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.