDY, and C. IRWIN, Queen's University Belfast, United Kingdom

The inflammatory response to pulpal injury or infection has major clinical significance. Neurogenic inflammation describes the local release of neuropeptides, notably substance P (SP), from afferent neurones, and may play a role in the pathogenesis of pulpal disease. The fibroblast is the most numerous cell type in the dental pulp and recent work has suggested that it is involved in the inflammatory response. Objectives: The aims of the study were to determine whether pulp fibroblasts could produce SP, and to investigate the expression of the SP receptor, NK-1, by these cells. Methods: Primary pulp fibroblast cell populations were isolated by enzymatic digestion from non-carious teeth extracted for orthodontic reasons. Whole pulp tissue was obtained from freshly extracted sound (n=35) and carious (n=39) teeth. Expression of SP and NK-1 mRNA was determined by RT-PCR. The effects of interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) on SP and NK-1 expression were also determined. The presence of NK-1 on fibroblast cell membranes was established by western blotting. The effects of the cytokines on each parameter were analysed by ANOVA. Radioimmunoassay (RIA) was carried out to quantify SP expression in pulp fibroblasts and in whole pulp tissue. Results: SP was expressed by pulpal fibroblasts both at the mRNA level and the protein level. In addition, NK-1 was detected in fibroblast cultures at the mRNA level and appeared as a double band on western blots of membrane extracts. IL-1β and TGF-β1 significantly stimulated the expression of SP and NK-1. SP levels were significantly greater (p<0.05) in carious compared to sound teeth. Conclusion: Pulp fibroblasts are capable of synthesising and secreting SP, as well as expressing the SP receptor, NK-1. These findings suggest that pulp fibroblasts play a role in neurogenic inflammation in pulpal disease. (Supported by the European Society of Endodontology).


0223 (111400)

Neuropeptides regulate expression of angiogenic growth factors in pulpal fibroblasts. I.A. EL KARIM, C.R. IRWIN, G.J. LINDEN, and F.T. LUNDY, School of Medicine and Dentistry, Queen's University Belfast, United Kingdom

In the dental pulp angiogenesis is crucial for tooth development and a prerequisite for successful repair following injury and inflammation. The role of neuropeptides in pulpal inflammation has been well documented but their role in the regulation of angiogenesis in the dental pulp has not been elucidated. Objectives: The aim was to profile the expression of angiogenic growth factors produced by pulp fibroblasts and to study the effects of neuropeptides on their expression. Methods: Human pulp fibroblasts derived from healthy molar teeth were stimulated with neuropeptides previously identified in dental pulp, namely, Substance P (SP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and calcitonin related gene peptide (CGRP) for 24 and 48 hrs. Simultaneous expression of ten growth factors was quantified using a novel human angiogenesis array (Ray Biotech, USA). Results: Pulp fibroblasts expressed human angiogenic growth factors, VEGF, bFGF, PDGF-BB, HGF, ANG2, HB-EGF, PIGF, angiogenin and leptin. Among the growth factors expressed VEGF, angiogenin and HGF were abundantly expressed compared to others. Neuropeptides induced variable effects on the expression of the angiogenic factors: CGRP potently up-regulated VEGF, bFGF, HGF and PIGF after 24 hr, while NPY tended to down regulate growth factors after 24 hr in culture but markedly up regulated ANG2, bFGF and leptin after 48 hr. SP down regulated expression of all angiogenic growth factors except for leptin, while VIP induced a small increase in expression of each growth factor, irrespective of time. Conclusion: Pulp fibroblasts express a range of angiogenic growth factors including angiogenin and leptin. Neuropeptides regulate the expression of these factors, suggesting an additional role for neuropeptides in the regulation of inflammation and healing in the dental pulp.

This work is supported by TC White Research Fund


0224 (110493)

Immunohistological Changes Observed Over Time in Neuronal-Intermediate-Filament-Protein after Neonatal Desensitisation. N. BERGMANN1, T. DE PERALTA2, M. SELTMANN1, T. STRUYS3, I. LAMBRICHTS3, and W.H.-M. RAAB1, 1Heinrich-Heine-University of Düsseldorf, Germany, 2University of Plymouth, United Kingdom, 3Hasselt University, Diepenbeek, Belgium

Objectives: The neonatal application of capsaicin produces a selective loss of nociceptive fibres in the dental pulp, resulting in many changes in the dentin-pulp-complex. The purpose of this study was to determine if age has an influence on the reduction or elimination of intermediate-nerve-filament in the neonatal capsaicin-treated rat over time. Methods: 48 wistar rats served as the experimental group where capsaicin (50mg/Kg body weight) in a sterile vehicle was systemically administered on the 3rd postnatal day. 48 control animals were injected with the sterile vehicle on the same day. Groups (n=12) of experimental and control animals were sacrificed via deep anaesthesia, cardial intravital-perfusion and fixation at 30 days, 60 days, 90 days and 155 days of life. Jaws were dissected and immunohistology was performed on frozen cryosections of left lower jaws with primary antibody against Peripherin (PER) in order to localize intermediate-nerve-filament within the dental pulp of each specimen. Micrographs were produced from the distal pulp-horn of the first molar at magnifications of 10X and 25X, where Scion image was applied. Here the pixel numbers per inch2 of positive immunohistological staining was measured. SPSS was used to calculate Student t-test in order to analyse differences between experimental and control groups within each age category. Results: Our results demonstrate significant differences between the experimental and control groups at 60, 90 and 155 days but not at 30 days. Conclusion: From our results we may conclude that globular neuronal proteins of neuronal intermediate-filament presenting within neuronal structures in the pulp tissue are changed with age in capsaicin-treated rats compared to control animals. Acknowledgements: This study was supported by the Heinrich-Heine-University Research-Commission and the German-Dental-Association (DGZMK).


0225 (110656)

The TRPV1 Antagonist SB705498 Reduces Trigeminal Fos Expression. M.A. WORSLEY1, N.M. CLAYTON2, J.B. DAVIS2, and F.M. BOISSONADE1, 1University of Sheffield, United Kingdom, 2GlaxoSmithKline, Harlow, United Kingdom

Objectives: Recently, novel, potent and selective vanilloid receptor 1 (VR1 or TRPV1) antagonists have been shown to be effective in animal models of inflammatory, neuropathic and postoperative pain. The aim of this study was to assess the ability of the TRPV1 antagonist SB705498 (GlaxoSmithKline) to modify central neurone activation in response to stimulation of inflamed ferret tooth pulp.

Methods: Seven adult ferrets were prepared under anaesthesia (ketamine 25 mg/kg, xylazine 2 mg/kg, IM) to allow tooth pulp stimulation, recording from the digastric muscle and intravenous injections at a subsequent experiment. In all of these animals pulpal inflammation was induced by introducing human caries into a deep buccal cavity. Five days later animals were re-anaesthetised (alphaxalone/alphadalone, induction: 6 mg/kg, maintenance: 6-8 mg/kg/h, IV) and the jaw opening reflex (JOR) threshold was measured. Animals were treated intravenously with either SB705498 (bolus: 0.6 mg/ml/kg, infusion: 0.5 mg/10 ml/kg over 1 h, n = 4) or vehicle (2% dimethyl sulfoxide and 5% glucose containing 10% hydroxypropyl-β-cyclodextrin, n = 3). Fifteen minutes after the initial bolus tooth pulp stimulation commenced at 10 times the threshold of the JOR for 90 minutes. All animals were perfused with fixative 120 minutes from the start of the stimulation and brainstems processed for Fos immunohistochemistry.

Results: Stimulation of inflamed tooth pulps induced ipsilateral Fos expression caudally in subnucleus caudalis (Vc) and rostrally in subnucleus oralis (Vo). SB705498 reduced Fos expression in Vc (P = 0.04, unpaired t-test) but not in Vo (P = 0.29).

Conclusions: These results suggest that SB705498 reduces the number of trigeminal brainstem neurones activated by stimulation of the inflamed tooth pulp. Therefore SB705498 may have significant analgesic efficacy in trigeminal inflammatory pain. (Supported by GlaxoSmithKline, UK).


0226 (110667)

The Effect Of Paracetamol on Trigeminal Fos Expression. M.A. WORSLEY1, N.M. CLAYTON2, P. GOLDSMITH2, and F.M. BOISSONADE1, 1University of Sheffield, United Kingdom, 2GlaxoSmithKline, Harlow, United Kingdom

Objectives: The efficacy of paracetamol in inflammatory pain, including dental pain, is well established. We developed a model to quantify central neuronal activity following stimulation of the tooth pulp in the ferret. The aim of this study was to assess the ability of paracetamol (Sigma-Aldrich) to modify this activity and further establish the use of this model to predict analgesic efficacy.

Methods: Seven adult ferrets were prepared under anaesthesia (ketamine 25 mg/kg, xylazine 2 mg/kg, IM) to allow tooth pulp stimulation, recording from the digastric muscle and intravenous injections at a subsequent experiment. Pulpal inflammation was induced by introducing human caries into a deep buccal cavity. Five days later animals were re-anaesthetised (alphaxalone/alphadalone, induction: 6 mg/kg, maintenance: 6-8 mg/kg/h, IV) and the jaw opening reflex (JOR) threshold was measured. Animals were treated intravenously with either paracetamol (bolus: 30 mg/5 ml/kg, infusion: 30 mg/10 ml/kg/h over 2 h, n = 4) or vehicle (2% dimethyl sulfoxide and 5% glucose containing 10% hydroxypropl-β-cyclodextrin, n = 3). Fifteen minutes after the initial bolus tooth pulp stimulation commenced at 10 times the threshold of the JOR for 90 minutes. All animals were perfused with fixative 120 minutes from the start of the stimulation and brainstems processed for Fos immunohistochemistry.

Results: Stimulation of inflamed tooth pulps induced ipsilateral Fos expression caudally in subnucleus caudalis (Vc) and rostrally in subnucleus oralis (Vo). Paracetamol reduced Fos expression in both Vc (P = 0.0003, unpaired t-test) and Vo (P = 0.002).

Conclusion: These results suggest that paracetamol reduces the number of trigeminal brainstem neurones activated by stimulation of the inflamed tooth pulp, and demonstrates that in this model a reduction in Fos expression correlates with analgesic efficacy. This provides further evidence that our model is useful in accurately predicting the analgesic efficacy of novel compounds. (Supported by GlaxoSmithKline).


0227 (110132)

Nav 1.7 expression in trigeminal pain states. K. BENENG1, T. RENTON1, Y. YIANGOU2, and P. ANAND2, 1King's College London, United Kingdom, 2Imperial College, London, United Kingdom

Objectives: To evaluate Nav1.7 levels in orofacial pain conditions including toothache, post traumatic lingual nerve injury and Burning Mouth Syndrome. Methods: 17 vital permanent molar teeth scheduled for extraction. 5 patients with painful lingual nerve injury and 10 patients with Burning Mouth Syndrome with matched control patients undergoing third molar surgery were recruited. A pain history was collected. The patients were divided into two groups, those with existing pain and those with no history of or existing pain. The gender distribution of the groups was M: F 1:1. All specimens were immediately snap-frozen at -70oC. Immunohistochemistry and computer image analysis was used to evaluate the relative expressions. The mean values of readings obtained by two independent observers, each blinded, were used for final analysis. Results: A subset of nerve fibres was immunoreactive with the Nav1.7 antibody in both non-painful and painful pulp groups. There was a significant increase of the visual intensity score for Nav1.7 in the painful group compared to controls. Strong Nav1.7 immunoreactivity fibre staining was seen in fascicles in all lingual nerve specimens studied. By image analysis there was a tendency for an increase of Nav1.7 staining in the injured lingual nerve group but was not statistically significant. Strong sub-epithelial Nav1.7 immunoreactive fibre staining was found in all tongue biopsy specimens studied. By image analysis there was no difference between the Burning Mouth Syndrome and control groups. Conclusions: Nav1.7 is significantly increased in association with dental pain. However the increased immunoreactivity of Nav1.7 in lingual tissues in association with neuropathic pain with Burning Mouth Syndrome and post traumatic nerve injury was not significant.


0228 (110152)

TRPV1 receptor expression in uninjured afferents following lingual nerve injury. Y.K.Y. FOK, M.A. WORSLEY, F.M. BOISSONADE, J.M. YATES, P.P. ROBINSON, and D. ANDREW, University of Sheffield, United Kingdom

Objectives: Peripheral nerve injury sometimes results in the development of pain. Recent spinal cord studies have suggested that this could result from changes in the properties of nearby uninjured nerves. We have investigated this possibility in the trigeminal system by determining the effects of lingual nerve injury on the characteristics of intact inferior alveolar neurones. We have previously shown that lingual nerve injury causes increased expression of transient receptor potential vanilloid 1 (TRPV1), a transducer of noxious stimuli, in the associated cells in the trigeminal ganglion. We have now sought changes in the nearby cells of axons in the inferior alveolar nerve.

Methods: In nine anaesthetised ferrets the left lingual nerve was sectioned and recovery permitted for 3 days, 3 weeks or 3 months (3 ferrets/group). Three days before the end of this period, the retrograde tracer Fluorogold was applied to the inferior alveolar nerve to label its cell bodies in the trigeminal ganglion. After the recovery period, under anaesthesia (sodium pentobarbitone 42mg/kg i.p., maintenance 3mg/kg i.v.), the animals were perfused with fixatives. Fourteen micron-thick cryostat sections were processed using indirect immunofluorescence, and the proportion of Fluorogold-positive cells that were labelled for TRPV1 was quantified.

Results: In controls the mean proportion of inferior alveolar neurones (± 1SD) that were TRPV1-positive was 10.9 ± 1.1%. Three days after lingual nerve section this proportion had significantly increased to 15.5 ± 0.9% (P = 0.005, ANOVA); the figures for 3 weeks and 3 months survival were 14.0 ± 2.7% (P > 0.1) and 15.9 ± 1.6% (P < 0.02), respectively.

Conclusion: Lingual nerve section caused a significant increase in the proportion of inferior alveolar neurones that were labelled for TRPV1. These data suggest that changes in TRPV1 expression in uninjured afferents may be involved in the sensory disorders that follow trigeminal nerve injury.


0229 (110293)

Interleukin-10 Reduces Scarring and Enhances Regeneration after Peripheral Nerve Repair. S. ATKINS1, K.G. SMITH1, A.R. LOESCHER1, F.M. BOISSONADE1, M.W.J. FERGUSON2, and P.P. ROBINSON1, 1University of Sheffield, United Kingdom, 2University of Manchester, United Kingdom

Objectives: Scar formation at a site of peripheral nerve injury can impede axonal regeneration and limit recovery. We have investigated whether the application of a scar-reducing agent, interleukin-10 (IL-10), to a nerve repair site would permit enhanced regeneration.

Methods: Regeneration of the sciatic nerve was assessed in four groups of C57-black-6 mice (8 animals/group). Under general anaesthesia (Fentanyl/Fluanisone 0.8ml/kg & Midazolam 4mg/kg, i.p.) the nerve was sectioned and repaired using 4 epineurial sutures. IL-10 (125ng or 500ng in 100μl of diluent) or phosphate buffered saline was injected into and around the proximal and distal nerve stumps, and comparisons made with sham-operated controls. After 6 weeks the outcome was assessed blind by determining; (1) the percentage area of picrosirius red staining (PAS) for collagen at the repair site (2) the ratio of the compound action potential (CAP) modulus evoked by electrical stimulation 2mm distal or proximal to the repair (3) the number of myelinated axons at the same sites.

Results: The median PAS for collagen was 1.73% in the controls, was higher in the saline (5.35%) and 500ng IL-10 (7.22%) repair groups (p<0.04, Kruskal-Wallis test), but not significantly different from the 125ng IL-10 group (3.35%, p=0.19). The median CAP ratio was 0.92 in the controls, was lower in the saline (0.34) and 500ng IL-10 (0.34) groups (p<0.04), but not significantly different from the 125ng IL-10 group (0.77, p=0.12). The myelinated fibre counts were always higher distal to the repair site, but there were no significant differences between groups.

Conclusion: Administration of a low dose of IL-10 to a site of sciatic nerve repair reduces scar formation and permits better regeneration of the damaged axons.

Supported by the Wellcome Trust (074500).


0230 (111452)

Forces, movements and reflexes produced by pushing human teeth. B.J.J. SCOTT, A.G. MASON, and S.W. CADDEN, Dundee Dental School, United Kingdom

Objectives: It is known that pushing on the crown of a tooth will result in a reflex inhibition of activity in jaw closing muscles. The purpose of this study was to investigate the tooth movements made by such pushes and relate this to the resulting reflexes.

Methods: Experiments were performed on six volunteers. EMG recordings were made from a masseter muscle. The subjects activated the muscle to approximately 12.5% of maximum with the help of visual feedback of the EMG. Reflexes were produced by applying gentle mechanical stimuli to an upper central incisor. The stimuli consisted of "ramp and hold" forces with a 5ms rise time and a 350ms duration; the forces plateaued at 0.25-4N. For each subject, the forces were applied in two positions – close to the incisal edge and close to the cervical margin. The resulting reflexes were recorded along with the actual forces applied and the resulting movements of the tooth crown.

Results: There was a linear relationship between force and movement regardless of whether the force was incisal or cervical (Pearson's r=0.91 and r=0.93 respectively). There was no difference between the slopes for these two relationships (ANCOVA p=0.42). There were also linear relationships between force or movement and the resulting inhibitory reflexes (r=0.84, 0.8, 0.8 and 0.64 for incisal and cervical forces and incisal and cervical movements respectively). The estimated thresholds for the reflexes were 0.33±0.1N (equivalent to 15±4 microns) and 0.46±0.1N (equivalent to 20±5 microns) for incisal and cervical stimuli respectively.

Conclusions: Interestingly neither the amounts of movement nor the resulting jaw reflexes were dependant on the position at which forces were applied to the tooth. These findings are not supportive of the notion that the tooth movement takes place around a fulcrum in response to the application of horizontal forces.


0231 (111156)

Relaxation and Contraction of Human Jaw Muscles Following Lip Stimulation. M. ATASSI, M.F. LYONS, A.G. MASON, and S.W. CADDEN, Dundee Dental School, Scotland

Objectives: Previous studies have established the electromyographic properties of the reflexes evoked in jaw-closing muscles, by stimulation of the upper lip. The purpose of the present study is to establish the mechanical properties of these same reflexes.

Methods: To date, six asymptomatic volunteers have participated. Bite forces between the anterior teeth, and electromyograms (EMGs) from both masseters, were recorded. The participants were provided with visual feedback of the bite force and were asked to maintain this around 50N. Reflexes were evoked by electrical stimulation of the skin of the upper lip. A range of stimulus intensities below and above a nociceptive threshold was used. The EMGs were processed by rectification, averaging and smoothing. The bite force recordings were simply averaged. Deviations following the stimuli, in any of the recordings (EMGs or bite force), were analysed with respect to a 300ms pre-stimuli period, to determine whether they could be designated as reflexes.

Results: Inhibitory reflexes (relaxations) were seen in the force records of all 6 subjects. The minimum latency and maximum duration of this response were 47.9±4.1 and 122.1±14.7ms respectively (means±S.E.M.). In all respects, this mechanical response was slower and longer lasting than the equivalent EMG inhibitions. In 4 subjects, the relaxation was immediately followed by a period of increased force generation (contraction) which again was more prolonged than the equivalent excitation in the EMGs (latency: 135.0±13.2ms; duration: 326.4±92.6ms). Interestingly, the ratio of the durations of the mechanical responses to EMG responses appeared to be substantially greater for the contractions (approx. 4:1) than for the relaxations (approx. 2:1).

Conclusion: These preliminary results show as one would expect, that the mechanical parameters of this jaw reflex are more prolonged than the electromyographic ones. More surprisingly, this discrepancy was much greater for the excitatory than for the inhibitory responses.


0232 (111368)

Factors Associated with Chewing Side Preference in a Dentate Population. M. LUJAN-CLIMENT, J. MARTINEZ-GOMIS, S. PALAU, R. AYUSO-MONTERO, J. SALSENCH, and M. PERAIRE, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain

Objectives: The aim of this study was to determine whether handedness or asymmetry of occlusal characteristics, muscular force and temporomandibular disorders (TMD) can explain chewing side preference in a dentate population. Methods: One hundred and seventeen dentate adults participated in this cross-sectional study. Static and dynamic occlusal characteristics were determined at maximal intercuspal position and at right and left lateral excursions of 1.5 mm by scanning interocclusal records and analyzing them using image software. Unilateral maximum bite force and finger-thumb grip force were measured by means of a gnathodynamometer. TMD were assessed according to the Research Diagnostic Criteria for TMD. Chewing side preference was determined by observing the direction towards which the jaw was moved while each subject chewed three pieces of silicon for 20 chewing strokes, repeated over for 5 trials. Asymmetry or side difference variables were calculated as the difference between right-hand-side values and left-hand-side values for all parameters. Stepwise multiple linear regression was performed to examine whether side difference variables explain chewing side preference. Results: Fifty-nine subjects (50.4%) chewed on the right, 15 (12.8%) chewed on the left, and 43 (36.8%) chewed on both sides. Ten subjects (8.5%) were left-handed. There was no relationship between preferred chewing side and handedness. Significant relationships were observed between chewing side preference and side differences in bite force, occlusal contact area, Angle class, type of dynamic occlusion and presence of disc displacement with reduction (P<0.05). Stepwise multiple linear regression showed that side differences in bite force, occlusal contact area and disc displacement were the factors related to the preferred chewing side (adjusted R square =0.22). Conclusions: Asymmetry of bite force and occlusal contact area at intercuspal position together with the presence of disc displacement in the TMJ explained 22% of the variation in chewing side preference in a dentate population.


0233 (110758)

Associations of Self-Reported Bruxism, Anxiety, and Stress in Healthy Subjects. K. AHLBERG1, A. SAVOLAINEN2, M. KÖNÖNEN1, M. PARTINEN3, C. HUBLIN4, and J. AHLBERG1, 1University of Helsinki, Finland, 2Finnish Broadcasting Company, Helsinki, Finland, 3Rinnekoti Research Centre, Espoo, Finland, 4Institute of Occupational Health, Helsinki, Finland

The aims of the present study were to analyze whether the levels of self-reported bruxism and anxiety associate among healthy subjects, and to investigate the independent effects of anxiety and stress on the probability of frequent bruxism. Objectives: All employees of the Finnish Broadcasting Company with irregular shift work (n=750; 57.0 % men) and an equal number of randomly selected controls in the same company with regular eight-hour daytime work (42.4 % men). Methods: A questionnaire included a) demographic data; b) self-assessed frequency of tooth clenching or grinding; c) anxiety: Symptom Checklist-90; d) level of perceived stress; e) dissatisfaction with current work shift schedule (irregular shifts vs. day time work). Results: The response rate in the shift work group was 82.3% (56.6% men) and in the daytime work group 34.3% (46.7% men). The mean age of males in shift work was 45.0 (SD 10.6) years and of females 42.6 (SD 10.7) years (p<0.001); the figures for daytime workers were 47.4 (SD 9.7) and 45.5 (SD 10.1) years (NS), respectively. Those with awareness of more frequent bruxism tended to report significantly more severe anxiety (p<0.001). According to logistic regression, subjects reporting stress or anxiety were 2.6-6.3 (95 % CI: 2.6-12.6) times more likely to report frequent bruxism (independently and as an interaction term). Dissatisfaction with one's work shift schedule was also associated with frequent bruxism (p< 0.05). Conclusions: The present findings suggest an association between the awareness of bruxism and psychological factors in healthy adults (i.e. not clinical bruxism patients). Further, self-reported frequent bruxism may indicate psychological states as anxiety, stress, or dissatisfaction.


0234 (110767)

Previous Pain and Stress Experiences Predict Persistent Jaw Muscle Pain. M. RANTALA1, T. SUVINEN1, M. KÖNÖNEN1, A. SAVOLAINEN2, and J. AHLBERG1, 1University of Helsinki, Finland, 2Finnish Broadcasting Company, Helsinki, Finland

The aim of the present study was to assess possible predictive factors for persistent myofascial pain (MFP) diagnosed over a 1-year period in a non-patient working population. Objectives: All 30-to 55-year-old employees of the Finnish Broadcasting Company (YLE) whose current employment had lasted at least five years in the Helsinki area (n=1784) were invited. Of these, 1339 (75%) completed a standardized questionnaire. Clinical examinations were performed on 241 randomly selected participants (18%) at baseline and, eventually, on 211 subjects who participated also in the 1-year follow-up examinations (88%). The mean age of these 211 employees (females 53%) was 46 years (SD 6) in both genders. Methods: Studied prognostic factors were gathered from the baseline questionnaire (Occupational Stress Questionnaire) which included demographic items, pain perceptions, and biopsychosocial questions. Clinical examinations were performed according to the Finnish translation of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Results: Altogether 7% had persistent myofascial pain. Studied age groups were not significantly associated with MFP, although the youngest age group was relatively larger in those with persistent MFP. In the bivariate analyses, those with previous frequent orofacial pain experience (p=0.004) and those with severe stress (p=0.037) were significantly more often diagnosed to have persistent MFP. A slight association was seen with previous frequent neck pain experience and persistent MFP (NS). Logistic regression also revealed that previous frequent orofacial pain experience (P=0.016) and perceived severe stress (P=0.049) were independently significantly associated with the probability of persistent myofascial pain. Conclusions: Previous frequent orofacial pain experience and perceived stress may predict persistent myofascial pain in the jaw muscles.


0235 (111000)

Static and dynamic occlusal characteristics in different diagnoses of TMD. S. PALAU, J. MARTINEZ-GOMIS, M. LUJAN-CLIMENT, R. AYUSO-MONTERO, J. SALSENCH, and M. PERAIRE, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain

Aims: To study the occlusal characteristics of subjects with temporomandibular disorders (TMD) according to Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD). Methods: One hundred and seventeen dentate adults participated in this cross-sectional population-based study. All subjects were examined and answered a questionnaire about RDC/TMD. Overjet, overbite, Angle's classification and crossbite were established for each subject. Occlusal contact area and number of teeth in contact were determined at maximal intercuspal position (ICP) and at right and left lateral excursions of 1.5 mm by scanning interocclusal records and analyzing them using image software. The type of dynamic occlusion was determined for both the working and the non-working side in any lateral position. Differences between TMD and non TMD subjects, and also between subjects with different TMD diagnoses, were assessed by variance analysis or the Mann-Whitney U-test. Results: Fifty-six subjects were diagnosed with TMD. Fourteen presented myofascial pain, 44 disc displacement with reduction, and 7 arthralgia (hence, eight of them had a multiple diagnosis). Subjects diagnosed with arthralgia had a significantly lower overjet than controls. The number of posterior teeth in crossbite in subjects with disc displacement was significantly higher than the corresponding number in controls. Furthermore, there was a significant relationship between the presence of posterior crossbite on the right side and disc displacement in the left TMJ and vice versa. Subjects without TMD had a significantly larger occlusal contact area at ICP than subjects with TMD, with the disc displacement group presenting the lowest values. The type of dynamic occlusion was not associated with TMD on either the working or the non-working side. Conclusion: Despite the limitations of the study, a higher number of posterior teeth in crossbite and a lower occlusal contact area at ICP were correlated with diagnoses of TMJ disc displacement.


0236 (111349)

Maintenance of the Herbst Appliance for Apnoea Treatment and Complications. J. MARTINEZ-GOMIS1, E. WILLAERT1, L. NOGUES1, M. PASCUAL1, C. MONASTERIO2, and M. PERAIRE1, 1Universitat de Barcelona, L'Hospitalet de Llobregat, Spain, 2Ciutat Sanitària i Universitària de Bellvitge, L'Hospitalet de Llobregat, Spain

Objectives: To analyse and to compare between responders and non-responders the number of additional dental visits due to side effects, adjustments and breakages of an oral appliance during the treatment of patients with sleep apnoea. Methods: Forty patients diagnosed with sleep apnoea participated in this study. All these patients received a Herbst appliance with 70% of the maximum protrusion, and this advancement was progressively increased until the patient stopped snoring. Six weeks after the patient stopped snoring or the appliance did not work, polysomnography was repeated. Therapy was considered to be efficacious when a subjective improvement in symptoms was reported and a more than 50% reduction of apnoea/hypopnoea index (AHI) and an AHI value of less than 10 was observed. A 5-year follow-up period was observed and additional visits to dental clinics and the repairs needed in dental laboratories were analysed. Routine check-ups were excluded from the analysis. Data for responders and non-responders were compared using the Mann-Whitney test. Results: Four patients were excluded due to their lack of collaboration. When the new polysomnography was carried out, eighteen patients had stopped using the device most of them because of a small reduction in their AHIs. After 5 years, the subjects had made a mean of 2.5 non-scheduled dental visits per year and a mean of 0.8 Herbst repairs/relines per year had been performed by a dental technician. The most frequent non-scheduled visits were needed during the first year and they were due to acrylic breakage on the lateral telescopic attachment (60%) followed by poor retention (14%) and other adjustments to improve comfort. No significant differences were observed between responders and non-responders. Conclusions: Several technical failures are prone to occur during apnoea treatment with a Herbst appliance but they do not seem to be related to the treatment success rates.


0237 (110944)

Assessing Gingival Capillary Density Variability Using Sidestream Dark Field Imaging. E.J. KAY1, A. SHORE2, J. TOOKE2, K. GOODING2, and H. KYTE2, 1Peninsula College of Medicine and Dentistry, Plymouth, England, 2Institute of Biomedical and Clinical Science, Exeter, England

Objective:

A link between periodontal disease and cardiovascular risk (CVR), mediated via inflammation, has been proposed. Inflammation has marked effects on the microcirculation, although whether the oral microcirculation contributes to the above link is not established. Recent advances in technology may enable exploration of its involvement. Thus, the aim of this study was to demonstrate the feasibility and reproducibility of Sidestream Dark Field (SDF) imaging in assessing the gingival capillary density in healthy subjects.

Methods:

The gingival capillary density of six healthy female subjects (22-49 years) was assessed using a handheld Microscan Video Microscope. Three specific sites were examined in each subject, the marginal gingivae of the central incisors, and between the cuspid canine and premolar on the left and right side of the upper jaw. Capillary density was calculated per mm2 using Capiscope and the intra-/inter subject variability analysed.

Results:

Mean capillary density was 184.6±21.7/mm2 (mean±standard deviation). The intra-subject coefficient of variation across the three sites assessed was 15.7±4.0% (mean±SD)

Conclusions:

This preliminary study demonstrates that SDF imaging of the gingival microcirculation is feasible and gives a reproducible assessment. Due to inherent variability between areas, several sites of measurement will be required to obtain a value representative of an individual's capillary density.

This study was funded by Colgate Palmolive


0238 (111539)

Angiogenic Growth Factors in human Dental pulp. T.G. WILLSON1, N. SILVER1, G.B. PROCTOR1, and K.A. DERRINGER2, 1King's College London, United Kingdom, 2King's College London

Angiogenesis is the process of new vessel formation. Growth factors including basic fibroblast growth factor (FGF-2), platelet-derived growth factor (PDGF), transforming growth factor beta-1 (TGFâ-1) and vascular endothelial growth factor (VEGF-A) are known to regulate this process. Previous studies suggest that these growth factors may be involved in the response of human dental pulps to orthodontic force application. Objectives: The aim of this study was to identify the presence of angiogenic growth factors within pulps of control and orthodontically treated teeth. Methods: In patients, an orthodontic force (0.5 – 1 N) was applied to premolar teeth for 2 weeks. Contralateral teeth were used as untreated controls. Teeth were extracted, pulps were removed and RNA was extracted for the purpose of reverse transcription (RT-) and qPCR. MG-63 osteosarcoma cells were grown under standard conditions for use as a positive control. Primers were designed using Primer Express. Results: RT-PCR using MG-63 cells and control pulp samples indicated expression of angiogenic growth factors: FGF-2, PDGF, TGFâ-1 and VEGF-A. qPCR performed on control and test samples using FGF-2, PDGF, TGFâ-1 and VEGF-A primers indicated a varied individual response in angiogenic growth factor expression after 2 weeks of orthodontic force application. Previous studies showing an increase in the microvasculature of pulp explants from teeth treated with an orthodontic force for 2 weeks have suggested an increase in angiogenic growth factor expression. Shorter durations of orthodontic force application will be used in order identify the time point at which this suggested increase in angiogenic growth factor expression occurs. Conclusions: The present study identified the expression of angiogenic growth factors within the human dental pulp. qPCR results suggest a varied individual response in growth factor expression occurs after a duration of 2 weeks of orthodontic force application.

We acknowledge the King's Dental Institute Research Studentship Programme for funding.


0239 (111640)

Localization of IL-1RI in Rat Dental Pulp. A. BLETSA, I. FRISTAD, and E. BERGGREEN, University of Bergen, Norway

Acute pulpitis is an inflammatory condition characterized by vascular responses such as vasodilatation and increased vessel permeability, and it may be painful. IL-1β is a major pro-inflammatory cytokine that is up-regulated during pulpitis. Although IL-1β seems to play a central role in the pathophysiology of pulpitis, there are no data on the exact sites of action of this cytokine in the dental pulp. Objectives: the purpose of this study was to identify binding sites of the pro-inflammatory cytokine IL-1β in rat dental pulp. Methods: Female Wistar rats (n = 6) were subjected to unilateral pulp exposures in the first maxillary and mandibular molars and the contralateral sides served as untreated controls. One, 2 and 3 weeks after pulp exposures the rats were sacrificed and the jaws were removed. Immunoreactivity (IR) for the interleukin-1 receptor type I (IL-1RI) was examined using multiple-labeling immunofluorescence together with calcitonin gene-related peptide (CGRP), Neuropeptide Y (NPY), CD31 and CD34 in parasagittal rat jaw sections. Results: IL-1RI was found on sensory (CGRP-IR) nerve fibers, on sympathetic (NPY-IR) nerve fibers and on blood vessels (CD34-IR). Conclusion: multiple binding sites of IL-1 were found in the rat pulp. The localization of IL-1RI on sensory nerve fibers implies a direct effect of IL-1β on nociceptor sensitization. The presence of IL-1RI on blood vessels indicates a direct effect of IL-1β on the vessel wall.


0240 (111631)

Is there a role for SSAO in mature human teeth?. J. O'SULLIVAN1, I. SOYINGBE2, D. REQUEJO MULERO2, and M. O'SULLIVAN1, 1Dublin Dental School & Hospital, Ireland, 2Trinity College Dublin, Ireland

Aims: Semicarbazide Sensitive Amine Oxidase (SSAO) found in human dental pulp exhibits unique properties amongst the SSAO family of enzymes in processing the ability to oxidise 5-hydroxytryptophan (5-HT) the potent inflammatory mediator. This leads to a conundrum for SSAO oxidation of 5-HT, as the enzyme has a km of ~320mM for 5-HT which given the high affinity rapid re-uptake of 5-HT by co-localised 5-HT transporters (5-HTT) in neuronal cells (and as dental pulp tissue is derived from neural crest cells) would prevent 5-HT oxidation by SSAO. Without available 5-HT the unique function of SSAO in pulp would appear redundant, this study aims to determine if such a source of 5-HT exists within pulp. Methods: RT-PCR was used to determine expression levels of candidate proteins capable of synthesising 5-HT. Western blot analysis semi quantitatively determined the relative protein levels of the components involved while immunohistochemical studies were used to identify any co-localisation of the candidate proteins. Results: 5-HT is synthesised by tryptophan hydroxylase (TPH) of which exist two isoforms, TPH-1 and TPH-2 are found in gut and neuronal tissue respectively. This study has determined that there is a likely 5-HT source in dental pulp derived from TPH-1 which is not neuronally linked and therefore is freely available. Co-localisation experiments have determined the proximity of the proteins involved in this putative pathway suggesting a feasible mechanism. Conclusion: We have determined that a 5-HT source can exist in mature human dental pulp synthesised by TPH-1, which can be metabolised by SSAO. This can result in downstream events through oxidation products, which include the secondary messenger H2O2. Further investigation is required into the functional role of this action within mature human dental pulp. Pain and inflammatory modulation are the most likely actions.


0241 (111774)

Alkaline Phosphatase Activity in Normal and Inflamed Dental Pulps. E.E. DEMIR, Y. AKSOY, S.P. KARAPINAR, and H. DOGAN BUZOGLU, Hacettepe University, Ankara, Turkey

Objectives: To determine the alkaline phosphatase (ALP) activity in healthy and inflame dental pulp.

Methods: Twenty-four pulp samples were collected from healthy donors , non-medicated for two weeks with analgesic or antibiotics and stored in PBS solution in -70 freeze before experimental procedures. ALP activity was analyzed in normal healthy pulp (n=8, mean age <30), reversible pulpitis (n=8, mean age <30) and irreversible (acute) pulpitis (n=8, mean age <30). Collected pulp tissues were homogenized and ALP activity was determined spectrophotometrically (SpectraMAX Plus, Moleculer Devices, Sunnyvale, CA) and the results expressed as milliunits/ per milligram protein (mU/ mg protein). The differences between the groups analyzed statistically using Mann-Whitney U test at the 95% confidential level.

Results: The recorded ALP activity levels were between (1909,5 ± 245,37 and 1110 ± 296,1). ALP activity in reversible and irreversible pulpitis increased when compared to control group. The differences between reversible pulpitis and control group were statistically significant (p< 0.05).

Conclusions: These results suggest that ALP may have a specific role in the initial pulp response to injury.


0242 (111706)

Signalling Mineralisation in Dental Pulp Derived Cells. R.B. CARTWRIGHT1, P. COOPER1, M. EDWARDS2, C.R. PARKINSON2, and A.J. SMITH1, 1University of Birmingham, United Kingdom, 2GlaxoSmithKline, Weybridge, United Kingdom

Objectives: Signalling of mineralisation in the mature tooth is a key event associated with both peritubular dentinogenesis and regenerative processes after injury in the dentine-pulp complex. We investigate whether solubilised dentine matrix proteins can stimulate mineralisation in dental pulp derived cells. Methods: Dentine matrix proteins (DMPs) were isolated by extraction of dissected and powdered sound human dentine with 10% (w/v) EDTA, pH 7.2, containing protease inhibitors for 7 days at 4oC followed by dialysis and lyophilisation. Odontoblast-like (MDPC-23) and pulp-derived (OD-21) cell lines, kindly provided by Dr J Nor (University of Michigan), and the 3T3 fibroblast-like cell line were cultured in DMEM medium with 10% FCS for 3, 7, 11, 14 and 18 days in the presence of various mineralisation supplements including a) β-glycerophosphate (βGP) and ascorbic acid (AA) [basal mineralisation supplement], b) βGP + AA + DMPs (1µg/ml) [experimental mineralisation supplement], c) βGP + AA + dexamethasone (DEX) [control mineralisation supplement]. Viable cell numbers were assessed by trypan blue staining and mineralisation was quantified by image analysis of von Kossa stained cultures. Mineralisation was expressed as % per cell by dividing the area of mineralisation by viable cell count. Results: Basal levels of mineralisation were observed in the MDPC-23 and OD-21 cells and to a much lesser extent within the 3T3 cell line in the cultures with basal mineralisation supplement. A significant increase in mineralisation was seen with both the addition of DMPs and the control mineralisation supplement. Conclusion: This work demonstrates that solubilised dentin matrix proteins can stimulate mineralization in dental pulp derived cells.


0243 (111258)

Effect of perinatal exposure to bisphenol-A on pubertal rats. A. POIMENOVA, C. RAHIOTIS, and E. KITRAKI, University of Athens (EKPA), Goudi, Greece

Objective: To examine in juvenile rats the effect of perinatal exposure to a low dose of bisphenol A (BPA) on spatial memory and on the basal and stress-induced secretion of corticosterone in plasma.

Methods: Female Wistar rats were exposed to BPA (40 microg/kg provided through corn flakes) from gestational day 1 to the end of lactation. At postnatal day 42, their offspring were randomly divided into two groups per sex. The one group was sacrificed under basal conditions and the other group was tested in the Y maze task and sacrificed immediately afterwards. Trunk blood was collected for corticosterone determinations by radioimmunoassay.

Results: BPA-treated animals of both sexes exhibited a reduced exploration attitude during the Y maze test vs. same sex controls. BPA exposure impaired spatial memory and novel arm discrimination, as BPA-treated animals of both sexes showed no significant preference for visiting the novel arm during the Y maze test, compared to the same sex controls. Exposure to BPA significantly increased basal corticosterone levels of females vs. non-treated females (Table 1). Following Y-maze, the BPA-treated, but not the non-treated males, exhibited significantly elevated corticosterone levels. Pubertal females, irrespective of perinatal treatment, showed elevated corticosterone levels following the test. However, this increase was significantly higher in BPA-treated females, as compared to the non-treated animals.

Table 1: Corticosterone levels in control and BPA animals. Mean ±SEM; 2-way ANOVA; *p≤0.05.

Plasma corticosterone

Male Control

Male BPA

Female Control

Female BPA

Basal (ng/ml)

187±28

151±33

141±29

338±66*

Post Y maze test

251±24

410±58*

336±31

449±23*

Conclusion: Perinatal exposure of rats to a low dose of BPA can modify spatial memory and plasma corticosterone secretion at the onset of puberty in a sexually dimorphic manner.


0244 (110407)

In vitro thermal effects of root canal Nd:YAP laser irradiation. S. BAREK, R. UZAN, M.-J. JAVELOT, and J. AZÉRAD, University of Paris 7, France

Objectives: The aim of this in vitro study was to determine the variation of the temperature at the external root surface arising from heat transfer after Nd:Yap laser irradiation delivered into the root canal.

Methods: Teeth (n=5) were placed into a 37°C thermostatic water container. Shaped (taper .04) root canal were irradiated using Nd:YAP 1.34µm pulsed laser (Lokki, France) at [0.9W/5Hz], [1.4W/5Hz], [1.8W/5Hz], [2W/10Hz], [3W/10Hz] and [4W/10Hz] without water cooling. One to five sequences of laser irradiation were delivered thru a 200µm glass fibre tip at the apical and medial third of the root canal. Temperature changes were recorded at the external surface of the root using a thermal camera (Thermacam B4, Flir, USA).

Results: Temperature maxima did not exceed 41°C after laser irradiation using recommended endodontics values (0.9W/5Hz, 1.4W/5Hz, 1.8W/5Hz). Whatever the power settings the temperature maxima did not exceed 41°C after a single sequence of irradiation. Whatever the power settings, the temperature increase was higher and faster in the apical third. The return of temperature to pre-irradiation values was reached after 60 s maximum.

Conclusions: The observed thermal effects of Nd:YAP root canal laser irradiation exhibit low potential damage to the periradicular tissues and can be considered as a safe procedure for clinical endodontic applications when used in the recommended power/frequency range.


