Antimicrobial action of calcium hydroxide, chlorhexidine and their combination on endodontic pathogens

BACKGROUND: The common recovery of Candida albicans and Enterococcus faecalis from failed root canals of teeth in which previous treatment has failed is notable. These organisms have been shown to be resistant to antimicrobial action of calcium hydroxide but are sensitive to chlorhexidine gluconate. The aim of the present in vitro study was to investigate the antimicrobial efficacy of calcium hydroxide paste, 2% chlorhexidine gel and their combination against Candida albicans and Enterococcus faecalis. METHODS: Inoculae of these organisms were used to make lawn cultures on Sabouraud's dextrose agar and blood agar plates. Wells were prepared with these lawn cultures and filled with calcium hydroxide paste, 2% chlorhexidine gel and their combination. The agar plates were kept overnight for incubation at 37 degrees C and the zone of inhibition was examined after 24 and 72 hours. RESULTS: The results suggest that 2% chlorhexidine gel alone is more effective at 72 hours than calcium hydroxide paste alone or in combination with 2% chlorhexidine gel against both the organisms, even though calcium hydroxide showed better antifungal efficacy against Candida albicans at 24 hours. CONCLUSION: In failed root canal treatments, 2% chlorhexidine gel may be a more effective intracanal medicament than calcium hydroxide paste or their combination against Candida albicans and Enterococcus faecalis.