Efficacy of chlorhexidine- and calcium hydroxide-containing medicaments against Enterococcus faecalis in vitro

Objective. We sought to assess the efficacy of chlorhexidine (CHX) and calcium hydroxide, Ca(OH)(2), against Enterococcus faecalis in vitro. Study design. The effect of CHX (0.2% and 2% in gel or solution) and Ca(OH), (alone or with 0.2% CHX gel) was evaluated by using the agar diffusion test and an in vitro human root inoculation method, to measure zone of inhibition or bacterial growth with optical density analysis, respectively. For optical density analysis, samples from infected root canals were collected after 7 days of medication and were cultured for 24 hours in brain-heart infusion to detect viable bacteria. Results. In the agar diffusion test, CHX was effective against E faecalis in a concentration-dependent fashion, but Ca(OH)(2) alone had no effect. In the root canal inoculation test, CHX was significantly more effective against E faecalis than Ca(OH)(2) was (P <.05), but there were no significant differences between the modes of medication or concentrations of CHX. Conclusions. CHX is effective against E faecalis in vitro. Further in vivo studies are needed to confirm the value of CHX in clinical treatment.