0245 (110646)

Root canal anatomy of third molars. J. COSIC1, N. GALIC2, V. NJEMIROVSKIJ2, and M. VODANOVIC1, 1Private Dental Practice, Zagreb, Croatia, 2University of Zagreb, School of Dental Medicine, Croatia

Morphology of third molars has been described as unpredictable. However restorative, prosthodontic, and orthodontic considerations often requires endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. OBJECTIVES: The purpose of this study was to investigate and characterize the anatomy of maxillary and mandibular third molars. METHODS: A total of 106 human extracted third molars (56 maxillary, 50 mandibular) were included in this in vitro study. With the aid of a carborundum disc in a straight headpiece, each specimen was prepared according to the standard techniques. The anatomy of the root canal system was then recorded. The following observations were made: number of roots, number of canals per root, root-canal configuration, frequency of root canal configuration, number of lateral canals, the average length of the root-canals. RESULTS: Most of the maxillary third molars (83.9%) had three roots, 8,9% had one root, 5.4% had two roots, and 1.8% had four roots. 56% of mandibular molars had one root, and 44% had two roots. 75% of the maxillary third molars had 3 canals, 10.7% had 4 canals, 7.1% had one canal, and 7.1% had two canals. 90% of the mandibular molars had 3 canals, and 4% had 1 canal. The frequency of deviation of the maxillary root-canals was 76.8%, and of the mandibular root-canals was 84%. 12% of the maxillary and two percent of the mandibular third molars contained lateral canals. The average length of the maxillary third molars was approximately 17.98, and of the mandibular third molars was approximately 18.9 mm. CONCLUSION: Third molars show great anatomic variability. Maxillary third molars may have one to four roots, while mandibular may have one or two roots. Maxillary third molars may have up to 4 root canals, while mandibular have up to 3 canals.


0246 (111396)

Endogenous Carbon Monoxide Participates in Basal Perfusion Maintenance of Gingiva. B. KEREMI1, P. KOMORA1, D. ABRAHAM1, B. BEKE1, S. DUHAJ1, A. SZEKELY2, A. FAZEKAS1, G. VARGA3, and Z. LOHINAI1, 1Semmelweis University of Medicine, Budapest, Hungary, 2Semmelweis University, Budapest, Hungary, Hungary, 3Semmelweis University, Budapest, Hungary

Carbon monoxide (CO) is commonly recognized as an enviromental toxin that arises from an incomplete combustion of fossil fuels. However, it is also generated endogenously in the body from heme via heme oxygenase (HO) isoenzymes (inducible HO-1 also termed as heat shock protein-32 or constitutive HO-2) and involved in both physiological and pathological processes as a gaseous mediator. Objectives: The aim of our study was to investigate the effect of CO produced by HO on the gingival resting microcirculation. Methods: The gingival blood flow was measured by laser Doppler fluxmetry in the upper central papilla before (bsl) and after the application of an HO inhibitor (zinc deuteroporphyrin 2,4-bis glycol, ip. 45 micromol/kg) for 45 min in anaesthetized rats. The same study was repeated after the blockade of nitric oxide (NO) synthase activity (1mg/ml L-NAME in tap water ad libitum for 1 week). At the end of the experiments the HO isoenzymes were localized by immunohistochemistry in the gingival vessels. Results: HO inhibition significantly decreased gingival blood flow (GBF, bsl vs. 45. min: 570±94 vs. 326±85 BPU, p<0.05) and increased gingival vascular resistance (GVR, bsl vs. 45. min: 0.23±0.04 vs. 0.39±0.06 mmHg/BPU, p<0.05) without altering the mean arterial blood pressure (MBP). NO deficiency significantly increased the start-up MBP (control vs. L-NAME pretreatment: 108±3 vs. 145±4 mmHg, p<0.05) and GVR (control vs. L-NAME pretreatment: 0.23±0.04 vs. 0.35±0.04 mmHg/BPU, p<0.05) and prevented the vasoconstrictor effect of HO blockade in the gingiva. There was a weak HO-1 immunostaining within the vascular wall and the perivascular nerves elicited HO-2 reactivity. Conclusions: Our data indicate that endogenous CO is involved in the adequate maintenance of basal gingival perfusion. The vasodilatory effects of endogenous CO are NO dependent. Supports: OTKA T042584 and T049708.


0247 (110796)

Folic acid and the cleft palate of Tgf-β3 null mice. A. DEL RÍO1, M.C. BARRIO1, J. MURILLO1, E. MALDONADO1, Y. LÓPEZ1, J. PÉREZ-MIGUELSANZ1, C. MAESTRO1, E. MARTÍNEZ-SANZ1, C. MARTIN2, and C. MARTÍNEZ-ÁLVAREZ1, 1UNIVERSIDAD COMPLUTENSE DE MADRID, Madrid, Spain, 2Faculty of Odontology, Universidad Complutesnse de Madrid, Spain

Tgf-ß3 null mutant mice (Tgf-ß3 -/-) have cleft palate (CP). This CP is mainly due to lack of bilateral medial edge epithelia (MEE) adhesion and disappearance, although a decrease of palatal mesenchymal cell proliferation may also cooperate. A low intake of dietary Folic Acid (FA) has been correlated with CP appearance, whilst supplements of FA have been seen to reduce the risk of this congenital malformation. Objective: Our aim has been to determine whether a supplement of FA added either to Tgf-ß3 +/- dams or Tgf-ß3 -/- palatal shelf cultures benefits the CP presented by the Tgf-ß3 -/- mice. Methods: The diet of Tgf-ß3 +/- females was 2 mg FA/kg diet (control) or supplemented with 40 mg FA/kg diet (20 fold the standard levels) for 2 to 16 weeks. Pregnant females were sacrificed at embryonic day (E) 17. The palate of Tgf-ß3 -/- embryos was observed macro and microscopically. In addition, E13.5 Tgf-ß3 -/- palatal shelves were apposed and cultured for 18 or 36 hours in 1% ascorbic acid DMEM/F12, in the absence (control) or presence of 4 or 20 fold supplement of FA. Analysis of the presence of dead cells (TUNEL assay) and palatal shelf adhesion and fusion was then performed. Results: The Tgf-ß3 -/- progeny of Tgf-ß3 +/- dams FA supplemented had 17.24% presence of a milder form of CP, whilst this was only observed in 3.4% of the controls. In the milder cases, palatal shelves appeared either partially adhered or in closer contact. No differences between groups were observed in the culture study. Conclusion: Dietary FA supplement to Tgf-ß3 +/- females softens the severity of the cleft palate presented by Tgf-ß3 -/- embryos, through mechanisms other than MEE cell death, adhesion and fusion.

Supported by grants from FIS (PI06/0184) and UCM-CM Research Group 920202, 2006.


0248 (110962)

Ex Vivo Myogenesis of Human Adult Masseter NCAM/CD56+ cells. A.C. SINANAN, N.P. HUNT, and M.P. LEWIS, UCL Eastman Dental Institute, London, United Kingdom

Objectives: We have previously identified a population of NCAM+ve cells (the myogenic fraction) isolated from human adult masseter muscle using magnetic activated cell sorting (MACS) to study jaw muscle regeneration (Sinanan et al 2004). This study describes the growth dynamics of these cells and optimization of their myogenic differentiation. Methods: Heterogenous cultures derived from masseter muscle biopsies were immunomagnetically labeled with CD56 microbeads and fractionated by dual-pass positive selection MACS. In addition to co-culture with unsorted parent cells or the CD56-ve fraction generated during cell sorting, multiple cytokine-augmented media were tested to optimize the survival, proliferation and myogenic differentiation of the cells; cultures were analyzed by immunoflurocytochemistry. Results: Optimal proliferation of myogenic masseter muscle cultures required serum-free growth media supplemented with insulin-like growth factor-1 (IGF-1), hepatocyte growth factor (HGF), heregulin-beta-1 (HRG-β1) and fibroblast growth factors (FGF 2,4,6). Myogenic differentiation was encouraged by either adjacent co-cultures (of unsorted masseter muscle cells or CD56-ve cells) or by myogenic inducers (IGF-1 and HRG-β1), the latter resulting in frequent formation of force-generating polynuclear (>20 nuclei) myosacs. A molecular profile for mononuclear cells (MC) and myotubes (MT) was also revealed: CD34, vascular cell adhesion molecule-1, α-smooth muscle actin, integrin α2/CD48b, MyoD1 (few MC); myf5, Thy1/CD90, integrins (αv/CD51, β3/CD61, β5), syndecan-3 and heregulin receptor-2 (HER 2) (MC); NCAM/CD56, desmin, m-cadherin, integrins (α7, β1/CD29), HGF-R/c-Met, FGF-R (1,4), HER (3,4), vascular endothelial growth factor receptor-2, syndecan-4 and myogenin (MC and MT) ; nerve growth factor receptor and α-saromeric actin (few MC, all MT); myf-6 and α-saromeric actinin (MT). Conclusions: These results indicate that MACS-selected human adult muscle-derived CD56+ cells are functional myogenic precursors but also co-express lineage markers of several non-myogenic muscle-associated cells; their survival, proliferation and myogenic differentiation are regulated by both autocrine and paracrine circuits, probably involving IGF-1, FGF, HRG-β1 and HGF.


0249 (110739)

Study of Apical Lesions in a Medieval Population. S. LUCAS, R. ESCLASSAN, A. SEVIN, and A.M. GRIMOUD, Université Toulouse 3, France

Objectives: The aim of this study was to determine the causes of apical lesions (periapical granuloma and cysts) on skeletal remains of a medieval sample (12th – 14th century A.D) from the south of France, in relation with tooth diseases.

Methods: The sample consisted of the skeletal remains of 60 individuals. Only mandibles in a good state of preservation were studied. All teeth were radiographed and observed macroscopically. Caries were diagnosed, and location and lesion level were noted. Wear was graded according to the Brabant index with two parameters, quantity and direction of wear. Apical lesions were classified into three groups: abscess (assumed if diameter <3mm), and cysts (assumed if diameter >3 mm), with or without fistulae. Two practitioners noted all data. The statistical significance of recorded values was tested. A P value of less than 0.05 was considered as statistically significant.

Results: Apical lesions affected 21 individuals and 36 lesions were diagnosed on the 788 teeth examined. 12 lesions were assumed to be periapical granulomas: 58.33% of teeth were not carious and attrition was more than level 3 in 58.33%. 14 lesions were cysts without fistulae: 64.28% were located on retained teeth and the quantity of wear was more than level 3 in the other cases. 10 lesions were cysts with fistulae: 70% with gross caries reaching the pulp but attrition was generally less than level 2.

Conclusion: To our knowledge no study has compared the association of coronal wear and dental caries in the development of apical lesions. These findings show that there could have been different ways of developing such a disease. Attrition has an important impact on small lesions. For cyst lesions, retained teeth and gross dental caries are the principal factors of disease. Presence or absence of fistulae is connected with coronal lesions.


0250 (110634)

Maxillar Dimensions Change in Croatia from 6th Century till Today. I. SAVIC PAVICIN1, M. VODANOVIC2, J. KEROS1, V. NJEMIROVSKIJ3, and H. BRKIC2, 1University of Zagreb,School of Dental Medicine, Croatia, 2Universtiy of Zagreb, School of Dental Medicine, Croatia, 3University of Zagreb, School of Dental Medicine, Croatia

Objectives: It is well documented that the changes in the lifestyle, primarily nutrition influenced evolutionary changes of the size of human jaw. This research presented herein aims at identifying the possible changes in the size of the maxilla within the population inhabiting the area of today's Croatia. Methods: We studied archeological remains of populations from antique period (AP, 6th - 7th century, Štrbinci, Osijek), early Middle Ages (EMA, 10th – 11th century, Bijelo Brdo), late Middle Ages (LMA, 18th – 19th century, Požega), and the recent population (RP, 20th century, Zagreb). Anterior and posterior upper dental arch widths and the palatal height were measured on 106 upper jaw archeological samples and 48 dental casts of contemporary population. Results: Whereas the differences in anterior upper width between the samples were negligible, the differences in posterior upper widths (PUW) were significant. PUW of RP (51.33±2.69 mm) was found to be significantly higher then that of both Middle Ages samples, whilst that of the LMA sample (48.88±3.53 mm) was significantly higher then the one from the EMA (47.18±2.32 mm). The AP sample had significantly larger PUW (50.26±2.96 mm) than those from the EMA. The palatal height was significantly higher in the RP (18.88±2.00 mm) than in medieval samples, whereas the Antiquity sample was higher than the EMA sample (16.19±2.52 mm). Conclusion: The deviation within the Antiquity sample could be caused by the mixing of different populations - Romans who inhabited the location until the 7th century when Croats (South Slavs) permanently displaced them. Our findings indicate that both posterior upper width as well as palatal height of the jaw increased in the analyzed population. Whether it is result of different genetic expression of one population or interbreeding of different nations on area of today's Croatia, still needs to be researched.


0251 (110346)

Comparison of facial measurements among three Malaysian ethnic groups. W.C. NGEOW, and S.T. AL-JUNID, University of Malaya, Kuala Lumpur, Malaysia

Objectives: This study was done to establish the quantitative norms and proportion indices of the face for the three major ethnic groups in Malaysia, namely the Malay, Chinese and Indians. Methods: The study group consisted of convenient samples with a total of 100 participants in each group and an equal number of female and male subjects. The age ranged from 18 to 25 years. The participants were generally healthy and exhibited no craniofacial abnormalities and had no history of plastic or reconstructive surgery. Subjects of mixed parentage were excluded from this study. Standard anthropometry instruments and methods were employed. Results: The facial index (facial length/breadth x100) was between 83 and 86 in all the three groups, indicating a mesoprosop-type face. Classically this is categorised as a short and broad face. The mean upper face index was between 53 and 55 in the whole sample indicating a mesen or medial type upper face. The Malay generally had the widest upper face. The lower face to face height index also indicated a more balanced relationship between the two measurements and was seen in all three races. Conclusion: The Malays and Chinese have more similar facial features than the Indians.


0252 (111307)

TEM interface characterization of a low-shrinking composite bonded to enamel/dentin. A. MINE, J. DE MUNCK, K. VAN LANDUYT, P. LAMBRECHTS, and B. VAN MEERBEEK, Leuven BIOMAT Research Cluster, Catholic University of Leuven, Belgium

The low-shrinking composite composed of combined siloxane-oxirane technology (Filtek Silorane, 3M ESPE) required the development of a specific two-step self-etch adhesive (Silorane System Adhesive), in particular because of the high hydrophobicity of the silorane composite. Objectives: to characterize using transmission TEM the interaction of this adhesive with enamel/dentin to elucidate the underlying mechanisms of adhesion. Methods: Non-demineralized/demineralized 70-90 nm sections were prepared following common TEM-specimen processing procedures. Results: Corresponding to the two-layered application of Silorane System Adhesive, including two separate light-curing steps, TEM revealed a typical two-fold build-up of the adhesive resin, resulting in a total adhesive layer thickness of about 20 µm. At bur-cut enamel, a tight interface was formed, mostly with only tiny micro-tags and without distinct dissolution of hydroxyapatite observable. Immersion of specimens in AgNO3 did reveal traces of Ag along some part of the enamel-adhesive interface and/or between the two adhesive resin layers. At bur-cut dentin, a relatively thin hybrid layer of maximum a few hundreds of nanometer was formed without clear surface demineralization. No clear resin tags were formed. At fractured dentin, the interaction of Silorane System Adhesive appeared very superficial. Distinct resin tags were formed due to the absence of smear plugs. Silver-nitrate infiltration showed a varying pattern of both spot- and cluster-like appearance of nano-leakage. This nano-leakage appearance has been observed to vary widely with the region. Substantially more Ag-infiltration was observed along the dentin-adhesive interface of bur-cut dentin, as compared to that of fractured dentin. Conclusion: The nano-interaction of Silorane System Adhesive should be attributed to its relatively high pH of 2.7. The obtained tight interface at both enamel and dentin indicates that the two-step self-etch adhesive effectively bridged the hydrophilic tooth substrate with the hydrophobic silorane composite.


0253 (110162)

Effect of cavity-configuration and thermo-cycling on adhesion of low-shrinking composite. A. MINE1, J. DE MUNCK1, K. VAN LANDUYT1, A. POITEVIN1, T. KUBOKI2, Y. YOSHIDA2, K. SUZUKI2, P. LAMBRECHTS1, and B. VAN MEERBEEK1, 1Leuven BIOMAT Research Cluster, Catholic University of Leuven, Belgium, 2Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan

Objectives: Polymerization shrinkage stress can impair bonding effectiveness, especially at the bottom of a high C-factor occlusal class-I cavity. The purpose of this study was 1) to evaluate the effect of a low-shrinking composite on the bonding effectiveness in a high polymerization shrinkage stress environment and 2) to evaluate the effect of thermo-cycling on these pre-stressed interfaces.

Methods: A new low-shrinking composite (els, Saremco) was bonded into standardized occlusal class-I cavities (4.5x4.5x2.5 mm) using a 3-step etch-and-rinse adhesive (cmf, Saremco). A 2-step etch-and-rinse adhesive (XP Bond, Dentsply) and a conventional composite (Z100, 3M ESPE) served as control. The restored teeth were subjected to 20,000 thermo-cycles or 3 weeks of water storage. Then, the teeth were sectioned to 1x1 mm sticks by an automated, water-cooled diamond saw (Accutom, Struers), of which the 4 central sticks were further processed for micro-tensile bond strength (μTBS) testing (5 teeth per group were used).

Results: 3-way ANOVA revealed a significant effect for the adhesive and composite (both p<0.0001), but no effect for thermo-cycling (p=0.994).

mean ± SD (ptf/n)

                control

    20,000 thermo-cycles

   cmf/els

 26.2 ± 9.2 MPaa,b (0/20)

 27.5 ± 9.2 MPaa (0/20)

   cmf/Z100

 16.3 ± 16.9 MPab,c,d (7/20)

 20.3 ± 13.6 MPaa,b,c (1/20)

  XP Bond/els

 13.7 ± 12.1 MPac,d (3/20)

 8.3± 10.5 MPad,e (9/20)

  XP Bond/Z100

 0.0 ± 0.0 MPae (20/20)

 0.1± 0.4 MPae (19/20)

ptf = pre-testing failure = 0 MPa. Means with the same superscript are not statistically different (Turkey multiple comparisons, p<0.05).

Conclusion: The low-shrinking composite in combination with the 3-step etch-and-rinse adhesive provided the best bonding performance, even after thermo-cycling. The 2-step etch-and-rinse adhesive suffered strongly from polymerization shrinkage stress, which could be partially restored by using the low-shrinking composite.


0254 (111576)

Bond strength of resin cements to intact and caries-affected dentin. B. OZTURK1, N. OZTURK2, S.T. TASDEMIR2, M. ULKER3, and F. OZER4, 1Selcuk University Faculty of Dentistry, Konya, Turkey, 2Selcuk Universitesi, Konya, Turkey, 3Erciyes University, Kayseri, Turkey, 4Selcuk University, Department of Operative Dentistry, Konya, Turkey

Objectives: The purpose of this study was to evaluate the micro-tensile bond strength(MTBS) of three self-etch resin cements to caries affected and intact dentin.

Methods: 30 extracted human molars (15 with occlusal caries lesions, 15 with intact occlusal) were used. Following the removal of occlusal enamel surfaces, flat dentin surfaces were obtained and polished with # 600 silicon carbide (SiC) paper. Quadrant CariTest (Cavex) was used as a guide for caries removal. The samples were divided into three resin cement groups of 10 teeth each (5 intact, 5 caries-affected); Panavia F (Kuraray Co. Ltd, Osaka, Japan), BisCem (Bisco, Canada) and Superbond C&B (Sun Medikal Co.Ltd, Shiga, Japan). Resin cements were applied to occlusal dentin surfaces in 2mm thickness. The specimens were then stored in 37oC distilled water for 24 hours. For the MTBS tests, teeth were prepared into I-shape sections, top half consisting of resin cement and bottom of half consisting of dentin. After application of MTBS tests, bonded surfaces of specimens were examined by stereomicroscope for evaluation of failure modes. The bond strengths to dentin were calculated as MPa and statistically analyzed by ANOVA (p=0.05, n = 15).

Results: The results of this study indicate that the bond strength of Panavia F and Superbond C&B to both normal (11,74±4,40 ; 14,52±2,89, respectively)and caries-affected dentin (12,10±3,70 ; 17,02± 3,87, respectively)was not significantly different (p>0.05). The bond strength of BisCem was significantly higher to normal dentin (10,34±2,75)than to caries-affected dentin (4,64±1,66) (p<0.05)

Conclusion: Although Panavia F and Superbond C&B exhbited similar bond strengths to caries-affected dentin and intact dentin. BisCem showed lower bond trength to caries-affected dentin. Bond strength of the self-etch adhesive cements to caries-affected dentin changed according to the chemical composition of the material.


0255 (111333)

Effect of pulpal pressure on bond strength of self-etch adhesives. A. ABDALLA, Faculty of Dentistry, Tanta, Egypt

Objective: To evaluate the effect of pulpal pressure on the microtensile bond strength of four self-etch adhesives to dentin. A total-etch adhesive was added for comparison. Methods: 60 freshly extracted human third molars were selected. For each tooth, the root was removed below the cemento-enamel junction. A second parallel section was made to remove the coronal enamel to form a crown segment. The root portion of the resulting crown segment was cemented to a Plexiglas platform using cyanoacrylate cement. The crown segment was then connected with a plastic tube to a water column to produce a pressure of 20 cm H2O at the dentin surface of the crown segment. The adhesive materials were: a total-etch adhesive (Scotchbond 1) and four self-etch adhesives (Clearfil SE Bond, Hybrid Bond, Futurabond NR, and AdheSE Bond). The adhesives were applied to the dentin surface in three test procedures: applied to dentin without pulpal pressure, applied to dentin with pulpal pressure for 24 hours, and applied to dentin with pulpal pressure and the pressure was maintained for 6 months during storage. Grandio resin composite was placed in 3-4 layers to a height of 5-6 mm to form a crown segment. For bond strength measurement, the composite-dentin segment was removed from the Plexiglas. This segment was then sectioned to prepare the specimens for microtensile bond measurement. Results: None of the tested adhesives showed bond strength reduction when applied to dentin supplied with water pressure. After 6 months of pulpal pressure, Scotchbond 1, Clearfil SE Bond and AdheSE Bond showed significant reduction in bond strength (P< 0.05). In contrast, Futurabond NR and Hybrid Bond were not significantly affected. Conclusion: pulpal pressure had no effect on bond strength during application procedures. However, after 6 months of continuous pulpal pressure, the bond strength of some materials was significantly reduced


0256 (111436)

Weibull analysis for evaluating contemporary adhesives. C.J. KLEVERLAAN, ACTA, Universiteit van Amsterdam en Vrije Universiteit, Netherlands, and A.J. FEILZER, ACTA, Universiteit van Amsterdam and Vrije Universiteit, Netherlands

Objectives: The aim of this study was to evaluate the microtensile bond strength of ten adhesives to dentine and enamel.

Methods: After grinding sixty freshly extracted caries free human molars an adhesive was applied, according to the manufacturer's instructions, to the dentin or the enamel surface. The adhesive layer was light cured and Z250 composite was applied in 3 successive layers of 2 mm, which were each light cured for 20 s. The specimens were stored in water at 37°C for 24 h until sectioning. Whereafter the specimens were cut into rectangular microbars (1 mm2). From the obtained microbars 10 specimens per tooth were randomly selected to evaluate their microtensile bond strength in a universal testing machine. The obtained strength values were analysed with ANOVA with random effects and Weibull survival analysis. The characteristic strength (h), the Weibull modulus (b), and L5, which refers to the bond strength at which 5% will fail, were calculated.

Results: A significant Spearman correlation for dentine between L5 (r=-0.782; P=0.005) and the type of bonding; (1) three-step total-etch, (2) two-step total-etch, (3) two-step self etch, and (4) one-step self etch, was found. The same significant correlation was found between L5 and the type of bonding for the enamel specimens (r =-0.625; P=0.048). In contrast, no significant correlation between the average microtensile bond strength and the type of bonding was found. Also pre-failures of specimens during manipulation coincided with the lowest L5 values, while the mean microtensile bond strength of these adhesives was not necessary the lowest value.

Conclusion: Understanding the laboratory measurements of the failure of adhesive systems is a prerequisite for eventual extrapolation of the obtained results to the clinical situation. Based on these data one should consider to include L5 as parameter in the description of the failure of dental adhesives.

 


0257 (110754)

Microtensile Dentin-bond Strength Study of Rigid Rod Polymer Modified Primers. A.-M. VUORINEN1, S. DYER2, P. VALLITTU1, and L. LASSILA1, 1University of Turku, Finland, 2Oregon Health & Science University, Portland, USA

Objectives: This study evaluated the effect of solvent-monomer-ratio and optional addition of initiator-activator system to the experimental rigid rod polymer (RRP) modified primer on microtensile dentin-bond strength (µTBS). RRPs are based on long stiff molecules (eg. polyphenylenes), which can act as reinforcing nanoscale fiber fillers after being dissolved with solvent. Methods: Primers with different solvent proportions were fabricated by dissolving RRP (Parmax, 1240, Mississippi PolymerTechnologies Inc., USA) into dichloromethane (DCM) and optionally further mixing it with monomers, activator and initiator; bis[2-(methacryloyloxy)-ethyl]phosphate (BMEP) and 3(methacryloyloxy)propyltrimethoxysilane (MPS) dimethylaminoethyl methacrylate (DMAEMA) and camphorquinone (Table). A commercial etch-and-rinse adhesive (Voco Solobond Plus) was used as a control. Primers were applied onto human dentin prior composite resin build-up was light-polymerised incrementally. After 48 hours in water at 37°C the teeth were sectioned and the specimens were then tested with the microtensile tester. Fracture surface analysis was performed. Results: Increase of the solvent-monomer ratio and addition of RRP into primers increased uTBS (3-way ANOVA, p=0.05). Adding activator and initiator into primer did not increase bond strength. Most of the failures in all groups were mixed type failures (adhesive-cohesive). Conclusions: Experimental primer of low viscosity (ratio 5:1) showed comparable results with the control primer-adhesive system.

 

Group

 

Solvent monomer ratio

BMEP

(vol%)

MPS (vol%)

DCM (vol%)

DCM/ RRP 2% (vol%)

 

 

Adhesive resin

 

Bond strength (MPa)(SD)

1 n=72

1:1

25

25

50

 

x

17.5 (6.7)a

2 n=74

1:1

25

25

 

50

x

20.8 (7.2)a b

3 n=100

5:1

8.3

8.3

 

83.3

x

31.2 (9.4)c

Group

 

Solvent monomer ratio

BMEP+ activator

(vol%)

MPS+initiator (vol%)

DCM (vol%)

DCM/ RRP 2% (vol%)

 

 

Adhesive resin

 

Bond strength (MPa)(SD)

 

4 n=68

5:1

8.3

8.3

 

83.3

 

23.5 (8.2)b

5 n=66

control

control

control

control

control

x

31.7 (11.3)c

ANOVA was performed (p=0.05). Superscript letter indicates homogenous subsets in one-way ANOVA (Tukey) (p=0.05).

 


0258 (111561)

Effect of Calcium-Hydroxide on Bond Strength of a Self-etching Adhesive. N. UNLU, Selcuk University School of Dentistry, Konya, Turkey, and A.R. CETIN, Selcuk University, Konya, Turkey

Objective: The purpose of this study was to determine the effect of three different calcium hydroxide (CH) bases placed under composite resins on micro tensile bond strength (µTBS) of a self-etch bonding system.

 Methods: Twenty deep coronal dentin surfaces were obtained from sound human molars with a diamond bur using a slow-speed turbine.  The teeth were randomly divided into four groups of five teeth. The CH bases used in this study were resin based CH, Kerr-life and Alkaliner. Three groups were treated with one of the calcium hydroxide bases according to the manufacturer's instructions and the fourth group was left uncovered and served as the control group. Bonding system (Clearfil SE bond (CSE)) was applied according to manufacturer's instructions and followed by composite application (Majesty posterior). After the storage in water at 37° C for 24 hours, the teeth were sectioned to obtain several bonded sticks of 1.0mm2 of cross sectional area. The specimens were then subjected to the µTBS test. µTBS values were calculated in MPa (n=15). Fracture analysis of the bonded enamel surface was performed using stereo microscope.

Groups

n

Mean± SD

Resin based CH

15

24,83±7,16a

Kerr life

15

21,85±4,57b

Alkaliner

15

21,80±6,02b

Control

15

30,19±8,04a

Results: µTBS were analyzed by One way ANOVA, Post Hoc Tukey tests and showed in the table below. Means with the same letter are not statistically different at p>0.05. µTBS of CSE significantly changed according to used some CH bases (p>0.05). Kerr-life and Alkaliner showed the lowest bond strength to dentin surface (p>0.05). There was not statistically difference between resin based CH and control groups.  fracture analysis of the surfaces showed that the failure was mostly adhesive in nature. Conclusions: The resin based CH placed under composite resins dramatically affected the µTBS of CSE to dentin (p>0.05).


0259 (109706)

Do Endogenous Enzymes Degrade Resin-Dentin Interfaces Produced by Self-etch Adhesives?. J. DE MUNCK1, P.E. VAN DEN STEEN2, A. MINE1, G. OPDENAKKER2, and B. VAN MEERBEEK1, 1Leuven BIOMAT Research Cluster, Catholic University of Leuven, Belgium, 2Rega Institute for Medical Research, Catholic University of Leuven, Belgium

Objectives: Endogenous MMP-2 or MMP-9 enzymes released by adhesive treatment procedures can hydrolyze collagen fibrils in the hybrid layer and so compromise bonding effectiveness. The purpose of this study was to evaluate this degradation pattern for ‘mild' self-etch adhesives that were modified with MMP-inhibitors.  

Methods: 1) Identification of enzyme release: Fresh human dentin powder was mixed with 35% solution of H3PO4 or a self-etch primer (Clearfil SE and Protect Bond, Kuraray; G-Bond, GC). Gelatinases were extracted by Sodium Dodecyl Sulphate and identified by gelatin zymography. 2) Micro-tensile bond strength (µTBS) testing: Self-etch primers were modified by adding two MMP-inhibitors: chlorhexidine (CHX, 0.05%) or SB-3CT (10 µM), a very specific mechanism-based inhibitor with a minimal inhibitory concentration in the nano-molar range. µTBS was evaluated after 1 week, 3 months and 6 months water storage.

Results: MMP-9 was not released and  MMP-2 was released by H3PO4, but not by the self-etch primers.

 Mean ± SD (n) in MPa

months

Clearfil SE

 

Protect Bond

G-Bond

Control (no MMP-inhibitor)

0

69.8 ± 23.7 (12)a,b

55.3 ± 21.3 (12)A

14.2 ± 8.5 (16)I,II

3

69 ± 14 (9) a,b

55.4 ± 14.2 (10) A

12.8 ± 9.6 (10) I,II

6

50.8 ± 17.2 (14)b

43.7 ± 14.3 (12) A

6.8 ± 6.4 (19)II

CHX

0

55.4 ± 20.6 (12) a,b

60.5 ± 16.6 (12) A

13.9 ± 12.8 (16) I,II

3

63.5 ± 14.5 (10) a,b

49.3 ± 10.2 (9) A

23.9 ± 26.3 (8)I I,II

6

50.0 ± 16.1 (11)b

40.5 ± 17.5 (13) A

9 ± 10.4 (12) I,II

SB-3CT

0

70.3 ± 15.7 (10 a,b)

57.2 ± 19 (13) A

20.4 ± 7.5 (12)I

3

64.3 ± 16.9 (10 a,b)

50.4 ± 22.8 (10) A

19.2 ± 12.2 (10) I,II

6

74.4 ± 11.2 (10)a

39.8 ± 19.6 (13) A

7.7 ± 5.6 (12) I,II

Means with the same superscript are not significantly different (Tukey multiple comparisons test, p < 0.05)

Regarding µTBS, no degradation in µTBS was measured (2-way ANOVA, p=0.1690) for Clearfil SE, in contrast to Protect Bond (p=0.0006) and G-Bond (p=0.0002).

Conclusions: As the release of proteinases was minimal and specific MMP-inhibitors had no effect, the effect of endogenous MMP-2 (and MMP-9) on the stability of hybrid layers produced by ‘mild' self-etch adhesives must be considered as minimal.


0260 (110294)

Effect of Bleaching on Staining Susceptibilty of Restorative Materials. C. CELIK1, B. YÜZÜGÜLLÜ1, S. ERKUT1, and A.R. YAZICI2, 1Baskent University, Ankara, Turkey, 2Hacettepe University, Ankara, Turkey

Objective: The aim of this study was to evaluate the effect of 20% carbamide peroxide(CP) bleaching agent on staining susceptibility of restorative materials after immersion in two different solutions (tea, coffee).

Methods: Forty-two disk-shaped specimens (10 mm in diameter, 2-mm thick) were fabricated for each of the composite resins, Filtek Supreme XT, Ceram-X Mono and Aelite APB. The baseline color values (L*, a*, b*) of each specimen were measured with a spectrophotometer according to the CIELab color scale. The specimens of each restorative material were randomly divided into two groups (n=21). While the first group specimens were stored in distilled water (non-bleaching group-control), bleaching agent (Opalescence PF 20%) was applied on the top surface of the specimen of the second group (bleaching group). After color change values were remeasured, specimens were randomly divided into three subgroups (n=7) according to the staining solutions (tea, coffee or distilled water as control). The color change value (DeltaE*ab) was calculated after 30-days immersion period. The data were subjected to analysis of variance (p<0.05). Results: There was no statistically significant difference within each restorative materials' DeltaE*ab values after bleaching (p>0.05). The staining solutions did not cause statistically significant difference between DeltaE*ab values of bleaching and non-bleaching groups (p>0.05). No significant interaction was found either between bleaching and restorative materials (p=0.714) or between bleaching and staining solutions (p=0.304). Significant interaction was only found between restorative materials and staining solutions (p=0.005). The DeltaE*ab values which were higher than 3.3 were considered visually perceptible (DeltaE*ab> 3.3). While tea and coffee caused perceptible color change in Filtek Supreme XT and Ceram-X Mono, only tea caused perceptible color change in Aelite APB group.

Conclusion: Bleaching did not affect staining susceptibility of restorative materials.


0261 (110633)

Effect of luting cement colour on all-ceramic restorations. T. BICAKCI1, M.S. ULUSOY1, M.A. BICAKCI1, and A. USER2, 1Ege Universitesi, Izmir, Turkey, 2Ege Universitesi, Ýzmir, Turkey

Objectives: The aim of this study was to investigate the effects of various composite resins on the restorations' shade and if it is affected by composite resins' color or different thickness of ceramic restorations. Methods: Four different composite resin systems (Variolink II, Bifix DC, RelyX-ARC, Nexus II) in two different shades were used for cementation of 192 IPS Empress specimens on polyethylene plates. The ceramic samples were prepared in two different thicnesses (0,8mm and 1,0mm). The shade differences of the Empress surfaces were examined spectrophotometrically (X-Rite, Smartscan MA60) in two stages; before and after the cementation. Results: The results of the statistical analysis (ANOVA) showed that the differences related with the kind of composite resin, the colour of the composite resin and the thickness of the ceramic specimens found to be significant (p<0.05). The shade difference of Variolink II composite resin was significantly greater, and the difference caused by Bifix DC was found to be significant than those of Rely X ARC and Variolink II. (Bonferroni, p<0.05). Conclusions: Because the luting cement colour affects the final shade of all-ceramic restorations, the enhanced knowledge on colour charesteristics of composite cements is required to achieve superior esthetics.


0262 (110888)

Reproducibility of Color Evaluation for Dentistry. K. MALKIEWICZ, and E. JODKOWSKA, Medical University of Warsaw, Warszawa, Poland

Objectives:

The aim of the study was an assessment of the reproducibility of colorimetric measurements of samples of the VITA Classic colour key with the use of two dental spectrophotometers.

Material and methods:

In order to determine the reproducibility of colorimetric measurements, 16 porcelain samples from the VITA Classic colour key were assessed. Each sample was assessed using the parameters: L*, a* and b*, describing the colour as a point in a three-dimensional system of co-ordinates. 10 measurements were taken using a Spectroshade spectrophotometer (MHT), and 10 using an Easyshade spectrophotometer (VITA GmBH). For each series of measurements taken by one appliance, comprising of 10 elements, a mean value of the parameters was determined, i.e., L* (lightness), a* (red/green chroma) and b* (yellow chroma), as well as their standard deviations. These results were than analyzed using the Mann-Whitney test, with the help of Statistica ver. 6.0.

Results:

In the case of measurements taken using the Spectroshade spectrophotometer, the average standard deviation was 0.0457 (p=0.0000) for L*, 0.1087 for a*, and 0.1324 for b*. In the case of Easyshade the respective values were: 0.1732, 0.1371 and 0.1121.

Conclusions:

1. Both appliances used for the colorimetric evaluation of teeth and restorations have a similar reproducibility of a* and b* measurements.

2. Under the conditions of this study, the Spectroshade spectrophotometer showed significantly greater reproducibility of measurements of lightness (L*) of samples of a colour key.


0263 (111496)

Reaching veneer color match by manipulating dentine, porcelain and cement. A. ÐOZIC, M. TSAGKARI, and A.J. FEILZER, ACTA, Universiteit van Amsterdam and Vrije Universiteit, Netherlands

Objectives: This study reveals the possibility to achieve color match (CM) with target veneer (TC) using porcelain veneers of different shade and translucency in combination with discolored dentine and different try-in adhesive resins.

Methods: TC specimen was 0.8 mm thick porcelain veneer, color ETC2 (corresponding to A3) (n=5) of IPS-Empress ceramics in combination with “natural die material” in color ND4 (represents average dentin) (n=10) and neutral cement color MV0 (Variolink), all from Ivoclar/Vivadent, Shaan, Lichterstein. CM specimens were 0.8 mm thick ET1 (translucent glossy), ETC0 (translucent + shade), ETC2 (translucent + shade A1, A2), EO1 (average opacity) and EO3 (very high opacity) in combination with 4 discolored dentins ND5, ND6, ND7 and 2 cements (low and high value). Color was measured with SpectroShade (MHT, Italy) in the imitated clinical situation. One-way ANOVA for dL*, da*, db* and deltaE was performed to evaluate the influence of background and cement. DeltaE<2.6 was utilized to define color match between TC and CM specimens. Results: The statistical analysis showed that the background (dentine color) had significant contribution to the overall color (p<0.05). The color shifts (a* of b*) depended more on the dentine- than on the veneer color, try-in cement did not significantly alter the final color and opaque ceramics showed less color variation due to their masking ability. Color match was the closest using opaque ceramics when dentine was slightly discolored. It was possible to achieve TC by discolored dentine when lighter veneer was used. Conclusions: The try-in cement had no influence on color prediction whereas the use of different ceramic translucencies and lightness could predictable mask discolored dentin in order to achieve pre-selected color match.


0264 (111518)

Relationship between thickness ratio and color in PFM restorations. G. CORCIOLANI, A. VICHI, C. GORACCI, and M. FERRARI, University of Siena, Italy

Objectives: The aim of this study was to check the influence of the thickness ratio of the different layer on the final color of PFM restorations by the use of a clinical spectrophotometer.

Methods: One ceramic system (Vita VM13, Vita Zahnfabrik, Germany) in 2M3 shade was selected for the study. 3 different total ceramic thickness (A=1,3mm; B=1,6mm; C=2,0mm) were tested. Different layering pattern (a-f) were used for the thickness ratio between the various component of the layering (Base Dentine, Dentine, and Enamel). 5 samples were fabricated for each combination of total thickness/layering pattern, for a total of 30 specimens. To control the thickness of the various layer, a proprietary steel mould was used, and each layer was checked after firing with a digital calliper. The thickness of Base Dentine was 0.30-0.90mm, Dentine 0.40mm-0.75mm, Enamel 0.20mm-0.50mm. Easyshade (Vita Zahnfabrik, Germany) clinical spectrophotometer was used for colour comparison. “Restoration” mode was selected in order to compare the specimen colour with the reference colour stored in the device.

Results:

Sample

DE

DL

DC

DH

Aa

0,72±0,08

-0,54±0,08

-0,40±0,07

-0,66±0,05

Ab

1,70±0,14

1,60±0,14

0,20±0,07

-1,30±0,04

Bc

2,32±0,13

0,04±0,13

-2,18±0,13

-2,28±0,08

Bd

1,08±0,04

-0,44±0,04

-0,20±0,14

-2,60±0,07

Ce

4,24±0,05

-0,36±0,05

-3,96±0,09

-4,26±0,09

Cf

2,52±0,04

-0,54±0,04

-2,32±0,04

-2,56±0,05

One-way Analysis of Variance of DeltaE values showed a statistically significant difference between groups (p<0,05).

Conclusions: in order to achieve the color correspondence with the selected shade, at 1.3 ceramic thickness the layer of Base Dentine should be equal to the Dentine's one leaving the thickness of the Enamel layer as thin as possible. When the ceramic thickness raise to 1.6mm and 2.0mm, the ratio between Base Dentine and Dentine should be 2:1, the Enamel layer should not exceed 0.5mm.


0265 (111727)

Effects of Various Disinfection Procedures on Color Stability of Shade-guides. S. AKMAN, O. ERASLAN, and F. AYKENT, University of Selcuk, Konya, Turkey

Objectives: Various disinfection or sterilization methods can be applied during disinfection of shade guides used in clinical practice. The purpose of this study was to evaluate the effects of autoclave sterilization and two chemical disinfectants on color stability of shade guides (VITA 3D-Master Shade System) at one year of usage.

Methods: The CIE Lab values of all shade samples at three, non-used VITA 3D-Master Shade guides were measured with Vita easy shade. Two chemical disinfectants (Mikrozid AF Liquid, sodium-hypochlorite solution) and autoclave were used for disinfection. In order to simulate 180 and 360 day usage, the first and second shade guides were immersed into disinfectant solutions for 5minX180 and 5minX360. The third shade guide was autoclaved at 135°C/10minX180 and 135°C/10minX360. CIE Lab measurements of all guides were repeated at 180 and 360 day periods. In order to measure the color changes at shade guides, 180 and 360 day CIE Lab values were compared with initial measurements by using the formula of “Delta E=([L1-L2]2+[ a1-a2]2+[ b1-b2]2)1/2”. Data were analyzed with Repeated Measures Anova test.

Results: Mean Delta E for the groups are as follows: Autoclave Delta E=1.35, Mikozid AF Liquid Delta E=0.62, sodium-hypochlorite solution Delta E=0.52. There were no significant differences among the time periods at any disinfection methods (p=0.262). All the disinfection methods caused a color change however mean Delta E values obtained with autoclave technique was significantly different from the others (p=0.000).

Conclusions: Within the limitations of this in vitro study, sodium-hypochlorite solution can be recommended for sterilization of the shade guides.


0266 (111119)

Clinical Evaluation of Different Light–Activated Office Bleaching Systems. S. GURGAN, F. YALCIN CAKIR, and E. YAZICI, Hacettepe University, School of Dentistry, Ankara, Turkey

Objectives: The aim of this clinical study was to evaluate the efficiency of light activated in-office bleaching systems using two different assessment methods for color change and possible side effects such as tooth and gingival sensitivity.

