ABSTRACT
BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) is a new technique introduced in endodontics that combines the action of a photosensitizer (dye) and a low intensity light source. Currently, there are no PDT studies evaluating the microbial disinfection of root canals in order to compare the effects of light delivery systems in the photosensitizer activation. The aim of this study was to evaluate the PDT effectiveness in reducing Enterococcus faecalis, with and without the aid of an intracanal optical fiber. METHODS: Extracted single-rooted teeth were selected, instrumented, inoculated with E. faecalis and divided into six groups: one control group (untreated), one conventionally-treated group (1% NaOCl irrigation) and four PDT-treated groups. Irradiation (diode laser) was performed with (OF) or without an intracanal optical fiber (NOF) using two different irradiation times: 1 min and 30 sec (IT(90)) or 3 min (IT(180)). Samples were collected before and after testing procedures and CFU/mL was determined. RESULTS: The greatest reduction of E. faecalis (99.99%) was achieved with irrigation with 1% NaOCl. PDT also significantly reduced E. faecalis in the following decreasing order: OF/IT(180), NOF/IT(180), OF/IT(90) and NOF/IT(90), with no significant statistical difference among the groups. CONCLUSIONS: These results suggest that PDT was effective against E. faecalis, regardless of the use of an intracanal optical fiber.