The effect of metronidazole on the anaerobic microorganisms of the root canal--a clinical study.

The antibacterial effect of 0.25% metronidazole solution as root canal irrigant on anaerobic bacteria was studied in ten central incisors. Each tooth was treated at four appointments, and the presence of anaerobes in the root canal was studied on each occasion. No antibacterial intracanal dressings were used between the appointments. No anaerobes could be recovered from any tooth on the fifth appointment. In the control group, where normal saline was used as an irrigant, anaerobes could be recovered in four of the ten canals. These results suggest that 0.25% metronidazole solution is more effective than saline solution as a root canal irrigant.