Methods: 40 volunteers aged 18 years and older (27.3) having all natural healthy teeth in shade A3 or darker on the Vita Shade Guide were randomly assigned to four groups (n=10). Group 1: received bleaching without light activation (Opalescence Xtra Boost, Ultradent); Group 2: with diode laser (Laser Smile /Biolase); Group 3: with plasma arc light (Remecure CL15 / Remedent); Group 4: with LED light (By White /Ensodent) according to the manufacturers' recommendations. Shade assessments were made using Classical Vita Shade Guide (Vita Zahnfabrik, H.Rauter GmbH) and a digital spectrophotometer (Vita Easy Shade, Vident) at baseline and after treatments. Any side effect on teeth or gingiva was recorded by Visual Analog Scale (VAS). Results were analyzed using one way ANOVA, Kruskal-Wallis and Mann-Whitney U test with Bonferroni correction.

Results: All the techniques resulted in shade change with Vita Shade Guide but there were no significant differences among four groups (p>0.05).Spectrophotometer readings exhibited significant differences among the groups (p<0,05). The overall shade change values expressed as DL, Da, Db, DE for group 2 was significantly higher than the other groups (p<0,05). Laser assisted bleaching system showed lower VAS scores (p<0.05) than the other groups.

Conclusions: Whether they are used with or without light, in-office bleaching techniques lead to an expected shade change. Although the use of shade guide didn't exhibit any differences among the groups, spectrophotometer readings showed different findings. As laser assisted bleaching resulted in less sensitivity and higher color change; it could be preferred among the other in–office bleaching systems.


0267 (110654)

Aesthetic Perceptions - Is There a Difference?. F. BURKE, and G. MCKENNA, National University of Ireland - Cork, Ireland

Introduction: In recent times, the demand for aesthetic dentistry has increased, with patients presenting for treatment expecting an improvement in their aesthetics. Therefore, it is increasingly important for the dental profession to appreciate perceptions of dental aesthetics in order to provide a patient-centred service. Objectives: The aim of this study is to quantify perceptions of aesthetics using a cross-sectional survey design. The hypotheses being tested were that differences exist in aesthetic perceptions of 1) dentists and dental students, 2) different age ranges and 3) gender. Methods: A questionnaire was distributed to dental staff and students in the Cork University Dental School and Hospital. The questionnaire sought information relating to aesthetic perceptions by asking participants to compare photographs of smiles. Results: 100 questionnaires were returned. It was found that differences existed in perceptions of dentists and dental students when certain aspects of a smile were evaluated, in particular when a minor flaw was present in a smile in addition to the major flaw being tested. Assuming that flaws were detected, more dental students (34%) than dentists (26%) were found to prioritise colour above more subtle flaws, such as a centreline shift. However, most results between the two groups are comparable in terms of their prioritising of importance of particular aspects of a smile, with no large significant differences. Conclusion: Differences exist in aesthetic perceptions of dentists and dental students, especially with regard to tooth colour.


0268 (109510)

Extracellular Integration of Cell Signalling During Tooth and Palate Development. T. PORNTAVEETUS1, A. OHAZAMA2, M.S. OTA3, N. ITOH4, J. HERZ5, and P.T. SHARPE1, 1King's College London, United Kingdom, 2Guy's Hospital, King's College, 3Tokyo Medical & Dental University, Japan, 4Kyoto University, Japan, 5University of Texas Southwestern Medical Center, Dallas, USA

Objectives: Many organs including teeth, hair, limbs, and kidneys develop through epithelial-mesenchymal interactions, which share signalling pathways such as Bmp, Shh, and Wnt. Lrp4 is a transmembrane co-receptor that binds Wnts and the Bmp antagonist, Wise and is thus capable of integrating different signalling pathways. Since Wnt and Bmp signalling are important in tooth and palate development, we investigated the role of Lrp4 in the development of these organs.

Methods: Lrp4 hypomorphic mutants were analysed by micro CT scanning, histology, immunohistochemistry and in situ hybridization.

Results: Lrp4 showed spatially restricted expression during tooth and palatal rugae development. In Lrp4 mutant mice, molar teeth were fused and the palatal rugae were highly disorganised. Supernumerary teeth and rugae were also present in the mutants. Bmp and Wnt signalling were upregulated while Shh activity was downregulated in fused molars and disorganised palatal rugae. Ectopic expression of Shh was however observed coincident with supernumerary tooth formation in Lrp4 mutants.

Conclusions: The data identify similar molecular and phenotypic changes in tooth and palatal rugae development in Lrp4 mutants and indicate common mechanisms of morphogenesis. Lrp4 thus acts as key cell surface protein integrating multiple signalling pathways that are essential for both tooth and palate morphogenesis.


0269 (110208)

Hypersecretion during Submandibular Gland Acute Inflammation. P.N. CORREIA, G. CARPENTER, K. PATERSON, and G. PROCTOR, King's College London, United Kingdom

Objective: Assess the mechanism of cholinergic evoked hypersecretion in lipopolysaccharide (LPS) treated rat submandibular glands.

Methods: Male Wistar rats were anaesthetized and LPS (Escherichia coli serotype O111:B4) was injected (50 µl, 0.5 mg/ml) in the right SMG duct from an intra-oral approach. The control left SMG duct received the same volume of sterile saline or was left untreated. Twenty four hours later, under anaesthesia, both SMG ducts were cannulated and salivary secretion was stimulated by an infusion of methacholine into the femoral vein before and after infusion of nitric oxide synthase (NOS) inhibitors. Salivas and salivary glands were collected, weighed and analysed. SDS-PAGE, Western-Blotting and immunohistochemistry were performed. In vitro experiments were also conducted using acini clusters from collagenase-digested SMG and previously infused with LPS. Acini were loaded with a calcium-sensitive dye, stimulated with methacholine and fluorescence levels were assessed by confocal microscopy. All experiments were conducted under Home Office licence.

Results: Methacholine induced a greater secretion from LPS-treated glands compared to controls, but the secretion was much reduced following infusion (i.v.) of the inducible NOS inhibitors L-NIL or aminoguanidine (4±1.32 µg/min/kg), compared to contralateral control glands (23±4.25 μg/min/kg; P<0.05) or LPS-treated glands before the inhibitors (41±3.8 μg/min/kg; P<0.001). Immunohistochemistry and Western-Blotting showed an increased expression of iNOS in LPS-treated glands compared with contralateral control glands. In vitro analysis revealed that intracellular calcium responses to methacholine stimulation were higher in cells from LPS-infused glands (P<0.05).

Conclusions: Methacholine-evoked hypersecretion, after 24h of LPS-induced sialadenitis seems to be due to an iNOS-mediated action on acinar cells.

This project was generously funded by the Wellcome Trust.


0270 (110969)

Evaluating the fracture strength of Y-TZP copings. S. SHETTY1, N. JONES2, M. SHERRIFF3, and R.V. CURTIS1, 1King's College London, United Kingdom, 2Renishaw plc, Gloucestershire, United Kingdom, 3King's College London

Objectives: Y-TZP (Yttria stabilised tetragonal zirconia polycrystal) is a biomedical ceramic material with unique mechanical properties, approaching that of stainless steel due to crystalline changes that occur to oppose crack propagation. A zirconia core can be machined by milling from a fully sintered or a partially sintered block and subsequently sintering it. The present study evaluated the fracture strength from both manufacturing processes.

Methods: Sixty standardized Y-TZP copings were manufactured with a CAD/CAM system. Out of these, twenty each were 0.4 and 0.5 mm thick, machined from fully sintered Y-TZP blocks. The remaining were 0.5 mm thick machined from partially sintered Y-TZP blocks and subsequently sintered. Ten copings from each group were cemented to epoxy resin glass laminate preparations using zinc phosphate cement (Healthcare products, UK) and the rest were cemented using a resin based luting agent (Kuraray Corp, Japan). After 24 hours, the samples were loaded to failure with a wrought carbon steel indenter of 4 mm diameter in the centre of the restoration in a universal testing machine (Instron 1193, USA) using a crosshead speed of 1mm min-1.

Results: The load to failure for each sample was recorded and Weibull plots were compiled. 90% confidence intervals show that there is a significant difference in the load to failure values for copings machined from pre sintered and fully sintered blocks, for both types of cement used. 0.4 and 0.5 mm thick copings machined in the hard state and bonded with resin showed highest characteristic strengths and Weibull moduli.

Conclusions: Weibull plots indicated good correlation of fit for all groups. Within the limitations of this study it can be concluded that the characteristic strengths of the copings are significantly affected by the machining strategy and thickness as well as the type of luting cement.(Supported by studentship from Renishaw plc, UK.)


0271 (110981)

Subtypes of Porphyromonas gingivalis that differ in epithelial cell invasion. S. SUWANNAKUL, M.H. THORNHILL, G.P. STAFFORD, S.A. WHAWELL, and C.W.I. DOUGLAS, University of Sheffield, United Kingdom

Introduction: P.gingivalis can invade and survive within epithelial cells (EC) but in vitro this rarely exceeds 10% of the inoculum. This might be due to restriction of available EC binding sites or to physiological variation of the bacteria.

Objectives: The aims of this study were to investigate the phenotypic and genotypic characteristics of invasive P.gingivalis.

Method: P. gingivalis NCTC 11834 and W50 cells were assessed for their invasion of H357 oral keratinocytes (EC). Cy-dye-labelled cDNA of those bacteria that invaded and those that did not was hybridized on P.gingivalis genome microarrays (TIGR). Selected genes were checked for expression by RT-PCR, normalising to 16SrRNA. Isolates were compared by RFLP analysis and arg-gingipain activity (Bapna).

Results: P.gingivalis cells that had invaded one set of ECs invaded a second set with higher efficiency, suggesting selection of an invasive phenotype. 6/60 colonies from a primary culture also showed increased EC invasion. This invasive type showed low arg-gingipain activity. Invasive and poorly invasive phenotypes had the same RFLP pattern. Gene array analysis showed 104 genes were up-regulated and 51 genes were down-regulated in the invasive phenotype (p<0.05). The arg-gingipain gene (rgpB) was down regulated in the invasive type while haemagglutinin (hagE), iron regulated (hmuY) and oxidative stress genes (sodB, oxyR) were amongst those up-regulated. Semi-quantitative RT-PCR largely confirmed these findings.

Conclusion: Phenotypes with different invasive capability are detectable in cultures of P.gingivalis and these differ at the transcriptome level. These phenotypes may represent phase switching, which in vivo could provide the organism with a mechanism for persistence at a subgingival site.


0272 (111190)

MicroRaman spectroscopy evaluation of the hybrid layer in carious dentine. S.L. ROLLAND, A. WALLS, M. GERMAN, and J. MCCABE, Newcastle University, Newcastle Upon Tyne, United Kingdom

Objectives: Treatment of caries is becoming more conservative and bonding to demineralised dentine affected by caries is considered acceptable. A thicker hybrid layer is expected in caries affected dentine, the stability of which is critical in predicting the longevity of the bonded interface. The aim of this study was to investigate the nature of the bonded interface in demineralised dentine using microRaman spectroscopy.

Methods: Discs of root dentine were demineralised in a lactic acid buffer (pH4) for 4 days. Bonding agents (ProtectBond (PB); Kuraray, OptiBond (OB); Kerr, XenoIII (X); Dentsply) were applied to overwet dentine, using 2 coats of the hydrophilic component and light cured for 30 seconds. Specimens were sectioned and microRaman spectroscopy performed at 8µm intervals across the hybrid layer. The height of 1610cm-1 (phenyl C=C) and 1640cm-1 peaks (C=C) were calculated and ratios compared to indicate degree of cure.

Results: Molecules associated with adhesive were detected to ~110µm into dentine for PB and ~160µm for OB and X. An inconsistent hybrid layer was observed for PB and OB with a reduced 1610:1640 ratio after 50-70µm accompanying an apparent change in molecular structure. X hybrid layers demonstrated a gradual dilution of adhesive resin. The nature of the hybrid layer differed for different materials.

Conclusions: A thick hybrid layer was observed with adequate degree of cure in superficial layers. The reduction in 1610:1640 ratio within PB and OB hybrid layers may be a consequence of reduced degree of cure, phase separation, enhanced penetration of primer (PB) and may be affected by peaks overlapping with dentine components (1667cm-1). PB and OB hybrid layers appear to have a high proportion of aliphatic groups at the base. The hybrid layer in X appears to be rapidly diluted, possibly leaving collagen exposed.

Project supported by ODRT 3M ESPE Dental Biomaterials Research Award 2007


0273 (111308)

Oral and Dermal Fibroblast Organotypic Co-cultures Show Differences in Phenotype. B. KAZMI, S.R. PORTER, and M.P. LEWIS, UCL Eastman Dental Institute, London, United Kingdom


 

Oral wound healing results in the restoration of mucosal continuity with less visible scarring than equivalent dermal healing. It is recognized that a major element of this response is related to intrinsic phenotypic differences in the response of fibroblasts within these tissues. Furthermore, the onset of scarring is thought to occur with the appearance of myofibroblast phenotype and α-smooth muscle actin (α-SMA) expression. Harnessing this preferential phenotype for extra-oral healing regimes could improve the effectiveness of skin substitutes.

 

Objectives:

To investigate whether phenotypic differences exist between human oral (HOF) and dermal fibroblasts (HDF) when in organotypic co-culture

 

Methods:

Heterotypic oral and dermal organotypic models were constructed by seeding patient matched fibroblasts into a type I collagen. Lattices were overlaid a suspension of human dermal keratinocytes and raised to the air-liquid interface. Lattice contraction was measured daily. After a 3-week culture period mRNA expression of α-SMA, αv integrin, uPA receptor and involucrin was studied using Real-Time RT-PCR.

Results:

Organotypic co-cultures appeared histologically normal. HOF contracted co-cultures faster than HDF, suggesting a greater efficiency at remodelling the extracellular matrix in vitro. Heterotypic models of oral mucosa had lower expression of α-SMA and related remodelling proteins, and higher involucrin expression than dermal counterparts. The faster contraction of these models may therefore be attributed to tractional movements rather than ‘activation' of these cells into myofibroblasts. Higher involucrin expression suggests greater differentiation of the epithelial layer.

Figure: Graphs show greater involucrin and lower α-SMA mRNA expression of oral organotypics compared to dermal counterparts in three patients (P<0.05).

Conclusion:

Oral fibroblasts encourage terminal differentiation of keratinocytes, remodelling the collagen matrices more efficiently with lower expression of α-SMA, when compared to their dermal counterparts. Thus, oral fibroblasts could be used in the dermal component of skin substitutes as alternatives to homotypic forms and also offer superior efficacy.

 


0274 (111536)

Oxidative stress and severe periodontitis. F. D'AIUTO1, L. NIBALI1, M. PARKAR1, J. SUVAN1, E. IORIO2, and N. DONOS1, 1UCL Eastman Dental Institute, London, United Kingdom, 2The International Observatory of Oxidative Stress, Salerno, Italy

Objectives: Periodontitis is thought to increase local and systemic levels of reactive oxygen species and lead to oxidative stress (OS). The aim of this study was to ascertain whether diagnosis of severe periodontitis and its treatment would influence patients' oxidant-antioxidant capacity using a periodontal treatment model (PTM) of human inflammation.

Methods: A group of 145 individuals suffering from severe generalized periodontitis (defined as probing pocket depths of >6 mm and marginal alveolar bone loss of >30% with 50% or more of their teeth affected) and 56 matched healthy controls were examined. PTM consisted of an intensive session of full mouth subgingival root debridement delivered within a 4-hr period under local anaesthesia. Blood samples were taken at baseline and 1 and 7 and 30 days after treatment. Diacron-reactive oxygen metabolites (d-ROM), biological antioxidant potential (BAP) and blood markers of inflammation (C-reactive protein, CRP and Interleukin-6, IL-6) were determined in serum by high sensitivity assays.

Results: Patients with severe periodontitis exhibited higher serum OS (P<0.001) and lower total anti-oxidant capacity (P<0.001) compared to healthy controls. d-ROM levels were positively correlated with markers of systemic inflammation (CRP, r=0.4 P<0.001, IL-6, R=0.3, P<0.05) but weakly correlated with clinical periodontal parameters (R=0.20, P<0.05) and influenced by gender differences (P<0.001). Acute changes of d-ROM levels (P<0.01) were also observed following PTM.

Conclusions: These data indicate that severe periodontitis is independently associated with increased serum OS and reduced antioxidant capacity. In addition acute inflammation following PTM may influence systemic levels of reactive oxygen species.


0275 (110380)

Degree of conversion of adhesives related to different curing times. V.J. MILETIC1, A. SANTINI1, V. IVANOVIC2, and R. IBBETSON1, 1The University of Edinburgh, Scotland, 2University of Belgrade, Serbia and Montenegro

Objectives: To calculate the degree of conversion (DC) of five self-etch adhesives light-cured for 5 s, 10 s and 20 s using a high-intensity LED light-curing unit (LCU).

Methods: Ten samples of each of the following adhesives were prepared: AdheSE One (Ivoclar Vivadent), Clearfil 3S bond (Kuraray Medical), G bond (GC Corp), Xeno III (Dentsply DeTrey) and Adper Prompt L-Pop (3M ESPE). One drop of adhesive was smeared on a microscopic slide using a disposable applicator. A Mylar strip was placed on top of the adhesive which was then cured using a high intensity LED LCU (Elipar Freelight2, 3M ESPE; 1000 mW/cm2). Micro-Raman spectroscopy was used to determine DC by calculating the ratio of the number of unreacted methacrylate groups pre- and post-curing. The data were statistically analyzed using Kruskal-Wallis non-parametric test at 95% significance level.

Results: For all curing times, there were significant differences in DC values in each group, except for the Cleafil 3S group (p<0.01). At manufacturers’ recommended time of 10 s, the DC of adhesives showed decreasing order: G bond (76.01%±11.65%) > Clearfil 3S bond (73.54% ±7.53%) > AdheSE One (43.52%±8.44%) > Xeno III (40.65%±8.66%) > Adper Prompt L-Pop (27.71%±9.24%).

Conclusions: Curing time in excess of manufacturers’ recommended time showed higher DC values of all adhesives irrespective of their chemical composition. Dimethacrylate-based adhesives associated with milder acidic functional monomers showed the highest DC values.


0276 (111493)

Production and Characterisation of Nanoparticulate Calcium Hydroxyapatite. A. BESINIS, R.V. NOORT, and N. MARTIN, University of Sheffield, United Kingdom

Objectives: To synthesize nanoparticulate HA by the sol-gel technique and characterise it. Also to evaluate the effect of deflocculating agents on particle size and morphology.

Methods: According to the sol-gel technique, thiethyl phosphite (P(OC2H5)3) was hydrolyzed with distilled water (DW). Calcium nitrate (Ca(NO3)2 was dissolved in DW and this solution was added to the hydrolyzed phosphate sol. The mixed solution was kept static at 45oC for 2 h (aging time). The aged sol was then subjected to thermal treatment (drying time). The dried gel was calcined by applying a constant heat rate of 10oC/min up to 500oC, and then further calcined for 10 min. The final product was ball-milled to get a fine powder texture. A sample of the synthesized HA was mixed with a deflocculating agent at a 3:1 ratio in an attempt to further reduce the size of the particles. The nano-HA was characterised using x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: The XRD results showed that there was a good match between the experimental and theoretical HA spectra. The manufactured HA was also compared with commercially available HA. Factors such as the aging and drying time, and the temperature play an important role in the crystallinity and morphology of nano-HA. SEM results indicated that nano-HA formed agglomerates, which were further characterised with TEM. These particles were found to have dimensions between 50nm and 70nm. In the samples that deflocculant had been used, individual HA particles appeared to be as small as 10nm. The deflocculant appears to affect the morphology and distribution of the HA particles.

Conclusions: Nanoparticulate HA was synthesized using the sol-gel technique. Sub 100nm particles were obtained and their size was further reduced by mixing with deflocculating agents.


0277 (111127)

The Grain Size of a Presintered Zirconia Ceramic. C. ABERT, Humboldt-Universitat, Berlin, Germany, and W.-D. MUELLER, Humboldt-Universität, Berlin, Germany

Objectives:

Aim of the study was the investigation of the influence of sintering temperatures and specimen volumes on the grain sizes of a presintered zirconia ceramic and the effect on material parameters.

Methods:

54 specimen bars of the tested ceramic, DCShrink (Bien Air, Switzerland) were cut in three different strengthes (1,5 mm; 2 mm and 2,5 mm). The resulting 18 bars of each strength were sintered at six different temperatures (1350°C, 1400°C, 1480°C, 1500°C, 1530°C and 1580°C), three bars a temperature.

Afterwards elastic modulus and fracture toughness were determined respectively calculated.

The specimens were prepared with thermal etching to examine the surfaces with scanning electron micrograph (SEM). The grains per area were calculated.

Results:

Reguarding the sintering temperature the smallest grains were measured at 1350°C (0,12 µm2), the biggest at 1580°C (0,24 µm2. The ascend of grain sizes was not linear.

It could be seen that a rising specimen volume led to a smaller grain size (1,5 mm : 0,19 µm2; 2 mm : 0,18 µm2; 2,5 mm : 0,16 µm2).

A comparison of the graphs for grain size with the graphs for elastic modulus and fracture toughness showed a correlation. An ascend of grain size led to a descend of the parameters and vice versa. These results revealed for specimen volume as well.

Conclusion:

The received results reflect the low heat conductivity of zirconia. As lower sintering temperatures and a higher volume come along with smaller grain sizes.

Through the results it also appears that material parameters of presintered zirconia ceramics mustn't be presumed as fix figures. It rather has to be assumed that sintering temperature and specimen volume have an influence on them.

This leaves room for further investigation on the topic, especially concentrating on a combination of fractographic and non- destructive testing to analyze grains and structure of a ceramic.


0278 (111765)

Evaluation of Fit of Zirconia Copings ByThree CAD/CAM Systems. P. GAITONDE, Charles Clifford Dental Hospital, Sheffield, United Kingdom, and R. VAN NOORT, University of Sheffield, United Kingdom

Objective: Accuracy of fit is one of the main requirements for crowns and bridge systems. The Procera, Lava, and Renishaw systems produce zirconium oxide copings and frameworks by three different CAD/CAM methods. There are no studies so far comparing the fit of zirconia copings manufactured by these three systems. The aim of this in vitro study was to measure and compare the marginal and internal fit of zirconium oxide copings produced by the Procera, Lava and Renishaw Incise systems.

Material and methods: The marginal and internal fit of 45 zirconia copings was evaluated by a replica technique using a light-bodied silicone. The polymerized silicones were retrieved from the coping and sectioned first in the bucco-palatal dimension and mesio-distal dimension resulting in 14 measurements per coping. The thickness of the polymerized silicone was measured with a traveling light microscope at ×30 magnification.

The differences in the means of the overall, marginal, internal fit and occlusal fit across the main groups was performed using 1-way ANOVA, using SPSS 11.5. and multiple comparisons using post-hoc Tukey's test (α=.05). There was no significant difference in the marginal fit. Procera was significantly different from lava and Renishaw in the internal fit.

Results: The means and standard deviations of the marginal fit were: AllZirkon 61.2 ± 19.3µm, Lava, 55.1 ± 16.5µm, and Incise 47.3 ± 12.4µm. The internal fit for the systems was: 128.8 ± 20µm, 93.4 ± 13.5µm, and 85.3 ± 6.7µm, respectively.

Conclusions: The marginal and overall fit of the 3 systems are within clinically acceptable


0279 (111772)

Novel Silane System (NSS) promotes resin-composite bonding to silica-coated zirconia. J.P. MATINLINNA, L.V.J. LASSILA, and P.K. VALLITTU, University of Turku, Finland

Objectives: Engineered silane blends may enhance significantly bonding. Silica-coated zirconia needs silanization when cementing with an organophosphate-resin-composite. Four experimental blends, a functional silane and a cross-linking silane (Novel Silane System), were evaluated in promoting adhesion of resin-composite to zirconia.

Methods: Zirconia (Procera, Nobel-Biocare) specimens were silica-coated (Rocatec, 3M ESPE) and silanized with the experimental silane blends. Blends consisted of 1.0 vol% of 3-acryloyloxypropyltrimethoxysilane (‘ACPS', Toray Dow Corning), glycidoxypropyltrimethoxysilane (‘GPS', Dow Corning), 3-isocyanatopropyltriethoxysilane (‘ICS', ABCR) or 3-styrylethyltrimethoxysilane (‘STYRX', ABCR) monomers in 95.0%/5.0% ethanol/water, with pH of 4.5. A cross-linking silane monomer bis-1,2-(triethoxysilyl)ethane (‘BTSE', Gelest) was added to each of the solutions, corresponding a final 2.0 vol% of silane. Fourier transformation Infra-Red (FTIR) spectroscopy was applied to monitor the chemical activation of the experimental silane solutions. RelyX Ceramic Primer (3M ESPE) was used as control. RelyX Unicem (3M ESPE) organophosphate-resin-composite was photo-polymerized as stubs (n = 14/group) onto zirconia. The shear bond strength was measured after dry storage (24 h) or thermo-cycling (5.0-55.0°C, 6000 cycles).

Results: FT-IR analysis suggested that silane blends were activated within 1 h. All shear bond strength values were enhanced during thermo-cycling: statistical analysis (ANOVA) showed that the highest shear bond strength, 14.9 MPa (SD 4.2 MPa), was obtained using glycidoxypropyltrimethoxysilane + bis-1,2-(triethoxysilyl)ethane. The lowest shear bond strength was 6.5 MPa (SD 2.6 MPa) with the control. Failure mode was 50% cohesive.

Silane

Shear bond strength (SD)/MPa      (dry storage)

Shear bond strength (SD)/MPa             (thermo-cycling)

Control

  4.5 (1.3)

  6.5 (2.6)

ACPS+BTSE

  6.9 (2.7)

13.5 (4.4)

GPS+BTSE

11.0 (2.2)

14.9 (4.2)

ICS+BTSE

  9.1 (2.1)

  9.7 (6.3)

STYRX+BTSE

  6.3 (1.8)

14.5 (3.0)

The storage conditions (p < 0.001) and type of silane (p < 0.001) affected significantly the shear bond strength.

Conclusions: Silanization with novel silane system yielded significantly higher shear bond strengths than the ready-to-use silane.  


0280 (111345)

Fractographic analyses of dental high-strength ceramics. M. ØILO, H.M. TVINNEREIM, and N.R. GJERDET, University of Bergen, Norway

Objective: Dental ceramics are susceptible to sudden, brittle fractures. Thorough analyses of the fractured surfaces may contribute to develop methods to reduce the number of fractures. The aim of this study was to assess the reliability of qualitative and quantitative analysis of the fracture patterns of four different high-strength ceramics.

Methods: Ten bar-shaped specimens of four high-strength ceramics (n = 4x10) with different material composition and manufacturing methods had been broken in water in a three point bending test (IPS Empress 2, Ivoclar Vivadent; DC Zircon, DCS Dental AG; Lava, 3M ESPE; EZ A5, CeramTools). The fractured surfaces were inspected by light microscopy at several magnifications. Commonly used fractographic patterns for brittle materials, such as mirror, mist and hackle regions, were used to analyze and quantify the fractured surfaces of these specimens, and to detect the initiating site of the fracture. The analyses were performed twice at separate occasions by the same operator. Repeatability assessments of the measurements were performed using Kappa statistics. Correlations calculations was performed using Spearman's r.

Results: The initiating site was detected in all specimens, but initiating flaws were not always detected. The repeatability of the measurements of the different fractographic patterns varied among the materials. The repeatability of two independent measurements of mirror radii expressed by Kappa was between 0.48 and 0.61. Statistically significant correlations were found between mirror radii and force at fracture for the dental zirconia materials tested (rs=-0.9, p<0.01).

Conclusion: Fractographic analyses can be useful for assessing fracture modes and fracture initiating site of dental ceramics.

This work was supported with free material for specimens from 3M ESPE and Ivoclar Vivadent, and blanks at a reduced price from DCS Dental.


0281 (111300)

Bond strength of veneering ceramics to zirconia framework. H.S. ÇÖTERT, and B. GÖKÇE, Ege Universitesi, Izmir, Turkey

Objectives: The aim of this research was to investigate the bond strength between one type of zirconia substructure material and a variety of veneering ceramic materials using Shell-Nielsen bond strength test. Methods: Fifty Zirconia rods (ICE Zirkon) were milled in the green state then sintered. After firing, the rods (4mm diameter and 20mm height) were sand-blasted and ultrasonically and steam cleaned. The zirconia rods were randomly assigned to five veneering groups (n=10/group) and veneered with five ceramics (Matchmaker Zr, Cerabien ZR, Ice Zirconia Ceramic, IPS E-max Ceram, ZirkonZahn, Vita VM9) in 2 mm height and 2 mm thickness circumferentially around the rods and were thermocycled for 6,000 times (5/55 degrees C per 30 seconds). The specimens were placed in a special mold and loaded from the top of the zirconia rods with a ball point at a crosshead speed of 0.5 mm/min on a universal testing machine (Autograph) until fracture. The Shell-Nielsen bond strengths of the specimens were calculated and expressed in Mpa. The surfaces of the zirconia rods were evaluated under SEM following testing. The measurements were statistically analysed using 1-way analysis of variance test (ANOVA) and a Tukey multiple comparisons tests at significance level of á=0.05. Results: Mean bond strengths (MPa) for Cerabien ZR(42.2+,7,2), Vita VM9 (43.6+,6,4) were significantly higher than those Matchmaker Zr (38.6+8,1), Ice Zirconia Ceramic (35.3+,6,7), IPS E-max Ceram (36.2+,8.4) (P<.05). Conclusions: Shell-nielsen bond strength test to evaluate the core-veneer bond strength is a useful method to study the behavior of core veneered all-ceramic restorations when subjected to shear stresses. The zirconia veneer bond strength was affected by the type of the layering ceramic used. Coefficient of thermal expansion plays an important role on the bond strength of the veneering ceramic to the high strength core materials.


0282 (110040)

Microleakage and Marginal Gap of Adhesive Cements for Full-cast Crowns. T. HOOSHMAND, Dental Research Center, Research Center for Science and Technology in Medicine, Medical Sciences/Tehran University, Iran, M. MOHAJERFAR, School of Dentistry, Medical Sciences/Tehran University, Iran, and A. KESHVAD, School of Clinical Dentistry, Shahed University, Tehran, Iran

Objectives: The purpose of this study was to evaluate the microleakage and marginal gap of different adhesive luing cements for the noble alloy full-cast crown restorations.

Methods: Forty non-carious human premolars and molars were prepared in a standardized manner for full-cast crown restorations. Crowns were made from a noble alloy using a standardized technique. The specimens were randomly divided into four groups of cementing agents and cemented according to the manufacturers' instructions: 1) Rely X Unicem with pretreatment (self-adhesive resin cement); 2) Rely X Unicem without pretreatment; 3) Panavia F2.0 resin cement, and 4) Fuji Plus hybrid ionomer cement. The specimens were stored in distilled water at 37°C for two weeks and then subjected to thermocycling. They were then placed in a silver nitrate solution and vertically cut in mesiodistal direction. Subsequently, the objects were evaluated for microleakage and marginal gap using a stereomicroscope. Data were analyzed using a non-parametric Kruskal-Wallis test at a P<0.05 level of significance. Results: The Rely X Unicem (with or without pretreatment) showed significantly the smallest degree of microleakage and marginal gap at both tooth-cement and cement-crown interfaces (P<0.01). The mean microleakage value for Fuji Plus hybrid ionomer cement was significantly higher at the cement-crown interface than all other cementing agents tested (P<0.05). No statistically significant difference in the marginal gap values was found between cementing agents tested (P>0.05).

Conclusions: The Rely X Unicem self-adhesive resin cement either with or without pretreatment provided a much better sealing ability for the noble alloy full-cast crowns.


0283 (111278)

Microleakage of a new restorative calcium based cement (Biodentin®). V. TRAN, University of medecine and Pharmacy in Ho Chi Minh, Vietnam, Ho Chi Minh City, Vietnam, P. COLON, faculté de Chirurgie Dentaire Paris 7, France, and N. PRADELLE-PLASSE, Faculté de Chirurgie Dentaire Paris 7, France

Objectives: The aim of this study was to evaluate the ability of a new restorative calcium based material Biodentin® (Septodont, France) to be used as class II restoration recording the microleakage by a dye penetration. methodology.

Methods: 18 freshly extracted human molars were used for this study. Standardized class II cavities in the mesial (enamel margin) and distal (dentin margin) surfaces were restored with Biodentin®. The teeth were randomly divided into 3 groups : 1 : direct application of Biodentin® ; 2 : treatment of the wall of cavity with polyacrylic acid before restoration ; 3 : application of Optiguard on Biodentin® surface. The specimens were stored at 37°C one day, thermocycled, stained, sectioned twice longitudinally in the mesio-distal direction. The silver nitrate penetration was measured.

Results:

Groups enamel margin (%) dentin margin (%)

1 : 17,65(± 4,38)(a) - 10,46 (± 3,23)

2 : 8,53 (± 7,44) (b) - 1,83 (± 3,94)

3 : 46,5 (±10,55)(a)(b) - 8,31 (± 4)

Same letters indicate significant differences (p < 0.05)

There was no statistically significant difference in microleakage between with and without treatment of enamel/dentine surface with polyacrylic acid. The microleakage at the enamel - Biodentin® interface with treatment of Optiguard® is more important than without (p<0.05). The cement particles are hydrophilic. After 1 day, the cement reaction was not achieved yet. It was observed that the Optiguard® layer limits the water contact with cement preventing the hydration phenomenon. The surface of the dentine is wetter than that of enamel explaining why no influence of Optiguard® on the microleakage at the Biodentin® - dentine interface was observed.

Conclusion: These data show the good sealing ability of this new material. However the setting time as to be considered regarding the short term results.


0284 (111563)

In vitro Evaluation of Marginal Fit of Ceramic Laminate Veneers. N. OZTURK1, B. OZTURK2, M.A. MALKOC1, and S.T. TASDEMIR1, 1Selcuk Universitesi, Konya, Turkey, 2Selcuk University Faculty of Dentistry, Konya, Turkey

Objectives: The purpose of this study was to evaluate the marginal fit of laminate veneers manufactured with IPS e.max and Cerec 3 system

Methods: 48 extracted maxillar santral teeth were used in this study. Each tooth was free of caries or restorations. Teeth were prepared using bevelled preparation technique. Teeth were randomly divided into two ceramic systems, IPS e.max and Cerec 3. Laminate veneers fabricated by computer-assisted design/computer-aided machining (CAD/CAM) using Vita blocks. IPS e. Max laminate veneers were done by same technician according to the manufacturer instructions. Marginal fit of laminate veneers measured at the margins and at several points in the stereomicroscope using digital image analysis.

RESULTS: The results were analyzed by independent t test. There was not significant differences between two different ceramic laminate systems (p<0.05). The fit of IPS E. Max and Cerec 3 laminate veneers showed the similar range of gap width.

CONCLUSION: The clinical performance of IPS E. Max and Cerec 3 laminate veneers confirm that the accuracy of fit of these systems are well acceptable


0285 (111382)

Microleakage of Different Contemporary Bonding Systems in Primary Teeth. G. TOSUN, E. YILDIZ, U. ELBAY, Y. SENER, and N. OZTURK, Selcuk Universitesi, Konya, Turkey

Objectives: The purpose of this study was to evaluate invitro microleakage of three contemporary bonding systems in occluso-proximal composite restorations of primary molars.

Methods:Occluso-proximal standard cavity preparations were made in 30 non-carious human primary molars. The cavities were restorated using two self etching bonding systems (AdheSE One +Tetric EvoCeram, Adper SE Plus+Filtek Z250) and a total etching bonding systems (Adper Single Bond2+Filtek Z250) by incrementally technique and polymerized with LED curing unit. The restored teeth were thermocycled 1000cycles between 5 and 55 degreesC with a dwell time of 10 s in each water bath. After thermocycling, teeth were isolated with nail varnish and immersed in % 0.5 basic fucsion for 24h for microleakage test. The specimens were sectioned mesiodistally into slabs with a diomand saw under water lubrication. The extend of dye penetration along the cavity walls were measured with digital image analysis (mm). Microleakage data of each restorations in each slaps was recorded indiviually. The data were analyzed with two-way ANOVA, Kruskal-Wallis and Mann Whitney U.

Results:The statistical analysis revealed that microleakage of Adper Single Bond 2 was significantly lower than that of Adper SE Plus and AdheSE One (p<0.05). No significant difference was found between Adper SE Plus and AdheSE One (p>0.05).

Conclusion: Neither of the three adhesive systems was able to completely prevent leakage in occluso-proximal cavity of primary molars. However, the lowest microleakage value was obtained with total etching bonding system-Adper Single Bond 2.


0286 (111387)

Microleakage of Silorane Restorations in Er, Cr:YSGG Laser Prepared Cavities. A. KIREMITCI, E. YAZICI, and S. GÜRGAN, Hacettepe University, School of Dentistry, Ankara, Turkey

Objective: To evaluate the microleakage of Class V Silorane and composite resin restorations at enamel and dentin interfaces following Er, Cr:YSGG laser preparation. Methods: Rectangular Class V cavities (4mm width, 3 mm height,2 mm depth) were prepared on the buccal or lingual surfaces of 20 extracted caries and restoration free human molar teeth with cervical margins located in dentin and the incisal margins in enamel. The teeth were then assigned to 4 groups (n=10). Group1: Diamond bur preparation + Silorane adhesive (3M ESPE) + Silorane (3M ESPE); Group2: Diamond bur preparation + acid etching + Single bond 2 (3M ESPE) + Filtek P-60 (3M ESPE); Group3: Er, Cr:YSGG laser preparation (5W, 85%air / 75% water) + Silorane adhesive + Silorane ; Group 4: Er,Cr:YSGG laser preparation + acid etching + Single Bond 2 +Filtek P-60. The cavities were restored with either of the restoratives according to the manufacturer's recommendations and polymerized with LED curing unit (Elipar, 3M ESPE). After polishing, the specimens were submitted to thermal cycling (1000 cycles;between 5-55 degrees C) followed by dye immersion. Leakage was evaluated under magnification (40X) based on a standard ranking. SEM evaluation of cavity – restoration interfaces of the respective test groups were made on cross section specimens. Data were subjected to Kruskal Wallis analysis. Results: The majority of the specimens were leakage free. Although dentin margins of laser prepared composite resin group (G 4) showed most leakage, there were no statistically significant differences among groups (P>0.05). There were no significant difference between enamel and dentin margins of all groups. SEM evaluation of cavity-Silorane (G 1-3) interfaces showed no gap formation. However laser prepared dentin-composite resin interfaces (G 4) exhibited gap formation. Conclusion: Both microleakage and SEM evaluations showed perfect sealing ability of Silorane restorations.


0287 (111393)

3D-marginal adaptation vs setting shrinkage rate of low shrinking composites. D. PAPADOGIANNIS, A. KAKABOURA, P. TSAKIRIDIS, and G. ELIADES, University of Athens (EKPA), Greece

Objectives: To evaluate the 3D-marginal adaptation of low shrinking composites placed in dentin cavities and compare it to their shrinkage strain rate.

Methods: The materials tested were Ceram-X Mono/CX (Dentsply), Premise/PR (Kerr), Clearfil Majesty/CM (Kuraray), ELS/EL (Saremco) and Filtek Silorane/FS (3M/Espe) all of A2 shade. Dentin cavities (n:4, h:1mm, dia:2mm) were prepared and filled with a single layer of resin composite without any adhesive cavity pre-treatment and light-cured (40s, 750W/cm2, halogen unit). The specimens were imaged by computerized X-ray microtomography with horizontal sections taken at 100kV and 5.66 pixel size and the micro-void volume fraction (%VF) was calculated via the software. Shrinkage strain rate (%SR) was calculated using the bonded-disk method (n:5) at 100s acquisition time and the same irradiation conditions. Statistical analysis of the %VF and %SR was performed by one-way ANOVA and Tukey's post-hoc test (a=0.05) and Pearson's correlation coefficient.

Results: The results of %VF were: CX 7.5±0.4a,b, PR 4.1±1.1a, CM 5.9±0.9c, EL 3.1±1.6b,c, FS 5.5±1.3 (same letters show mean values with statistically significant differences). The maximum strain rate (%/s) for each material was: CX 0.151±0.014, PR 0.113±0.01a, CM 0.093±0.004a, EL 0.103±0.02a, FS 0.067±0.003 (same letters show mean values with no statistically significant differences). No correlation was found between %VF and %SR.

Conclusion: The results imply that %SR does not directly affect %VF. Other factors, like handling characteristics (packing, viscosity etc) may contribute to interfacial porosity.


0288 (111614)

Microleakage of Two-Adhesive Systems after Na-ascorbate on Non-vital Bleached Teeth. N. UNLU1, C. YILDIRIM2, A.R. CETIN3, and F. KONT COBANKARA3, 1Selcuk University School of Dentistry, Konya, Turkey, 2Selcuk Universitesi, Konya, Turkey, 3Selcuk University, Konya, Turkey

Objectives:

The purpose of this study was to evaluate the effect of Na-ascorbate on microleakage interface tooth/ composite resin when submitted to nonvital tooth bleaching.

Methods:

One hundred human root filled incisor teeth were used in this study. Standardized cavities were prepared including enamel edge. The teeth assigned to 10 groups (n=10). 40 teeth bleached with office bleaching system (35% HP Opalescence extra) then were divided into two subgroups bonded with self and total etch system (Single Bond (SB), Clearfil SE (CSE) ) 40 teeth bleached with walking bleaching system (Na-perborate+H2O2) then were divided into two subgroups bonded with self and total etch system ((SB), (CSE)). 20 teeth were bonded with self and total etch system ((SB), (CSE) ) as a control. The teeth were immersed in distilled water at 37 C degrees for 24 hours. Microleakage was assessed by dye penetration.  Teeth were sectioned from buccal to lingual, through the centre of the restoration, using a diamond disk. Leakage was assessed using scores from 0 to 3 under magnification (x20). Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (p> 0.05). Microleakage scores (means ± S.D., n=10 for each group) were summarized in the table below.

Results: The results showed that there are no significant differences at self etch groups. Sodium perborate+H2O2  with Na-ascorbate  significantly increase the microleakage in composite restoration

 

35% HP+CSE

35% HP+SB

(Na-perborate+H2O2) +CSE

(Na-perborate+H2O2)+SB

Control

CSE

Control

SB

With Na-ascorbate

O, 50±0,70a

0,30±0,48a

0,10±0,32a

0,00±0,00b

-

-

Without Na-ascorbate

0,10± 0,31a

0,40±0,52a

0,50±0,97a

0,30±0,67a

0,00±0,00b

1,60±1,34a

Means marked by the same letters are not significantly different.

Conclusion: This presented study exhibited that there is no effect of bleaching treatment on microleakage of self-etching bonding. However, Na-ascorbate increased the microleakage of sodium perborate+H2Ogroup  when a total-etching bonding agent was used.


0289 (111118)

Sensitivity of micro-CT for microleakage detection around dental composite restorations. S.V.N. JAECQUES, M.V. CARDOSO, E. COUTINHO, J. DE MUNCK, and B. VAN MEERBEEK, Leuven BIOMAT Research Cluster, Catholic University of Leuven, Belgium

Objectives: Microleakage is often studied in vitro using tracers that can infiltrate the composite-tooth interface, such as silver nitrate. Conventionally, microleakage is assessed microscopically on cross-sections. X-ray microfocus computed tomography (micro-CT) allows 3D-characterisation of tracer distribution but with detection sensitivity lower than the conventional protocol. The effect of specimen radiodensity and micro-CT resolution on detection sensitivity was studied.

