Evaluation of Photodynamic Therapy Efficacy in Eliminating Enterococcus faecalis Biofilm: A Preliminary Study

Background. Photodynamic therapy is a new treatment protocol used in many areas of medicine. It has the potential to eliminate bacteria, fungi and parasites that may cause different pathological states. Objectives. The aim of the study was to evaluate the efficacy of a specific photodynamic protocol in the reduction of Enterococcus faecalis biofilm inside the canals of extracted teeth. Material and Methods. Thirty two extracted human, single-rooted, single-canalled, fully developed teeth were subjected to observation under in vitro conditions. After chemomechanical preparation, the specimens were infected with a clinical strain of E. faecalis and divided into four groups. Two served as a positive and a negative control group. The first of the experimental groups was subjected to a single photodynamic protocol with the use of toluidine blue as a photosensitizer and laser light for the induction of reaction. In the second experimental group, photodynamic protocol was repeated on the previously irradiated specimes. The last group was disinfected with 5.25% NaOCl. The CFU method was used to determine the number of viable bacterial colonies inside the root canals after completion of the experiment. Results. The single application of PDT eliminated 78% of the initial Enterococcus faecalis colonies. The repeated photodynamic protocol reduced 86% of the bacteria colonizing the root canal dentine. Irrigation with 5.25% NaOCl completely disinfected the internal surface of the root canal. Conclusions. Photodynamic therapy is an effective antibacterial protocol and can be used as a complementary disinfecting method after conventional endodontic treatment