| 0765 Blue-light activated photosensitizers generate ROS for endodontic disinfection | ||
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O. ZAPATA, University of Geneva -Section of Dental Medicine, Switzerland, J. WATAHA, University of Washington, Seattle, USA, N. LANGE, University of Geneva -School of Pharmacy, Switzerland, J. SCHRENZEL, University of Geneva-School of Medicine, Switzerland, and S. BOUILLAGUET, University of Geneva-Section of Dental Medicine, Switzerland Objectives: Photo-activated disinfection has been proposed for endodontic disinfection because light-activated photosensitizers can kill bacteria by generating lethal levels of reactive oxygen species (ROS). In the current study, we compared the amount of ROS generated in aqueous solution by conventional disinfectants (NaOCl, H2O2) with those induced by photoactivation strategies. Methods: Toluidine blue was activated with a red (660-675 nm)diode laser (PeriowaveTM, Odine Biopharma,Canada);Riboflavin and Pheophorbide a-PLL, were activated using an Optilux 501 light-curing unit (Kerr-Hawe, Bioggio, Switzerland) emitting blue light (350-500 nm). Sodium hypochlorite and hydrogen peroxide were used as controls. ROS generation was measured using an iodine/triiodine colometric assay (n=4 per condition). Each chemical was mixed with buffer (0.5 M) and potassium iodide (KI, 1.5 M) before the UV absorption of the solution was recorded at 350 nm. ROS production was plotted versus concentration of the chemicals and a least squares linear regression analysis was used to determine the slope of the best fit line. The appropriateness of the linear model was assessed using R2 and the presence of a non-zero slope also was tested (&alpha=0.05). One-way ANOVA with Tukey post-hoc analysis (&alpha=0.05) was used to compare the efficiencies of ROS production for the various chemicals. Results: NaOCl and H2O2, produced ROS spontaneously, but pheophorbide a-PLL, riboflavin, and toluidine required light exposure. Slopes of least squares regression lines varied from 0.006 OD/µmolar for NaOCl to 7.5 OD/µmolar for pheophorbide a-PLL. All slopes were non-zero (p<0.05). The efficiency of ROS production was significantly higher for Pheophorbide a-PLL, followed by toluidine blue and riboflavin. Sodium hypochlorite was the least efficient ROS producer. Conclusion: The current study demonstrated the possible utility of blue-light activated photosensitizers as producers of ROS that would be useful for endodontic disinfection This study was supported through grant #310000-119938 of the Swiss National Sciences foundation | ||
| Seq #83 - Microbiology - Disinfection, Antibacterial actions 11:30 AM-1:00 PM, Friday, September 12, 2008 Queen Elizabeth II Conference Centre Poster Hall 2 | ||
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