Methods: Specimens were prepared on sound human third molars (<6 months extracted). Cavities were restored with Gradia® (GC) composite and either Clearfil® SE (Kuraray) adhesive (Class V) or MaxCem® (Kerr) composite cement (Class II). After 5000 thermocycles (5-55°C) specimens were infiltrated (50% AgNO3, 24h). After sectioning, light-microscopy microleakage scores (range 0-4) were assigned. To reduce radiodensity, sections were demineralised (2 weeks EDTA) and embedded (Epon). Micro-CT scans (Skyscan1172, Skyscan) were taken (1) before sectioning at 100kV, 7.8µm pixel size (PS), (2) after sectioning at 85kV, 7.8µm, (3) after demineralisation/embedding at 50kV, 7.8µm, (4) after further size reduction at 50kV, 3.6µm, and (5) idem at 50kV, 1µm. Micro-CT data sets were reduced to maximum-intensity projections in the section planes (thickness=360µm) and regions of interest (ROI) close to restoration margins were selected. Grey-value histograms over the ROI were decomposed into Gaussian peaks (PeakFit 1.2).

Results: In conditions (1)-(2), no histogram peaks attributable to Ag could be discerned. In conditions (3)-(5), Ag peaks appeared as shoulders in the peak caused by attenuation from demineralised dental tissue, and average relative error on Ag peak areas decreased from 0.030 (PS 7.8µm) to 0.007 (1µm) (Pearson, n=9, r=0.69, p<0.05).

Conclusion: When micro-CT of silver tracer is used to visualise microleakage, specimen demineralisation and a pixel size of 3.5µm or less are recommended. By extrapolation of the observed trend, micro-CT with sub-micrometer resolution can be recommended for detailed quantitative 3D-study of microleakage. Supported by K.U.Leuven Grant OT/06/58.


0290 (109668)

Color Analysis of Suspicious Oral Mucosal Lesions. P. GÜNERI1, A. KAYA2, A.C. KAZANDI1, A. VERAL1, and H. BOYACIOGLU1, 1Ege Universitesi, Izmir, Turkey, 2Yeditepe University, Istanbul, Turkey

Objectives: Staining of suspicious mucosal lesions with toluidine blue, application of a chemiluminescent light source and exfoliative brush biopsy are methods which have been used to increase the efficacy of clinicians in early diagnosis of oral cancer. In this study, color analysis on the digital clinical images of lesions after application of toluidine blue and chemiluminescent light source was performed and compared with diagnoses obtained by brush and scalpel biopsies.

Methods: Clinical digital images of 43 suspicious oral mucosal lesions were obtained after visual examination, toluidine blue staining and chemiluminescent light application. Then, brush biopsy and scalpel biopsy specimens of each lesion were obtained and examined. Color data of the lesions were determined by a software using CIELAB system.

Results: Differences in colour as measured by ΔE, &DeltaL, &Deltaa and &Deltab values obtained on the images after toluidine blue and chemiluminescent light application did not establish the malignancy potential (p>0.005). However, when all malignant lesions that showed darker color characteristics with toluidine blue were further examined with brush biopsy, the malignant and benign lesions were diagnosed with 100% sensitivity. With this “combination” method, the false positive rate was 7.14% , and true negative rate was 92.86%.

Conclusions: Toluidine blue staining and brush biopsy appeared to be more effective when used as a combination method. Chemiluminescent light source was not an appropriate method for color analysis of oral mucosal lesions.


0291 (110422)

Oral Cancer Over Four Decades. A. ZINI1, R. CZERNINSKI2, and H.D. SGAN-COHEN1, 1Hebrew University - Hadassah School of Dental Medicine, Jerusalem, Israel, 2Hebrew University, Israel

Objectives: Oral cancer is defined as affecting the lips, tongue, buccal mucosa, floor of the mouth, and salivary glands. As some of these tumors are rare, epidemiological analysis is often inadequately described. Collecting data over almost four decades offers a unique opportunity to analyze rare and specific sites with significant case numbers. The aim of this study is to analyze distribution and trends of oral cancer, 1970-2006 among the Israeli population. Methods: Incidence and survival data were derived from the Israel National Cancer Registry and included all registered cases, 1970-2006. Results: Most prevalent cancer was Squamous Cell Carcinoma (SCC), with most cases among men above the age of 55 years. Females had higher levels of SCC in the lateral tongue, gums and buccal mucosa. Lymphoma and sarcoma were most prevalent among the youngest group. Tumors of salivary gland origin were the second most prevalent cancer in the palate, floor of mouth, tongue base and retromolar area. Buccal Cell Carcinoma (BCC) had highest survival rates, melanomas and metastatic disease the worst. Intra-orally best survival was for the lip, worse was the tongue base and gums. Over the time period, an increasing rate of tumors was found for the parotid gland vs. decreasing for the lips. Conclusions: Oral cancer presents a challenging disease for head and neck clinicians. In the current study 9,780 cases of oral cancer were registered in Israel between 1970 and 2006. It indicates that the age of above 55 years should be included as a risk marker. The high percentage of BCC is suggested to be due to the combination of sun exposure with a high proportion of fair skinned population. Highest cumulative 5-yr survival rate was for basal cell carcinoma, which is known to demonstrate a relatively good prognosis.


0292 (111896)

CD44 down-regulation reduces self-renewal of oral carcinoma stem cells. F.K. KIDWAI1, D.E. COSTEA2, L. GAMMON1, L. HARPER1, and I.C. MACKENZIE1, 1Barts and The London School of Medicine and Dentistry, United Kingdom, 2University of Bergen, Norway

Background: The CD44 adhesion molecule acts as a marker of “tumour initiating cells”, the putative “cancer stem cells” (CSCs) in oral squamous cell carcinomas (OSCC), and there is increasing evidence that such cells drive the growth of a wide range of malignancies. However, little is known about the role of CD44 in CSC maintenance or about differential expression of CD44 splice variants on CSCs. Objective: To investigate the function of CD44 in maintaining the self-renewal properties of CSCs in cell lines derived from OSCC. Materials and Methods: CD44 expression was down-regulated in the UK1, 5PT, Ca1, and H357 cell lines by butyrate or by siRNAs. Down regulation was confirmed by immunofluorescence, flow cytometry and QPCR. The effects of CD44 down-regulation were assessed by quantification of stem cell markers (Oct4 and Bmi1) and assays of growth and clonogenicity. Results: For all cell lines, both 1mM sodium butyrate treatment and siRNAs against CD44 resulted in a significant decrease of CD44 at both protein and mRNA levels. CD44 down-regulation reduced expression of mRNAs for Oct4 and Bmi1, decreased in cell yield (p<0.01), and altered colony forming patterns with a significant (p<0.01 ) decrease in holoclones, the colony type containing CSCs. Conclusion: CD44 appears to have a functional role in maintaining the self-renewal of CSCs in OSCC-derived cell lines. In addition to bringing novel knowledge about the role of CD44 in maintenance of the stem cell properties, the present study highlights the possibility of developing novel and more efficient treatment strategies for oral cancer by depletion of stem cell populations through down regulation of CD44. Work continues to examine whether differential expression of CD44 isoforms on CSCs can be exploited to enable specific targeting of malignant stem cell populations.

Supported by the Fanconi Anemia Research Foundation and the Norwegian Research Council.


0293 (111032)

FOXM1 is Upregulated in Oral Cancer and Induces Genomic Instability. E. GEMENETZIDIS1, D.E. COSTEA2, T. CHAPLIN1, B.D. YOUNG1, F. FORTUNE1, and M.T. TEH1, 1St. Bartholomew's & The Royal London, United Kingdom, 2University of Bergen, Norway

Objectives: Squamous cell carcinoma of the head and neck (HNSCC) is a significant cause of mortality and morbidity worldwide. HNSCC is characterized by sequential genomic alterations, including the amplification of FOXM1 gene locus. FOXM1 transcription factor is abundantly expressed in majority of human solid tumours, regulating cell proliferation, mitotic division, genomic stability and differentiation. To investigate whether FOXM1 expression is upregulated in HNSCC and its role in the cell cycle of human epithelial keratinocytes. This study examined whether upregulation of FOXM1 in human keratinocytes may induce genomic instability required for human oral cancer progression.

Methods: A high efficient retroviral gene transfer method was used to deliver FOXM1 and/or EGFP transgenes in human keratinocytes. Real-time quantitative PCR was used to quantify gene expression in a series of normal, oral premalignant and HNSCC derived keratinocytes. A high-resolution Affymetrix single nucleotide polymorphism (SNP) mapping technique was used to measure genomic instability in the form of loss of heterozygosity (LOH) and copy number abnormalities (CNA) in human keratinocytes.

Results: FOXM1 is upregulated in oral pre-malignant and HNSCC derived primary keratinocytes. FOXM1B was found to be the main isoform driving cell cycle progression, expressed mainly at the G2 phase of human keratinocytes. We provide the first evidence that FOXM1B upregulation was sufficient to induce genomic instability in human keratinocytes. FOXM1B-induced genomic instability was enhanced and accumulated with increasing passage number, and keratinocytes with upregulated FOXM1B showed enhanced sensitivity to subsequent genotoxic insult causing an increased accumulation of genomic instability.

Conclusions: We hypothesise that aberrant upregulation of FOXM1B is important in oral carcinogenesis whereby it serves as a ‘first hit' where cells acquire genomic instability. This predisposes cells to a ‘second hit' whereby subsequent exposure to genotoxic insults may expedite the selection of transformed cells to proliferate and accumulate further genetic aberrations required for cancer initiation.


0294 (111427)

The Use of Dielectrophoresis in Oral Cancer. H.J. MULHALL1, B. KAZMI2, F. LABEED1, M.P. HUGHES1, and M.P. LEWIS2, 1University of Surrey, United Kingdom, 2UCL Eastman Dental Institute, London, United Kingdom

Objectives:

Oral squamous cell carcinoma (OSCC) is the eighth most common cancer worldwide. If early stage (stage I) diagnosis occurs, the 2 year survival rate is 87.5% (Cancer Research, U.K.). However, most oral cancers are diagnosed at late stage and, consequently, the overall survival rate for OSCC remains poor (approximately 50% at 5 years post-presentation). A novel screening assay is investigated in which a malignant cell population derived from the oral mucosa is distinguished from normal oral cells on the basis of its dielectric phenotype.

Methods:

Dielectrophoresis (DEP) is a phenomenon whereby a force is exerted on a dielectric particle (a cell) when exposed to a non uniform electric field. The magnitude and direction of the force is dependent, in part, on the dielectric properties of the cell. The response of cell populations with different dielectric phenotypes, when exposed to an electric field, will be dissimilar. In this study, DEP has been used to determine the difference in dielectric phenotype between OSCC cell lines (H357, FADU and CAL-27) and normal human keratinocytes (NHKs). In addition, cells derived from organotypic models of the normal oral mucosa and models of OSCC have been analysed with DEP.

Results:

The results show significant electrophysiological differences in the cytoplasm of NHK's and malignant keratinocytes.

Conclusions:

Malignant keratinocytes exhibit an altered dielectric phenotype to normal keratinocytes, in vitro. It is proposed that DEP has the potential to be used in a clinical setting as a cheap, non-invasive screening tool for OSCC.


0295 (111799)

Expression of Matrix Metalloproteinases in Actinic Cheilitis. A. POULOPOULOS, A. EPIVATIANOS, T. ZARABOUKAS, and D. ANTONIADES, Aristotle University, Thessaloniki, Greece

Objectives: Long term exposure to ultraviolet irradiation from sunlight, causes to the lower lip vermillion a lesion known as actinic cheilitis.We investigated the role of matrix-degrading metalloproteinases (MMPs), a family of proteolytic enzymes, as mediators of functional connective tissue damage in actinic cheilitis.

Methods: Twenty formalin-fixed, paraffin embedded specimens of actinic cheilitis, and five specimens of normal lower lip vermillion, were examined. The streptavidin-biotin complex method was performed for MMP-9 and MMP-12 in serial sections of our specimens. MMP immunohistochemistry was evaluated using a semiquantitative immunoreactive score based on the percentage of positive cells and their staining intensity.

Results:Immunostaining for MMP-12 was clearly detected enhanced in most of the cases of actinic cheilitis (18/20),examined within the fragmented, distorted, and thickened elastic fibers.MMP-9 showed very weak reaction with the elastotic material (1/20) in actinic cheilitis lesions.Furthermore immunoreactivity for MMP-12 was detected in macrophages and for MMP-9 in polymorphonuclear leukocytes. In normal specimens we did not find any immunoreactivity for MMP-9 and MMP-12.

Conclusions: The restricted distribution of potential MMP-9 producing cells may explain the diminished immunoreactivity of MMP-9 in elastotic materials in sun damaged lip.In normal lip MMP-12 does not bind to normal elastin or in this condition, no abnormal accumulations of macrophages exist, as possible sources of MMP-12. MMP-12 possibly takes part in the reparative remodeling process by trying to cleave the abnormal elastotic material. Our results suggest that especially matrix metalloproteinase-12 may play an important role in remodeling events occuring in the connective tissue during long-term exposure to sunlight in the actinic cheilitis lesions.


0296 (110178)

Pilot Oral Cancer (OPC) Screening Study in High Risk Population. E.M. O'SULLIVAN, Cork University Dental School & Hospital, Ireland

OBJECTIVES:

Heavy usage of tobacco and alcohol may greatly increase the risk of OPC. This study investigates the feasibility and acceptability of targeted oral screening for addiction centre residents, and assesses potential benefits of national targeted screening.

METHODS:

Four addiction treatment centres were visited periodically over 12-month period. Data was collected on alcohol, tobacco and drug habits (type, quantity, duration) and attitudes to dental care. Participants underwent comprehensive oral examination; all soft tissue pathology/abnormalities were recorded; potentially sinister lesions/symptoms were referred for further investigation. Data analysis utilised SPSS-14. Funded by Irish Cancer Society (No:06-090307).

RESULTS:

220 residents (78%, 220/283) underwent screening (148 males; 61 females); 7% refused; 15% were unavailable. 53% reported dual addiction, 44% Alcohol only, 3% Drug only. While subject age ranged from 18-73 years, 60% participants were <40years; only 21% were over 50yrs. Extremely high rates of tobacco (87.6%) and alcohol usage recorded (91.5% alcoholics, 5.3% ex-alcoholics), reported intake ranging from 0-784units/wk. Last Dental Visit (LDV) ranged from 3 days to 30+ years; none of the edentulous participants reported LDV <15years. 82% participants required urgent dental care, 23% needed extraction(s), <50% had ~full dentition, 12.5% had significant pain. 84 mucosal abnormalities were detected in 61 subjects (29%). Subjects with mucosal abnormalities were significantly older (41.8 yr versus 35.9, P<0.05). 21 residents were referred for further investigation; seven (33%) attended. Despite poor compliance rate, two premalignant lesions and one carcinoma were detected – yield 1.3% (3/220).

CONCLUSIONS:

Study addresses the paucity of data on the prevalence of mucosal abnormalities in high-risk individuals. The high incidence of dental disease and LDV confirm a lack of engagement with GDP services among high-risk individuals, highlighting need for alternative screening mechanisms. Targeted oral screening was acceptable, feasible and achieved a high rate of detection of mucosal abnormalities. Plans for national targeted screening formulated.


0297 (111540)

Dose Responsive Effects of Smoking/Drinking Habits on Oral Lesions. Y.-H. YANG, Kaohsiung Medical University, Taiwan

Objectives: To investigate the dose response effects of betel quid chewing, cigarette smoking and alcohol drinking on leukoplakia and oral submucous fibrosis from a community screening of Taiwan. Methods: An oral cancer/precancer screening was conducted in 1 remote island and 4 aboriginal communities of Taiwan. Diagnosis of oral lesions was determined by dentists and specialists. Personal habits on chewing, smoking and drinking were collected by one to one interview. Dose response effects of oral habits were investigated by multiple logistic regressions with adjustment of the other two habits, age and gender. Three measures of dose responsive effects in this study included daily amount, years of duration and year-pak. Results: There were 2020 participants examined for oral cancer/precancer lesions. The prevalence rates were 11.1% for leukoplakia and 4.4% for oral submucous fibrosis. Both leukoplakia and oral submucous fibrosis were significantly associated with betel quid chewing habits on 3 dose response measures. In terms of cigarette smoking, only leukoplakia was significantly associated with daily amount, years of smoking and year-paks. The 3 dose response measures of alcohol consumption were not associated oral lesions. Conclusion: Although alcohol drinking is an important risk for oral caner/precancer in European countries, it usually does not show significance in South-east Asia. The betel quid in Taiwan does not contain any tobacco. Our study still identified that leukoplakia is related to both chewing and smoking habit, and oral submucous fibrosis is only related to betel quid chewing.


0298 (110017)

Injectable Degradable Polymeric Adhesives Containing Reactive Calcium Phosphate Filler Particles. E.A. ABOU NEEL, X. ZHAO, S.M. HO, J.C. KNOWLES, V. SALIH, and A.M. YOUNG, Eastman Dental Institute for Oral Health Care Sciences, London, England

Aim: Characterization of novel calcium phosphate filled degradable bone adhesives.

Methods: Polypropylene glycol (molecular weight =1000 g/mol) was used as a catalyst for ring opening polymerization of lactide. Methacrylate groups were subsequently attached to each oligomer chain end. The resultant degradable adhesive was filled with a phosphate glass [(P2O5)0.45(CaO)0.30(Na2O)0.15] or an equimolar mixture of tri - and mono -calcium phosphates. Rates of light activated polymerization were quantified via FTIR. Water sorption catalysed chemical and mechanical changes of set degradable adhesives were assessed using Raman microscopy, XRD, SEM with elemental analysis and DMA. Water sorption and degradation kinetics were quantified via gravimetric and ion chromatography studies. Cyto-compatibility of degradation products was monitored using MG63 cells and Alamar Blue Assay.

Results: Addition of filler particles caused only slight reduction in the adhesive rapid polymerisability. After placement in water, finely dispersed dicalcium phosphates (e.g. brushite) formed within the set polymers. With the mixture of tri- and mono-calcium phosphates this reaction caused a fast and surprisingly substantial (100 fold) increase in material modulus which was then maintained for several weeks. Both types of filler beneficially raised the rather slow polymer surface degradation kinetics and simultaneously buffered acidic polymer degradation products. With the phosphate glass, porous structures could form with time whereas the mixed fillers gave denser adhesives. The use of mixed fillers also improved adhesive degradation product cell compatibility.

Conclusions: Release of calcium phosphate fillers from polymeric bone adhesives can provide the inorganic elements required for bone repair. The above results show they may additionally provide greater control over various other adhesive properties including degradation kinetics and cell compatibility. With fast filler release porous scaffolds for cell support can form. Additionally, precipitation of finely dispersed dicalcium phosphate species directly within the polymer may enhance mechanical properties.

This project is funded by EPSRC & DHPA.


0299 (110305)

RD94, a Portland Cement, Stimulates in Vivo Reactionary Dentin Formation. T. BOUKPESSI, F. DECUP, D. SEPTIER, M. GOLDBERG, and C. CHAUSSAIN-MILLER, University Paris Descartes, Dental School, Montrouge, France

RD94 is a novel experimental Portland cement aiming to be a glass ionomer cement and composite- resin substitute in restorative dentistry. Objectives: To explore the effects of RD94 on the formation of reactionary dentine, in vivo experiments were carried out on the rat upper molars.

Methods: Half-moon cavities were prepared on the mesial aspect of the first molar without pulp exposure. Comparison was made with a sham group (preparation of cavities alone), with a group of molars where the cavities were occluded with a conventional glass-ionomer cement and with a group where cavities were filled with RD 94. After 8, 15 and 30 days, the rats were killed by heart perfusion with the fixative solution. Measurements were done on images obtained after histological analysis.

Results: Eight days after tooth preparation, a few inflammatory cells were seen, mostly located in the pulp surface near the cavity. In the RD94 group, a 20-40 mm thick layer of reactionary dentin was formed beneath a calico-traumatic line, in contrast to the two other groups where the reactionary dentin thickness was about 10mm. After 15 days, the inflammatory process was resolved in the pulps of all the groups. In the RD94 group, the outer part of the pulp chamber was filled with a 40-80 mm thick layer of reactionary dentin beneath the calciotraumatic line. After 30 days using RD94 as restorative material, reactionary dentin was about 160mm thick, whereas the rest of pulp looked normal.

Conclusion: The present data show that the novel RD94 cement displays good pulp biocompatibility, and has bioactive properties by stimulating the formation of reactionary dentine in the rat molar model. These results suggest that restorative treatment with RD94 provides new prospects for dental therapy.

We acknowledge SEPTODONT, France, for their financial support to this investigation.


0300 (110363)

Growth and differentiation of osteoblasts on Polylactide/Hydroxyapatite composite films. A. TALAL1, I. MCKAY2, E. TANNER1, and F.J. HUGHES2, 1University of Glasgow, United Kingdom, 2Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives: Biocompatible composite materials have potential in tissue regeneration, being degradable, having appropriate mechanical properties and being capable of delivering growth factors. The proliferation of osteoblasts on polylactic acid (PLA) films containing varying nano-Hydroxyapatite (nHA) concentrations has been investigated. Pre-treating the films with Platelet Derived Growth Factor (PDGF) was considered.

Methods: PLA (PURAC Biochem, The Netherlands) and nHA (synthesized by the sol-gel method) composite films with 10, 40 or 70 wt% nHA (4, 21 and 48vol % nHA) were manufactured. Films additionally had either 100ng PDGF pre-adsorbed on to the films, or 1ml of 100ng/ml PDGF added to the culture solutions. Osteoblasts were cultured for 14 days. Cell growth and proliferation was measured by MTS assay. Alkaline phosphatase (ALP) activity was tested by measurement of PNP production from p-NPP substrate.

Results: The rate of cell proliferation decreased with increase of nHA content. Cells reached confluence at 10 days on PLA and 10%nHA-PLA films whereas the cells were still growing on 40 and 70%nHA-PLA films by day 14. 70% nHA-PLA films showed the lowest rate of cell growth compared to other films. However cells on PLA and 70% nHA-PLA films showed increased ALP activity whereas the lowest ALP activity was seen in control and 10% nHA-PLA films (ALP activity on 10%nHA films 0.3093 ± 0.0579 OD units/ cell; 70% nHA 0.8327 ± 0.0057 OD units/cell). Pre-adsorption of PDGF to films caused a greater increase in cell proliferation than was seen with PDGF in solution.

Conclusions: PLA/nHA composite is biocompatible for osteoblasts. High concentrations of HA may enhance osteoblast differentiation, as seen by increased ALP activity. Furthermore the high bioactivity seen with PDGF pre-adsorbed to films, compared with PDGF in solution, suggest that this material may also be useful for the delivery of active growth factors in regenerative treatments.


0301 (110581)

Morphometric Comparison of Barrier Function in Lateral Augmentation-Preliminary Results. A. FRIEDMANN, K. GISSEL, J.-P. BERNIMOULIN, and B.-M. KLEBER, Zentrum fur-Zahn-, Mund-u Kieferheilkunde, Berlin, Germany

Objectives: Cross linked (CLC-test) and non-cross linked collagen (NCLC-control) membranes were clinically compared by the outcome in terms of width alterations due to newly formed tissue after lateral augmentation.

Material&Method: Impressions using individual plastic trays and sterile A-silicone were taken initially and repeated at each surgical step. Implant surgery included augmentation of lateral dehiscences/fenestrations. Exclusively biphasic calcium-phosphate ceramic was applied as grafting material combined with either CLC or NCLC membrane. Complete soft tissue closure was achieved; healing lasted for 6 months. At re-entry flap design was repeated for impression taking. Impressions were casted for reproducible morphometrical analysis. Silicone templates were adjusted on alveolar crest on casts, which showed integrated implants and area augmented. To determine reference points templates were trimmed parallel with basis of casts, implant of interest was labelled and the casts with mounted template were sectioned bucco-lingually. Cross-sectioned template was concomitantly transfered on cast obtained during implant surgery to reproduce later implant position thus projecting reference point on it. Measurements were performed by blinded investigator using digitalized sliding calliper dropping a perpendicular from the edge of template to the crest middle of cross-sectioned implant. At crossing point with alveolar crest the most buccal extension was measured horizontally (Δ0). Second measurement (Δ1) was taken “subcrestally” at the level of most pronounced buccal aspect of augmented area to perpendicular labelled on the template during first measurement.

Results: In 20 out of 37 patients analyzed, median values for alveolar ridge width showed significant gain in tests (n=14; Δ0=1.51mm (IQ 0.83-2.81); p=0.002; Δ1=2.49mm (IQ 0.37-3.39); p=0.003) and controls (n=12; Δ0=1.45 (IQ 0.50-3.40); p=0.005; Δ1=1.64 mm (IQ 0.50-3.40); p=0.008) at both reference levels. Differences in measurements between both groups did not reach the level of statistical significance.

Conclusion: Both collagen membranes contributed to significant improvement of alveolar width in the augmented area.


0302 (111445)

Development of an Ex Vivo Mandible Model of Local Inflammation. S.Y. TAYLOR, E. SMITH, X.-Q. WEI, R. WADDINGTON, and A.J. SLOAN, University of Wales, Cardiff, Wales

Osteoclastogenesis following stimulation with pro-inflammatory mediators, such as bacterial factors and pro-inflammatory cytokines is an essential prerequisite to bone resorption during periodontitis. Understanding these processes will facilitate the development of novel clinical therapies. Objectives: Investigate the effects of bacterial lipopolysaccharide (LPS) or Receptor Activator of Nuclear Factor κβ ligand (RANKL) and macrophage colony stimulating factor (MCSF) in an ex vivo murine mandible culture model and the viability of generating a local inflammatory response. Methods: Trowel-type cultures of 1mm transverse murine mandible slices from 10-12 week old male CD1 mice were maintained over 7-14 days in the absence or presence of 100ng/ml LPS or 10ng/ml M-CSF and 30ng/ml RANKL. Following culture, slices were processed and sections stained for histomorphometric analysis and periodontal ligament (PDL) nuclei quantification. Resident osteoclasts were quantified following TRAP assay and fluorescent immunolabelling used to quantify markers of proliferation, bone matrix, and LPS signalling (PCNA, BSP, TLR4). To develop local bone resorption, preosteoclast cell suspensions isolated from bone marrow and labelled with cell tracer were microinjected into the PDL prior to culture. Results: Tissue histomorphometry was maintained during culture and following stimulation with LPS or RANKL/MCSF. LPS significantly increased (p<0.05) PDL nuclei numbers after 7 days, with reduced numbers at longer time points compared to RANKL/MCSF stimulated slices and unstimulated controls. Cellular proliferation was unaffected following either LPS or RANKL/MCSF stimulation. Significant (p<0.05) increases in TRAP positive osteoclasts, TLR4 antigenicity and decreases in BSP were LPS-dependent. Tracer fluorescence indicated microinjected preosteoclasts remained at the injection site, while slice histomorphometry and PDL nuclei numbers were maintained. Conclusion: LPS, but not RANKL/MCSF directly induced an osteoclastogenic response via TLR4 signalling in this culture model. Microinjection of preosteoclasts may provide a viable model for generating a localised inflammatory response via RANKL/MCSF stimulation. (Supported by NC3Rs research grant No 77844)


0303 (111446)

Influence of Titanium Surface Treatments on Progenitor Cell Behaviour. J.S. COLOMBO1, S. CREAN2, A.H. DOWLING3, G.J.P. FLEMING3, A.J. SLOAN1, and R.J. WADDINGTON1, 1Cardiff University, United Kingdom, 2Peninsula College of Medicine & Dentistry, Universities of Exeter & Plymouth, United Kingdom, 3Dublin Dental School & Hospital, Ireland

Osseointegration involves the migration, proliferation and differentiation of progenitor cells from the bone marrow spaces. Interaction of these cells with the titanium surface is an important consideration of this process. Objectives: To investigate how topography and chemistry of titanium implant surfaces influences attachment and behaviour of rat bone marrow stromal cells (BMSCs). Methods: Surfaces of titanium discs were treated using one of three methods: machined (Mach); grit blasted /acid etched (AE); grit blasted / TCP-alpha coated (TCP). Profilometry data was obtained using a Taylor-Hobson Precision Talysurf running in contact mode. Analysis of surface chemistry was carried out using X-ray Photoelectron Spectroscopy (XPS). BMSCs were extracted from femurs of Wistar rats, seeded onto titanium discs at 1x105 cells/cm2 and cultured for one week under mineralising conditions. Fixed cells were stained for actin fibres with phalloidin-FITC and vinculin focal adhesion points by immunocytochemistry. DAPI was used as a nuclear counterstain. Results: Profilometry generated three dimensional representations of surface topography where average surface roughness were as follows for surfaces: (Mach) Ra= 0.09µm±0.024, (AE) Ra= 1.51µm±0.164 and (TCP) Ra= 2.09µm±0.128. XPS analysis showed the presence of a titanium oxide surface and trace elements Al, Zn, Na on all surfaces. AE surfaces contained F- and TCP surfaces additional presence of phosphates. Cell adherence was highest on AE surfaces and lowest on TCP surfaces, correlating to surface roughness. Cell morphology on machined surfaces was rounded, whilst those cells on AE surfaces presented more cellular processes and high number of focal adhesion points. Conclusions: Surface roughness appeared to be a major influence on the adherence and morphology of cells on the titanium surface. Observing the impact of these factors on cell interaction with these surfaces gives an insight into the biological basis for the clinical efficacy of the three surface treatments. Funded by GIFT.


0304 (110035)

Epithelial cell adhesion on a new laminin-5 functionalized titanium material. S. WERNER1, O. HUCK1, B. FRISCH2, L. KOCGOZLU1, R. ELKAIM3, D. VAUTIER1, J.-C. VOEGEL1, and H. TENENBAUM1, 1ERT 1061, Unite INSERM 595, Dental Faculty, University Louis Pasteur, Strasbourg, France, 2Faculty of Pharmacy, University Louis Pasteur, Illkirch, France, 3Parogène, Strasbourg, France

Objectives: we investigated the possibility of improving titanium implants with a focus on their use in dentistry. Methods: we combined modifications of the implant's topology with chemical surface modifications. Porous titanium was used as a new material to create a three dimensional surface able to tightly seal the implant/soft tissues interface. Chemical modifications were introduced by functionalized polyglutamic acid / polylysine polyelectrolyte multilayers films (PGA/PLL PEM films) in order to get a bioactive titanium material with enhanced cell-adhesion properties. These films were tested either in their native state or cross-linked. Functionalization was provided by a laminin-5 derived peptide, a protein involved in the scaffolding of epithelia basal membranes. The biological properties of this bioactive material were investigated by means of oral keratinocytes adhesion/proliferation assays and the formation of adhesion structures.

Results: porous titanium showed good cell adhesion properties but the colonization of the material could be improved by coating with laminin-5 functionalized PGA/PLL films. Cross-linked PGA/PLL film also showed very good cell adhesion properties, which were not clearly improved by the functionalization with the laminin-5 peptide. We observed focal contact formation on cross-linked architectures, which reflects a strong cell anchorage on the substrate. In contrast, the cells formed only very diffuse focal contacts on native functionalized films even though they were spread on the substrate and could proliferate. Very interestingly, epithelial cells adhered to (PGA/PLL) films with laminin-5 peptide via hemidesmosomes, which are adhesion structures naturally involved in the adhesion of gingival soft tissues on the tooth surface.

Conclusions: the increased epithelial cell attachment, spreading, and hemidesmosomes formation on laminin-5 peptide-coated porous titanium indicate an enhanced integration of the tissue in the pores of the titanium material and thus predict significant utility of this molecule for long-term implant stabilization.


0305 (110636)

Effects of Ultrasound on VEGF expression in odontoblast-like cells. B.A. SCHEVEN, J. MAN, J.L. MILLARD, P.R. COOPER, A.D. WALMSLEY, and A.J. SMITH, University of Birmingham, United Kingdom

Objectives: The biological effects of ultrasound on dental tissues are not fully known. We addressed the question whether low frequency ultrasound generally used in clinical practice to remove calculus or in root canal treatment is able to influence the activity of odontoblasts. In this study we investigated the effects of ultrasound on the expression of vascular endothelial growth factor (VEGF) in an odontoblast-like cell line, MDPC-23. In addition, the effects of recombinant VEGF on MDPC-23 cell proliferation were studied.

Methods: MDPC-23 odontoblast-like cells were exposed to different levels of 30 kHz ultrasound using a dental scaler probe and subsequently cultured for 24h in DMEM with 10% foetal bovine serum. Viable cell numbers were assessed using the WST-1 assay. VEGF gene expression was analysed by semi-quantitative RT-PCR normalised to GAPDH expression. VEGF protein levels in the conditioned media were determined with a specific ELISA.

Results: Gene expression analysis demonstrated that the MDPC-23 cells expressed the main VEGF isoforms, i.e. VEGF120 and VEGF164 as well as to a minor extent VEGF188. Treatment of ultrasound at low power settings increased VEGF120 and VEGF164 expression in the odontoblast-like cells, but no significant gene expression changes were evident at high ultrasound doses. VEGF188 expression was enhanced in all ultrasound groups. Ultrasound induced a dose-dependent increase in the concentration of VEGF in the culture supernatants indicating a stimulation of VEGF secretion by the odontoblastic cells. Addition of recombinant VEGF to MDPC-23 cell cultures resulted in a moderate albeit significant increase in cell proliferation suggesting an autocrine role of VEGF in odontoblast regulation.

Conclusions: These findings indicate that ultrasound promoted VEGF expression and production by odontoblast-like cells. It is proposed that low frequency ultrasound may influence odontoblasts and dentine repair by modulating production of endogenous angiogenic growth factors in the dentine-pulp complex.


0306 (111512)

Clinical and genetic factors as predictors for presence of periodontopathogens. L. NIBALI1, N. DONOS2, D. READY3, M. PARKAR1, P. BRETT1, and F. D'AIUTO2, 1UCL Eastman Dental Institute, London, United Kingdom, 2UCL Eastman Dental Institute and Hospital, London, United Kingdom, 3University College London, United Kingdom

Objectives: Interleukin-6 (IL6) genetic factors have recently been associated with presence and severity of periodontitis, and with presence of periodontopathogenic bacteria. Elevate proportions of specific bacteria subgingivally is one of the secondary features for differential diagnosis between Aggressive (AgP) and Chronic periodontitis (CP). The aim of this analysis was to assess whether in a mixed sample of patients with periodontitis, clinical diagnosis or IL6 genetic factors were best predictors for presence of periodontopathogenic bacteria.

Methods: Logistic regression analysis was performed to assess associations between clinical diagnosis, IL6 genetic factors and presence of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis (assessed by PCR) in subgingival biofilms of a group of 142 patients diagnosed with severe forms of periodontitis (CP n=115, AgP n=27).

Results: A. actinomycetemcomitans was detected in 45.7% and 48% of CP and AgP subjects respectively. The corresponding figures for P. gingivalis were 80.2% and 68.0%. IL6 -6106 AA genotype was associated with detection of A. actinomycetemcomitans (p=0.009, O.R. = 3.5, 95% C.I. = 1.38- 9.16). IL6 -6106 AA and IL6 -174 GG were also associated with concomitant detection of A. actinomycetemcomitans and P. gingivalis (p=0.015, O.R. = 3.6, 95% C.I. = 1.28-10.04 and p=0.042, O.R. = 2.8, 95% C.I. = 1.04-7.75 respectively).

Conclusions: In this subject sample, genetic factors were more predictive of the presence of periodontopathogenic bacteria than clinical diagnosis.


0307 (110658)

Experimental gingivitis and the impact of diet restriction. S. BAUMGARTNER, University of Bern, Switzerland, and G.R. PERSSON, University of Berne, Switzerland

Objectives: To assess if the microbiota from subgingival and tongue samples changed during four weeks of no oral hygiene in subjects on a sugar restricted diet.

Methods: 10 subjects participating in an environment replicating stone age during four weeks limited to food available to stone age man were enrolled. A thorough medical and dental examination was performed before and after the four weeks. At baseline and after four weeks, subgingival microbiological samples were collected at the mesiobuccal aspects of all teeth and from the dorsum of the tongue and processed by the checkerboard DNA-DNA hybridization methods. Results: Subjects had no evidence of periodontitis. Bleeding on probing (BOP) decreased from an average of 34.8% to 12.6% (p<0.001). Mean gingival index scores (Löe-Silness) at baseline and at week 4 were 0.38 and 0.43 respectively (N.S.) whereas mean plaque scores (Silness-Löe) were 0.43 and 1.42 respectively (p<0.001). Decreases in probing pocket depth (PPD) at sites from which bacterial samples were taken were found ( mean diff :0.2, 95%CI: 0.1-0.3, p<0.001). Total bacterial counts were higher at week 4 (p<0.001). Higher bacterial counts (p<0.001) were found for 62/73 species including Prevotella intermedia, Parvimonas micra, Porphyromonas gingivalis, and Tannerella forsythia, but not Aggregatibacter actinomycetemcomitans (Y4) nor Treponema denticola. Pseudomonas aeruginosa, Staphylococcus aureus, Echerichia coli, Haemophilus influenzae were found at higher counts at week 4 (p<0.001). At the tongue samples, lower bacterial counts were found at week 4 for i.e. Streptococcus mitis, Streptococcus, oralis, and Streptococcus sanguinis (p<0.01). Conclusions: Although plaque levels increased, decreases in BOP and PPDs were found. Diet restriction with abstinence of oral hygiene does not result in increased gingival inflammation but in increases of bacterial counts in subgingival samples but with decreases in counts in samples from the tongue. Acknowledgement: Supported by the Clinical Research Foundation, University of Berne.


0308 (111768)

A Pilot Investigation of Sub-gingival Yeast Spp. in Untreated Periodontitis. F.R.P. MAGUIRE1, K. NYLUND1, D.C. COLEMAN2, and N. CLAFFEY1, 1Dublin Dental School and Hospital, Dublin 2, Ireland, 2Dublin Dental School and Hospital, University of Dublin, Trinity College, Ireland

Yeasts may play an important yet undefined role in periodontal disease.Aim: to examine the prevalence of yeast species in the sub-gingival biofilm of healthy and diseased periodontal sites of patients with untreated periodontal disease.Methods: Twenty patients with untreated periodontal disease and meeting the inclusion criteria, underwent a medical and dental history and clinical examination including a periodontal examination. Patients rinsed with 10 mls of sterile distilled water for thirty seconds and emptied the rinse into a sample container. Sub-gingival sites selected included the two deepest sites displaying bleeding on probing (Disease Site) and one shallow site with an absence of bleeding on probing (Healthy Site). Sampling sites were isolated, supra-gingival plaque removed with cotton wool pellets and samples obtained using three no. 35 sterile paper points. Also a curette sample was taken of the sub-gingival plaque deposits. Sub-gingival paper point and curette samples were transferred separately to the laboratory in Yeast Peptone Dextrose Broth and processed within twenty-four hours. Samples were cultured on chrome agar, identified visually, number of colony forming units counted and their identity confirmed using the ID32 test.Results: Candida spp. were isolated from both the oral rinse and sub-gingival samples. Candida spp. isolated from periodontal sites included C. albicans, C. kefyr, C. dubliniensis, C. parapsilosis. Candida spp. were present in 36% of Disease Sites and 0.05% of Healthy Sites (at a density of greater than 100 c.f.u.). Presence of candida spp. were highly statistically significantly related to disease state (Fisher's exact test: p=0.02). Differential colonization patterns were observed between the oral rinse and sub-gingival samples.Conclusion: 1.Candida spp. were present in the subgingival biofilm of patients with untreated periodontal disease at a prevalence of 36%. 2. The presence of Candida spp. within the sub-gingival site was significantly associated with the clinical signs of periodontal disease (p=0.02).


0309 (110814)

Electrical Enhancement of Chlorhexidine Efficacy Against Porphyromonas Gingivalis Biofilms. J. LASSERRE, and P. BERCY, Universite Catholique de Louvain, Bruxelles, Belgium

Objectives: In biofilms, bacteria are less sensitive than their planctonic homologues. The aim of this study was to compare the bactericidal effect of chlorhexidine 0,2% (CHX) (Corsodyl®) on Porphyromonas gingivalis W83 (P.g) within dual-species biofilms when used with (Test) or without (Control) the addition of low intensity direct electric currents (DC).

Methods: In order to form the biofilms, we inoculated a Brain Heart Infusion broth with Streptococcus gordonii ATCC10558 and P.g before perfusing it, in anaerobiosis, for 7 days via a closed circuit containing 2 Modified Robbins Devices (MRD-LPMR-12E) (Tyler Research-Canada) assembled in parallel. Biofilms grew on hydroxyapatite discs bonded on the bottom of the MRD plugs and were then treated for 30min with CHX on the first MRD and with CHX plus low intensity DC (1,5mA or 10mA) on the second one. The bactericidal effect against biofilms was evaluated after culture by comparing the mean proportion of P.g killed at T=10min.

Results: In the first series of biofilm treatments (CHX +/- 1,5 mA DC), the mean proportion of P.g killed was respectively 81,06% (+/- 8,55) for the biofilms undergoing CHX only and 79,08% (+/- 9,96) when they were treated as well with 1,5mA DC. The difference was not statistically significant (p>0,05).

In the second series (CHX +/- 10mA DC), we found a proportion of P.g killed of 84,9% (+/-2,76) with CHX and 98,93% (+/- 0,55) when CHX was used in addition with the DC. Here, the difference was significant (p<0,05). Conclusion: These results show that CHX 0,2% is efficient against P.g when the latter is located within a biofilm as is the case in subgingival plaque. Moreover, we also report an electrical enhancement of chlorhexidine 0,2% efficacy against Porphyromonas gingivalis biofilms when used in conjunction with 10 mA currents. The improvement discribed here is called the BIOELECTRIC effect.


0310 (110235)

Clinical evaluation of a mouthrinse in supportive periodontal care. M. ESCRIBANO, S. MORANTE, I. GONZÁLEZ, D. HERRERA, and M. SANZ, Complutense University, Madrid, Spain

Objectives: To evaluate the clinical activity and safety of a mouthrinse containing 0.05% cetyl-pyridinium chloride and 0.05% chlorhexidine in patients on supportive periodontal care (SPC). Methods: This investigation was designed as a randomized, double-blinded, placebo-controlled clinical trial. 34 subjects with a history of chronic periodontitis patients and currently on SPC were selected on the bases of demonstrating an inadequate plaque control (Turesky index >1). After a supragingival profilaxis and oral hygiene reinforcement, they were asked to rinse twice a day for 3 months with either the test or placebo rinse. Primary outcome variables included plaque and gingival indices (Turesky and Mühlemann-Son, respectively). Probing pocket depths, bleeding on probing and probing atachment levels were also examined as secondary outcome variables. The appearance of undesirable side effects, such as staining, burning feeling and soft-tissue irritation were also recorded. Outcome variables were compared by the ANCOVA test for the parametric data and the chi-square test for the nominal data. Results: Plaque index was significantly reduced in the test group (-0.68; confidence interval (CI): -0.96 to 0.39) while in the control group the plaque index increased (+0.32; CI: +0.01 to +0.64). Differences between groups were statistically significant (p=0.0001). Bleeding on probing was also reduced in the test group (-0.09), while it increased in the control group (+0.08), being the differences between groups statistically significant (p=0.01). The gingival index was reduced in both groups, and no significant differences were detected between them. The same was true for changes in probing pocket depths. In regards to the safety of the tested product, when compared with the placebo rinse, differences were found for tooth staining (p=0.07) and burning sensation (p=0.08). Conclusions: The tested mouthwash demonstrated significant efficacy in reducing plaque and bleeding in patients undergoing SPC but demonstrating an inadequate mechanical plaque control. Supported by Dentaid.


