Antimicrobial activity of 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate separately and combined, as endodontic irrigants.

Sodium hypochlorite irrigant is known to be toxic to periapical tissues. Chlorhexidine gluconate, a safer and effective antimicrobial irrigant, is not known to dissolve pulpal tissues. To obtain their optimal properties, their combined action within the root canal was evaluated. Ten single rooted nonvital anterior teeth were irrigated using either 2.5% sodium hypochlorite alone, 0.2% chlorhexidine gluconate alone, 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate combined within the root canal, or 0.9% saline, respectively. Microbiological samples for culture and Gram's staining were taken before and proceeding irrigation. This study indicates that the use of sodium hypochlorite and chlorhexidine gluconate combined within the root canal resulted in the greatest percentage reduction of postirrigant positive cultures. This may be due to formation of "chlorhexidine chloride," which increases the ionizing capacity of the chlorhexidine molecule. This reduction was significant compared to use of sodium hypochlorite alone but not significant compared to use of chlorhexidine gluconate alone.