Evaluation the antibacterial efficacy of sodium hypochlorite in combination with two different photodynamic therapy protocols against Enterococcus Faecalis in Infected root canals: An in-vitro experiment

Background: Photodynamic therapy (PDT) is an antimicrobial approach that can be used as an adjunctive safe technique for root canal disinfection. In this study, we aimed to evaluate the antibacterial efficacy of PDT with indocyanine green and toluidine blue in combination with sodium hypochlorite (NaOCl) in compared with NaOCl alone against Enterococcus faecalis in infected root canals.Methods: Sixty five root canals of sound human premolars were collected. First, the teeth were sterilized, then 60 root canals were inoculated with the E. faecalis, and 5 samples served as negative control remained uncon-taminated. The contaminated root canals were randomly assigned into 4 experimental groups (n=15): (1) NaOCl, (2) NaOCl+ PDT-1 (toluidine blue + 630nm LED), (3) NaOCl+ PDT-2 (indocyanine green + 808nm diode laser), and (4): positive control (no treatment). Then, the colony-forming units (CFU/mL) of E. faecalis were calculated in all the groups. Moreover, 5 samples from each group were examined under a scanning electron microscope. The data were analyzed by independent T-test and the Mann-Whitney U test at the significance level of 0.05.Results: The CFU count was significantly lower in the indocyanine green-PDT group in comparison with other groups (p<0.05). The mean of CFU in the positive control group was significantly higher than the other groups (p<0.05). No significant difference was detected between NaOCl and toluidine blue -PDT group (p=1.00). Conclusion: Indocyanine green-PDT improved the antibacterial effects of NaOCl against E. faecalis, while tolu-idine blue - mediated PDT had no significant additional effect on NaOCl.