0311 (111268)

Plaque Inhibitory Effect of a 0.05% Cetyl-Pyridinium Chloride Mouth-rinse. V. GARCÍA, M. RIOBOO, J.J. SERRANO, I. GONZÁLEZ, D. HERRERA, and M. SANZ, University of Complutense, Madrid, Spain

Objective: To determine the plaque inhibitory effect of a 0.05% Cetyl-pyridinium Chloride (CPC) mouth-rinse using a de novo plaque formation model. Methods: Fifteen dental students were selected to participate in a double-blind, randomized, four-day cross-over experimental model, without mechanical oral hygiene. Three products were compared: a negative control (placebo without active ingredients), a positive control (0.12% Chlorhexidine-CHX and 0.05% CPC) and a test product (0.05% CPC). At baseline of each of the 3 experimental periods the Modified Gingival Index (MGI) was evaluated and microbiological samples were taken. Then each patient received a prophylaxis and the assigned product was given with proper instructions. At the day four of each period, MGI and Modified Plaque Index (MPI) were recorded, microbiological samples and photographs were taken and secondary effects were evaluated. One week was used as wash-out period between the experiments. Obtained data was analysed using ANOVA, Multiple Range Test, Friedman and Dunn Tests. Results: MPI was significantly different among groups (p=0.0003). Differences were detected between the positive control (2.86, confidence interval-CI: 2.53-3.19) and the negative control (3.87, IC: 3.29-3.95), between the positive control and the test product (3.62, IC: 3.54-4.19) and also between the test product and the negative control. The test product had a 25% plaque inhibitory effect compared with CPC plus CHX. We did not detect any side-effects in any of the groups in this experimental model. Conclusions: Within the limitations of this study model, the present study demonstrated that a 0.05% CPC mouth-rinse has a significant plaque inhibiting effect. Supported by Dentaid.


0312 (111277)

Clinical Effects of a Chlorhexidine-Xanthan Gel as Adjunct to Scaling. P. MATESANZ, A. ECHEVARRÍA, A. O`CONNOR, D. HERRERA, and M. SANZ, University of Complutense, Madrid, Spain

Objectives: To assess the clinical outcomes of the application of a xanthan gel with clorhexidine as an adjunct to scaling and root planning (SRP). Methods: Chronic periodontitis patients, with 5-10 isolated pockets after initial therapy or during maintenance, were randomly assigned to the test group (xanthan gel with clorhexidine after SRP), or to the control group (identical placebo gel after SRP). Each subject was evaluated at the initial visit, and one, three and six months after the treatment. At each visit probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP) and plaque levels were evaluated at the selected teeth. Results were analysed by t-test, both to assess differences between groups and within groups. Results: 22 patients were included in the study, 10 in the test group, and 12 in the placebo group. At baseline, BOP was significantly higher (p<0.02) in the test group. In the test group, after 1 and 6 months, statistically significant improvements were observed in PPD, CAL and BOP, while at 3 months, significant benefits were observed in PPD and BOP. In the control group, statistically significant differences in BOP were found at all three follow-up visits. The 6-month mean reductions in PPD in the test and control groups were 0.32 (±0.26) mm and 0.22 (±0.52) mm, respectively. The corresponding figures for CAL changes were 0.29 (±0.34) mm and 0.01 (±0.87) mm, respectively. Intergroup differences were only found in changes in BOP after 3 months, favouring the test group. Conclusions: Within the limitations of the limited sample size, the adjunctive use of the evaluated product could improve the clinical outcomes in localised periodontal pockets. Supported by Guimas.


0313 (111035)

Chlorhexidine's effects on human osteoblasts, periodontal ligament and gingival fibroblasts. T.P. VRAHOPOULOS, C.E. MARKOPOULOU, X.E. DEREKA, A.A. MAMALIS, and I.A. VROTSOS, Athens University, Greece, Greece

Chlorhexidine (CHX) is the most widely used antiseptic in the treatment of periodontal disease, exhibiting a wide spectrum of antimicrobial activity. Cytotoxicity of CHX has been the focus of numerous studies, in an attempt to evaluate its possible effects on human periodontal cells.

OBJECTIVES: The aim of this study was to evaluate the in vitro effects of chlorhexidine mouthrinse solution (0.12%), on the morphology and cell viability of three different cell populations of human periodontal tissues, including osteoblastic cells, periodontal ligament cells (PDL), and gingival fibroblasts (GF), in a time-dependent mode.

MATERIALS AND METHODS: PDL and GF cell cultures were derived from maxillary premolars, and osteoblastic cells from human osteosarcoma (MG-63 cell-line). Cells were cultured in Dulbecco's modified eagle's medium (DMEM), supplemented with 10% fetal bovine serum (FBS) and antibiotics, followed by treatment with CHX solution in concentrations of 0,12% (v/v). Cell viability was performed using Trypan Blue Exclusion Assay. Morphological changes were evaluated by high-definition phase contrast microscopy, at selected time intervals. Statistical analysis was performed using Poisson regression analysis.

RESULTS: The effects of CHX on the cells were immediate and profound. The intensity of the morphological changes was gradually increasing, analogously to exposure time. The most characteristic changes observed, included gradual shrinking of the cells, widening of the intercellular spaces, gradual loss of cytoplasmic organelles and appearance of vacuoles. The intensity of the changes on PDL and GF cells was greater than that on the osteoblastic cells. After 24 hours, all three types of cell-cultures showed signs of complete cell lysis. Cell viability of all cell types was gradually reduced in a time dependent mode.

CONCLUSIONS: The 0.12% CHX solution seems to have an immediate cytotoxic effect on human periodontal cells, affecting the cell structure and viability in a time-dependent manner.


0314 (111089)

Proteomic Analysis of Streptococcus mutans: Exposure to Fluoride. J.T. DAVIES1, R. MCNAB2, G.C. MARTIN2, G.R. BURNETT2, D. BEIGHTON1, and K.A. HOMER1, 1King's College London, United Kingdom, 2GlaxoSmithKline, Weybridge, United Kingdom

Objectives: Streptococcus mutans is implicated in dental caries. It is acidogenic and aciduric, producing organic acids from dietary carbohydrates and tolerating low pH conditions. Fluoride ions are commonly used anti-caries agents which have been shown in vivo to enhance the remineralisation of tooth enamel and prevent demineralisation caused by acids. In vitro, fluoride has been shown to inhibit the S. mutans enolase, a key glycolytic enzyme, and the H+-ATPase, which regulates intracellular pH. The objectives of this study were to characterise the S. mutans sub-proteome and to determine the effects of growth in the presence of fluoride on protein expression.

Methods: SDS-PAGE was used to separate membrane proteins extracted from S. mutans UA159, cultured in the presence and absence of 5 mM sodium fluoride. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to identify proteins in conjunction with interrogation of the S. mutans translated genomic database.

Results: Proteins containing up to 10 predicted transmembrane domains were detected in the S. mutans membrane sub-proteome. Preliminary data suggest that expression of a number of S. mutans membrane proteins are altered in bacteria cultured in the presence of fluoride. Proteins with a putative role in bacitracin synthesis and stress response were up-regulated in bacteria exposed to fluoride. Differential expression of some key S. mutans virulence determinants was also demonstrated.

Conclusion: Membrane proteins fulfil a wide range of important biological functions but are often greatly under-represented in proteomic analyses using two-dimensional gel electrophoresis. A combination of SDS-PAGE and LC-MS/MS has allowed the most comprehensive description of the S. mutans membrane sub-proteome to date. Growth in the presence of fluoride affects the expression of many S. mutans proteins in addition to enolase and the H+-ATPase. This in turn may affect the ability of S. mutans to cause dental caries.

Funded by a BBSRC/GlaxoSmithKline CASE award.


0315 (111100)

Binding of Salivary Agglutinin to Bacterial Surface Components. A.J.M. LIGTENBERG, I. JACOBS, J.M.A. DE BLIECK-HOGERVORST, J.T. LEITO, and E.C.I. VEERMAN, Academic Centre for Dentistry Amsterdam, Netherlands

Salivary agglutinin (SAG) is a 340 kDa glycoprotein that belongs to the Scavenger Receptor Cysteine Rich (SRCR) protein superfamily. Members of this protein superfamily are secreted or cell surface-bound, possess one or more SRCR domains and frequently play a role in innate immunity. Originally, SAG was described to bind to antigen I/II polypeptides on the surface of oral streptococci. Later SAG was shown to have a broad bacterial binding spectrum which is typical for so called pattern recognition receptors, innate immune proteins recognizing conserved microbial structures.

Objectives: to identify the SAG-binding components on bacteria.

Methods: several Gram-positive bacteria (oral streptococci, Staphylococcus aureus and Lactobacillus casei) and Gram-negative bacteria (Escherichia coli, Salmonella typhimurium) were tested for SAG binding in fluid phase and adhesion assays. In addition, microplates were coated with lipopolysaccharide, lipoteichoic acid and peptidoglycan and tested for SAG binding.

Results: in general, Gram-positive bacteria bound SAG better than Gram-negative bacteria. Of the bacterial surface components tested peptidoglycan showed much better binding of SAG than lipopolysaccharide and lipoteichoic acid. This binding was inhibited in the presence of EDTA suggesting calcium-dependent binding. Trypsin treatment of peptidoglycan reduced binding of SAG, but treatment of peptidoglycan with lysozyme or periodic acid did not, suggesting the peptide moiety of peptidoglycan was recognized by SAG.

Conclusions: SAG recognizes peptidoglycan on the bacterial surface thus showing characteristics of pattern recognition receptors. This is in line with the finding that Gram-positive bacteria bind better than Gram-negative bacteria.This study was supported by the Netherlands Institute for Dental Sciences (IOT).


0316 (111408)

Sequence Diversity of Actinomyces naeslundii Fimbriae Subunit Proteins. U. HENSSGE, D. RADFORD, and D. BEIGHTON, King's College London Dental Institute, United Kingdom

Objectives: fimA and fimP genes code for the major subunit proteins of actinomyces type-2 and type-1 fimbriae respectively. A. naeslundii genospecies 2 possesses both types of fimbriae while genospecies 1 possesses only type-2. The fimbriae exhibit different binding affinities for salivary proteins and β-linked N-acetylgalactosamine. The complete nucleotide sequences of a small number of fimA genes have been reported but there is no comprehensive sequence analysis of the fimP gene. We have therefore undertaken an analysis of major fragments of both genes in a collection of A. naeslundii reference strains and clinical isolates (n=116).

Methods: A 690bp fragment of the fimA and a 680bp fragment of the fimP gene were amplified, sequenced and aligned in-frame. Phylogenetic trees were constructed for each gene and the sets of sequences were tested for evidence of recombination.

Results: The analysis of the fimA sequences indicated that the majority of genospecies 1 and 2 were well separated but a distinct branch was present which included 9 genospecies 1 and 8 genospecies 2 strains. The fimP sequences were obtained primarily from genospecies 2 isolates and these were present in a single cluster but other discrete clusters were observed and fimP gene sequence was identified in a small number of genospecies 1 strains. There was statistical evidence of recombination within the fimA and fimP gene sequences.

Conclusions: The sequence diversity of both fimA and fimP genes of A. naeslundii was greater than previously appreciated but the functional consequence of this diversity requires investigation. The sequence of fimA is not genospecies-specific.

This work was funded by Dental Institute King's College London.


0317 (111484)

Active carious lesions harbour Bifidobacteriaceae. M. MANTZOURANI, M. FENLON, E.C. SHEEHY, N. HODSON, and D. BEIGHTON, King's College London, London Bridge, United Kingdom

Objectives: The proportions and distribution in dental caries of the family Bifidobacteriaceae were studied.

Methods: Root caries samples, collected from 45 patients, ranged in severity from healthy exposed dentine to soft active carious lesions. Occlusal samples from the deciduous dentition were collected from 5 caries free children and from occlusal caries in 23 children. Occlusal lesions were also sampled from 4 adult patients. Bifids were isolated on a mupirocin-containing medium and total anaerobic counts were determined using FAA medium. The identification of bifids was based on morphological and growth characteristics, detection of fructose-6-phosphate phosphoketolase and partial 16S rRNA sequencing and BLAST searching.

Results: A total of 979 bifids were identified and these included Bifidobacterium dentium, B. subtile, Parascardovia denticolens, Scardovia inopicata, S. genomosp. C1, B. breve. and B. longum. B. dentium was present in the majority of the samples and was the predominant species. Bifids formed 7.1 per cent of the cultivable flora from the active root caries lesions, 1.6 per cent from the leathery lesions and 0.06 per cent from the sound root surfaces (p<0.01) while from the occlusal lesions of the permanent dentition they formed 8.3 per cent and 7.4 per cent of the deciduous lesions. Bifids were isolated from all active root carious lesions and occlusal permanent carious lesions and not from the caries-free surfaces in the children.

Conclusion: The occurrence of the family Bifidobacteriaceae in dental caries was more complex than previously reported and there was an increased prevalence and proportion of bifids with root lesion severity. Bifids formed a significant proportion of the cultivable flora of root caries, deciduous and permanent occlusal caries lesions.

Supported in part by the Biomedical Research Centre of Guy's and St Thomas' Foundation Trust Hospital. Sample collection was approved by the local Ethics Committee.


0318 (111505)

Comparison of Active Site Regions of NanH in Actinomyces naeslundii. T. DO, U. HENSSGE, S. GILBERT, D. CLARK, and D. BEIGHTON, King's College London, United Kingdom

Objectives: To study nucleotide variation within a sialidase gene of A. naeslundii genospecies 1, 2 and WVA963 strains isolated from different individuals and to determine evidence of recombination within and between them. Actinomyces spp. are predominant colonizers of the human oral cavity, and their adhesion to the buccal epithelial cells is mediated by the action of sialidases.

Methods: A. naeslundii strains (n=107) isolated from human clinical and oral samples (caries-active and caries-free subjects) including type and reference strains of A. naeslundii genospecies 1, 2 and WVA963 and A. viscosus, were cultivated on fastidious anaerobes agar. All selected isolates were sialidase positive. A fragment size of 1077 nucleotides was obtained from all isolates, which covered the active site and the five bacterial neuraminidase repeats (BNRs) found in the gene. The sequence data were aligned in-frame, and recombination events between and within genospecies were investigated.

Results: Data analyses indicated that the gene is under stabilizing selective pressure (mean value for dN/dS < 1), also confirmed by the non-significant D value in the Tajima's test (D = -1.67906, P > 0.05). The Phi test in SplitsTree4 revealed statistically significant evidence for recombination (P < 10-10). The Recombination Detection Program (RDPv3.24) also identified extensive recombination events within and between genospecies 1 and 2, with the various methods (Max Chi, Chimaera, and SiScan). Overall, between 5.6% (for BNR1) and 39.3% (for BNR4) of isolates exhibited amino acid polymorphism within the BNRs. The active site regions exhibited limited variation. Conclusion: The nanH gene of A. naeslundii genospecies 1, 2 and WVA963 exhibited the conserved structure of sialidase genes. There is clear evidence of recombination between genospecies 1 and genospecies 2.

Funded in part by the Welcome Trust.


0319 (111070)

Synergistic effects of amoxicillin and metronidazole on whole plaque samples. C. WALTER, E. KULIK, R. WEIGER, and T. WALTIMO, University of Basel, Switzerland

Objective:

Clinical studies on aggressive periodontitis have revealed improved outcomes for mechanical biofilm removal combined with metronidazole and amoxicillin. In-vitro information on the susceptibility of oral bacteria of this combination is hitherto scarce. The aim of this preliminary study was to determine the susceptibility of whole subgingival plaque-samples to amoxicillin and metronidazole and to their combination.

Methods:

Subgingival plaque samples of untreated patients with severe –by age- advanced periodontitis were selected for analysis. For the determination of the total anaerobic bacterial count 100µl of the dilutions were plated on Columbia blood agar plates supplemented with the following concentrations of the respective antimicrobial agents: 3 µg /ml amoxicillin, 8 µg /ml amoxicillin, 8 µg /ml metronidazole, 16 µg /ml metronidazole, 3 µg /ml amoxicillin plus 8 µg /ml metronidazole or 8 µg /ml amoxicillin plus 16 µg /ml metronidazole. All plates were incubated anaerobically for 14 days and the Colony forming units were determined.

Results:

The total anaerobic counts of the samples varied within 3.1 x 10-6 and 7.2 x 10-7. The percentage of black-pigmented colonies varied within a range from 40-80% of the respective total count. All samples showed resistance against metronidazole indicated by a decrease of bacterial growth on agar by approximately 1 log with both concentrations of the antibiotic agent. Similarly, all agar plates supplemented with 3 µg/ml amoxicillin showed bacterial growth with a mean log reduction of 2.4, whereas 50% of the samples did not grow on the plates supplemented with 8 µg/ml of amoxicillin. There was no anaerobic bacterial growth on agar plates supplemented with a combination of amoxicillin and metronidazole even at the lower antibiotic concentrations.

Conclusion:

Susceptibility screening using whole subgingival samples to metronidazole and amoxicillin and to their combination seems to offer a rational diagnostic tool for the selection of adjunctive antibiotic therapy..


0320 (111133)

Reduced susceptibility to amoxicillin of oral streptococci in healthy patients. K. YASUKAWA1, N. NOUACER2, P. AUCOUTURIER3, R. TOLEDO-ARENAS4, J. AZÉRAD5, J. LOUBINOUX2, A. BOUVET2, and H. CHARDIN1, 1GHU Albert Chenevier- Henri Mondor, Créteil, France, 2Hôpital de l'Hôtel Dieu, Paris, France, 3Hôpital Européen Georges Pompidou, Paris, France, 4Hôpital Pitié-Salpétrière, Paris, France, 5University of Paris 7, France

Objectives:

Reduced susceptibility to penicillins is commonly observed in oral streptococci from neutropenic patients, but little is known on the susceptibility to penicillins of the commensal oral flora of the healthy population.

The aims of this study were to evaluate the presence of oral streptococci with reduced susceptibility to amoxicillin in healthy patients undergoing tooth extraction and to follow the evolution of this susceptibility after amoxicillin therapy.

Methods:

Thirty three healthy patients undergoing tooth extraction were randomly assigned in a double blind control fashion to a 7-day amoxicillin treatment or a 3-day amoxicillin+4-day placebo treatment (day 0). The patients treated with any antibiotic during the last 45 days were excluded. The tooth was extracted at day 2 and the post-operative follow-up was done at day 9. Oral flora was collected at day 0 and 9 and cultivated on several selective Columbia blood agar containing 0mg/L, 0,5mg/L, 2mg/L or 16mg/L of amoxicillin. The MICs were determined on streptococci by E-tests. Intermediate (I) and resistant (R) strains were identified according to the antibiogramme commitee of the French Society for Microbiology.

Results:

At day 0, amoxicillin-I and –R streptococci were isolated in 31 and 2 patients respectively. In most cases, the amoxicillin-I strains represented less than 5% of the total streptococcal flora.

At day 9, amoxicillin-I streptococci were isolated from all patients and amoxicillin–R strains from 7 patients. The proportion of the I-strains increased greatly between day 0 and 9, and the amoxicillin-I strains became the dominant flora in 8 patients at day 9. No significant differences were observed among the two groups of patients.

Conclusion:

These results demonstrate that amoxicillin treatment rapidly selects streptococci with reduced susceptibility to amoxicillin in the commensal flora of the oral cavity.


0321 (110430)

Tooth Loss and Osteoporosis: The Osteodent Study. H. DEVLIN1, K. NICOPOLOU-KARAYIANNI2, P. TZOUTZOUKOS2, A. MITSEA2, A. KARAYIANNIS2, K. TSIKLAKIS2, R. JACOBS3, C. LINDH4, P.F. VAN DER STELT5, P. ALLEN1, J. GRAHAM1, K. HORNER1, and J. YUAN1, 1University of Manchester, United Kingdom, 2University of Athens (NKUA), Greece, 3Katholieke Universiteit Leuven, Belgium, 4Malmö University, Malmo, Sweden, 5ACTA - Vrije Universiteit, Amsterdam, Netherlands

Objectives: The aim of the study was to determine whether the osteoporotic status of the patients was predictive of the number of their teeth, independent of their age or smoking status.

Methods: The study recruited perimenopausal and postmenopausal females aged 45-70 years. The BMD at three different sites (total hip T-score, femoral neck T-score and lumbar spine T-score) was measured using DXA. Patients with a standardized T-score value less than -2.5 at any of the three sites were classified as osteoporotic. Those with a score above this were classified as normal/osteopenic. The subjects received a panoramic radiograph and using these films the number of teeth was counted.

Results: The mean numbers of teeth, patients' age, osteoporotic and smoking status were known for 651 subjects, of whom 140 were osteoporotic. The mean number of teeth in the osteoporotic subjects was 20.3 (sd=8.32) and in the normal subjects was 23.57 (sd=6.3). After adjusting for smoking status and age, those with osteoporosis had about 2 fewer teeth than subjects with a normal or osteopenic BMD.

Conclusions: Whether a patient has osteoporosis or not will be predictive of the number of their remaining teeth, irrespective of their age or whether they are smokers.

Acknowledgments: This work was supported by a research and technological development project grant from the European Commission FP5 'Quality of Life and Management of Living Resources' (QLK6-2002-02243).


0322 (109709)

Caries and tooth wear in a French medieval population. R. ESCLASSAN1, M.P. RUAS2, A. SEVIN1, S. LUCAS1, F. ASTIE1, and A. GRIMOUD1, 1Université Toulouse 3, France, 2CNRS UMR 5059 CBAE, Montpellier, France

Objectives: The aim of this study was to determine the frequency and distribution of caries and tooth wear on skeletal remains of a French medieval sample (12th-14th century A.D.) from south of France, in relation with the diet of this population.

Methods: The sample consisted of the skeletal remains of 58 adult individuals, with determined sex (29 men and 29 women), unearthed during archaeological excavations of the Vilarnau mediaeval cemetery. Each of the selected individuals had paired maxilla and mandible and at least six teeth on each dental arch. Caries were diagnosed macroscopically and numbers of caries and their locations were noted. Wear was graded according to the Brabant index with two parameters : quantity and direction of wear. Frequencies were calculated and the statistical significance of the recorded values was tested. A P value less than 0.05 was considered as statistically significant.

Results: The frequency of antemortem tooth loss for the sample was 8.67% and the frequency of caries was 17.46 %. The frequencies of carious lesions in men and women's dentition were 21.88% and 14.04% (P>0.05). The most frequent caries were approximal. All 58 individuals and all groups of teeth were concerned by attrition, mostly with presence of dentin clusters. There was no significant difference between men and women for attrition.

Conclusions: These findings are similar to those of studies of other European samples having the same socio-economic status. The relatively low frequency of caries can be explained by a soft cariogenic diet. Considering our sample, tooth wear was intense and generalised. The importance of tooth wear would indicate a regular consumption of abrasive food: meat or cereals with chaff or particles.


0323 (110409)

Risk Factors Associated with Tooth Wear. M.A. HARDING1, H.P. WHELTON1, S. SHIRODARIA2, D.M. O'MULLANE1, and M. CRONIN1, 1University College Cork, Ireland, 2GlaxoSmithKline Consumer Health Care, Weybridge, Surrey, United Kingdom

Objectives: Investigate factors associated with the number of surfaces affected by toothwear in the permanent dentition of 12-year-old school-children. Data were collected using the Exact Tooth Wear Index (ETWI), a modification of the Smith and Knight ToothWear Index (TWI). Data on toothwear in the four upper primary incisors of the same children was collected at age 5 using a modification of the TWI.

Methods: Data on correlates were collected via questionnaire from the parents at age 5 and self-completed at 12-years. A generalised linear regression model was used.

Results: The mean number of total surfaces affected by loss of enamel in both genders was 5.56 (±4.27); in males 6.66 (±4.17) and females 4.56 (±4.15). Males (50%) had a significantly higher number of enamel surfaces affected (p=0.0192). The mean number of total surfaces affected by dentine loss was 0.93 (±1.56); in males 1.21 (±1.58) and females 0.64 (±1.49), (p=0.0066).

Children whose parents reported that they had frequent stomach upsets (36%) had more surfaces affected by both enamel and dentine loss (p=0.0239) and (p=0.0175) respectively. Children whose parents reported that they brushed after breakfast (56%) had less enamel and dentine loss (p=0.0207) and (p=0.0270) respectively.

First permanent molars were analysed separately; the first permanent teeth to erupt. Males had more molar surfaces affected by enamel loss (p=0.0282). Families with a medical card (low socio-economic status)(22%) had more enamel (p=0.0193) and dentine loss (p=0.0267) on first permanent molars .

Children who had tooth wear with dentine loss in their primary teeth(21%) had more toothwear with dentine loss in their first permanent molar teeth (p=0.0186).

Conclusion: Males and children with frequent stomach upsets (age 5) had more surfaces affected by toothwear, while brushing after breakfast was associated with less. More molar surfaces were affected in males, low SES and dentinal toothwear at 5-years.

Facilitated byGlaxoSmithKlineConsumerHealthcare


0324 (111629)

Systematic Review of Tooth Wear Prevalence Studies in Youngsters. C. KREULEN1, A. VAN 'T SPIJKER1, D. BARTLETT2, J.M. RODRIGUEZ2, and N.H.J. CREUGERS1, 1Radboud University Nijmegen Medical Centre, Netherlands, 2King's College London, United Kingdom

Objective: To systematically review studies on tooth wear prevalence in children and adolescents.

Material and Method: Dental literature was searched using PubMed (1980 to 9/2007) with combinations of the keywords “tooth”, “wear”, “attrition”, “erosion”, “abrasion” and ”prevalence”. Eligible references were independently assessed by two investigators and those original articles, in English and for subjects under 19 years old, were selected. The Cochrane database and articles' reference lists were cross-checked for additional studies. Five investigators jointly scrutinized the full texts of the eventually selected articles to retrieve research details and additionally exclude studies if not reporting prevalence data.

Results: The initial electronic search identified 1953 references and from these 43 references were selected by the two observers (inter-observer Kappa=0.78). Cross-checking reference lists added a further two studies. Full text assessment revealed that some articles did not have data on prevalence. Eleven articles repeated data from 4 studies. Of the remaining 25 studies, 13 were from the UK and remainder from other countries. Ten studies used random clusters, 12 used (multiple) convenience samples and 3 were case-control studies. The sample sizes ranged from 42 to 10,381 subjects (23,697 subjects in total). Eight studies evaluated deciduous dentitions (age 3–5 yrs), another eight included mixed dentitions (age 6–11 yrs) and 13 were on permanent dentitions (age 12–15 yrs). All studies assessed tooth wear clinically, but indices were not always transferable. Dichotomizing wear (with/without dentine exposure) indicated that 8 of 15 cohorts (ages 3-8 yrs) showed ‘dentine involvement' between 10-25% of subjects. Five of 13 cohorts (10-17 yrs) showed ‘dentine involvement' between 30-63%, while the remaining 8 reported virtually no dentine involved.

Conclusion: Designs of the studies are not homogeneous and different wear indices hindered data analysis. Dentine exposure in youngsters is common, but reported prevalence varied considerably (0-82% at subject level).


0325 (109998)

Calcifications of the Pulp Chamber: Prevalence and Implicated Factors. S. SENER1, F. KONT COBANKARA2, and F. AKGUNLU2, 1Selcuk Universitesi, Konya, Turkey, 2Selcuk University, Konya, Turkey

Objectives: To describe the prevalence of pulp chamber calcifications in a sample of Turkish dental patients and to report associations between presence of pulp chamber calcifications and dental status, gender, age, and cardiovascular diseases (CVDs).

Methods: Data were collected through radiographic examination of periapical and bitewing radiographs of 15.326 teeth from 536 dental patients, comprising 270 males and 266 females aged between 13-65 years. Definite radiopaque focuses inside the radiolucent pulp chamber were defined as pulp chamber calcifications. When the pulp chamber was completely radiolucent, that tooth was scored as tooth without pulp chamber calcification. The dental status was scored as intact, carious, restored, or restored + carious.

Results: Pulp chamber calcifications were identified in 204 (38%) patients examined. 747 (4.8%) of the 15,326 teeth had pulp chamber calcifications. Gender and dental status were found to be correlated with the presence of pulp chamber calcifications.

Conclusions: The high prevalence of pulp chamber calcifications in carious, restored and restored+carious teeth support the view that the occurrence of pulp chamber calcifications can be a response to long-standing irritants. However, to report any associations between occurrence of pulp chamber calcifications and different dental or clinical status, further studies are still needed.


0326 (109821)

Children's oral health needs after cancer therapy for solid tumours. A. HUTTON1, M. BRADWELL1, I.L. CHAPPLE2, and M. ENGLISH1, 1Birmingham Children's Hospital, United Kingdom, 2University of Birmingham, United Kingdom

Objectives:

The oral health of an individual is central to their general health, level of nutrition and quality of life. This study investigated: if the effects of cancer therapy resulted in reduced levels of oral health during and after treatment; if patients had knowledge of the effects of cancer therapy on the oral cavity; and if oral health care needs differed within tumour type and treatment regime.

Methods:

The study had 2 parts. Part A: a dental examination recording caries prevalence, enamel opacities, microdontia and gingivitis. Part B: a questionnaire completed by the parent/guardian assessing reported experiences of oral health care. 120 patients aged 0-17 years, attending the solid tumour follow up clinic at Birmingham Children's Hospital from 01/07/06- 07/02/07 were investigated and analysed, with stratification according to tumour diagnosis and medical treatment regime. The results were compared with UK national data from the 2003 Child Dental Health Survey. Funding was awarded by Birmingham Children's Hospital Charities. Ethics approval number 05/Q2701/93.

Results:

The results were largely descriptive due to the nature of the data collected. The neuroblastoma diagnostic group and the high dose chemotherapy with stem cell rescue (HDCSCR) therapy group had an increased level of decay in the primary teeth and greater oral health needs compared to the remaining study group and general population. Chi squared test showed a statistically significant relationship between the age at receipt of chemotherapy (under 3.5) and the presence of microdont teeth (p<0.05).

Conclusion:

Oral health input is important for all patients suffering from a solid tumour, particularly those with a neuroblastoma or who are receiving HDCSCR. The possible adverse sequelae on the oral cavity are significant and arise during and after cancer therapy. Children receiving chemotherapy under the age of 3.5 years should be warned of possible microdontia affecting the permanent dentition.


0327 (111419)

Oral Health of Sudanese Children in School Sectors; a Comparison. N. NURELHUDA, and T.A. TROVIK, University of Bergen, Norway

Objective: The objective of this cross-sectional epidemiological survey was to test the hypothesis that children in private schools in Sudan have better oral health (DMFT, GI, PI) and attitude towards dental caries than children from public schools.

Methods: This sample was representative of 12-year-old school children in Khartoum state. Stratified sampling, by locality and gender, yielded a total sample of 1116 students split equally between private and public schools. The random selection that followed was weighted according to schools and students in each locality. Data was collected through interviews and clinical examination by a single examiner. DMFT was measured according to WHO criteria. Gingival index (GI) of Loe&Silness and Plaque index (PI) of Silness&Loe were used.

Results: Only 26.9% had caries experience (44% in public and 56% in private). DMFT among all 12-yr-olds was 0.5. DMFT among children with caries experience from private and public schools, respectively, was 1.86 (sd 1.5) and 1.71 (sd 1.2). The children from public schools had a higher risk for high GI (OR1.4 95%CI 1.1 – 1.9) and high PI (OR1.9 95%CI 1.4 – 4.6. In bivariate analysis, private school children were twice as likely to notice friends with poor oral health (OR1.96 95%CI 1.54 – 2.52). They visited dentist more (OR3.5 95%CI 2.7 – 4.5) and were more likely to be satisfied with their oral health (OR1.6CI 1.25 – 2.10).

Conclusions: Although children from private schools have better chances of noticing decay, better access to professional dental care and were more satisfied with their oral health, they had a higher caries experience. Public school children, with their comparatively poorer oral hygiene, did not experience caries as often. The dietary habits or salivary microbiology picture of these children, which shall be discussed in the forthcoming study, may explain some of the observed difference.


0328 (111822)

Clinical Indicators for Caries among Individuals with Alzheimer's Disease. B.S. ELLEFSEN1, D. MORSE2, and P. HOLM-PEDERSEN1, 1University of Copenhagen, Copenhagen N, Denmark, 2New York University, College of Dentistry, USA

OBJECTIVE: To describe the prevalence of coronal and root caries in a population of elderly with AD and to examine whether differences in caries prevalence is influenced by age, sex, social relations, social position, chronic diseases, functional ability, medication, self-rated health and oral health.

MATERIAL AND METHODS: Patients with newly diagnosed AD were recruited from two memory clinics. Data was obtained from hospital records, interviews and an oral clinical examination.

RESULTS: In total 61 dentate persons with AD participated in the study. Mean age was 82.8 years, mean MMSE-score 20.4. Sixty-four percent were females and 87% of the participants had children. The mean number of decayed total (coronal + root), coronal and root surfaces (DS) for the participants was 7.8±8.8, 2.9±3.69 and 4.9±6.1 DS, respectively. Subjects with lower IADL-score had significantly higher number of mean total (8.8±9.8 vs. 4.5±3.1), coronal (3.3±4.0 vs. 1.5±0.5) and root DS (5.5±6.8 vs. 2.9±0.6), p<0.05. Participants with children had significantly higher total (8.5±9.2 vs. 2.9±3.6) and coronal DS (3.2±3.8 vs. 0.5±0.8), p<0.005 and those being afraid of dental treatment had significantly more coronal DS (5.3±4.8 vs. 2.5±3.4), p=0.05. For a subgroup (n=43) who had a caregiver present, results showed that those persons with Disability Assessment for Dementia (DAD) Index scores lower than 50% had significantly more root caries (p<0.05). Participants with ≥2 decayed coronal surfaces had significantly more somatic diagnoses (p<0.01). In contrast, participants that were taking less than 5 medications, those with self-rated good health and those with self-rated no dental problems, had significantly more coronal caries (p<0.05).

CONCLUSION: Patients with newly diagnosed Alzheimer's disease already had a high level of caries when they were referred to the memory clinics. The high caries prevalence was related to ADL and IADL impairment, having children and number of somatic diagnoses.


0329 (111552)

Cytotoxicity of Dentin Bonding Agents on Human Fibroblasts. N.Ç. BERIAT, A.A. ERTAN, C. ŞAHIN, and S. ODABAS, Hacettepe University, Ankara, Turkey

Objective: The aim of this study is to compare the cytotoxic effects of dentine bonding agents polymerized with two different curing units.at different time intervals on human fibroblast cells.

Methods: Disc shaped samples were prepared according to manufacturers' instructions with either conventional quartz tungsten halogen or light-emitting diode (LED) light curing units. After curing, cytotoxicities of the Adper Prompt L-Pop and G Bond were investigated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide MTT assay using primary human fibroblast cells. Human fibroblast cell cultures (1x105 cells/ml) were incubated with the samples in 96 well culture plates for evaluation after 1th, 2nd, 3rd, 7th days. At the end of each period, cells were counted and examined under a light microscope, and MTT assay was performed. The degree of cytotoxicty for each sample was determined according to the reference value represented by the cells with a control group (culture without sample).

Results: There was significant three factor interaction occurred among LCUs, dentin bonding agents and time factors (p<0.005). In general, the test materials cured with the LED light curing unit demonstrated higher cell survival rates when compared with those cured with halogen light curing unit.

Conclusion: This study shows that polymerization of dentin bonding agents with a light emitting diode light curing unit positively influences the human fibroblast cell viability.


0330 (110307)

Posterior Zirconia Substructures With Overpressed Veneering Porcelain: 3-year Clinical Results. F. BEUER1, D. EDELHOFF1, W. GERNET1, and J.A. SORENSEN2, 1LMU Munich, Germany, 2Pacific Dental Institute, Portland, OR, USA

Objectives: This clinical study evaluated posterior three-unit fixed dental prostheses (FDP) made of zirconia frameworks veneered with a new pressable glass-ceramic instead of conventional powdered veneering porcelain.

Methods: Nineteen patients received 21 FDP replacing either the second premolar, first or second molar. Zirconia substructures were fabricated by a CAM only system (Cercon, DeguDent) and overpressed with glass-ceramic (Cercon Ceram express). The FDP were cemented with glass ionomer. Baseline evaluation was performed 2 weeks after cementation with recall examinations performed at 12, 24 and 36 months by calibrated investigators. The mean service time of the FDP was 40 months.

Results: At the 12 and 24 months follow-ups no failures were observed. At 30 months one maxillary FDP exhibited zirconia framework fracture at a thinned occlusal area of the retainer requiring replacement. No chipping of the overpressed ceramic was observed. Loss of retention at a distal retainer led to the removal of one FDP after 38 months. The Kaplan-Meier survival probability was 90.5 % after 40 months for all types of failures and 95.2 % concerning framework fractures. No influence on gingival parameters from the restorations was observed compared to control teeth.

Conclusion: The overpressing technique appears to be superior to the powder build-up technique in terms of ceramic chipping. However, one framework fracture was observed in the study.


0331 (110391)

2-Year Clinical Effectiveness of a Self-Adhesive Luting Agent. M. PEUMANS, J. DE MUNCK, K. VAN LANDUYT, A. POITEVIN, P. LAMBRECHTS, and B. VAN MEERBEEK, Leuven BIOMAT Research Cluster, Catholic University of Leuven, Belgium

Objectives: Among the materials used for luting indirect restorations, a growing interest has been directed towards the use of self-adhesive resin cements. The aim of this prospective randomized controlled clinical trial was to evaluate the 2-year clinical performance of the self-adhesive resin cement RelyX Unicem (3M ESPE, Seefeld, Germany) used for luting of ceramic inlays. In addition, the influence of selective acid-etching enamel prior to luting on the clinical performance of the restorations was assessed. The hypothesis tested was that there was no significant difference in clinical behaviour between restorations with (Etch) or without prior enamel acid-etching (Non-etch). Methods: Sixty-two IPS Empress 2 inlays/onlays were placed in 31 patients by two experienced clinicians. The restorations were luted with RelyX Unicem with (=experimental group; Etch) or without (=control group; Non-etch) prior enamel etching with 35% phosphoric acid. At baseline, 6 months, 1 year and 2 years after placement, the restorations were assessed by two calibrated investigators using modified USPHS criteria. Results: The recall rate at 24 months was 96.6%. Two restorations were clinically unacceptable due to loss of retention, leading to a survival rate of 96.6% (Kaplan-Meier). No significant difference was noted between the experimental group and the control group regarding marginal integrity, inlay integrity, tooth integrity, complications and sensitivity (McNemar, p>0.05). An obvious deterioration in marginal adaptation was observed after 24 months as only 21.7% (Etch=23.4%; Non-etch=20%) of the restorations exhibited an excellent marginal adaptation compared to 70.7% (Etch=75%; Non-etch=66.7%) at baseline. In 74.9% of the restorations, small (still clinically acceptable) marginal deficiencies were observed (Etch=76.6%; Non-etch=73.2%). Conclusion: The self-adhesive resin cement RelyX Unicem showed an acceptable clinical behaviour after two years of clinical service. Selective enamel etching prior to luting had no significant influence on the clinical performance of the restorations after 24 months.


0332 (110850)

Reasons for restorative interventions with direct restorations. N.J.M. OPDAM1, B.A.C. LOOMANS2, J.D. SCHOLTANUS3, and E.M. BRONKHORST2, 1Radboud University Nijmegen Medical Center, Netherlands, 2Radboud University Nijmegen Medical Centre, Netherlands, 3University Medical Centre Groningen, Netherlands

Objectives: To investigate the reasons for restorative interventions with direct restorations in a general practice setting.

Methods: Three general practitioners (also part-time university workers) participated in the study and were calibrated on determining the reasons for restorative intervention. For all direct restorations placed between November 2007 and March 2008 they recorded the reasons for intervention. Caries risk of individual patients was assessed by the operator as ‘high-caries risk' or ‘low-caries risk'. Data were statistically analyzed using Chi-square tests (p<0.05).

Results: 914 direct restorations were placed in 468 patients (age 7–82y) , The main reasons for restorative intervention were primary caries (25%), secondary caries (19%), esthetic reasons (17%), fracture of the tooth (7%) and fracture of the restoration (6%). 32% of the patients were labeled as ‘high risk'(n=150). In the high risk group, 75% of the restorations were placed due to primary (43%) or secondary (32%) caries. Also a low incidence of interventions due to fracture of the tooth (4%), fracture of the restoration (2%) and esthetic reasons (3%) was found. In the patient group with a low caries risk, only 26% of the restorations were placed due to caries (15% primary caries, 11% secondary caries). Other important reasons for restorative intervention in this group were esthetic reasons (24%), fracture of the tooth (8%) and fracture of the restoration (9%).

The Chi-square Test revealed a high significance (p<0.0001) of the differences between the ‘low-risk' and ‘high-risk' group for all reasons for failure. After excluding caries (primary and secondary) also the other reasons for failure were found to be statistically significantly different between the two patient groups (p<0.0001).

Conclusion: Although the most common reason for restorative intervention with a direct restoration is caries, large differences exist between reasons for intervention between patients in the ‘low-risk' and ‘high-risk' group.


0333 (111465)

Fracture Resistance of Teeth Endodontically Filled with Different Systems. J. TANALP, M. KARAPINAR-KAZANDAG, H. SUNAY, and G. BAYIRLI, Yeditepe University, Istanbul, Turkey

FRACTURE RESISTANCE OF TEETH ENDODONTICALLY FILLED WITH DIFFERENT SYSTEMS

 

Jale Tanalp, Meric Karapinar Kazandag,  Hakki Sunay, Gunduz Bayirli

 

OBJECTIVES:

 

To assess the fracture resistance of endodontically treated single rooted teeth filled using

different techniques.

MATERIALS AND METHODS:

 

100 single rooted teeth were used . 80 teeth were divided into four groups.  The root canals were  shaped using the Endo-Sequence  ( Brasseler, Savannah-USA).

The teeth were sectioned from the CEJ producing 12 mm.long samples.

The experimental groups were filled as follows:

  1. AH Plus ( Densply, Konstanz-Germany)  + Gutta-percha ( Lateral compaction)
  2. Resilon ( Pentron Clinical Wallingford USA) + Epiphany ( Lateral compaction)
  3. Activ GP( Brasseler, Savannah, USA)  + Gutta-percha ( Single cone)
  4. Activ GP ( Brasseler, Savannah, USA) + Gutta-percha ( Lateral compaction)

The control groups having 10 teeth in each were as follows:

(+) Control: No shaping or filling .

