Objective To evaluate the antibacterial effect of sodium hypochlorite solutions on four endodontic pathogens. Methods The agar dilution method was used to observe the antibacterial effect of sodium hypochlorite against selected endodontic pathogens Porphyromonas gingivalis（P.gingivalis）, Prevotella intermedius（P.intermedius）, Fusobacterium nucleatum（F.nucleatum）, Enterococcus faecalis（E.faecalis）. Minimum inhibitory volume fraction and minimum bactericidal volume fraction（MBVF） were performed. Results MIVF of sodium hypochlorite for P.gingivalis, P.intermedius, F.nucleatum, E.faecalis were 0.035%, 0.07%, 0.018%, 0.28% respectively, while MBVF were 0.035%, 0.07%, 0.035%, 0.28% respectively. The rankings of the microorganisms were from most to least effective: F.nucleatum, P.gingivalis, P.intermedius, E.faecalis. Conclusion Sodium hypochlorite had excellent antibacterial effects especially for anaerobic microorganisms. The antibacterial effect of 0.5%MBVF sodium hypochlorite can satisfy the clinical need.
