in vitro comparison of the antibacterial effect of three intracanal irrigants and diode laser on root canals infected with enterococcus faecalis.

introduction: bacteria are the primary etiology of pulpal and periradicular pathosis. in endodontically treated teeth with persistent infections only one or a few bacterial species are present of which the most important is enterococcus faecalis. the aim of this study was to compare antibacterial efficacy of canal disinfectants including 5.25% sodium hypochlorite, 2% chlorhexidine, mtad (a mixture of doxycycline, citric acid and a detergent (tween 80) and 830 nm diode laser. methods and materials: the canals of 135 extracted single rooted human teeth were prepared using rotary instruments. the canals were contaminated with enterococcus faecalis for 4 weeks and then were divided into 4 groups of 30 teeth in each, a positive control group containing 10 teeth and a negative control group of 5 teeth. after using the disinfectants, samples obtained from canals by paper points and also shaving the canal walls were cultured. the kruskal-wallis test was used to analyze the results. results: the results showed the bacterial reduction as follows: 99.97 ± 0.14 for sodium hypochlorite, 99.65 ± 1.13 for chlorhexidine, 97.56 ± 6.36 for laser and 96.91 ± 5.60 for mtad. the count of cfu obtained from dentin shavings was:16/96 ± 91/23 for sodium hypochlorite, 82/73 ± 186/63 for chlorhexidine, 47/26 ± 112/21 for laser and 341/34 ± 1139/83 for mtad. conclusion: according to the results, sodium hypochlorite was the most effective agent against enterococcus faecalis .