Atividade antimicrobiana da terapia fotodinâmica sobre biofilme de Enterococcus faecalis no sistema de canais radiculares: estudo in vitro

Abstract

The purpose of this study was to evaluate in vitro antimicrobial activity of Photodynamic Therapy (PDT) in the root canal system, using different concentrations of photosensitizer toluidine blue (TBO) and laser doses on biofilms of Enterococcus faecalis, ATCC 51299. Used 42 extracted human teeth, single-rooted and the canals prepared to rotary instrumentation. The teeth were autoclaved and canals inoculated with a suspension Enterococcus faecalis in brain heart infusion and were incubated for 21 days. The specimens were subjected to PDT using combinations with different concentrations of the photosensitizer TBO (0.5, 5 and 10μg/ml) and irradiation times (60, 120, 300 and 600s) equivalent to doses of energy 6, 12, 30 and 60J, using an optical fiber intracanal and irradiation with diode laser (GaAlAs) to 100mW. The controls groups no treatment. Before and after the respective treatments the canal contents were sampled with sterilized paper points, the sample was dispersed in transport medium, serially diluted and culture on blood agar to determine the number of colony forming units per mL (CFU / mL). The data obtained in the microbiological analysis (CFU / mL) were analyzed by analysis of variance and Tukey test. And to confirm biofilm formation, two specimens of each group were selected and analyzed by scanning electron microscopy (SEM). Combinations of TBO 0.5μg/ml and 600s and TBO 5μg/ml, 10μg/ml and in all irradiation times tested resulted in significant reduction of micro-organisms but the combination TBO 5μg/ml and 600s showed significantly higher percentage of reduction. It was concluded that the use of PDT with the photosensitizer TBO and laser irradiation low power presents significant antibacterial action on biofilm of Enterococcus faecalis, is a promising therapy in the face of persistent micro-organisms to conventional endodontic treatment.