Both dental caries and periodontal disease are biofilm-dependent oral diseases. Thus, innovative techniques for biofilm control are important in the management of these diseases. Studies on photodynamic antimicrobial therapy (PACT) have shown bacterial susceptibility to death when using photosensitive agents activated by a light source; however, the combination of nanoparticles to the photosensitive agent could enhance this effect. Thus, the objective of this study will be to test the effect of PACT on oral biofilm using methylene blue associated with nanoparticles of cyclodextrin and red laser light source (660 nm). This project will consist of two studies: 1. setting the activity parameters for PACT on Streptococcus mutans biofilm and 2. establishment of activity parameters for PACT in salivary micro-organisms microcosm biofilm model. The reduction of microorganisms will be assessed by viable micro-organism count of the biofilm before and after PACT in selective culture medium and also the proportion of live/dead micro-organisms will be evaluated by confocal laser microscopy. The decrease in log will be calculated by subtracting the initial values from the final values of CFU/mg of biofilm and evaluated by analysis of variance one-way followed by Tukey-Kramer test. The normal proportion of live/dead bacteria on the biofilm will be assessed by the Shapiro-Wilks test and the results will be evaluated by ANOVA or Kruskal-Wallis analysis of variance. The significance level of all statistical tests will be of 5%.
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