(-)  Control: Shaping done using Endo Sequence system; however no filling performed.

The teeth were stored under 37° C for two weeks .

The samples were embedded in acrylic resin blocks and mounted on a universal testing

machine ( Instron,USA) . The teeth were subjected to a compressive force increasing at a constant speed of 1 mm/ min. until fracture and  values recorded.

     

 

 

 

 RESULTS:

The distribution of the mean fracture values for each group is as follows:

AHPLUS+ Gutta-percha (lateral compaction)

521,15a

RESILON + Epiphany sealer

( lateral compaction)

416,85a,b

ActiV GP + single cone

500,50a,b

ActiV GP+ lateral compaction

410,45b

Positive  control

420,10ab

Negative  control

284,80

*Values with the same supercript are not statistically different.

 The fracture values of the experimental teeth were significantly higher than  the negative control group ( p< 0.05). Teeth filled with AH Plus had higher fracture resistance values compared to ActiV GP  filled with the lateral compaction technique ( p< 0.05).

CONCLUSIONS:

 It can be concluded that systems that aim to obtain a monoblock system are not superior to the conventional AH Plus + Gutta-percha technique in terms of fracture resistance. Further studies may focus on the different aspects of these techniques.


0334 (111501)

6-Month Clinical Performance of a Brand New Self-Etch Adhesive. E. YAZICI, A. KIREMITCI, and S. GURGAN, Hacettepe University, School of Dentistry, Ankara, Turkey

Objectives: The aim of this practice-based, randomized, controlled pilot study was to evaluate the 6-month clinical performance of a brand new self-etch adhesive and an etch-rinse adhesive in combination with a nanocomposite for the restoration of Class V non-carious cervical lesions.

Methods: Eighteen patients with at least 2 but not more than 6 equivalent non-carious cervical lesions were enrolled in this study. A total of 80 non-carious cervical lesions were randomly divided into two groups according to adhesive systems used (n=40). After the application of a brand new self-etch adhesive (Adper SE Plus/3M ESPE) in Group 1, and an etch-rinse adhesive (Single Bond 2/3M ESPE) as control in Group 2, a nanocomposite restorative material (Filtek Supreme XT/3M ESPE) was placed according to the manufacturer's instructions by one operator. Two other independent examiners evaluated the restorations at baseline, after 1 week and 6 months according to the modified USPHS criteria. The differences between two groups were statistically evaluated by McNemar chi-square test (p=0,05).

Results: At 6 month recall, 80 restorations were reviewed in 18 patients. Retention rates, anatomic form, recurrent caries, wear, surface texture, post-operative sensitivity were scored as Alpha for all restorations in the two groups. Five restorations in Group 1 were scored as Bravo and all of the restorations in Group 2 were scored as Alpha for color match. No significant difference was observed between Group 1 and 2 in terms of color match. For marginal adaptation, all restorations in Group 2 were scored as Alpha, whereas 7 restorations in Group 1 were scored as Bravo. The difference in terms of marginal adaptation was statistically significant (p<0,05).

Conclusions: At the end of 6 months, except the marginal adaptation, the clinical performance of the new self-etch adhesive was as good as the etch–rinse adhesive.


0335 (111643)

The Evaluation of Stres Patterns in Laminate Veneers:FEM study. O. USTUN, and N. OZTURK, Selcuk Universitesi, Konya, Turkey

Objectives: The aim of this study was to evaluate stress distribution in different designed ceramic laminate veneers under functional loads by using finite element stress analysis method.

Methods:A 3-D FEM model of maxillary central incisor was presented. Porcelain veneers with 3 different preparation designs (incisal overlap, incisal bevel and featheredge) were modeled by SolidWorks. A cement layer of 100 ìm of luting composite resin was assumed, and a thickness of 500 ìm of porcelain veneers were used. All models were loaded at 0, 60 and 120 degrees to the long axis of the tooth for simulate functional loading. 200 N total forces were applied from the incisal edge of the models. Using the CosmosWorks structural analysis program performed the analysis.

Results:The maximum Von Misses equivalent stress values were observed at buccal cervical margins of tooth preparations (53.30 MPa) in the overlap design of restoration for 120° load angulation. When the featheredge and insizal bevel preparation design was simulated, maximum stresses were concentrated on force application areas for both 0°, 60° and 120° load angulations.

Conclusions:The most appropriate type of the restoration according to stress distribution was incisal bevel preparation. An increase in stresses appeared for all situations with a more transverse angulation of load.


0336 (111701)

Rate-dependence of Resin-Composite Stickiness During Simulated Clinical Placement. D.C. WATTS1, B. GLEAVE1, K. ERTL2, and A.O. ARIGBEDE3, 1University of Manchester, United Kingdom, 2Medical University of Vienna, Austria, 3University College Hospital, Ibadan, Nigeria

Objectives:

The aim was to design an improved instrument for characterization of the stickiness of un-set dental composites, at different speeds and temperatures, and to determine the characteristic behaviour.

Methods:

This instrument refines the concept previously described (Dent Mater 19: 182-7, 2003). Unset composite pastes were leveled and temperature-equilibrated to +/- 0.5 oC, range 10-50 oC, within a 3 mm deep cylindrical well. The normal probe was a flat-ended stainless-steel rod. This was moved in a vertical-axial direction via a linear-motor. The rod tip was positioned in surface-contact with the composite, to permit tack-adhesion. The probe was then raised axially within selected speed-range 0.1-5.0 mm/s. Experiments were repeated at 6 speeds, per material. With probe elevation, composite-paste was raised until it detached from the rod. Then composite was light-cured rapidly by surrounding LEDs, the probe lowered to re-establish contact with the composite ‘mountain-peak' and the height determined. Graphs of peak-height versus probe-speed were generated for representative resin-composites at 23 and 37 oC.

Results:

Peak-height was taken as a quantitative measure of ‘stickiness' (S, mm), normally 1 – 6 mm and exponentially-decreasing with probe-speed; characteristics of a viscoelastic medium. Regression plots were obtained between S and log (speed), with r2 typically 0.97 or better, and gradients typically 1.2. Magnitudes of S, for a given material, were greater at 37 oC. As expected, ‘packable' and ‘hybrid' composites exhibited lower stickiness (S) curves than ‘flowable' composites. Differentiation between materials in the same generic category was feasible and reproducible.

Conclusions:

A method has been developed for quantitative characterization of composite-paste stickiness to the equivalent of stainless-steel instruments. This rheological property is both temperature and rate dependent. This enables experimental formulations to be evaluated for this critically-important handling behaviour. The method can be extended to evaluate stickiness to other surfaces such as human dentine.


0337 (111545)

Effects of Laser, Acid Etching, Air Abrasion on Mineral Content. M.A. MALKOC1, S.T. TASDEMIR1, N. OZTURK1, B. OZTURK2, and G. BERK3, 1Selcuk Universitesi, Konya, Turkey, 2Selcuk University Faculty of Dentistry, Konya, Turkey, 3Denta Form, Ankara, Turkey

Objectives:

To evaluate the mineral content of dentin prepared by using at four different power settings erbium, chromium: yttrium scandium, gallium garnet (Er,Cr:YSGG) laser, acid etching , and air abrasion methods.

Methods:

Twenty -four third molar teeth were selected for this study. The teeth were randomly distributed in six experimental groups, each containing 4 teeth. The enamel of the teeth was removed with a conventional bur under water cooling to expose the dentin surface. The teeth were mounted in a slow-speed, diamond-saw, sectioning machine. Occlusal thirds of the crowns were cut with a slow-speed, diamond-saw, sectioning machine under water cooling.The six groups were as follows: Group A: Dentin etched with 35% buffered phosphoric acid for 30 seconds, B: Dentin abraded 60psi with 50 µm Al-oxide for one seconds , C: Dentin irradiated with the Er,Cr:YSGG laser at 1.50 W ,D: Dentin irradiated with the Er,Cr:YSGG laser at 2.25 W , E: Dentin irradiated with the Er,Cr:YSGG laser at 3.00 W , F : Dentin irradiated with the Er,Cr:YSGG laser at 3.50 W .

The Er,Cr:YSGG laser used for the study had a pulse duration of 140 ìs, a pulse repetition rate of 20 Hz and a power output range of 1.5 W to 3.5 W. The levels of seven elements: magnesium (Mg), phosphorus (P), calcium (Ca), potassium (K), and sodium (Na), iron (Fe),sulphur (S) in each slab were measured by inductively coupled plasma–atomic emission spectrometry (ICP-AES). Data were analyzed by two way analysis of variance and Tukey HSD tests.

Results:

There were not significant differences among the groups (p>.05) Mean percentage weight of Ca (14.91± 2.35) and P (12.81±1.40) elements were higher than the others.

Conclusion:

Mean percentage weights of Ca, Mg, K, Na, P, Fe, and S of the groups were not affected from the surface treatments.


0338 (113008)

Effects of Enamel Treatments on Fissure Sealant Shear Bond Strength. J. SALEM, Dental School, University of Damascus, Syria

Objectives: to compare sealant bond strength on human enamel etched using one of the following techniques: standard acid etching, air abrasion with and without a subsequent acid etching treatment and laser irradiation with and without a subsequent acid etching treatment.

Methods: 35 extracted sound third molars were divided into 5 groups: group 1; etched with 35% phosphoric acid for 15 sec, group 2; abraded with 27.5 µm aluminum oxide 3.2 bar for 10 sec, group 3; abraded with the abovementioned aluminum oxide followed by the aforementioned acid etching treatment, group 4; irradiated using Er, Cr:YSGG laser 2.78µm (300 mJ, 20HZ for 15 sec) and group 5; irradiated using the abovementioned laser followed by the aforementioned acid etching treatment. The PrimaDry was applied in all the five groups. In addition, a teflon matrix of 3mm in diameter and 3mm in height was placed and filled with Ultraseal XT Plus (Ultradent) and lightcured to each tooth. A shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5mm/min. Bond strength was recorded in KG and converted into Mpa. Data were analyzed using ANOVA and Bonferroni tests at 0.05 significance level.

Results: No statistically significant difference in shear bond strength was observed between group 1 (26.79 ± 6.16 Mpa), group 3 (27.18 ± 4.79 Mpa) and group 5 (32.27 ± 8.04 Mpa) (P=1.000). These groups showed a statistically significantly higher shear bond strength than Group 2 (7.39 ± 8.97 Mpa) (P>0.001) and group 4 (4.39 ± 5.83 Mpa) (P>0.001).

Conclusions: Air abrasion and Er, Cr:YSGG laser do not substitute acid etching. The association between these techniques and Acid etching is necessary to obtain adequate adhesion to the enamel.


0339 (111927)

Surface Modification of Dental Hard Tissues Using Pulsed UV Lasers. R. VILAR, S. EUGÉNIO, V. OLIVEIRA, and M. SIVAKUMAR, Instituto Superior Tecnico, Lisboa, Portugal

Objectives:

Pulsed infrared radiation lasers with nanosecond pulse duration can effectively remove dental hard tissues but they lead to non-negligible thermal and thermomechanical side effects. Because of the higher energy of UV photons, pulsed UV radiation tends to minimize these effects in many materials. The objective of the present work was to study the influence of UV laser treatment on dentin and enamel, and to assess the possibility of using UV lasers as an alternative to infrared lasers in dental treatments.

Methods:

Dentin and enamel specimens from the crown of caries-free human molars were subjected to laser treatment with a KrF excimer laser. The surface topography, structure and chemical constitution of the treated surfaces were studied using optical profilometry, scanning electron microscopy, X-ray diffraction, FTIR, and X-ray photoelectron spectroscopy.

Results:

For enamel, material is preferentially removed at the prisms sheaths leading to the formation of surface pits of a few micrometers, independently of the fluence used. For dentin, a cone-like topography develops provided that tubules are parallel to the laser beam direction and the radiation fluence does not exceed 1-2 J/cm². For higher fluences, the treated surfaces are flat and covered with a layer of re-solidified material that seals the dentinal tubules. Despite these changes of surface morphology, the thermal effects of the laser treatment are negligible. In both dentin and enamel, the only modification of the X-ray diffractograms due to the laser treatment is a slight shifting of the peaks due to a loss of structural water of hydroxyapatite. X-ray photoelectron spectroscopy and FTIR revealed a loss of organic matter from the treated surfaces, but no significant changes in the mineral phase. The ablation rates and the ablation threshold were measured.

Conclusions:

Pulsed UV laser can remove dentin and enamel with negligible deterioration of the underlying material.


0340 (110743)

Influence of the Smear Layer on Caesium Diffusion within Dentine. M. KAWABATA1, G.D. REES2, M.P. HECTOR1, G.R. DAVIS1, C.R. PARKINSON2, and P. ANDERSON1, 1Barts and the London School of Medicine and Dentistry, United Kingdom, 2GlaxoSmithKline, Weybridge, United Kingdom

Objectives: Hand and mechanical caries excavation creates a smear layer on the dentine surface that occludes dentinal tubules. In vitro studies have shown a clear increase in dentine permeability after smear layer removal. The aim of the present study was to measure diffusive transport of caesium ions using X-ray microtomography (XMT) before and after removal of the smear layer.

Methods: Five 2.0mm thick dentine discs were cut from human third molars parallel to the occlusal surface and perfused with Earle's solution. An artificial smear layer was created using silicon carbide abrasive paper whose presence was confirmed by SEM. The dentine specimens were masked using polyethylene tape exposing the top surface of the dentine only prior to mounting in plastic syringes filled with Earle's solution. Discs were subsequently immersed in 0.50M caesium acetate solution for 3.5h to identify the baseline diffusion profile for the disc. Caesium acetate was then purged from the discs by successive immersion in Earle's solution for a period of 8h. The smear layer was then removed using 0.5M citric acid for 2min. The treated discs were immersed in caesium acetate solution for 3.5h. XMT scans (15µm resolution) were taken to compare changes in X-ray attenuation as a function of caesium acetate ingress into dentine before and after smear layer removal.

Results: XMT images showed a progressive ingress of caesium acetate via the dentinal tubules as a function of time. The rate of ingress was only marginally increased following smear layer removal indicating that the smear layer is surprisingly permeable and does not provide a significant diffusion barrier to the caesium cations monitored in this study.

Conclusion: The presence of an artificially created smear layer does not significantly inhibit the diffusion of caesium acetate into dentine.

Supported via a GSK funded CASE studentship and Institute of Dentistry, QMUL.


0341 (111425)

Inhibition of Acidic Enamel Disolution by Statherin Fragment STN21. P.W. GROSVENOR, G.R. DAVIS, M.P. HECTOR, P. ANDERSON, F.S.L. WONG, and J.A. DAVIES, Barts and The London School of Medicine and Dentistry, United Kingdom

Objectives:To quantify the effect of STN21 treatment on sound enamel loss over large surface areas of intact human molars using X-ray microtomography (XMT).

Methods:STN21 (21 amino acid N-terminal of the salivary protein statherin) was synthesized using solid-phase Fmoc chemistry and HPLC purified. Demineralizing buffer [0.1M acetate, 1mM CaCl2, 0.6mM K2HPO4 at pH4.5](DB) was changed daily. Three caries-free 3rd molars were microtomed in half and nail varnished twice each, exposing 2 windows of enamel (4x5 mm2) on the buccal and lingual crown sides for both halves of each tooth, which were then epoxy resined onto kinamatic mounts. Demineralization was carried out with stirring in 100ml DB for 96hr with 4min exposure to STN21 (0.18mM in phosphate buffer(PB) pH7.4) or PB control every 12hrs with xray scanning every 24hrs. XMT system: x-ray generator (Ultrafocus HMX 160, X-Tek Systems, 5µm source, tungsten target, 160 KVmax), CCD camera (Applied Technologies, UK), 600 projections were collected over 360 degrees, final reconstructed images comprised (480x480x238 cubic voxels of sidelenght 29.55µm) representing 3D distribution of linear attenuation coefficient (LAC) at nominal monochromatic beam energy of 40KeV. For image analysis and voxel data manipulation VGStudio-max1.6 (VGstudio, Germany) and IDLv6.3 (Research Systems, USA) were used respectively.

Results: Untreated sound enamel LAC had a range of 2.0-2.6 cm-1, voxel extraction from images used this value for calculations. Rate of mineral loss for both treatments were broadly linear over time, average STN21 rate of 0.193 mg cm-1 h-1 compared to control average rate of 0.362 mg cm-1 h-1. Average depth loss of sound enamel for STN21 was 0.0582mm and control was 0.1084mm, STN21 treatment reduced depth loss by 46% (p<0.001, Mann-Whitney U Test) compared to control.

Conclusion: These results show STN21 can significantly decrease sound mineral depth loss under acidic demineralizing conditions.


0342 (111599)

Erosion and the Role of Fluoride: A Nanomechanical Study. C.R. PARKINSON, GlaxoSmithKline Consumer Healthcare Research and Development, Surrey, United Kingdom

Objective: Nanoindentation and atomic force microscopy have been employed to characterise the nanomechanical properties and surface topographic structure of enamel. The role of the saliva and fluoride in conferring protection from acid erosion on the aforementioned properties has been investigated. Methods: Enamel specimens were cut from buccal sides of bovine incisors and polished using standard procedures. A Hysiton Ubi 1 Nanoindentor in combination with a Nanoscope IV AFM, operating under standard conditions and in accordance with published operating procedures, was employed to explore the mechanical properties and topography of enamel as a function of treatment and subsequent acid challenge exposure time. Treatments consisted of (i) no treatment, (ii) human saliva (2 minute maturation time with dH2O rinse) or (iii) 2 minute exposure to 1000 ppm fluoride (sodium fluoride) followed by saliva as per (ii). Following pre-treatment, the surfaces were exposed to 3x10-2M citric acid, pH3.8 for exposure times of 5 and 10 minutes without agitation at room temperature. Results: The nanohardness values of enamel as a function of pre-treatment and acid challenge exposure time are summarised in table 1 below. Fluoride and saliva are observed to inhibit near-surface (top 300 nm) softening of enamel. Complementary AFM images reveal fluoride and saliva inhibit enamel surface dissolution. Fluoride is observed to inhibit the dissolution of the c-axis of enamel rods. In the absence of either saliva or fluoride, enamel dissolution is initiated at the rod core/wall interface and preferentially at defects inherent within the enamel surface. Conclusion: Utilising a combination of AFM and nanoindentation, it has been shown that fluoride and saliva confer protection to the structural integrity of enamel against the deleterious effects of an aetiologically-relevant acid challenge.


0343 (111615)

Chitosan microparticles for the controlled release of fluoride. G.M. KEEGAN1, J.D. SMART2, M.J. INGRAM2, L.-M. BARNES2, G.D. REES3, and G.R. BURNETT3, 1Vectura Ltd, Chippenham, United Kingdom, 2University of Brighton, United Kingdom, 3GlaxoSmithKline R&D, Surrey, United Kingdom

Objectives: To develop mucoadhesive fluoride-loaded chitosan microparticles for the controlled release of fluoride.

Methods: Fluoride-loaded chitosan microparticles were prepared by spray-drying solutions of 1%w/v and 2%w/v chitosan containing 0.2%w/v NaF and glutaraldehyde.  Microparticles were characterised in terms of size and morphology using laser diffraction and scanning electron microscopy respectively.  Fluoride content was determined using a total digestion method.  In vitro fluoride release was measured in isotonic solution pH5.5.  Microparticle adhesion to oesophageal mucosa was quantified using texture probe analysis.

Results: Microparticle characteristics are shown below.  Fluoride-loaded microparticles appeared as collapsed spheres with a narrow particle size distribution.  High entrapment efficiencies of fluoride were achieved; notably at 2%w/v chitosan.  Release profiles were characterised by an initial rapid release of fluoride followed by prolonged slow release.  Microparticles prepared from 1%w/v chitosan and 0.001%w/v glutaraldehyde achieved the highest total in vitro fluoride release.  Fluoride release between 10-360 minutes was greatest in microparticles prepared without glutaraldehyde.  NaF significantly (P<0.05) decreased the tensile strength of microparticle mucoadhesion.

Chitosan

(%w/v)

Glutaraldehyde

(%w/v)

Volume Mean Diameter

(µm)

Total fluoride (µg/mg)

Initial %

release

(0-10min)

Slow %

release

(10-360min)

Total %

release

(360min)

1.0

0

4.37

59.2

39.7

20.0

59.7

1.0

0.001

3.49

56.9

59.3

18.1

77.4

1.0

0.05

3.83

54.3

45.0

9.8

54.8

2.0

0

5.31

61.7

47.8

25.8

73.6

2.0

0.002

5.35

62.8

52.8

14.9

67.7

2.0

0.1

4.99

60.5

57.5

4.8

62.3

Conclusion:  Fluoride-loaded chitosan microparticles have been investigated as a potential platform for local fluoride delivery to the oral cavity.  Microparticles produced in this study exhibit small particle sizes and high fluoride loading with in vitro release profiles suggesting 40-60% of the total fluoride is situated at or near the particle surface.  Mucoadhesion is significantly reduced by the addition of sodium fluoride; therefore further investigation is required to optimise particle characteristics.


0344 (111741)

Equilibrium salivary-fluoride levels (18-ESF) as a measure of toothbrushing frequency. H. WHELTON1, R. FREEMAN2, R. KINGSTON1, D. SADLIER3, M. ORMSBY4, and D. O'MULLANE1, 1National University of Ireland - Cork, Ireland, 2Dental Health Services Research Unit, Dundee, United Kingdom, 3Dental Health Foundation, Dublin, Ireland, 4Health Services Executive, Dublin, Ireland

Objectives:

Toothbrushing twice a day with a fluoride toothpaste is a well-established caries preventive strategy in health promotion programmes. Measurement of compliance with this strategy can be difficult. To objective of this study was to assess the feasibility of using 18-ESF to measure the frequency of use of fluoride toothpastes.

Methods:

The children were selected from primary schools in Dublin City (Winning Smiles - Schools oral health promotion programme for 7-8 year-olds. Dental Health Foundation Ireland, Ireland, 2007). Children in the experimental schools participated in the programme, which included the provision of fluoride toothpaste (1,450ppmf) and toothbrushes over a 12-month period. Those in control schools received no intervention. Unstimulated saliva was collected 18 hours after brushing the previous evening at baseline, 6-months and 12-months.

Results:

Salivary fluoride levels were analysed using pairwise t-tests on log-transformed data. It was found that there was an increase in 18-ESF in the experimental group (n=52) between baseline and 6-months (p=0.0001) and 12-months (p=0.0001). In contrast, in the control group (n=46), 18-ESF increased between baseline and 6-months (p<0.0001) but decreased, though not significantly, between baseline and 12-months (p=0.067).

Conclusion:

As evidenced by 18-ESF levels, all children increased their use of fluoride toothpaste between baseline and 6-months, suggesting that a visit by the dental team to the school had a positive impact on use of fluoride toothpaste regardless of whether an intervention was introduced. Inclusion of the intervention programme resulted in a sustained increase in the frequency of use of toothpaste.


0345 (111644)

3-Year Randomized Controlled Trial Comparing Immediately Versus Early Loaded Implants. A. ZEMBIC, A. KHRAISAT, R. GLAUSER, and C.H.F. HÄMMERLE, University of Zurich, Switzerland

Objectives:

was to test whether or not immediately loaded implants exhibit the same survival and success rates as early loaded implants.

Methods:

11 patients with bilateral free end mandibles were randomly assigned to either immediately loaded (test) or early loaded implants (control). Test implants received temporary prosthesis in occlusion the day of surgery. Control implants were reconstructed with provisionals after 6 weeks. Clinical parameters included the assessment of implant stability measures (ISQ), plaque, prosthesis stability and radiographs at baseline (implant insertion), at 1 and 3 years. The statistical analysis was performed by means of Student's paired t-test. The level of significance was set at p<0.05.

Results:

after a mean observation period of 39.8 months (36.7 – 53.1) 3 test implants were lost in 2 patients resulting in a survival rate of 86.4% compared to 100% for control implants. The bone level was significantly higher at test implants (mean = 0.27 mm; SD ± 0.4) compared to control implants (mean = 0.88 mm; SD ± 0.56) at baseline. For both test and control implants, the bone level significantly decreased from baseline to 1 year (test: 1.33 ± 0.77 mm; control: 0.75 ± 0.90), and from baseline to 3 years (test: 1.51 ± 0.60 mm; control: 0.71 ± 0.92). Concerning the ISQ no significant difference at test implants was detected from baseline to 1 year (63.59 ± 4.62 to 66.58 ± 6.34) and from baseline to 3 years (63.59 ± 4.62 to 66.47 ± 7.47). At control implants a significant increase of ISQ was observed from baseline to 1 year (65.35 ± 7.42 to 69.76 ± 6.80) and from baseline to 3 years (65.35 ± 7.42 to 68.80 ± 8.75).

Conclusions:

Immediate loading was associated with a lower implant survival rate and more marginal bone loss compared to early loading.


0346 (110529)

Immediate Implants at Fresh Extraction Sockets: De novo Bone Formation. F. VIGNOLETTI1, C. JOHANSSON2, T. ALBREKTSSON3, M. DE SANCTIS4, and M. SANZ1, 1Complutense University, Madrid, Spain, 2Örebro University, School of Health and Medical Sciences, Sweden, 3University of Goteborg-, Sweden, 4Universita di Siena - Clinica Odontoiatrica, Italy

Objectives: To investigate how changes at the implant surface nano-topography may influence early osseointegration.

Methods: Sixteen beagle dogs received 64 straight-walled, 3.25 mm diameter implants (Osseotite-Certain®). Control devices presented a dual acid-etched surface (Osseotite®, Biomet 3i) and experimental devices a nanometer-sized scale calcium phosphate discrete crystalline deposition (Nano-CaP DCD Nanotite®, Biomet 3i). After flap elevation and extraction of third and fourth mandibular premolars (3P3 and 4P4), test and control implants were randomly installed into the distal socket (3P and 4P). Healing abutments were secured and flaps sutured to allow a transmucosal healing. Five healing periods were investigated: 4 hours, 1-, 2-, 4- and 8 weeks. Histomorphometric analysis of bone to implant contact (BIC) and bone area (mineralized tissue fraction) at 64 bucco-lingual ground sections was performed. Two-way Anova and Bonferroni post hoc tests were performed for statistical analysis.

Results: Four hours after implant placement BIC was mostly limited to the thread tip level and amounted to 10% and 7% for the control and experimental implants, respectively. At two weeks the experimental surface showed a tendency towards higher percentage of contact. The increase in BIC % from one to two weeks was statistically significant only for the test group (P < 0,05). At 4 weeks results were similar for the two surfaces with an overall mean percentage of BIC of 36% (SD 10.6) and 34% (SD 15.7), control and experimental implants respectively. At 8 weeks the BIC % gradually increased to 55% (SD 10.6) for the control surface and to 48% (SD 13.4) for the experimental surface.

Conclusion: A significant effect of the Nanotite® surface was observed in the early healing (1-2 weeks) towards higher BIC levels. This effect was more pronounced at the distal wider socket (4P).

This study was supported by grants from Biomet 3i (Palm Beach Gardens, Florida).


0347 (110044)

Stimulating Bone Growth around Intra-oral Implants with Crestal Bone Loss. A. KESHVAD, School of Dentistry, Shahed University, Tehran, Iran, and T. HOOSHMAND, Dental Research Center, Research Center for Science and Technology in Medicine, Medical Sciences/Tehran University, Iran

Objectives: One of the main factors in implant failure is crestal bone loss. Although there is no general agreement, National Institute of Health and some of relevant researches have suggested some percentage of bone loss is reversible and thus further work on this area is required. Based on the initial pilot report that was presented in CED meeting in Thessaloniki Greece (2007) and the limited research available in the literature, a protocol was designed on how to treat the surface of dental implants with crestal bone loss to stimulate bone growth or cease the continuation of bone loss around them.

Methods: Twenty dental implants that had the inclusion criteria of the study and at least 30% of bone loss around them were selected for the study. Only implants with fixed prostheses were considered in this study. Bone loss was confirmed and measured by PA X-ray. Surface of the implants were cleaned using prophylactic paste and 37% Phosphoric acid for 2 minutes. To further treat and clean the surface of the implants, they were sandblasted with 50 micron aluminium oxide and 1 bar of pressure. A combination of bone substitute and Guided Bone Regeneration materials (GBR) were used to cover the exposed threaded area of the implants.

Results: Over the period of 1 year, all implants showed the average of 0.3 mm of bone loss which was much smaller than the amount of bone loss they showed before the treatment period. In 7 implants the average of 1mm of bone growth was observed around implants.

Conclusions: Based on the results, the surface treatment used in this study is an effective method of reducing or discontinuation of crestal bone loss around dental implants although further studies with larger sample size are required to confirm the obtained results.


0348 (110428)

Ten to sixteen-year follow-up of implant treatment. P. SIMONIS, and H. TENENBAUM, ERT 1061, Unite INSERM 595, Dental Faculty, University Louis Pasteur, Strasbourg, France

Objectives:the aim of the present study was to evaluate the long-term results of implant therapy using implant survival and implant success as outcome variables.

Methods:of the 71 patients who have received implant therapy ( 162 ITI implants ) during the years 1990-1997 at the Department of Periodontology, Dental Faculty, Strasbourg, France, 55 patients ( 131 implants ) were recalled to the department 10 to 16 years after implant placement for a complete clinical and radiographic examination followed by a questionnaire of satisfaction. Success was defined as being free of all complications over the entire observation period. The prevalence of biological and technical complications has been carefully analysed. Associate factors related to peri-implant lesions were analysed on patient and implant basis.

Results:the long-term implant survival rate was 82.44%.The prevalence of biological complications was 16.79% and the prevalence of technical complications was 31.30%. The summary estimate of the cumulative complication rate after an observation period of 10 to 16 years was 48.09% which meant that substantial amounts of chair time was needed following implant placement. The majority of implant losses and biological complications were concentrated in a relative small number of patients.

Conclusion:despite a relatively high long-term survival rate, biological and technical complications were frequent. Patients with a history of periodontitis may have lower implant survival rates and were more prone to biological complications such as peri-implant mucositis and peri-implantitis.


0349 (110134)

Case Series on Minimising Nerve Injury in Relation to Implants. N.I. KHAWAJA, King's College London, England, and T. RENTON, King's College London, United Kingdom

Introduction: Nerve injury during implant placement is a preventable, serious complication with major medico-legal implications. The incidence of implant related inferior alveolar nerve injuries (IANI) varies from 0-40%. This article presents 4 cases of IANI following mandibular implant placement with early removal, referred to the Oral Surgery department, Kings College Hospital, London Objectives: To assess sensory disturbance and recovery in patients with implant related IANI and assess whether early removal of the implants promotes neural recovery. To present recommendations on how to best deal with suspected/ actual nerve injuries and prevent their occurrence. Methods: Over the last 2 years, four patients referred for specialist opinion to the Oral Surgery department were identified as having sustained implant related IANI with early removal (18 hours to 4 days post-injury). Data was collected by referral to health records. Results: All patients suffered from numbness of the affected inferior alveolar dermatome with 3 out of 4 cases also experiencing some form of neuropathic pain. Cases 1 and 2, whom had their implants removed at 18 and 36 hours post-injury respectively, regained almost complete sensory recovery. Case 1 also had adjunctive NSAID and steroid therapy. Cases 3 and 4 suffered complete numbness in the inferior alveolar dermatome and did not experience any improvement in sensation following removal of their implants at 2 and 4 days post-injury respectively. Functional problems were only reported in Case 3. Conclusion: This cohort of patients may demonstrate that early removal of implants associated with IAN injury (less than 36 hours post-injury) may assist in minimising or even resolution of IAN neuropathy. Adjunctive corticosteroid and high dose non-steroidal anti-inflammatory therapy also appears effective. Implant related IANI is a preventable, elective procedure and a suggested protocol of management of suspected injuries, for dental practitioners, is presented.

Table 1 showing neurosensory test results.

 

Duration post Injury

Neuropathic area

%  skin/ vermillion affected

LTPS

SBD

TPDT

MTPDT

SF skin/ vermillion

Neuropathic pain/ neuralgia

Other findings

Function

Case 1

1 day

Right IAN

25-30% /

60%

normal

normal

 

increased

normal

3-4 / 6-7

-

Electric-shock when implant removed

Case1

6weeks

Right IAN

10% / 10%

normal

normal

-

 

reduced

7 / 10

Cold and mechanical allodynia

Marked reduction in neuropathic area over 2/12

Case 2

7days

Left IAN

Pt report 100%

-

-

-

-

 

-

-

-

Case 2

3 month

Left IAN

1% / 0%

normal

normal

normal

 

normal

10 / 10

-

Nil functional problems

Case 3

7 days

Right IAN

100% / 100%

-

-

-

-

-

-

Dribbling and lip biting

Case 3

2 months

Right IAN

100% / 100%

reduced

 

reduced

 

reduced

 

normal

14 / 11

Mechanical allodynia with hyperalgesia

Difficulty eating drinking speaking sleeping

Case 4

2 days

Left IAN

100% /

100%

reduced

 

reduced

 

reduced

 

increased

-

-

-

Case 4

3 months

Left IAN

100% /

100%

reduced

 

reduced

 

reduced

 

normal

14 / 11

Mechanical allodynia with hyperalgesia

Nil scarring or functional deficits

 


0350 (110379)

Topographical and Compositional Surface Analysis of Three Titanium Dental Implants. T. PAPADOPOULOS, University of Athens (EKPA), Greece, and J. FANDRIDIS, Asklepieion Voulas Hospital, Greece

Objectives: The aim of this study was to evaluate topographically and compositionally the surface of three commercial titanium dental implants. Methods: The examined implants were the Brånemark System Mk III TiUnite, the Standard Plus Implant and the XiVE TG CELLplus. Their rough surface morphology was analysed using Scanning Electron Microscopy (SEM) and rough surface composition using Energy Dispersive Spectroscopy (EDS). Their smooth surface topography was analysed using Atomic Force Microscopy (AFM). Results: The SEM analysis showed that the rough surfaces of the implants have a distinct morphological profile depending on their treatment. The EDS analysis of the rough implant surfaces indicate considerable differences in the oxide layer width of the examined implants, being minimal in Standard Plus Implant and very thick in Brånemark System Mk III TiUnite. Also revealed the presence of foreign elements in Brånemark System Mk III TiUnite and XiVE TG CELLplus. The AFM analysis of the smooth implant surfaces revealed considerable topographical differences in the nanometer scale. Conclusion: The examined implants had a different rough and smooth surface topography and a different rough surface composition, which were directly dependent on the treatment used. These differences might have an influence on the osseointegration process.


0351 (110651)

Superplastic Prosthetic Forming for Enhanced Bioactive Surfaces. R.V. CURTIS1, A. GIL2, and L. DISILVIO1, 1King's College London, United Kingdom, 2University of Wales Swansea, Wales

Objectives: Superplastic forming has been explored as a manufacturing process for creating the complex shapes needed for a range of dental and maxillofacial prostheses. Computer aided simulation is an important part of the forming process that enables flat Ti-6Al-4V disks to adapt over time to low cost ceramic dies produced from dental investments. 2D and 3D computer simulation strategies can be adopted to achieve the required deformation in the titanium alloy sheet.

Methods: A 2D geometrical simulation strategy known as Multiform (King's College London) and a 3D FE-based strategy known as Superflag (University of Wales Swansea) were created and adopted to form a variety of shapes for clinical use in dentistry and maxillofacial technology. The 2D cross-section and entire 3D surface are digitised as input in each case. Assumptions based on measurements of materials properties were made for the deformation behaviour of the Ti-6Al-4V alloy at the forming temperature around 900°C.

Results: Results show good adaptation of Ti-6Al-4V sheet to investment dies for all die forms, whether for dental or maxillofacial applications. Clinically all prostheses are suitable for use. An additional benefit of the forming process is the interaction that takes place between titanium alloy and investment die material which seems to produce an enhanced biocompatible response at the formed titanium surface.

Conclusions: Superplastic prosthetic forming is shown to enable the complex shapes of dental and maxillofacial prostheses to be fabricated using titanium alloy sheet of between 0.5 mm and 1 mm thickness in most cases and which retains stiffness for clinical use through the complex shape that is produced even though in thin cross-section down to 0.1 mm and also benefits from a metal sheet - ceramic die interaction for enhanced bioactive properties.


0352 (111375)

Surface characterization of zirconia dental implants. S. ZINELIS1, A. THOMAS2, N. SILIKAS2, K.L. SYRES2, D.S.-L. LAW3, and G. ELIADES1, 1University of Athens, Greece, 2University of Manchester, United Kingdom, 3STFC Daresbury Laboratory, National Centre for Electron Spectroscopy and Surface Analysis, Warrington, Cheshire WA 5 4AD

Title: Surface characterization of zirconia dental implants.

Objective: To characterize the surface chemistry and topography of two Zirconia dental implants.

Methods: The implants tested were White Sky (Bredent Medical) and Zit-Z (Ziterion). The elemental and molecular composition of cervical collar and root region were analyzed by LV-SEM/x-ray EDS analysis and monochromated X-ray Photoelectron Spectroscopy (XPS). Surface roughness of root regions was studied by optical profilometry and Sa, Sq, Sz and St parameters were measured.

Results: LV-SEM revealed that both implants have a relatively smooth cervical collar and a rough serrated root region, with a characteristic atomic number contrast. X-ray EDS analysis showed the presence of Zr, O, Y, Hf and Al in both implants. Al was mainly located at the root portion as shown by elemental mapping. XPS demonstrated higher Al surface content on Zit-Z. Binding state analysis showed that the chemical states of Zr, Y and Al were ZrO2, Y2O3 and Al2O3. Surface roughness parameters obtained between two successive serrations ranged as follows (um) Sa: 0.3~0.5, Sq: 0.5~0.8, Sz: 8.9~9.8 and St:16.3~19.2.

Conclusions: The zirconia implants tested showed variations in the morphology and roughness of the root portion which should be attributed to the Al2O3 surface roughening technique.

 


0353 (110369)

Feasibility Study of Interdental Cleaning Methods in Primary Dental Care. V. CLEREHUGH, M.A. JACKSON, Y. CHENG, and M.S. GILTHORPE, University of Leeds, United Kingdom

Background: Previously, a randomised control trial (RCT) of 77 patients showed that by interdental cleaning, especially with interdental brushes, periodontal patients were able to improve clinical outcomes even before thorough root surface debridement (RSD). Most periodontal treatment is provided in primary dental care, yet no similar studies have been found in the literature within the general dental practice (GDP) setting.

Objectives: To determine the feasibility of undertaking a GDP-based study* to compare the clinical effects of two methods of interdental cleaning prior to RSD.

Methods: Plaque index (PI), probing depth (PD) and bleeding on probing (BOP) were recorded on interproximal sites in patients from 3 GDPs. Clinical measurements were recorded by the practice hygienist/therapist at baseline and 6 weeks and were binary: PI (0-1/2-3), PD (<4mm/≥4mm), BOP (yes/no). Patients received a 10-minute gross scale to facilitate interdental cleaning and were allocated randomly to either floss (control) or curved interdental brushes (test) group. Customized oral hygiene and interdental cleaning advice was given and supplies provided for 6 weeks. Questionnaire data were collected though not reported here.

Results: 29 of the 30 recruited patients completed the study, with some incomplete data which diminished as patients were recruited. Aggregate (patient-level) summary statistics showed some baseline imbalance; aggregate statistical analyses revealed no significant treatment differences. These aggregate findings were anticipated due to the small study size. In contrast, multilevel logistic regression, with adjustment for baseline imbalance, revealed that each outcome had significantly greater improvement in the brush group compared to the floss group.

Conclusions: This feasibility study indicates that with an increased number of practices, GDP-based RCTs are able to evaluate robustly interdental cleaning interventions. Multilevel modelling is statistically more powerful than aggregate analyses, though adjustment for baseline imbalance might occur unless the study size is increased.

*Supported by Leeds PCT Research Consortium


0354 (110606)

Structural equation models for patients' attitudes to oral hygiene methods. Y.-K. TU, M. JACKSON, and V. CLEREHUGH, University of Leeds, England, Uk

Introduction: Oral health education is an important part of periodontal treatment plan and for disease prevention and maintenance. Without satisfactory plaque control, periodontal treatments show little long-term benefit. It is therefore important to understand patients' attitudes toward oral hygiene and the advice given by dentists or hygienists on oral hygiene.

Methods: 77 patients with chronic periodontitis were measured for plaque indices and probing pocket depths at interdental sites at baseline, 6 and 12 weeks. Participants were randomly allocated to the use of one of two customized methods of interdental cleaning involving dental floss (control group) and precurved interdental brushes (test group). Participants were also asked to fill in a questionnaire at each session of oral hygiene education. Subjects were asked to limit their oral hygiene to the methods they had been shown and to the interdental cleaning method to which they had been allocated.

Results: Three of the 30 questions in the questionnaire related to patients' attitudes toward interdental cleaning (IC) and four related to their attitudes to the interdental cleaning method (ICM) allocated. Structural equation modeling showed that patients with a positive attitude toward IC tended to show a greater positive attitude to ICM at 6 (r=0.98) and 12 (r=0.75) weeks. Patients in the interdental brush group showed a more positive attitude toward both IC and ICM at 6 and 12 weeks. Both structural equation models for questionnaire data at 6 and 12 weeks showed an acceptable overall model fit: Chi-square value (df=18) was 19.51 and 27.99; RMSEA=0.033 and 0.085, respectively.

Conclusion: This study demonstrated that patients with a more positive attitude toward oral hygiene showed a more positive attitude toward the advised oral hygiene methods. Patients seemed to feel more positive toward interdental brushes than flossing, and this may contribute to better plaque control.


0355 (111679)

Ultrasonic Probe Oscillation Detected with 3D Scanning Laser Vibrometry. B. FELVER, S.C. LEA, and A.D. WALMSLEY, University of Birmingham, United Kingdom

Objectives: The motion of ultrasonic probes under different clinically relevant situations is made using accelerometers or 2D Scanning Laser Vibrometers but do not provide a true pictorial representation of the movement. The aim of this study was to detect the 3D motion of different designs of ultrasonic probes using 3D Scanning Laser Vibrometry.

Methods: A magnetostrictive (FSI-SLI-10S) and a piezoelectric (EMS Piezon P) probe were operated under two different power settings. Recordings were taken using a 3D Scanning Laser Vibrometer (Polytec PSV-400-3D) with focus upon the tip of the probe. The water flow during operation was 20 ml/min and contact load of 100g and 200g was applied with the tip of the probe contacting a flat, polished resin surface. Statistical analysis was made with SPSS 14.0 software.

Results: Both probes move in an ellipsoidal motion at the tip. The FSI-SLI-10S probe resulted in one nodal point whereas the P probe had only one. When load was applied maximum displacement amplitudes occurring around the second anti-node of the P probe decrease when increasing load is applied. It was also noted that this reduction occurred along the length of the probe.

Conclusion: All ultrasonic scaling probes oscillated with an ellipsoidal motion at the tip. This was seen with both magnetostrictive and piezoelectric designs. When the instrument is loaded in a similar manner to the clinical situation it was found that the two designs used result in different vibration patterns.

This work is supported by a project grant from the EPSRC (EP/C536894/1).


