the antibacterial efficacy of photo-activated disinfection, chlorhexidine and sodium hypochlorite in infected root canals: an in vitro study

introduction: this study compared the efficacy of light-activated low-power laser, 2% chlorhexidine (chx) and 2.5% naocl in eliminating enterococcus faecalis ( e. faecalis) from the root canal system. methods and materials: the root canals of 60 maxillary central incisors were contaminated with e. faecalis and then the bacteria were incubated for 24 h. all the root canals were instrumented in a crown-down manner with #4 and 3 gates-glidden drills, followed by race rotary files (40/0.10, 35/0.08, and 30/0.06). the samples were randomly assigned to three experimental groups and one control group ( n =15). in the control group no intervention was made. in the photo-activated disinfection (pad) group, laser therapy was undertaken with diode laser beams (with an output power of 100 mw/cm 2 ) for 120 sec. for the other two experimental groups, root canals were irrigated either with 5 ml of 2% chx or 2.5% naocl solutions, respectively. the kruskal-wallis test was used to compare the cfu values of the bacteria and post-hoc bonferroni test was used for pairwise comparisons. the level of significance was set at 0.05. results: the inhibition of bacterial growth in all the experimental groups was significantly superior to the control group ( p <0.05). there was no significant difference between the effect of pad and 2% chx ( p =0.05). the effect of 2.5% naocl was significantly better than that of the pad technique ( p <0.001). in addition, 2.5% naocl was significantly better than 2% chx ( p =0.007). conclusion: photodynamic therapy was effective in reducing the e. faecalis counts in comparison with the control group, but 2.5% naocl solution was the most effective protocol.