The efficacy of photodynamic therapy and sodium hypochlorite in root canal disinfection by a single-file instrumentation technique

Aim: The aim of this in vitro study was to evaluate the efficacy of photodynamic therapy (PDT) and sodium hypochlorite (NaOCl) in root canal disinfection by a single-file instrumentation technique. Material and methods: Seventy human single-rooted mandibular premolars were infected with Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans, and divided into seven groups (n=10) according to the protocol of disinfection used. Group 1: 1% NaOCl; Group 2: 5.25% NaOCl; Group 3: saline + PDT; Group 4:1% NaOCl + PDT; Group 5: 5.25% NaOCl + PDT; Group 6: positive control; Group 7: negative control. For PDT, methylene blue (15 mu g/mL) remained in the root canal for 2 min, followed by irradiation with diode laser. Samples were collected before and after instrumentation and plated in specific media cultures, to assess the presence or absence of microbial growth and determine the average reduction of viable microorganisms. Results: 5.25% NaOCl + PDT resulted in the highest number of specimens with no microbial growth. Also, 1% NaOCl and 1% NaOCl + PDT exhibited similar antimicrobial effects. Saline + PDT was not able to eliminate all microorganisms. There was statistical significant differences between the groups and the microorganisms. Conclusion: The association of 5.25% NaOCl with PDT was the most effective treatment against microorganisms from endodontic infection in root canals instrumented by a single-file instrumentation technique. This result shows that PDT can be useful to improve the root canal disinfection. (C) 2015 Elsevier B.V. All rights reserved.