0356 (111577)

A Clinical and Biochemical Evaluation of Local Sodium Piperacillin Delivery. N. MENEMENCIOGLU1, S. DIRIKAN IPCI1, U. NOYAN2, B. EREN KURU2, and S. YILMAZ1, 1Yeditepe University, Istanbul, Turkey, 2Marmara University, Istanbul, Turkey

Objective: The present study describes results on selected clinical and biochemical parameters obtained by treatment with initial periodontal therapy alone and in combination with local use of piperacillin sodium (Periofilm) in chronic periodontitis. Methods: A total of 20 patients with probing depth (PD) of > 5mm and gingival index (GI) of > 2-3 in at least 2 single-rooted teeth were included and randomly divided into 2 groups. Group 1 received scaling and root planing (SRP), whereas group 2 received SRP+Periofilm application. The clinical and biochemical effects of treatment modalities were monitored over a period of 90 days. At 0 and 90 days, plaque index (PI), GI, bleeding on probing (BOP), PD, relative attachment level (RAL) and gingival recession (GR) were measured and gingival crevicular fluid (GCF) samples were collected. Matrix metalloproteinase-8 (MMP-8) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were measured by ELISA. Results: All periodontal sites treated with either SRP or SRP+Periofilm revealed a decrease in MMP-8 concentration and an increase in TIMP-1 concentration which was parallel to the clinical parameters. Considering the selected sites, 2.2±0.8 mm and 2.28±0.68 mm of PD reduction, 1.49±0.84 mm and 1.71±1 mm of attachment gain were obtained in Groups 1 and 2, respectively. The decrease in MMP-8 concentration (Groups 1 and 2, respectively (p<0.05, p<0.01)), and the increase in TIMP-1 concentration (Groups 1 and 2 (p<0.001)) was significant in both treatment groups. At 90 days, MMP-8 concentration was 15.8±11.64 µg/ml and 8.95±9.44 µg/ml in Groups 1 and 2, respectively and intergroup difference was statistically significant in favor of the Group 2 (p<0.05). Conclusion: Within the limits of this study, although both treatment groups responded to therapy with similar resolution of infection reflected to clinical and biochemical parameters, Periofilm seems to have adjunctive effects to SRP in terms of differences in MMP-8 concentration.


0357 (111560)

Inflammatory, Oxidative and Diabetes Status Changes Following Periodontal Therapy. E.M. ALLEN, National University of Ireland Cork, Ireland, I.L.C. CHAPPLE, University of Birmingham, United Kingdom, J. MATTHEWS, University of Birmingham, England, D. O' HALLORAN, Cork University Hospital, Ireland, and R.M. O' CONNOR, University College Cork, Ireland

Oxidative stress and up-regulated inflammation are associated independently with type 2 diabetes mellitus (T2DM) and periodontitis within the peripheral vasculature, and may combine to further compromise both disease states when they co-exist. Objectives: To determine the impact of periodontal therapy on plasma oxidative/inflammatory status and metabolic control in T2DM. Methods: 20 Type 2 diabetics with periodontitis (DP) (BMI 30+5), 20 age/gender-matched periodontally healthy T2DM controls (DH) (BMI 29+6) and 17 non-diabetic-periodontitis controls (NDP) (BMI 25+2) had full periodontal examinations and fasting, baseline plasma samples collected. Standard non-surgical periodontal therapy was provided to the DP and NDP groups, with the DH group receiving oral hygiene instruction and prophylaxis. Periodontal examination and fasting, post-treatment plasma samples were performed 3-months after completion of treatment. Oxidative stress was determined by plasma total antioxidant capacity (pTAOC) and protein carbonyl levels; inflammatory status by high sensitivity C-reactive protein (hsCRP); diabetic status by HbA1c levels. Statistical analysis was performed using SPSS. Results: Periodontal therapy significantly decreased periodontal pocket depths (p<0.001), bleeding on probing (BOP) (p<0.001), and plaque indices (PI) (p<0.001) in DP and NDP patients. The DH group exhibited decreased BOP (p=0.01) and PI (p=0.007). In the DP group, pTAOC was significantly increased (p=0.015) and plasma carbonyls decreased (p=0.03), following treatment. HsCRP levels were significantly reduced in the DP (p=0.037) and NDP (p=0.031) groups. HbA1c levels reduced in the DP group only (p=0.002). Conclusions: Successful periodontal therapy is associated with improvements in plasma biomarkers of oxidative stress and inflammation in T2DM patients with periodontitis and a reduction in plasma inflammatory biomarkers in non-diabetic patients with periodontitis. Periodontal therapy is further associated with improvements in indices of glycaemic control in the T2DM patients studied.


0358 (111763)

Oral Complications in Non-smoking Type 1 Diabetics. P.J. HODGE, D. ROBERTSON, and J. YOUNG, University of Glasgow, United Kingdom

Objectives: The aim of this study was to investigate oral complications in non-smokers with type 1 diabetes.

Method: Non-smoking type 1 diabetic patients were recruited from four out-patient departments within Glasgow. Non-smoking non-diabetic controls (NDS) were recruited using the buddy system. All subjects underwent a detailed oral examination at Glasgow Dental Hospital and School including full mouth periodontal charting, plaque and gingivitis chartings, hard tissue charting and examination of the mucous membranes.

Results: 108 patients and 44 control subjects have been examined so far. The type 1 diabetics were divided into a poorly controlled group (PCD) and a better controlled group (BCD) based on the median HbA1c over the previous two years. A significantly higher percentage of sites in type 1 diabetics bled on probing compared with NDS (p < 0.05). The percentage sites with clinical attachment loss of more than or equal to 5 mm in the PCD (56%) was higher than in the BCD (44%) which in turn was higher than in the NDS (36%). There were no differences between the groups in DMFT or DMFS but the PCD had significantly more missing teeth than NDS (p < 0.05). No difference in the clinical health of the mucous membranes was found between type 1 diabetics and NDS.

Conclusion: Non-smoking type 1 diabetics showed worse periodontal health and PCD had more missing teeth than NDS which could be related to raised blood glucose levels.

This study was supported by a grant from the Chief Scientist Office of the Scottish Government Health Department.


0359 (111788)

Predictors of tooth loss eleven years after active periodontal therapy. B. RIEP1, L. SKARABIS1, H. SKARABIS2, J.-P. BERNIMOULIN1, B.-M. KLEBER1, and S. HAEGEWALD1, 1Charité - Universitätsmedizin Berlin, Germany, 2Freie Universität Berlin, Germany

Objectives: The aim of this eleven-year retrospective study was to evaluate the longterm outcome of periodontal treatment with subsequent supportive periodontal therapy (SPT), and to identify predictors of tooth loss. Material and methods: Data were collected from 112 patients (54 male, 58 female; mean age 49,7 years) who received periodontal care at the Department of Periodontology, Charité Berlin. All patients were treated for moderate to advanced periodontitis and were observed during SPT for a mean observation period of 11.6 years (SD=2,7). Probing pocket depth was >4 mm at approximately 50% of the teeth and >6 mm at 20% of the teeth. Treatment consisted of oral hygiene instructions, scaling and root planing under local anesthesia, and if necessary periodontal surgery. Logistic regression analysis, sequential tree analysis and causal modeling were used to determine predictors of tooth loss. Results: Of the 2748 teeth initially present, 1.1% were extracted during active treatment and 8.0% during SPT. Baseline findings of increased attachment loss, furcation involvement of multirooted teeth, non-vital pulp, and increased tooth mobility significantly (p<0.01) contributed to tooth-loss during SPT. Highest predictor of tooth loss was attachment loss at non-approximal sites of >6 mm. Additional patient based factors were smoking (p<0.01) and increased bleeding index (p<0.05). Significant different patterns were evident for different groups of teeth as revealed by sequential tree analysis. Conclusion: Combinations of different predicting factors seemed to play the most substantial role for longterm tooth survival.


0360 (109940)

Residual pockets and tooth loss: Eleven years of maintenance. N.P. LANG1, G. MATULIENE2, B.E. PJETURSSON3, G.E. SALVI4, K. SCHMIDLIN5, U. BRÄGGER4, and M. ZWAHLEN5, 1University of Hong Kong, Hong Kong, 2University of Berne, Switzerland, Switzerland, 3University of Iceland, Reykjavik, Iceland, 4University of Berne, Switzerland, 5University of Bern, Berne, Switzerland

Background: Limited evidence exists on the significance of residual probing pocket depth (PPD) as a predictive parameter for periodontal disease progression and tooth loss.

Aim: to investigate the influence of residual PPD≥5mm and bleeding on probing (BOP) after active periodontal therapy (APT) on the progression of periodontitis and tooth loss.

Material & Methods: In this retrospective cohort, 172 patients were examined after APT and supportive periodontal therapy (SPT) for 3-27 years (Mean 11.3 years). Analyses were conducted using information at site, tooth and patient level. The association of risk factors with tooth loss and progression of periodontitis were investigated using multilevel logistic regression analysis.

Results: The number of residual PPD increased during SPT. Compared to PPD≤3mm, PPD=5mm represented a risk factor for tooth loss with odds ratios of 5.8 and 7.7 respectively, on site and tooth level. The corresponding odds ratios for PPD=6mm were 9.3 and 11.0 and for PPD≥7mm were 37.9 and 64.2, respectively. On patient level, heavy smoking, initial diagnosis, duration of SPT and PPD≥6mm were risk factors for disease progression, while PPD≥6mm and BOP≥30% represented a risk for tooth loss.

Conclusions: Residual PPD≥6mm represent an incomplete periodontal treatment outcome and require further therapy.

Supported by the Clinical Research Foundation (CRF) University of Berne, Switzerland


0361 (111459)

Gene Expression Profile of Early Regenerated Submandibular Gland: Discovering Pathways. E. COTRONEO, N. SILVER, G.B. PROCTOR, and G.H. CARPENTER, King's College London, United Kingdom

We have recently identified morphological and cellular similarities between submandibular gland regeneration following duct ligation induced-atrophy and glandular embryonic development. These data suggest that embryonic signalling pathways, like Wnt/β-catenin, may be re-activated during regeneration. Objective: to investigate the gene expression profile of early regenerated glands and a possible correlation with the embryonic pathway of salivary gland development. Methods: 9 rats (Wistar) were used in this study. Atrophy was induced by applying a metal clip on the main duct of submandibular gland. After 2 weeks the glands of 3 rats were collected. In 3 rat the ducts were ligated for 2 weeks, deligated for 3 days then glands were collected. Rats were killed by anaesthetic overdose. RNA was extracted, integrity was assessed, and microarray analysis was carried out. Glands from 3 unoperated rats were used as controls. Results: microarray analysis from regenerating glands (compared against ligated glands) revealed up-regulation (p<0.005) of some genes reportedly up-regulated during embryonic development: Nidogen-1, Ccnd2 and Sp4, along-side up-regulation (p<0.005) of some genes involved in liver regeneration: UHRF1 and Decorin. Most interestingly it also revealed down-regulation of Dishevelled (p<0.005) a key element of the Wnt-pathway, along-side up-regulation of the Wnt-pathway inhibitor Sfrp1 (p<0.005) which was not expressed in control glands. Qualitative PCR carried out after reverse-transcription confirmed the absence of Sfrp1 in the controls and its presence in the regenerated gland. In the Wnt-pathway “Dishevelled” prevents degradation of cytoplasmic β-catenin which is then able to translocate into the nucleus activating the expression of specific genes. However, in the regenerating gland β-catenin immocytochemistry did not reveal any nuclear localization. Conclusion: early regenerated (3 days)submandibular gland shows up-regulation of some genes involved in embryonic development. However our data also suggest that the Wnt-pathway may not be functional at this stage of regeneration.

We gratefully acknowledge Wellcome Trust funding.


0362 (111245)

Acetylcholine Vasodilation in Feeding Parotid Artery of Diabetic Rabbit. D. STOJIC, J. ROGANOVIC, and E. KRSLJAK, Faculty od Stomatology, University of Belgrade, Serbia and Montenegro

Objective: The influence of diabetes on muscarinic receptors involved in the dilatory response of the isolated glandular branch of the external carotid artery (supplying the parotid gland) to acetylcholine (ACh) was examined.

Methods: In organ bath studies with pre-contracted arterial rings of glandular branches of external carotid artery, changes in isometric tension were recorded. Diabetes was induced in rabbits by a single iv injection of alloxan (100 mg/kg).

Results: ACh (0.01µm-3µm) produced endothelium- and concentration-dependent vasodilation in arterial rings of both control and diabetic rabbits with significantly different EC 50 values ( control=0.278µm, diabetic=0.123µm). The PA2 values (determined by Schild analysis) for pirenzepine (selective M1 antagonist), metoctramine (selective M2 antagonist) and PFHHSID (selective M3 antagonist) were 6.7, 5.6 and 6.9 in control group and 7.5, 6.7 and 7.9 in diabetic group. Schild plot slopes of unity were obtained for all antagonists in both control and diabetic animals.

Conclusion: The study indicates that M3 receptors are solely involved in ACh-induced relaxation of the isolated glandular branch of external carotid artery in controls while in diabetic rabbits the same effect of ACh is mediated through activation of M1 and M3 muscarinic receptors.

The study was supported by MNRS grant 145015 B.


0363 (110489)

Oral mucosal pellicle formation by salivary statherin. G.B. PROCTOR1, R. PRAMANIK2, S.M. OSAILAN1, and G.H. CARPENTER1, 1King's College London, United Kingdom, 2NIHR Biomedical Research Centre, London, United Kingdom

The salivary protein statherin has a high affinity for hydroxyapatite. It not only plays a key role in oral calcium homeostasis but appears to act as a boundary lubricant at the surface of enamel.

Objectives: the present study examines whether statherin also binds to the soft surfaces of the mouth to form a mucosal protein pellicle which may be of importance in soft tissue lubrication.

Methods: two series experiments were undertaken on volunteer subjects who gave informed consent to take part in the study which was given approval by the local ethical committee. In series one, water alone or a solution of sodium dodecyl electrophoresis (10 mM SDS) were used to sample proteins from oral mucosal surfaces before and after removal of the fluid film. In series two, buccal epithelial cells were harvested from subjects, washed in physiological buffer and then the protein content compared before and after incubation with parotid saliva. Results: SDS gel electrophoresis and immunoblotting of samples revealed that: (1) statherin but not cystatin S could be detected on dry mucosal surfaces, (2) statherin was enriched in oral rinses containing SDS compared to water alone, (3) statherin was depleted from centrifuged whole mouth saliva and present in the pellet, (4) buccal epithelial cells bound statherin when incubated with parotid saliva.

Conclusion: Statherin is a component of an oral mucosal protein pellicle and may serve to lubricate soft tissue surfaces in mouth.

Acknowledgements: the authors are grateful for funding from GlaxoSmithKline Oral Care.


0364 (111555)

Calcium affects the interfacial properties of parotid saliva. G. CARPENTER1, P. WILDE2, M. RIDOUT1, and G. PROCTOR1, 1King's College London, United Kingdom, 2Institute of Food Research

Saliva is supersaturated with calcium and is highly viscoelastic. In particular the rheology of the air/ liquid interface is extremely strong and after 30 mins is dominated by a single protein; statherin and high levels of calcium. Previously we showed that chelating calcium with EDTA destroys all viscoelastic properties but did not affect the surface activity of proteins. Objectives: to examine the effect of adding calcium to the interfacial rheology and protein composition of parotid salivary films. Methods: using shear rheology (AR2000) parotid saliva was assessed before and after the addition of 1mM Calcium chloride. In a separate experiment the protein composition and calcium concentrations of parotid salivary films, either with or without added calcium (1 mM) were examined by SDS-PAGE and immunoblotting with an anti-statherin antibody and ion-selective electrodes. Results: The elastic modulus of parotid saliva increased nearly 100 fold with the addition of calcium although it was noticeable that the film was more brittle. Despite the greater strength of the film there was no increase in the amount of statherin. Ion selective electrodes suggested a greater amount of free (as opposed to protein bound) calcium in films formed after 30 mins.

Conclusions: Interfacial properties of saliva are affected by free calcium levels.

The authors gratefully acknowledge the support of Unilever.


0365 (110356)

Search for type2 diabetes biomarkers using innovative quantitative salivary proteomics. C. HIRTZ1, S. EVESQUE2, F. CUISINIER1, M. ROSSIGNOL3, N. SOMMERER3, and D. DEVILLE DE PÉRIÈRE1, 1UFR Odontologie, Montpellier, France, 2Faculte de Chirurgie Dentaire, Montpellier, France, 3INRA, Montpellier, France

Summary: Large variations in the relative abundance of proteins and complexity of the salivary proteome generate permanent challenges for the development of bio-analytical technologies, from sampling to mass spectrometric detection. The analytical techniques are still largely based on polyacrylamide two-dimensional gels, which play a crucial role in the field of proteomics, but are somewhat weakly sensitive and poorly reproducible.

For our study, we used innovative methods of quantitative mass spectrometry based on LC / MS-MS and isotopic peptide labelling: The principle is to modify proteins chemically in order to compare two different biological samples.

Objectives: Are there quantitative or qualitative variations of the salivary proteome, that would allow us to identify the presence of salivary markers of type 2 diabetes associated with obesity?

Methods: A group of 10 healthy subjects (44,4 ± 2,1 years) and three groups of 10 patients (46 ,2 ± 5,1 years) have been included: Obese non diabetic, Obese with type 2 diabetes, Obese with bad-controlled type 2 diabetes (HBA1C>7%). Whole excreted salivary proteins were separated using mono dimensional gel. Trypsic peptides were labeled using formaldehyde (Heavy and Light), to label the N-terminus and -amino group of Lysine through reductive amination. LC/MS/MS mass spectrometry was used for protein identification and quantification.

Results: Image analysis of mono dimensional gels using specific software (MultiGauge, Fujifilm) discriminated 7 bands of proteins differentially expressed in Obese with bad-controlled type 2 diabetes compared to control. The mass spectra analysis showed significant variation for proteins such as immunoglobulin, alpha amylase, small proline-rich protein or cathepsin.

Conclusion: This experiment shows that quantitative proteomics using isotopic peptide labelling and mass spectrometry analysis could be a way to discriminate salivary biomarkers of systemic disease such as type 2 diabetes.


0366 (110907)

Salivary function in paediatric allogeneic stem cell recipients. G. DAHLLÖF1, K. GARMING-LEGERT1, M. HASSAN2, M. REMBERGER3, and O. RINGDÉN2, 1Karolinska Institutet, Huddinge, Sweden, 2Karolinska University Hospital Huddinge, Stockholm, Sweden, 3Karolinska University Hospital Huddinge, Stockholm

Salivary secretions are affected by conditioning prior to stem cell transplantation in children and adolescents. Single dose total body irradiation (sTBI) combined with cyclophosphamide (CY) may induce a permanent salivary dysfunction. Objective: To study if fractionated TBI or busulfan (BU) induces less salivary dysfunction compared to TBI and if treatment at younger age will cause a more severe salivary dysfunction. Methods: Thirty-seven children received sTBI (10 Gy), 9 children received fractionated TBI (3 x 4 Gy; fTBI) and 23 children received oral BU (16 mg/kg) all combined with CY (120 mg/kg). They were treated for haematological malignancies, genetic diseases and immune deficiencies between 1 and 13 years of age. At 15, the children were examined and both the unstimulated and stimulated salivary secretion rates were determined. Results: At 15 years of age there were no significant differences in unstimulated salivary secretion rate between the three groups. sTBI/CY resulted in a significantly lower stimulated salivary output (0.8±0.4 ml/min) compared to fTBI/CY (1.2±0.7 ml/min; p=0.0404). Seventeen percent of children conditioned with BU/CY exhibited salivary dysfunction (simulated secretion rate < 0.5 ml/min) compared to 32% in the sTBI group (n.s.). In children conditioned with sTBI there was a significant inverse correlation between age at TBI and stimulated salivary secretion rate (r=0.341; p=0.0384). This correlation was not found in children treated with BU/CY or fTBI/CY. The bioavailability of BU has a 6-fold variation in paediatric patients and the saliva/ plasma concentration ratio is 100%. This may explain the lack of correlation between age at treatment and salivary secretion rate at 15. Conclusion: Children conditioned with sTBI had a significantly lower stimulated salivary secretion rate compared to fTBI. Young age at exposure to sTBI results in significantly lower stimulated salivary secretion rate at 15 year of age.


0367 (111185)

Wnt Signalling in Submandibular and Sublingual Gland Development. N. PATEL, King's College London, United Kingdom, D. HINDOCHA, King's College, London, P.T. SHARPE, King's College London, and I. MILETICH, King's College London, Vanuatu

Objectives:

Saliva produced by salivary glands has a number of important roles ranging from the protection of the oral mucosa and teeth to the lubrication of the mouth essential for eating, speaking and tasting.

Many signalling pathways, including FGF and Shh signaling, are involved in the development of salivary glands. Studies have demonstrated a role for Wnt signalling in the development of branching organs such as the lungs and kidneys, however the function of Wnt signalling in salivary gland development has not yet been investigated. Here we look at the role of Wnt signalling during mouse embryonic development of the submandibular (SM) and sublingual (SL) salivary glands.

Methods:

Axin2LacZ mice were used to identify the sites of active canonical Wnt signalling (CWS) throughout embryonic development of SM/SL salivary glands. RT-PCR was then used to investigate which Wnt ligands and Frizzled receptors were involved in this CWS and expression pattern of the corresponding genes was studied using whole mount in situ hybridisation.

Results:

CWS was present in SM/SL glands from E12.5 onwards. From E12.5 to E14.5, CWS was present in the mesenchyme and from E14.5 onwards in the epithelial cells of the developing glands. Interestingly, mesenchymal CWS was restricted to the mesenchyme facing the branching epithelium of the SM gland. Mesenchymal cells facing the SL gland were devoid of CWS.

We have found a number of genes encoding canonical and non-canonical Wnt ligands, frizzled receptors and Wnt inhibitors that are expressed during SM/SL gland development.

Conclusions:

CWS is active in developing mouse salivary glands and appears to be different in SM and SL salivary glands. Our research currently focuses on identifying which Wnt ligands and Frizzled receptors are involved in this CWS.


0368 (111468)

Regenerating Protein (Reg3a) Expression during Rat Submandibular Gland Atrophy. N. SILVER, G.B. PROCTOR, M.J. ARNO, K.L. PATERSON, and G.H. CARPENTER, King's College London, United Kingdom

The Reg family of proteins has been studied in the context of growth and regeneration in several organs and tissues including the pancreas and liver. Recent microarray analysis of an atrophic rat submandibular gland, induced by duct ligation for 2 wks, showed that one of the highest expressed proteins was the regenerating protein, Reg3a. Objectives: To examine REG3A gene expression levels in progressive atrophy in the rat submandibular gland model. Methods: Under recovery anaesthesia, the excretory duct of the right submandibular gland in the rat model was ligated twice with thread to induce atrophy. Ligated submandibular glands were removed after 1, 2, 3, 5, 7, 9, 11 and 14 days of ligation under terminal anaesthesia, and investigated using histological and immunocytochemical staining to confirm atrophy, cell phenotype and cell proliferation. Rats were killed with an overdose of pentobarbitone. Quantitative real-time PCR (Q-RT-PCR) normalised to ubiquitin C (UBC) was used to accurately measure gene expression levels. Results: Histology confirmed atrophy of experimental glands. A significant decrease in acinar cells, indicated by actin staining of surrounding myoepithelial cells was seen in the experimental glands when compared with the control glands, while the development of ductal branch structures as well as ki67-positive proliferating cells was seen. Analysis of REG3A gene expression by Q-RT-PCR during progression of atrophy indicated a significant increase after 1 day of ligation, followed by a periodic decline at day 3 and thereafter a gradual increase peaking at the most atrophic stage day 14. Conclusion: Observations indicate that REG3A in the rat submandibular gland acts as a sensitive reactant to tissue injury. Furthermore, REG3A expression levels concomitant with branching morphogenesis and ductal cell proliferation suggest an associated role in the survival of an atrophic submandibular gland. Acknowledgements: Gratefully supported by the Wellcome Trust


0369 (110124)

Bond strength of a fluorcanasite glass-ceramic to a resin cement. S. POLLINGTON, and R. VAN NOORT, University of Sheffield, United Kingdom

Objective: This study evaluated the effect of surface treatments on the bond strength of fluorcanasite and lithium disilicate glass-ceramics, with the possibility of eliminating hydrofluoric acid (HF) etching of these ceramics.

Methods: Fifteen blocks of an experimental fluorcanasite and a lithium disilicate glass-ceramic (IPS e.max CAD®) were assigned to one of the following three surface treatments: (1) machined with 60µm finish, (2) machined and grit blasted, (3) machined and HF etched. The ceramic blocks were duplicated in composite resin (Spectrum®) and cemented together with a resin luting agent (Variolink II®). Thirty microbars per group (1.0 x 1.0 x 20mm) were obtained and subjected to a tensile force at a crosshead speed of 0.5 mm/min using a universal testing machine until failure. The mode of failure was determined using scanning electron microscopy. The appropriate bonding procedure was assessed for durability by storing in water at 1000C for 24 hr. Statistical analyses were performed with ANOVA and Tukey's test (P<0.05).

Results: Machining alone significantly increased the bond strength (MPa) of the fluorcanasite (27.79 ± 6.94) compared to the lithium disilicate (13.57 ± 4.52) (P<0.05). HF etching resulted in the lowest bond strength (8.79 ± 2.06) for the fluorcanasite but the highest for the lithium disilicate (24.76 ± 9.38). Regarding durability, the machined fluorcanasite (15.24 ± 5.46) demonstrated significantly higher bond strength than the machined and HF etched lithium disilicate (12.28 ± 3.30).

Conclusion: The fitting surface of the fluorcanasite glass-ceramic should retain the machined finish and be directly treated with silane. The use of HF acid is contraindicated.


0370 (110347)

Bond Strengths of Intra-Oral Porcelain Repair Systems. C.M. TAN, C.J. TREDWIN, M. NESBIT, and D.R. MOLES, UCL Eastman Dental Institute, London, United Kingdom

Objective: The purpose of this laboratory study was to investigate the bond strength of three commercially available porcelain repair systems. Three different shear bond strengths of composite were evaluated; to porcelain, to porcelain and metal and to metal only.

Methods: Thirty cylinders were constructed from a porcelain bonding metal (Degudent U) and randomly divided into three surface groups; metal only, porcelain only and a metal porcelain combined surface. Using three different porcelain repair systems; GC system, Clearfil Repair and the Cojet system and two control groups consisting; of a silane coupling agent and a composite bonding system (G bond) and a composite bonding system alone (G bond) the shear bond strength of 5mm diameter discs of GC Gradia composite was evaluated using a Instron Universal load testing machine. Statistical analysis was undertaken using two way ANOVA.

Results: Clearfil Repair and Cojet gave statistically significantly greater (P<0.01) bond strengths than the GC system and the two control groups in all surfaces tested. Clearfil gave statistically significantly greater (P<0.01) bond strengths than all other groups in the porcelain surface only group.

Conclusion: Based on the results of this study the Clearfil Repair system offered the best overall shear bond strengths for all the surfaces tested. However it should be noted that this is the only system that used an acid etchant as part of its kit.


0371 (110697)

Bond strength to feldspatic ceramic: Etching period and ultrasonic cleaning. F.P.P. LEITE1, M.G.A.M. CHAVES2, J.C.B. FARIA2, E. KIMPARA3, and M. ÖZCAN4, 1Unesp, Recife PE CEP, Brazil, 2Universidade Federal De Juiz De For a, Juiz de Fora, Brazil, 3Paulista State University, São josé dos Campos, Brazil, 4University of Groningen, Netherlands

Objectives: The following hypotheses were tested: (1) different etching periods with hydrofluoric acid (HF) do not effect the bond strength between a feldspatic ceramic and a resin cement; (2) ultrasonic cleaning of the precipitates created by HF application improve the bond strength. Methods: 48 blocks of Vita VM7 ceramic (VITA) (6x6x5mm) were obtained. The cementation surface of each block was duplicated in resin composite (W3D Master, Wilcos). Ceramic blocks were randomly assigned into 6 groups (n=8/per group): G1: etching with 10% HF (Dentsply) for 30s + Silane (Porcelain Primer, Bisco); G2: 10% HF for 1min + Silane; G3: 10% HF for 2min + Silane; G4: 10% HF for 30s + ultrasonic cleaning (Vitasonic) for 4min in distilled water + Silane; G5: 10% HF for 1min + ultrasonic cleaning + Silane; G6: 10% HF for 2min ultrasonic cleaning + Silane. The ceramic blocks were cemented to the composite blocks using the resin cement (RelyX ARC, 3M-ESPE). The cemented blocks were sectioned with a diamond disk under coolant irrigation to obtain microbars with 0.8mm² of bonding area. Each bar was attached to an adapted device and the microtensile test was performed using a universal testing machine. Results: The etching period did not create significant difference among the groups (P=0.156) but significant influence of ultrasonic cleaning was observed (P=0.001) (Two-way ANOVA and Tukey's test, á=0.05).The mean bond strengths (MPa) were as follows: G1: 16.2±3.5a; G2: 14.7±1.2a G3: 17.8±3.9a; G4:19.4±4.2b; G5: 19.2±1b; G6: 20±1.1b. Conclusions: The results confirmed the two tested hypotheses. Bond strength between the feldspatic ceramic and the tested resin cement is not effected by different etching periods with HF but ultrasonic cleaning increased the bond strength between the ceramic surface and the resin cement in all etching conditions.


0372 (110898)

Longevity of Resin Cements-Zirconium Oxide Ceramic Bonded Interfaces. R. CASTILLO DE OYAGÜE1, F. MONTICELLI2, M. TOLEDANO3, P. ESTEFAN1, M. FERRARI4, and R. OSORIO3, 1University of Madrid (U.C.M.), Spain, 2University of Zaragoza, Huesca, Spain, 3University of Granada, Spain, 4University of Siena, Italy

Longevity of resin cements-zirconium oxide ceramic bonded interfaces.

Raquel Castillo de Oyagüe1, Francesca Monticelli2, Manuel Toledano3, Piedad Estefan1, Marco Ferrari4, Raquel Osorio3.

 

1 Department of Prosthodontics, University of Madrid, UCM, Spain.

2 Department of Surgery, University of Zaragoza, Huesca, Spain.

3 Department of Dental Materials, University of Granada, Spain.

4 Department of Dental Materials and Restorative Dentistry, University of Siena, Policlinico “Le

  Scotte”, Italy.

 

Objectives: To evaluate the hydrolytic stability of different dual-cure resin cements when luted to zirconia ceramic. Methods: Eighteen cylinder-shaped zirconia ceramic blocks (Cercon Zirconia, Dentsply) were conditioned with: 1. sandblasting with 125 mm alumina (Al2O3) particles; 2. silica coating (50 mm silica-modified Al2O3 particles); 3. no treatment. Ceramic blocks were duplicated in composite resin (Tetric Evo Ceram, Ivoclar-Vivadent). Composite blocks were luted to pre-treated ceramic surfaces using: 1. Calibra (CAL; Dentsply Caulk); 2. Clearfil Esthetic Cement (CEC; Kuraray); 3. Rely X Unicem (RXU; 3M ESPE). After 24h storage, bonded samples were cut into microtensile sticks (1 mm2). Half of the sticks were loaded in tension until failure (crosshead speed of 0.5 mm/min). The remaining half was tested after six months of water storage at 37 ºC. Data were analyzed with three-way ANOVA and Tukey test for multiple comparisons (p<0.05). Results: Mean bond strengths (MPa) and standard deviations are reported in the table. Letters in rows and numbers in columns indicate significant differences. Bond strength of CEC significantly decreased after 6 months of storage, independently from the ceramic treatment. No significant differences in bond strengths were recorded for RXU after water aging. Using CAL, all samples failed prematurely except when luting sandblasted zirconia surfaces. Conclusions: The phosphate monomer-containing luting agent (CEC) and the self-adhesive cement (RXU) are suitable for luting zirconia ceramics. Resin-ceramic interfacial longevity depends on cement selection rather than on surface pre-treatments.

 

 

 

 

CEC

RXU

Cal

Mean (SD)

 

No treatment

 

24h

 

17.04 (5.7) A1

8.73(2.5) B1

-

6 months

10.82 (3.03) A2

6.59 (1.72) A1

-

 

Sandblasting

24h

18.63 (6.4) A1

11.44 (2.5) B2

10.84 (2.4) B1

 

6 months

 

11.82 (2.92) A2

13.16 (1.53) A2

-

 

Silica Coating

 

24h

18.19 (5.5) A1

8.88 (2.2) B1

-

 

6 months

 

15.36 (3.63) A2

6.07 (2.29) B1

-


0373 (110974)

Push-out Bond Strength of Cements on Class I Ceramic Inlays. P. MAURÍCIO1, C. MANSO1, S. FÉLIX1, M.V. BOLAÑOS-CARMONA2, and S. GONZÁLEZ-LÓPEZ2, 1Instituto Superior de Ciências da Saúde Egas Moniz, Almada, Portugal, 2University of Granada, Spain

Objectives: The purpose of this study was to compare push-out bond strength on ceramic inlays to tooth structure, using five luting materials in class I cavities.

 

Methods: Standardized class I were made in 50 intact caries-free, human extracted and perfused molars, with a special device made to prepare the cavities.

The standardized C C    eramic Inlays were made in IPS e.max Press® and luted on oclusal cavities. The molars were divided in five groups, according to luting cements: Group I - Excite® DSC + Variolink II®; Group II - Multilink® Sprint; Group III - Multilink® Automix; Group IV - Ketac Cem™ Aplicap; Group V - RelyX™ Unicem. Cementation procedures w   ere used according to manufacturers instructions. After storage for 48h at 37ºC and 100% humidity, the teeth were sectioned in disks: 1 of superficial dentin and 1 of deep dentin (circa 1.0mm). Each samples were tested in shear using an Universal Testing Machine - IBERTEST 500®, pushed out with a cross-head speed of 1.0m/min. Data were treated with analysis of variance one-way ANOVA, and Scheffexs test was used for post-hoc comparisons (α=0.05).

 

Results:

Group

Class I

Superficial

Mean(ds)

Deep

Mean(ds)

S vs D

Group I

13.18(1.97)a

25.34(2.85)e

*

Group II

12.55(3.40)a

19.88(3.15)d

*

Group III

8.50(2.05)b

10.73(4.57)b

NS

Group IV

2.73(0.57)c

5.38(1.93)a

***

Group V

11.16(2.02)ab

15.51(3.04)c

**

One way

By levels

F=37.376

p<0.001

F=57.871

p<0.001

Total

One way

F=35.921

p<0.001


Means with the same letter are statistically similar.

* p<0.001   ** p<0.005   *** p<0.05   NS p>0.05

ANOVA results showed that bond strength in Mpa to deep dentin was significantly higher than superficial dentin for 4 groups.

Groups I, II and V had higher bond strength. Groups III and IV had lower.

 

Conclusion: Dual cure mode cements had significantly higher bond strength than Self cure. Curing degree is an important factor that influences the bond strength.

 


0374 (111011)

Push-out Bond Strength of Cements on Class II Ceramic Inlays. C. MANSO1, P. MAURÍCIO1, S. FÉLIX1, M.V. BOLAÑOS-CARMONA2, and S. GONZÁLEZ-LÓPEZ2, 1Instituto Superior de Ciências da Saúde Egas Moniz, Almada, Portugal, 2University of Granada, Spain

Objectives: The purpose of this study was to compare push-out bond strength on ceramic inlays to tooth structure, using five luting materials in class II cavities.

 

Methods: Standardized class II were made in 50 intact caries-free, human extracted and perfused molars, with a special device made to prepare the cavities

The standardized C C    eramic Inlays were made in IPS e.max Press® and luted on oclusal proximal cavities. The molars were divided in five groups, according to luting cements: Group I - Excite® DSC + Variolink II®; Group II - Multilink® Sprint; Group III - Multilink® Automix; Group IV - Ketac Cem™ Aplicap; Group V - RelyX™ Unicem. Cementation procedures w   ere used according to manufacturers instructions. After storage for 48h at 37ºC and 100% humidity, the teeth were sectioned in disks: 1 of superficial dentin and 1 of deep dentin (circa 1.0mm). Each samples were tested in shear using an Universal Testing Machine - IBERTEST 500®, pushed out with a cross-head speed of 1.0m/min. Data were treated with analysis of variance one-way ANOVA, and Scheffexs test was used for post-hoc comparisons (α=0.05).

 

Results:

Group

Class II

Superficial

Mean(ds)

Deep

Mean(ds)

S vs D

Group I

16.76(6.47)ab

28.81(6.61)a

*

Group II

22.77(5.86)a

31.32 (8.23)a

**

Group III

9.95(3.43)bc

12.24(5.29)b

NS

Group IV

6.71(3.43)c

3.96(3.47)b

NS

Group V

19.80(7.71)a

30.57(8.35)a

*

One way

By levels

F=14.131;

p<0.001

F=35,305;

p<0.001

Total

One way

F=26.283, p<0.001

Means with the same letter are statistically similar.

* p<0.001   ** p<0.005   *** p<0.05   NS p>0.05

ANOVA results showed that bond strength in Mpa to deep dentin was significantly higher than superficial dentin for 3 groups.

Groups I, II and V had higher bond strength. Groups III and IV had lower.

 

Conclusion: Dual cure mode cements had significantly higher bond strength than Self cure. Curing degree is an important factor that influences the bond strength.

 


0375 (111052)

Bonding of Dual-Cured Resin Cements to Pre-Treated Aluminum-Oxide Ceramic. P. ESTEFAN1, R. CASTILLO DE OYAGÜE1, F. MONTICELLI2, M. TOLEDANO3, E. OSORIO3, and R. OSORIO3, 1University of Madrid (U.C.M.), Spain, 2University of Zaragoza, Huesca, Spain, 3University of Granada, Spain

Objectives: To evaluate the effect of sandblasting and tribochemical silica coating on the bond strength of dual-cured resin cements to pre-treated aluminum-oxide ceramic. Methods: Nine cubic-shaped aluminum-oxide ceramic blocks (Vita InCeram Alumina) were treated with: 1. airborne particle abrasion with 125 mm aluminum-oxide (Al2O3) particles (sandblasting); 2.  silica coating  (50 mm Al2O3 particles modified by silica); 3. no treatment. Each ceramic block was duplicated in composite resin (Tetric Evo Ceram, Ivoclar-Vivadent) using a silicon mold. Composite samples were luted to ceramic surfaces with three different dual-cured resin cements: 1. Clearfil Esthetic Cement (Kuraray); 2. Rely X Unicem (3M ESPE); 3. Calibra (Dentsply Caulk). After 24h storage (37ºC and 100% humidity), samples were cut into microtensile sticks (1 mm2) and loaded in tension until failure (crosshead speed: 0.5 mm/min). Failure modes were recorded. Bond strength data were analyzed with two-way ANOVA and SNK test for multiple comparisons (p<0.05). Results: Mean (SD) bond strength values (MPa) are shown in the table. Identical letters in columns and numbers in rows indicate no significant differences. No significant differences were recorded for Clearfil Esthetic Cement and Rely X Unicem independently from the ceramic pre-treatment. When using Calibra, all samples failed prematurely. A high percentage of mixed failures were recorded when using Clearfil Esthetic Cement on pre-treated ceramic surfaces. Conclusions: The phosphate monomer-containing luting system (Clearfil Esthetic Cement) and the self-adhesive resin cement (Rely X Unicem) may ensure reliable bonds to alumina ceramics. Resin cement selection rather than tested surface treatments play a crucial role when luting indirect adhesive-retained ceramic restorations.

 

Cement type

Surface treatment

No Treatment

Sandblasting

Silica Coating

Clearfil Esthetic Cement

13.27 (2.43) A1

13.42 (1.5) A1

11.61 (2.09) A1

Rely X Unicem

11.84 (1.32) A1

12.57 (1.14) A1

11.65 (1.64) A1

Calibra

Pre-testing failures

Pre-testing failures

Pre-testing failures

 

 


0376 (111657)

Freeze Casting of High Strength Ceramic Composites for Dental Applications. C. MILLER1, D. LATH1, T. WANG2, and R.V. NOORT1, 1University of Sheffield, United Kingdom, 2HP Technical Ceramics, Sheffield, United Kingdom

Hydroxyapatite (HA) is used in bone repair and augmentation, but its use is limited to low load-bearing applications. High strength cores for dental crowns are produced from pure zirconia (ZrO2) and alumina, however they cannot be bonded directly to the tooth tissues and significant post-densification machining is required. Ceramic composites of HA and ZrO2 have been produced. The materials have excellent biocompatibility, osteoconductivity, high strength and fracture resistance. In addition, the composites can be etched creating a microscopically highly retentive surface, allowing restorations to be bonded to tooth tissues using widely available dental composite resins. However, their potential use is limited by their manufacturing methods. Objectives: The aim of this research was to produce HA-ZrO2 composites by a novel manufacturing method known as freeze-casting. Fully densified near net shape objects can be produced, omitting costly machining, making the material and process a viable alternative. Methods: Solutions consisting of HA and ZrO2 powders of differing ratios and colloidal silica were cast into moulds and rapidly cooled using liquid nitrogen. The solution is solidified by an irreversible transformation of the colloidal dispersion. Therefore the resultant material remains solidified when removed from the mould and warmed to room temperature. The samples were then sintered at 1000°C to produce the final fully densified article. The composition and microstructure of the materials were evaluated using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results: All samples successfully cast except the 100% ZrO2. The optimum ratio for sample preparation was 70/30 HA/ZrO2. Initial results from powder XRD confirmed the ratios of the starting materials and resultant materials were comparable. SEM analysis showed a good distribution of HA and ZrO2. Conclusions: it was concluded that freeze casting is a valuable processing tool for the production of HA-ZrO2 composites for dental applications.


0377 (111804)

Improvement of Ti-ceramic bond strength using low melting point layer. C. HEGEDUS, L. DAROCZI, and D. BEKE, University of Debrecen, Hungary

Objective: Owing to its excellent biocompatibility, titanium has been used in health care, including in the prosthetic dentistry, for a long time. The relatively poor adhesion between Ti and covering dental porcelains is the most important drawback of its application. The surface modification of the titanium surfaces is a perspective way for the improvement of bonding strength. The aim of this study is to demonstrate the increase of bonding strength using a special intermediate alloy layer on the surface of the titanium. Methods: The bonding strength was measured by standard three-point bending test. For the mesurments, 2x10 identical Ti samples were cast from Dentitan (Dentaurum) with dimensions of 25mm x 3mm x 0.5mm. 10 samples were produced from each type of bonding systems a.) A low melting point alloy as a special intermediate layer was formed on the Ti surface by an additional firing process. b.) In case of control samples bonding materials (VITA) were fired followed the manufacturer's recommendations. Low fusion porcelain (Vita Titankeramik) was applied to the center of one of the sides of each Ti sample with dimensions of 8mm x 3mm x 1mm. The microstructure of the modified Ti surface was investigated by scanning electron microscope (Hitachi S-4800). The bending test measurements were performed by using an Instron 4302 instrument.Results: Data were statistically analyzed using two-way ANOVA and Tukey's test.The crack initiations test was a.) 29.8 ± 2.8 MPa b.) 37.7± 3.2 MPa respectively. Conclusions: Our new bonding process can improve the crack initiation test results, and the bond strength at the Ti- ceramic systems.

