Comparing the Efficacy of Toluidine Blue, Methylene Blue and Curcumin in Photodynamic Therapy Against Enterococcus faecalis

Introduction: Antimicrobial photodynamic therapy (aPDT) as a supplement to the conventional root canal preparation has shown promising results. Previous studies have adopted various combinations of light sources and photosensitizers, which makes it difficult to compare the disinfection efficacy of different PDT protocols. The aim of the present study was to compare the efficacy of three photosensitizers (toluidine blue, methylene blue, and curcumin) in PDT using LED against Enterococcus faecalis in root canal disinfection. Methods: Root canals of 54 single-rooted extracted teeth were prepared using the ProTaper Gold rotary system and were incubated with E. faecalis for three weeks. They were then randomly divided into five experimental groups and a control group: (1) Irrigation with 2.5% NaOCl for 30 seconds, (2) NaOCl irrigation followed by TB-PDT, (3) NaOCl irrigation followed by MB-PDT, (4) NaOCL irrigation followed by curcumin-PDT, (5) Curcumin solvent (1% ethanol+1% BSA), (6) Control (irrigation with normal saline). Sampling was done by collecting dentin shavings from the root canals, and colony-forming units were determined for each treatment group. The data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. The significance level was set at P˂0.05. Results: In all treatment groups, the mean values of colony forming unit (CFU) decreased by 99% compared to the control group. The lowest mean values of CFU were observed in groups 2 and 4, followed groups 3, 1, and 5 respectively. The mean CFU count in group 2 was significantly lower than that of group 1 (P value=0.011), while there were no significant differences among groups 1, 3, and 4 (P value >0.05). Conclusion: The adjunction of toluidine blue-mediated PDT by means of a light-emitting diode to NaOCl irrigation increased its antibacterial efficacy against E. faecalis and could be an effective complementary method in root canal disinfection.