Bacteriologic evaluation of the effect of 0.5 percent sodium hypochlorite in endodontic therapy

The antibacterial effect of 0.5 percent sodium hypochlorite solution as root canal irrigant was studied in fifteen single-rooted teeth. Each tooth was treated at five appointments, and the presence of bacteria in the root canal was studied on each occasion. No antibacterial intracanal dressings were used between the appointments. When 0.5 percent hypochlorite was used no bacteria could be recovered from twelve of fifteen root canals at the fifth appointment. This should be compared with eight of fifteen root canals when saline solution was used as irrigant. These results suggest that 0.5 percent sodium hypochlorite solution is more effective than saline solution as a root canal irrigant.