Synergistic antimicrobial efficacy of 2% Chlorhexidine and 3% Hydrogen Peroxide for infected extracted human teeth: An Ex-Vivo Study

An endodontic irrigation solution with low toxicity and high antimicrobial activity is required in the process of endodontic treatment. Using a combination of intracanal irrigants is one solution to achieve this goal. The aim of this study was to evaluate the synergistic antimicrobial efficacy of chlorhexidine and hydrogen peroxide against bacteria in the infected extracted human root canals. Forty-two teeth with periapical lesions were chosen for this study. The teeth were extracted and preserved in normal saline at 37°C for less than 24 hours. Canals were prepared with nickel titanium rotary files (S1 to F3) and irrigated with 10cc of the respective irrigants (group 1:14 teeth irrigated with 3% hydrogen peroxide; group 2: 14 teeth irrigated with 2% chlorhexidine and group 3: 14 teeth irrigated with a combination of 3% hydrogen peroxide and 2% chlorhexidine). Samples were obtained with paper cones before and after root canal preparation (S1, S2) and transferred to a microbiology lab for colony counting. Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests. The results showed that all the understudy irrigants significantly decreased the bacterial colony count. A combination of chlorhexidine and hydrogen peroxide was significantly more effective than hydrogen peroxide. Chlorhexidine is an effective irrigant with high antimicrobial activity but its antimicrobial efficacy does not significantly increase in combination with hydrogen peroxide.