RET-DNR 06/423/2004.


0378 (111825)

Bond strength between intra-oral porcelain repair systems and Cerana restorations. N. NIKOLINAKOS1, M. BARBOUR1, B. MILLAR2, and I. BLUM1, 1University of Bristol, United Kingdom, 2King's College London, United Kingdom

Objectives: Cerana direct ceramic inserts (Nordiska Dental, Sweden), in common with all restorations, suffer deterioration and degradation in clinical service. In some circumstances it is preferable to repair, rather than replace, Cerana restorations. Although various methods have been suggested to establish adequate bond strength between porcelain and resin-based composites, there is currently no consensus regarding which repair protocol is most successful. The aim of this in vitro study was to evaluate the shear bond strengths of four intra-oral porcelain repair kits, based on different repair protocols, for the repair of Cerana inserts.

Methods: One hundred extra-large Cerana ceramic inserts were stored in artificial saliva for 21 days, thermocycled (5 and 55 °C, 1000 cycles) and randomised into 4 groups. Composite resin was bonded to the Cerana specimens using four porcelain repair systems: Ceramic Repair (Ivoclar Vivadent, Liechtenstein), Cimara (Voco, Germany), Clearfil Repair (Kuraray, Japan) and CoJet system (3M ESPE, Germany). Whenever the repair kit did not include its own repair composite resin, NanositTM composite resin (Nordiska Dental, Sweden) was used as the repair composite. Bonded specimens were stored in artificial saliva for 24 hours before being subjected to shear bond strength testing using a Universal mechanical testing machine.

Results: A one-way ANOVA (á = 0.05) revealed no statistically significant difference (p = 0.186) between any of the groups at a 95% confidence level. The means and 95% confidence intervals for the groups were as follows: Ceramic repair 23.5±4.4 MPa; Cimara 18.3±4.4 MPa; Clearfil 28±4.4 MPa; CoeJet system 22.2±4.4 MPa.

Conclusion: Within the limitations of this study, there was no clear advantage to using any one of the porcelain repair kits over any other, although there was a directional trend indicating that the combination Clearfil Repair Kit – NanositTM may be marginally superior to the other combinations.


0379 (109560)

Bond Strength of Denture Teeth to Base: a comparative study. A.A. AL KHERAIF, King saud university, Riyadh, Saudi Arabia

Objectives: This investigation evaluated the effect of Three Different polymerization Methods on the tensile bond strength of acrylic teeth to a processed denture base acrylic resin. Materials and methods: Light-polymerized (Rodex Heat Bayer), heat-polymerized ((ProBase Hot) and microwave-polymerized (Acron MC) acrylic resins were used. One brand of artificial teeth was milled to a fixed diameter according to ADA specification no. 15. Ten specimens were prepared from each of the denture base materials according to the manufactures, instruction. Specimen were placed in a custom alignment device and subjected to tensile force until failure. Data were statistically analyzed with Tukey test (P>0.05). Results: The results of this work indicated that the difference between heat-polymerized base (12.31 MPa) and microwave polymerized and light polymerized bases (6.04, 5.55 MPa respectively) highly significant But, no statistically significant difference between microwave polymerized base and light polymerized base. Conclusion: The results showed statistical significant difference between the different polymerization methods. Light polymerized showed only a small influence on bond strength.


0380 (110830)

Bond strength of denture teeth determined by modified bending test. R. LANG, S. BERNHART, M. ROSENTRITT, and G. HANDEL, University of Regensburg, Germany

Objectives: Bond strength between different denture teeth and a heat-cured denture base resin was determined by a modified three point bending test.

Methods: 192 specimens (5 mm x 5mm x 45 mm) of heat-cured denture base resin SR Ivocap Plus (Ivoclar-Vivadent) combined with 4 different acrylic denture teeth (Vitapan, VITA, G; Genios P, Dentsply, G; SR Orthotyp DCL and SR Orthotyp PE, Ivoclar-Vivadent, FL) were divided into six groups with different surface pre-treatments of teeth (A = teeth without pre-treatment, B = using Al2O3 250 µm, C = using monomer, D = using Al2O3 250 µm + monomer, Probase Cold, E = using Al2O3 250 µm + Palabond, Kulzer, F = using Rocatec, 3M ESPE). After 14 days of storage in water (37°C), all specimens were provided with a predetermined breaking point and loaded to fracture by three point bending test using a universal testing machine (Zwick 1446, v=2mm/min). Medians and 25%/75% percentiles were calculated. Statistics: Mann-Whitney-U-Test (a=0.05).

Results:

Bond strength [N]

Median (25%/75%)

A

B

C

D

E

F

Vitapan

115 (94/133)

105 (100/145)

110 (99/123)

91 (86/113)

139 (109/152)

151 (145/166)

SR Orthotyp DCL

102 (101/105)

114 (94/124)

113 (102/120)

147 (122/155)

142 (134/150)

150 (135/157)

SR Orthotyp PE

114 (111/124)

127 (120/139)

118 (117/140)

128 (113/155)

148 (129/162)

160 (149/163)

Genios P

116 (110/128)

121 (120/138)

116 (104/130)

123 (120/136)

157 (138/169)

138 (95/162)

 

Conclusions: This three-point bending test indicated a significant positive effect regarding bond strength between denture teeth and denture base resin concerning the method of teeth pre-treatment as well as the type of acrylic tooth used. The highest bond strength was found using pre-treatment methods E and F and using SR Orthotyp PE and Genios P teeth. This modified bending test showed more reliable results compared to the normal 3-point bending test.

 


0381 (111625)

Tensile Bond-Strength of Chairside Soft Denture Liners to Acrylic Resin. A. ATAY, E. SAGIRKAYA, M.E. COMLEKOGLU, E. CAL, C. ARTUNC, and A. KESERCIOGLU, Ege University School of Dentistry Department of Prosthodontics, Izmir, Turkey

Objectives: The purpose of this study was to investigate the bonding properties of four soft chairside lining materials to a denture base resin. Methods: Four different soft lining materials, two of silicone based: Mollosil(M), Detax; Ufi Gel SC(U), Voco; and the others acrylic based: Viscogel(V), Denstply; FITT(F), Kerr) were chosen. A conventional heat-cured polymethylmethacrylate ( PMMA ) was used as the denture base resin. PMMA resin bars (10x10x25 mm)(N=96) and 1 aluminum spacer bar to be replaced with lining materials (3x10x300 mm) were prepared and polished. Resin bars were divided into 4 soft liner groups (n=24/group) and 12 bars in each group were bonded to the other 12 with the liner. Bars in each group and spacer were invested in silicone rubber. Each liner was packed into the space remaining after the removal of the spacer, the mold was reassembled and the liners were processed according to the manufacturers' directions. All specimens were thermocycled(5-55°C, x1000) and placed under tension until failure in a universal testing machine (Autograph, Shimadzu, Japan) at a crosshead speed of 0.5 mm/min. The maximum tensile stresses (MPa±SD) and modes of failures were recorded. Complementary to the bond strength tests, failure modes were examined at 65 magnification under the Scanning Electron Microscope (JEOL JSM-5200, Kyoto, Japan) at the debonding site. The tensile bond strength (TBS) data were analyzed statistically with One-way ANOVA and Dunnett T3 tests (alpha=0.05). Results: Significant differences among soft liner groups were observed (Mª: 8.2±O.93; Ub:4.85±1.63; Fc:2.14±0.54; Vd:1.31±0.25) (P=0.000) (ANOVA). Mainly adhesive type of failures were observed in SEM. Conclusion: Silicone-based soft liners exhibited high tensile bond strengths to tested PMMA resin that might fulfill the requirements of chairside relining of full dentures.


0382 (111669)

Tensile Bond Strength of Hard Liners to Denture Resin. E. SAGIRKAYA, A. ATAY, E. COMLEKOGLU, E. CAL, C. ARTUNC, and A. KESERCIOGLU, Ege Universitesi, Izmir, Turkey

Objectives: To investigate the tensile bond strength of chairside hard denture liners to heat-curing polymethylmethacrylate (PMMA) denture base resin. Methods: Conventional heat-curing PMMA (I.Q.15 heat-cure, Imicryl) resin bars (20x13x14 mm.)(N=80) and 1 aluminum spacer bar to be replaced with lining materials (300x14x3 mm.) were prepared. Four different hard lining materials to replace the aluminum spacer bar : Ufi Gel Hard C, Voco(U); GC Reline, GC(G) ; self (IC) and heat-cured (IH) PMMA (Imicryl) were selected. Forty resin bars were bonded to the other 40 with these liners. Bars in each group (n=10/group)and spacer were invested in silicone rubber. Each liner was packed into the space remaining after the removal of the spacer, the mold was reassembled and the liners were processed according to the manufacturers' directions. The specimens were thermocycled (1000 cycles, 5-55°C) and placed under tension until failure in a universal testing machine (Autograph, Shimadzu, Japan, cross-head speed: 0.5 mm/min). Maximum tensile stresses (MPa±SD) and modes of failure were recorded. Fractured surfaces were examined by SEM (JEOL JSM-5200,Kyoto,Japan). The data were statistically analyzed (One-way ANOVA, Bonferroni,alpha=0.05). Results: Mean tensile bond strength values are: U=65.37±1.6, G=70.80±1.9, IC=44.02±1.3, IH=82.76±1.4. One-way ANOVA reveals that all the materials tested showed statistically significant differences from each other(p=0.000). According to Bonferroni post-hoc test, IC showed significantly lower tensile strength values than G (p<0.05), IC (p<0.05) and IH (p<0.05). No significant differences were seen between U-G(p>0.05), U-IH(p>0.05), U-IC(p>0.05). Conclusions: According to this in vitro study chairside hard reliners can be safely used in clinical conditions.


0383 (109722)

Effect of Surface Treatments on Retention of Quartz- Fiber Posts. A. DALLARI1, P. MASON2, L. ROVATTI1, and B. DALLARI3, 1University of Verona, Modena, Italy, 2UNIVERSITY OF PADOVA, Venezia Mestre, Italy, 3Private Practice, Modena, Italy

The use of quartz fiber-reinforced posts, adhesively luted into root canal, has increased in popularity for the post-endodontic restorations. Objectives: The aim of this in vitro study is to verify the influence of different surface pre-treatments on micro-tensile bond strength between quartz posts and composite luting cement. Methods: 50 quartz fibers posts (40 DT Light-Post, RTD, France + 10 Macro-Lock Post, RTD, France) have been subdivided into 5 groups: 1) 10 DT Light-Post with no surface treatment ( as control ). 2) 10 DT Light-Post pre-treated with hydrofluoric acid 9.6 % for 15 sec. 3) 10 DT Light-Post coated with industrial procedure by the factory. 4) 10 DT Light-Post pre-treated with methyl-methacrylate for 1 minute. 5) 10 Macro-Lock Post, with carved surface and not subjected to chemical pre-treatments. Posts have been luted using the same composite cement ( BisCem, Bisco, USA ) in plastic cylinders ( Endo Trainers, Frasaco, USA ), and slices 2.0 mm thick have been obtained with a diamond wheel ( Leitz 1600 ). Slices have been subjected to pull-out test with Instron Machine. Results: Group 1: 13.28 MPa; Group 2: 24.60 MPa; Group 3: 26.90 MPa; Group 4: 34.20 MPa; Group 5: 32.05 MPa. Conclusions: All the post-surface pre-treatments lead to a real (double or more) improvement of tensile bond strength values. Macro-retention provided by carving of the surface (Macro-Lock Post) and micro-retention obtained with methyl-methacrylate pre-treatment reached the highest results. Industrial coating of posts, because of good results and easy handling, seem to be a very interesting choice


0384 (109726)

Surface Pretreatments Affect the Failure Mode in Quartz Posts Cementation. L. ROVATTI1, P. MASON2, B. DALLARI3, and A. DALLARI1, 1University of Verona, Modena, Italy, 2UNIVERSITY OF PADOVA, Venezia Mestre, Italy, 3Private Practice, Modena, Italy

The effects of surface pre-treatment on the retention of quartz fiber endodontic posts are still not well understood. Objectives: the aim of this SEM study is to evaluate the failure mode of posts with different surface treatments adhesively luted in root canals and subjected to tensile strength with Instron machine. Methods: 40 posts (DT Light-Post, RTD, St Egreve, France) have been subdivided into 4 groups: 1) no surface pre-treatment (as control); 2) surface pre-treatment with hydrofluoric acid 9.6% for 15 sec ; 3) surface pre-treatment with methyl-methacrylate for 1 minute; 4) surface coated with industrial procedure by the factory. Posts have been luted in single-rooted human teeth by using the same dual composite cement (Calibra, Dentsply-Caulk, Milford DE, USA); the post-space was previously etched with orthophosphoric acid and treated with adhesive (XP Bond, Dentsply-Caulk, Milford, DE USA ). Slices 2.0 mm thick have been obtained with a diamond wheel (Leitz 1600), then subjected to pull-out test with Instron Machine. Results: in group 1 (no surface pre-treatment), posts observed with SEM seem to be completely free of luting agent, and the composite-to-dentine interface shows no gaps and/or detachments. In group 2, the presence of luting cement can be observed both at the resin-dentin interface and at the resin-post interface. In groups 3 and 4 a more homogeneous resin layer is visible at both interfaces, and only a few small areas seem to be free of composite cement. Conclusion: a purely adhesive failure mode occurs at the resin-post interface for all non-treated posts. All posts with surface pre-treatments show a mixed failure mode, with detachments at the resin-dentine and resin-post surface, and mostly with cohesive fractures in the composite resin cement, which leave a varying thick resin layer at the opposite interfaces.


0385 (110590)

The effect of chlorhexidine on attachment of root canal posts. R.M. LINDBLAD1, L.V.J. LASSILA2, P.K. VALLITTU2, and L. TJADERHANE3, 1City of Helsinki Health Centre, Finland, 2University of Turku, Finland, 3University of Helsinki, Finland

Objectives: Chlorhexidine is recommended as final disinfectant before endodontic obturation because of its substantive antimicrobial effect. Fiber-reinforced composite (FRC) posts are commonly used because of good biomechanical properties. Previous studies have shown chlorhexidine to be beneficial for long term stability at resin-dentin bond. The objective was to determine the effect of chlorhexidine on attachment of FRC root canal posts to dentine by composite resin luting cements.

Methods: Eighty human extracted third molar root canals were prepared for post cementation with each post systems' own burs. Four commercially available FRC posts (Glassix, D.T.Light-Post, Unicore, everStickPOST) with three cements (Duo-link with All-bond 2, PermaFlo DC with PermaFlo DC primers, RelyX Unicem) were used. After etching, except with self-etching RelyX Unicem, the post spaces were irrigated either with 2% Chlorhexidine (Consepsis) or physiological saline for 60s. The roots (n=5 per group) were cut into 2 mm thick dentine discs. The bond strength was measured with push-out method, and the failure mode was evaluated with a stereomicroscope. Two-way ANOVA with Tukeyxs post-hoc test was used to analyse the differences in bond strength, and Wilcoxon Signed Ranks Test to analyse the differences in failure modes.

Results: Unicore/PermaFlo DC and everStickPOST/RelyX Unicem showed significantly higher bond strengths than Glassix or D.T.Light-Post with Duolink both with saline and chlorhexidine. Chlorhexidine improved the bond strength slightly with all posts/cements except with D.T.Light-Post, but the differences were not statistically significant. However, with chlorhexidine significant reduction of adhesive failures towards dentin cohesive or mixed failures was observed with all posts/cements except with everStickPOST.

Conclusions: Chlorhexidine doesn't have adverse effects on post bond strength with any tested adhesive/cement, but may improve adhesion. 2% chlorhexidine can be recommended as final irrigant before post cementation.

Acknowledgements: The study was financially supported by the Finnish Dental Society Apollonia and the Academy of Finland.


0386 (111834)

Adhesion of various Core Build-Up Materials to RelyX Fiber Post. R. PEEZ, S. HADER, B. LACHERMEIER, and P. BRAUN, 3M ESPE AG, Seefeld, Germany

Objectives: The aim of this in-vitro study was to evaluate the influence of different surface treatments of RelyX™ Fiber Post (RLXFP, 3M ESPE) on the adhesion of Filtek™ P60, Z250, Supreme and Z100 composites (P60, Z250, SUPR, Z100 all from 3M ESPE).

 

Materials and methods: The conical part of RLXFP (Size 3) was used. The surface was either left untreated or silanized with RelyX™ Ceramic Primer (RLXCP) or treated with Adper™ Easy Bond Self-Etch Adhesive (ADEB) (all from 3M ESPE). Composites were added and light-cured (discs: d = 6,0 mm, h = 4,0 mm). All specimens were stored for one hour at 36 °C / > 95 % rel. humidity and for 23 hours in water at 36 °C, some were additionally thermocycled (5.000 cycles 5 °C / 55 °C) (TC). For adhesion testing a pull-off test was made (6 specimens; universal testing-machine; crosshead speed = 1 mm/min).

Results: Two way analysis of variances showed that coating (P < 0,05) had a significant effect on adhesion. Thermocycling did not have a significant effect on adhesion values (P > 0,05). Treatment of the post surface with ADEB resulted in increased bond strength compared to untreated or silanized surfaces.

 

 

Core Build-UP Material

Surface Treatment

P60

Z100

Z250

SUPR

None [24 h]

9,5 ± 2,1

20,3 ± 1,2

15,7 ± 1,6

19,2 ± 1,4

RLXCP [24 h]

15,7 ± 2,2

21,5 ± 0,6

19,0 ± 2,2

20,3 ± 1,1

ADEB [24 h]

27,4 ± 1,4

26,0 ± 0,8

27,5 ± 1,8

26,5 ± 0,9

ADEB [TC]

26,0 ± 1,2

27,0 ± 1,9

27,7 ± 1,7

26,0 ± 1,2

 

Conclusions: To increase adhesion of core build-up materials to fiber posts, surface treatment is recommended. While using the bonding agent ADEB with core build-up materials is advantageous, there is no need to silanize the post.

 


0387 (110049)

Heat-polymerized Acrylic Resin Repairs with Autopolymerizing & VLC Resins. C. BURAL, G. BAYRAKTAR, I. AYDIN, I. YUSUFOGLU, N. UYUMAZ, and M. HANZADE, University of Istanbul, Turkey

Objectives: Repair strength can be improved by the roughening of the surfaces of a fractured denture. This study investigated heat-polymerized specimens repaired with autopolymerizing and visible light curing resins after the repair sites were pre-treated with monomers or acetone to promote better adhesion. Materials and Methods: Fifty-four specimens (65x10x2.5 mm) were prepared and 48 of 54 specimens were sectioned to clinically simulate the denture fracture. Repair sites were pre-treated with heat-polymerizing, autopolymerizing monomers and acetone for 180 s and then repaired with autopolymerizing and visible light curing resins. After repairs, specimens were subjected to a 3-point bending test. Data were statistically analyzed with Student t-test to compare the difference between the specimens repaired either with autopolymerizing or visible light curing resin. LSD test was used for the post-hoc analysis of the effect of application of different agents between the repair materials at p<0.05. Results: Overall, flexural strength, strain, fracture load and extension values of specimens repaired with visible light curing resin were statistically higher than the specimens repaired with autopolymerizing acrylic resin for all types pre-treatment (p<0.05). When the repair sites were pre-treated with chemicals, repairs with VLC resins produced better mechanical results than the repairs with auto-polymerizing resin. Conclusion: In clinical use, chemical pre-treatment of repair sites of a fractured denture may result in stronger repairs.


0388 (110365)

Microscopic Evaluation of Sealing by Adhesives Between Glass-ionomers and Composites. B. CZARNECKA, K. SZEWCZYK, P. DERÊGOWSKA-NOSOWICZ, and E. PASZYÑSKA, Poznañ University of Medical Sciences, Poznan, Poland

Objectives: To evaluate the sealing of three dental adhesive systems when used between glass-ionomer cements, GIC (base), and resin composites (restorative).

Methods: The study used Fuji IX Caps (GC) (A) and Ketac Molar Aplicap (3M-ESPE) (B) and three different composite resins and bonding systems. Experimental groups were as follows: I: Four step etch-rinse-prime-bond Optibond (Kerr) with Point (Kerr); II: Three step etch-rinse-prime & bond Adper (3M-ESPE) with Valux (3M-ESPE); III: Self-etching Prompt (3M-ESPE) with Filtek Z250 (3M-ESPE). Glass-ionomers were prepared as cylinders (4mm diameter, 6 mm high). After setting, they were cut transversely and the cut surface used for bonding. Etching for groups I and II employed 37% phosphoric acid (30 s). The composite resin was applied in two 1 mm layers, each light-cured for 40 s. Samples were then cut with slow speed diamond saw and examined in the metallographic microscope and by SEM (Jeol).

Results: SEM showed Group I: Excellent seal with each GIC. Group II: Excellent seal with cement A, but distinct gaps observed in 50% of cement B samples. Group III: No sealing observed between composite system and either glass-ionomer. For cement A, gaps were 2-10 µm wide; for cement B 10 µm. Similar observations were made with the metallographic microscope at ambient pressure, hence these gaps are not artifacts created by the SEM vacuum.

Conclusion: Composite materials are capable of being bonded to glass-ionomer cements so that a complete seal exists at the interface. The four-step bonding system showed the most complete seal. The self-etching bonding system shows significant gaps at the interface and fails to bond properly with GIC.

Sponsored by Polish Ministry of Science and Higher Education No 1 T09B 089 30


0389 (110543)

Factors Affecting Bond Strength Between Resin Composite and Glass Ionomers. T. PAMIR, H.B. SEN, and O. EVCIN, Ege Universitesi, Izmir, Turkey

Objectives: The objective of this study was to determine the effect of various surface treatment modalities relating two different types of adhesive systems on shear bond strength of resin composite (RC) to glass ionomer cements (GICs).

Methods: Conventional (KetacTM Molar Quick ApplicapTM) or resin-modified (PhotacTM Fil Quick AplicapTM) glass ionomer cement samples were prepared in Delrin® mold. Two-step total-etching adhesive (AdperTM Single Bond 2) or single-step self-etching adhesive (AdperTM PromptTM L-PopTM) were applied on the set cements. In the total-etching adhesive group, surface of the samples were pre-treated with one of the following etching-time period using 37% phosphoric acid: (1) no etching, (2) 15 seconds, (3) 30 seconds and (4) 60 seconds. Self-etching adhesive was directly used. Following the adhesive application, RC (FiltekTM Z250) was placed upon the GICs. Thus, ten experimental groups, each having 15 samples were produced. Shear bond strength was measured in a universal testing machine, and the fractured surfaces were examined under a stereomicroscope.

Results: Bond strength of RC to conventional glass ionomer cement (C-GIC) was significantly lower than that of to resin-modified glass ionomer cement (RM-GIC) (p<0.001). There was insignificant interaction between GICs and adhesives (p=0.318). No significant differences were determined between single-step self-etching and two-step total-etching adhesive at any etching-time period (p>0.05). For total- etching adhesive, however, greater bond strength was obtained with 30 seconds etching-time compared to 15 seconds and no etching-time (p<0.05). Examination of the bonded interfaces revealed the adhesive-cohesive mix failure in all experimental groups.

Conclusion: Within the limitation of this study, the use of RM-GIC improves the bond strength of RC to GIC. Both two-step total-etching and single-step self-etching adhesive may be preferred in the bonding of RC to GICs. Optimal etching-time for total etching, however, seems like 30 seconds and up.


0390 (110947)

Adhesion of Resin Composite to HF-Exposed Tooth Surfaces in Repairs. O. KUMBULOGLU1, M. ÖZCAN2, M. TURKUN3, A. SARACOGLU3, and A. USER1, 1Ege Universitesi, Ýzmir, Turkey, 2University of Groningen, Netherlands, 3Ege Universitesi, Izmir, Turkey

Objectives: Intraoral ceramic repairs of fixed-partial-dentures (FPD) often include cervical recessions that requires conditioning of the cervical tooth surfaces after conditioning of ceramic with Hydrofluoric Acid (HF). This process may contaminate the exposed etched enamel or dentin during rinsing process. This study evaluated the influence of HF with two concentrations (5 and 9.6%) on enamel and dentin in repair bond strengths. Methods: Extracted human molar teeth (N=80, n=10 per group) with similar sizes were selected and randomly divided into 8 groups. Flat surfaces of enamel (Groups 1 to 4) and dentin (Groups 5 to 8) were created after wet ground finishing. Following conditioning protocols were tested on both enamel and dentin: a)Phosphoric acid (P)+HF (either 9.6 or 5%) (Ultradent HF or IPS Empress gel)+neutralizing agent (N)+Bonding agent (B) (Excite)+composite resin (C) (Tetric EvoCeram), b)HF (either 9.6 or 5%)+N+B+C. Repair resin was bonded onto the conditioned enamel and dentin in polyethylene molds incrementally. Each layer was light-polymerized for 40 s. All specimens were thermocycled (5-55oC, x6000) and subjected to shear test (universal testing machine, 1mm/min). Specimens debonded during thermocycling were considered 0 MPa. Results: Significant effect of conditioning protocols were found between the protocols (p=0.001) (ANOVA, alfa=.05). While the highest mean bond strengths (MPa) were obtained after phosphoric acid etching followed by 9.6% HF, neutralizing agent, bonding agent for both enamel (11.5±2.1) and dentin (7.3±1), the lowest were obtained when no phosphoric acid was applied (1.5± 1.6 - 1.9± 1.4 and 3.6±1 - 2.2±1.2 for enamel and dentin, respectively) (p<0.05 Dunnett-T3 post-hoc test). Conclusion: Contamination of the enamel or dentin surfaces with HF impairs the repair bond strength. Application of phosphoric acid before HF and the use of 9.6% concentration is recommended when dental tissues are to be repaired next to ceramic.


0391 (111276)

Effect of Master-point-taper to Bond-strength of Different Root Canal Sealers. E. NAGAS, E. ALTUNDASAR, and A. SERPER, Hacettepe University, Ankara, Turkey

Objectives: The aim this study was to compare the push-out bond strength of different tapered master points when three different root canal sealers were used.

Methods: Crowns of 45 extracted maxillary incisor teeth were removed, and the root canals were prepared with NiTi rotary files (0.06 taper, Profile, Maillefer/Dentsply) to ISO size 30. The roots were then randomly divided into three groups according to root canal sealers used: 1. AH Plus (Dentsply Caulk, Milford, DE), 2. Ketac-Endo (3M ESPE AG, Seefeld, Germany), and 3.EndoREZ (Ultradent, South Jordan, UT). The specimens in all groups were further sub-grouped according to obturation technique: a. .02 tapered gutta-percha master cone using lateral condensation of size 20 accessory gutta-percha cones, b. .04 tapered gutta-percha master cone using lateral condensation of size 20 accessory gutta-percha cones, c. .06 tapered gutta-percha master cone as a single cone. All specimens were stored at 37ºC and 100% humidity for 1 week to allow sufficient time for the sealer to set. Thereafter, the roots were cut perpendicular to their long axis to obtain a series of 1.0 mm thick discs. The bond strength of each test slice was measured with push-out testing machine. Statistical analysis was completed by using Kruskal-Wallis test with Bonferroni correction at p=0.05.

Results: Results showed that both the type of the master cone point and root canal sealer had significant effects on push-out bond strength (p<0.001). A statistical ranking for bond strength values was obtained as follows: AH Plus > KetacEndo >EndoRez and .06 tapered gutta-percha master cone > .04 tapered gutta-percha master cone > .02 tapered gutta-percha master cone.

Conclusion: Within the limits of this study, roots filled with single cone technique and AH-Plus had a significantly higher bond strength compared with all other groups tested.


0392 (109897)

Color stability of composite based temporary crown and bridge materials. S. HADER, U. HOHEISEL, R. HECHT, and C. THALACKER, 3M ESPE AG, Seefeld, Germany

Objectives: To compare color stability of composite based crown and bridge

materials with regard to exogenic staining against coffee and red wine.

 

Methods: Test samples (diameter: 20mm, height: 3.5 mm) for coffee test (n=3)

and red wine test (n=6) were fabricated of each material and cured for 1 hour

against glass plates at room temperature. The inhibition layer was removed

with alcohol. Cielab L*, a* and b* values were determined by using Hunterlab

Labscan Spectrocolorimeter (aperture: 12 mm; measuring field: 12 mm). Then

the test samples were immersed in coffee (extract of 200 g coffee with 1000 ml

boiling water) and red wine for 72 hours at 36°C. After removal test samples

were rinsed with water and cleaned with a toothbrush for 30 seconds on each

side. Cielab L*, a* and b* values were determined again and the discoloration

dE* was calculated. Descriptive statistics were performed by using one way ANOVA

with a Fisher test and a confidence interval of 95%. Results including standard

deviations (STD) are summarized in the table below.

Results:

Material

Red Wine

 dE* : (STD)

Coffee

 dE* : (STD)

New Protemp

3.13 (0.27)a

3.70 (0.28)a

 Structur Premium

5.92 (0.42)d

5.29 (0.67)b

Luxatemp Fluorescence

3,73 (0.35)b

7.99 (0.53)c

Integrity Fluorescence

3.73 (0.27)b

7.61 (0.42)c,d

Kanitemp Royal

5.26 (0.23)c

9.11 (0.69)d


 

New Protemp showed the best color stability over time in this in vitro test set up

with coffee or red wine staining solutions

 

Conclusions: These results are an indicator that New Protemp with its improved

surface properties has significantly better color stability than other composite based

crown and bridge materials and will be able to meet increasing aesthetical customer needs.

 

 


0393 (110741)

Roughness evaluation after surface treatments of aluminous ceramic. E. OSORIO1, B. LOPES2, A.C. ARANHA2, C.P. EDUARDO2, R. OSORIO1, and M. TOLEDANO1, 1University of Granada, Spain, 2University of São Paulo-USP, Sao Paulo, Brazil

Bond strength between high-alumina ceramic and luting cements may be improved if alumina surface roughness is increased. Objective: The aim of this study was to evaluate the influence of different surface treatments on surface roughness of In-Ceram Alumina (aluminous ceramic, 82% vol. alumina, infiltrated by glass: Vita). Methods: Ceramics blocks were polished (4000 grit) and following treatments were performed: 1) Sandblasting (SB)- airborne particle abrasion Al2O3 (110 μm particle size), (2.8 bars; 20s). 2) Rocatec System (RC)- after SB treatment, sandblasting with silica powder (50 μm particle size), (2.8 bars, 20 s). 3) Nd:YAG Laser (ND)- after SB treatment, application of graphite powder (stain) on the ceramic surface and Nd:YAG laser irradiation (distance: 1 mm; 100 mJ, 20 Hz, 2 W, and 141.54 J/cm2). 4) Nd:YAG Laser plus Rocatec System- after SB and ND treatments, RC was applied. Digital images (20x20 microns) from the surfaces were obtained by means of an AFM microscope in taping mode (Nanoscope IIIa- Digital Instruments). Roughness was measured in 10x10 microns boxes. Roughness (Ra) data (nm) were analyzed by One-way Anova (p<0.05). Results: Mean roughness (Ra-nm) and standard deviations are presented in the table. No differences were found between groups (P=0.5441). Conclusions: Tested treatments were not able to increase surface roughness of the tested alumina surfaces.

Acknowledgements:CICYT/FEDER-MAT2004-06872-C03-02,FAPESP#2005/01918-5.

 

Ra (nm)

Mean (SD)

Sandblasting

   279.64   (57.96)

Rocatec System

   277.01   (86.26)

Nd:YAG Laser

   262.09   (94.69)

Nd:YAG/Rocatec

   239.09   (56.67)  


0394 (110800)

Safety of Paint On Versus Tray Whitening: Randomized Controlled Trial. J.R.O.F. MARQUES1, D.N.S. MARQUES1, J.M.L. SILVEIRA1, J.R.C. CABRITA2, J.P.A.R. AMARAL2, and A.D.S.P. MATA1, 1Faculdade de Medicina Dentária da Universidade de Lisboa, Portugal, 2Instituto Superior de Ciências da Saúde Egas Moniz, Caparica, Portugal

Objectives: To study the clinical safety profile of two different whitening products using a paint on formulation or a customized tray designed for at home bleaching.

Methods: 60 patients attending a Portuguese dental school clinic were recruited for this study. This was a two arm parallel RCT in which each patient was randomized to one of two groups: Vivastyle Paint On Plus (PO+) with 6 % hydrogen peroxide (HP) designed as a paint on formulation or Vivastyle 10% (VS10) with 10% Carbamide Peroxide (CP) designed for customized tray at home use (both from Vivadent, Lichenstein PL). Bleaching regimen was followed as determined by manufacturer protocols. Safety parameters assessed were: Total amount of HP applied  (THP) determined by a cerium based titration method, HP released into the saliva (HPS) and HP remaining in oral cavity and tray/varnish after the bleaching period (HPR) determined by an established photometric method and expressed in Mean±S.E.M. of mg of HP per kg of bodyweight (mg/kg/bw). Mean differences were tested with Student t Test, significance level was set at α= 0.05. Total systemic HP exposure was recorded for each patient as over or under 0.26 mg/kg/day which is the threshold value for over exposure obtained from literature. This study was approved by the local ethical committee.

Results:

Product

THP (mg/kg/bw)

HPS (mg/kg/bw)

HPR (mg/kg/bw)

Mean

S.E.M.

Mean

S.E.M.

Mean

S.E.M.

VS10

5.437E-01

3.818E-02

4.773E-02

5,368E-03

4,700E-02

9,917E-03

PO+

1.091E-01

7.400E-03

4.742E-03

8,600E-04

2,525E-04

6,000E-05

In both groups tested, the number of patients with over recommended daily systemic exposure to HP, was equal to zero.

Conclusions: The results of this study suggest that both Paint on and tray whitening bleaching using 6% HP and 10% CP are safe regarding HP systemic exposure.


0395 (110846)

Effect of Experimental Coloring Agents on Biaxial Strength of Zirconia. J.I. HJERPPE1, L.V. LASSILA2, and P.K. VALLITTU2, 1University of Turku, Helsinki, Finland, 2University of Turku, Finland

Objectives: Shading of green-stage zirconia has previously been shown to affect to material strength. The aim of this study was to determine effect of experimental color shading agents on some mechanical properties of zirconia. Methods: 70 zirconia (ICE Zirkon, ZirkonZahn, Italy) discs (n=10/group) were divided into seven groups according to the different experimental color shading liquids the discs were dipped into: 1) Control discs were un-colored, 2) 2% ferrichloride (FeCl3), 3-4) 2% ferrichloride + 2% zirconiachloride (ZrCl4) + 2% yttriumnitrate [Y(NO3)] in two different proportions 10:1:1 and 10:2:2, 5) ZrCl4 containing 3Mol%Y, 6-7) 2% FeCl3 + 2% ZrCl4 (3Mol%Y) in two different proportions 10:1:1 and 10:2:2. All of the ceramic discs were sintered at 1500 °C in the sintering oven (ZirkonZahn). Biaxial flexural strength of the sintered discs (diameter 19mm, thickness 0.8mm) were measured dry at room temperature. Surface microhardness (VHN) was measured and the data was calculated using ANOVA-analysis. Results: Some of the shades revealed slightly lowered mechanical properties. Groups 2 and 5 had similar properties with the control group whereas groups 6 and 7 had some mechanical difference (p<0.05). No statistically significant difference (p>0.05) was found in terms of surface microhardness (VHN). Results were:

Group

Color shading agent

Flexural strength MPa (SD)

Vickers VHN (SD)

1

Control

1132 (162)a

1501 (194)

2

2% FeCl3

1027 (96)ab

1438 (117)

3

FeCl3:ZrCl4:Y(NO3) [10:1:1]

998 (99)ab

1469 (70)

4

FeCl3:ZrCl4:Y(NO3) [10:2:2]

961 (101)ab

1452 (57)

5

ZrCl4(3Mol%Y)

1031 (102)ab

1446 (44)

6

FeCl3:ZrCl4(3Mol%Y) [10:1]

901 (120)b

1488 (88)

7

FeCl3:ZrCl4(3Mol%Y) [10:2]

958 (135)b

1566 (84)

*Different superscript letter describes statistical differences in flexural strength (p<0.05).

Conclusions: Some reduction in flexural strength of zirconia occurred in terms of using different experimental color shading agents.


0396 (110887)

Effect of tooth-bleaching strips on gloss and color of composites. M. ANAGNOSTOU, G. CHELIOTI, S. CHIOTI, and A. KAKABOURA, University of Athens (EKPA), Greece

Objectives: The purpose of this in vitro study was to evaluate the gloss and color changes of hybrid and nano-hybrid resin composites after tooth-whitening strips and carbamide peroxide bleaching gel application. Materials and methods: The resin composites used were: a hybrid (Herculite-HR, Kerr) and a nano-hybrid (Premise-PR, Kerr), A2 shade and the bleaching agents: 10% carbamide peroxide bleaching gel (Nite White-NW, Discus Dental); 6.0% (Crest Whitestrips Classic-Cs, Procter&Gamble) and 14% hydrogen peroxide strips (Crest Whitestrips Supreme-Ss, Procter&Gamble). Three groups of disk-shaped (10x1mm thickness) specimens per resin composite were prepared (n=8), which were subjected bleaching treatment with the three agents evaluated, for two weeks, according to their respective protocols. Surface gloss and color (CIE-L*a*b* system) measurements were performed before (baseline) and after bleaching applications. Gloss changes were expressed as % value differences and color changes were assigned as ÄE relative to the baseline measurements. Statistical analysis of the % gloss differences and ÄE values were performed by two-way Anova and Sheffe's tests (a=0.05). Results: The gloss change (%) and ÄE values were, accordingly: HR-NW 45,6±7,1/1,0±0,3; HR-Cs 49,2±5,4/1,2±0,3; HR-Ss 50,6±4,2/0,8±0,2; PR-NW 29,6±5,8/1,9±0,7; PR-Cs 50,0±3,9/1,2±0,3; PR-Ss 41,7±4,1/1,4±0,2. Regarding gloss, Herculite revealed higher changes compared to Premise after NW gel and Ss application; Ss and Ps caused higher effect on Premise relative to NW, whereas no differences were established for Herculite. In respect to color, NW and Ss induced higher ÄE changes in Premise compared to Herculite; treatment of Premise with NW provided higher color changes than Cs and Ss. Conclusions: All bleaching agents provided gloss and color changes on the resin composites evaluated. More aggressive effect was noted on gloss than on color changes for both resin composites. The degree of the influence on gloss and color parameters is resin composite- and bleaching agent-depended.


0397 (110997)

Efficacy of Adaptable Versus Custom Tray Bleaching: Randomized Controlled Trial. D.N.S. MARQUES1, J.M.L. SILVEIRA1, J.R.O.F. MARQUES1, J.P.A.R. AMARAL2, J.R.C. CABRITA2, and A.D.S.P. MATA1, 1Faculdade de Medicina Dentária da Universidade de Lisboa, Portugal, 2Instituto Superior de Ciências da Saúde Egas Moniz, Caparica, Portugal

Objectives: To study the clinical efficacy of two different whitening products using a recently marketed adaptable versus a traditional customized tray formulation, both designed for at home bleaching.

 

Methods: 50 patients attending a Portuguese dental school clinic were recruited for this study. This was a two arm parallel RCT in which after initial screening visit and dental prophylaxis, each patient was randomized to one of two groups: Tres White Supreme (Ultradent, USA) (TWS) with 10 % hydrogen peroxide (HP) designed as an adaptable tray formulation or Opalescence 10%PF (Ultradent,USA) (OPL) with 10% Carbamide Peroxide (CP) designed for customized tray at home use. Bleaching regimen was followed as determined by manufacturer protocols. Efficacy was assessed visually using the Vita pan classical shade guide (VITAPAN classical, VITA Zahnfabrik, Bad Säckingen, Germany) on the facial surface of the six anterior maxillary and mandibular teeth at pre-treatment (PT), Half-treatment (HT) and End-treatment (ET). Of the twelve anterior teeth only the ones with a gradable VITA shade A3 or darker were selected at baseline. All shade guide colour evaluations were carried out under standard colour corrected operatory light and photo documentation of tooth shade was made. Efficacy was expressed in Mean±S.E.M. of vita shade guided values. Mean differences were tested with Student t Test, significance level was set at α= 0.05. This study was approved by the local ethical committee.

 

Results:

 

Product

Vita Shade Guided Values

PT (Mean±S.E.M.)

HT (Mean±S.E.M.)

ET (Mean±S.E.M.)

OPL

10.763±0.132

6.376±0.224

4.360±0.184

TWS

10.258±0.155

6.927±0.230

3.797±0.275

 

At end-treatment the Δ Vita shade improvement was 6.280±0.177 and 6.584±0.269, for OPL and TWS, respectively.

 

Conclusions: The results of this study suggest that both TWS and OPL bleaching using 10% HP and 10% CP achieved significant whitening and presented similar efficacy results.

 


0398 (111079)

Effect of Polishing Systems on Surface Roughness of Resin Composites. D. DIONYSOPOULOS1, E. KOLINIOTOU-KOUMPIA2, P. KOUROS1, L. ZAFIRIADIS1, and P. DIONYSOPOULOS1, 1University of Thessaloniki (AUTH), Greece, 2Aristotle University of Thessaloniki, Greece

Finishing and polishing of composite resins are important steps in restorative dentistry.

Objectives: The aim of this study was to evaluate the effect of different polishing systems on surface roughness of various resin composites.

Methods: The resin composites used in this study were:

A. Filtek Supreme (3M. ESPE) B. Admira (Voco) C. Alert (Jeneric/Pentron) and

D. Definite (Degussa).

Thirty specimens of each resin composite were polymerized for 40sec under a Mylar strip in cylindrical molds (6cm diameter, 3mm height). Each type of polymer was divided into five subgroups: unpolished, polished with abrasive disks Super-Snap (Shofu), polished with silicon-impregnated polishing devices Astropol (Ivoclar Vivadent), polised with Diacomp (EVE), and polished with Astrobrush polishing system (Ivoclar Vivadent). The surface roughness of each specimen was determined using a profilometer (Mitutoyo 5J 201) and by observation under a scanning electron microscope (JEOL, J.S.M.-840, Japan). Statistical analysis was performed using two-way ANOVA and Dunnett's test.

Results: The Mylar strip group had the lowest roughness value (Ra in ìm), (range: 0.08 to 0.11 Ra) and was significantly different from all of the polishing procedures (p<0.05). No significant differences in surface roughness among the materials were found on unpolished surfaces (p>0.05).

A significant difference was observed among the polishing procedures (p<0.05). The use of the Astrobrush polishing system caused the greatest roughness (range: 0.50 to 0.68 Ra) on all resin composites (p<0.05). The smoothest surface was produced with abrasive disks Super-Snap and Astropol .

Conclusion: The four composite resins used in this study display variable surface roughness depending on the polishing system used. The highest surface roughness values were achieved after the Astrobrush polishing system was used. The Super-Snap and Astropol provided the smoothest surface.


0399 (111135)

Surface Roughness of Composites Finished and Polished with Different Methods. I.H. BALTACIOGLU, O. IR