Chlorin as a photosensitizer for photodynamic therapy on Streptococcus mutans

Abstract

Photodynamic therapy (PDT) has shown to be effective in reducing pathogenic microorganisms from the oral cavity, helping in the treatment of stomatological diseases until then treated in a conventional manner. Different photosensitizers for PDT have been described, including chlorin. However there are no studies in the literature that tested the effects of PDT mediated chlorin against cariogenic bacteria, such as Streptococcus mutans. Thus, the aim of this study is to evaluate the effect of photodynamic therapy (PDT), mediated by the association of the photosensitizer chlorin and laser light of gallium arsenide and aluminum, on planktonic cultures and biofilms formed by S. mutans. For the planktonic cultures study, standardized suspension of S. mutans will be add in 96 well plates. For the biofilm study, enamel fragments will be made from bovine incisor teeth as substrate for the biofilm formation in 24-well plates. The planktonic culture growth and biofilms will be treated according to the experimental groups: photosensitization and laser irradiation (F+G+); only laser irradiation (G-F+); only photosensitizer (F+L-); and a control group without treatment (F-L-). The results will be analyzed by S. mutans CFU/ml counting in agar Brain Heart Infusion (BHI) incubated for 48 h at 37°C under microaerophilic conditions. After the treatments, the biofilms formed on the enamel fragments will be analyzed by Atomic Force Microscopy seeking to detect the effects of PDT on the biofilms surface. Statistical analysis will be performed by Analysis of Variance (ANOVA) and Tukey test. In all experimental tests will be used GraphPad Prism 5.0 software, with 5% of significance level. (AU)