Residual antimicrobial activity associated with a chlorhexidine endodontic irrigant used with sodium hypochlorite

To evaluate the in vitro efficacy of 2.0% chlorhexidine gluconate (CH) as an endodontic irrigant combined with the traditional irrigant, sodium hypochlorite (SH).

Extracted single-rooted human teeth were instrumented using one of three regimens: CH alone; SH alone until instrumentation with the last file, at which time CH was used as the filing irrigant; or SH alone followed by a single rinse with CH. After instrumentation, 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 absorbed with an endodontic paper point, and the canal was irrigated and refilled with sterile water. The paper points containing root canal fluids were assayed for antimicrobial activity by placing them on agar plates inoculated with Streptococcus mutans, and measuring zones of inhibition after incubation.

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 teeth.