Evaluation of antimicrobial activity of different photodynamic therapy protocols in root canals infected by Enterococcus faecalis biofilm: an in vitro study

Abstract

Photodynamic therapy (PDT) is based on physical, chemical and biological processes occurring when a photosensitizer (FS) is activated by laser or LED to destroy a target cell. Microbial studies have shown the reduction of Enterococcus faecalis by endodontic PDT, enhancing the action of biomechanical preparation and intracanal medication. However, there are no studies comparing the green indocyanine with other FS commercially available. The objective of the present study is to analyze different protocols of PDT testing the FS methylene blue, curcumin and green indocyanine in the elimination of E. faecalis biofilm. The canals of 60 single-rooted extracted human teeth will be mechanically prepared for the study. The canals will be inoculated with E. faecalis and incubated for 14 days at 37°C. After the inoculation period an initial sample collection will be performed with paper points (S1). Distribution of experimental groups: G1-Saline (negative control); G2-Chlorhexidine 2% (positive control); G3-Methylene Blue 0.01%; G4-Curcumin 0.05%; G5-Indocyanine Green 0.05% (1W); G6-Indocyanine Green 0.05% (3W). After PDT in each group, a second sample collection will be performed with the paper points immediately after PDT(S2), and then the specimens will be inoculated with sterile BHI broth and stored at 37 ° C for 7 days for a third collection (S3). After each collection the samples will be homogenized, diluted, cultured and incubated for 18 to 24 hours at 37oC. After the incubation period, the number of colony forming units will be counted. The obtained data will be submitted to the normality test and the means compared by specific statistical tests with a significance level of 5%.