Intracanal medicaments: evaluation of the antibacterial effects of chlorhexidine, metronidazole, and calcium hydroxide associated with three vehicles.

The use of an intracanal medicament may be helpful in eliminating remaining bacteria that survived inside root canals after complete chemomechanical preparation. This study evaluated the antibacterial activities of medicaments that act by means of contact, and not by vapor release, against obligate and facultative anaerobic bacteria commonly found in endodontic infections. The medicaments used were 0.12% chlorhexidine gel; 10% metronidazole gel; calcium hydroxide plus distilled water, calcium hydroxide plus camphorated paramonochlorophenol (CPMC); and calcium hydroxide plus glycerin. An agar diffusion test was used, and the zones of bacterial inhibition around each medicament were recorded and compared. The results revealed that calcium hydroxide/CPMC paste was effective against all bacterial strains tested. Chlorhexidine was also inhibitory to all strains. It was about as effective as calcium hydroxide/CPMC paste against most of the strains. Metronidazole also caused inhibition of growth of all obligate anaerobes tested and was more effective than calcium hydroxide/CPMC against two strains. Calcium hydroxide mixed with distilled water or glycerin failed to show zones of bacterial inhibition, probably because of limitations of the agar diffusion test.