Quimioterapia fotodinâmica antimicrobiana (PACT) em veículo surfactante para inativação de micro-organismos periodontopatogênicos

Abstract

Periodontal disease (PD) is a chronic inflammatory disease caused by the presence of bacterial biofilm. As a complementary treatment to conventional treatment of periodontitis, antimicrobial photodynamic chemotherapy (PACT) aims at the production of reactive oxygen species, eliminating residual microorganisms. The aim of this study was to evaluate the behavior of PACT with phosphate buffered methylene blue (PBS) and surfactant vehicle (0.25% SDS) on the bacterial death of A. actinomycetemcomitans and P. gingivalis. For this, two distinct groups were created with 4 subgroups: control group, laser group (irradiated for 5 min), photosensitizer group at 100 µM (FS) without irradiation, and PACT group with FS and 1, 3 and 5 min of irradiation. A laser (Photon Lase III, DMC, São Carlos, Brazil) with a wavelength of 660 nm, output power of 0.1 W, well irradiation of 250 mW/cm2, energy of 6.18 and 30 J was used. corresponding to the time of 60, 180 and 300s and radiant exposure of 15, 45, 75 J/cm2. Subsequently, they were grown into anaerobiosis, counted and converted to colony forming units per mL for analysis and comparison. MBSDS (0.25% methylene blue in SDS) was found to have a smaller amount of dimers compared to MBPBS (methylene blue in PBS). A. actinomycetemcomitans showed microbial death in PBS, but in SDS no reduction was observed. On the other hand, P. gingivalis was sensitive to PACT and in the presence of SDS, the toxic and phototoxic effects were more evident. It is concluded that the presence of SDS may lead to different responses, depending on the metabolic behavior of each microbial species.