antibacterial efficacy of different concentrations of sodium hypochlorite gel and solution on enterococcus faecalis biofilm

introduction: this in vitro study compared the antibacterial efficacy of 2.5% sodium hypochlorite gel and 2.5% and 5.25% sodium hypochlorite solutions on enterococcus faecalis ( e. faecalis ) biofilm. methods and materials: the root canals of 60 extracted human single-rooted teeth were contaminated with e. faecalis and incubated for 6 weeks. the samples were randomly assigned to three experimental groups and one control group ( n =15). the study protocol in the experimental groups consisted of injection of 5 ml of each irrigant into the root canals. samples were collected from the root canal walls and 1:10 serial dilutions were prepared and added to muller hinton agar (mha) plates and incubated at 37 ° c for 48 h. a classic colony counting technique was used for determining vital e. faecalis bacterial counts in mha plates. the kruskal-wallis test was used for statistical analysis of the data. the level of significance was set at 0.05. results: the antibacterial effect of the irrigants in all three experimental groups was significantly greater than the control group ( p <0.05), with no significant difference between 2.5% and 5.25% naocl solutions ( p >0.05). the effect of 2.5% and 5.25% naocl solutions were significantly superior to 2.5% naocl gel ( p <0.05). conclusion: under the limitations of this study, 2.5% naocl gel was effective in reducing e. faecalis counts; however this effect was less than that of naocl solutions.