Efficacy of sodium hypochlorite combined with chlorhexidine against Enterococcus faecalis in vitro

The aim of this study was to investigate in vitro the efficacy of the combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) in different concentrations against Enterococcus faecalis compard with the antimicrobial activity of the same irrigating substances when applied alone. The substances tested were 2.0% CHX gel, 2.0% CHX liquid, 1% NaOCl, 2.5% NaOCl, 5.25% NaOCl, and combinations of them in the same proportions. Two methods were used: the agar diffusion test and the broth dilution test. The largest mean microbial growth zone was obtained by 2.0% CHX gel, and the smallest zones were obtained by 1% and 2.5% NaOCl (P < .05). 2.0% CHX (gel and liquid formulation), 5.25% NaOCl, and the combination of 2.0% CHX liquid and 5.25% NaOCl, all of which needed ≤1 min to eliminate E. faecalis. The association of NaOCl and CHX did not improve the antimicrobial activity of CHX alone.