Residual antimicrobial activity associated with a chlorhexidine endodonticirrigant used with sodium hypochlorite

Purpose: To evaluate the in vitro efficacy of 2.0% chlorhexidine gluconate (CI-I) as an endodontic irrigant combined with the traditional irrigant, so dium hypochlorite (SH). Materials and Methods: Extracted single-rooted huma n teeth were instrumented using one of three regimens: CH alone; SH alone u ntil instrumentation with the last file, at which time CH was used as the f iling irrigant; or SH alone followed by a single rinse with CH. After instr umentation, each root canal was dried with endodontic paper points, filled with sterile water, and maintained in a water-saturated environment. At 6, 12, 24, 48 and 72 hours after instrumentation, the root canal fluid was abs orbed with an endodontic paper point, and the canal was irrigated and refil led with sterile water. The paper points containing root canal fluids were assayed for antimicrobial activity by placing them on agar plates inoculate d with Streptococcus mutans, and measuring zones of inhibition after Incuba tion. Results: Comparisons of the results obtained from the three treatment regimens indicated there were no significant differences (P > 0.5) in the relative in vitro antimicrobial activity remaining in the three groups of t eeth.