Objective: The purpose of this study was to evaluate, in vitro, the effectiveness of photodynamic therapy and sodium hypochlorite over root canal system infected with Enterococcus faecalis.Methods: The root canals of 45 single-rooted human extracted teeth were enlarged up to a file 60, autoclaved, inoculated with Enterococcus faecalis and incubated for 30 days. The samples were divided into five groups (G1 – n=5; G2-G5 – n=10) according to the protocol of decontamination: G1 (negative control)

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... no procedure was performed; G2 – distilled water; G3 – hotodynamictherapy (PDT); G4 – 2.5% sodium hypochlorite (NaOCl); and G5 – 2.5% NaOCl+PDT. Scanning electron microscopy (SEM) were performed to evaluate the effectiveness of proposed treatments. The assessment was made by images of each third at 5000x magnification for the canal wall and 10000x for the exposed tubule area. The presence of bacteria was scored by position ranks from 1 to 45, where the higher the value, the cleanliness of the sample. Data were subjected to one-way ANOVA followed by post-hoc Tukey test (α=0.05).Results: Group 4 (2.5% NaOCl) and 5 (2.5% NaOCl + PDT) had the highest mean of position ranks for all thirds of the root canal in the canal wall, which was statistically different from groups 1, 2 and 3 (p<0.05). Group 3 (PDT), group 4 (2.5% NaOCl) and 5 (2.5% NaOCl+PDT) had the highest mean of position ranks in the exposed tubule area, which was statistically different from groups 1 and 2 (p<0.05).Conclusion: the association of 2.5% sodium hypochlorite + photodynamic therapy can be considered an effective protocol for the elimination of Enterococcus faecalis.