Objective:To evaluate the effectiveness of a mixture of calcium hydroxide and chlorhexidine digluconate for root canal disinfection.Methods:The 105 subjects for this study were selected from the patients of out-patient clinic.The canal was packed with either 2% chlorhexidine and Ca(OH)2 slurry(35 samples) or aqueous Ca(OH)2 slurry(35 samples) or 2% chlorhexidine(35 samples).The bacterium samples of root canals were obtained in every visit for 3 visits.Every sample in each group harbored enterococcus faecalis was cultured.Then every subject was followed up for one year to get the message about treatment state.Results:After two intracanal disinfection

5 teeth where enterococcus faecalis were found at the initial sampling were successfully disinfected when Ca(OH)2 was mixed with 2% chlorhexidine.Only 3 of the 5 teeth with initial content of enterococcus faecalis were successfully disinfected in Ca(OH)2 group and 4 of 5 teeth with initial content of enterococcus faecalis were successfully disinfected in 2% chlorhexidine group.The infection rate of enterococcus faecalis in mixture medicine group was lower than in other two groups in the second visit and there were statistical differences(P<0.05).The failure number in mixture group was less than in other two goups in one-year follow-up

but there was no statistical difference(P>0.05).Conclusion:A mixture of 2% chlorhexidine and Ca(OH)2 slurry has effective disinfection for enterococcus faecalis in failure cases of root canal therapy and is worth of further study.