Substantive antimicrobial activity in chlorhexidine-treated human root dentin

Objective. The aim of this in vitro study was to assess the substantive antimicrobial activity of different medicaments in human root dentin. Study design. Canals of 98 roots were enlarged to standard size and medicated for 7 days with the following: (1) 2% chlorhexidine (CHX) gel, (2) 0.2% CHX gel, (3) 2% CHX solution, (4) Ca(OH)(2), (5) Ca(OH)(2) + 0.2% CHX gel, (6) 2% CHX solution + a 25% CHX-containing control led-release device, (7) saline, and (8) gel vehicle. After medication, canals were inoculated with Enterococcus faecalis for 21 days. Dentin samples were collected with Gates-Glidden burs into brain heart infusion broth, and bacterial growth was assessed with spectrophotometric analysis of optical density after 72 hours of incubation. Results. Mean optical densities were significantly lower for groups with 2% CHX (1, 3, and 6) when compared with those of the controls (P <.05, analysis of variance with the Tukey test). Other groups did not differ significantly from the controls. Conclusions. Canal dressing for 1 week with 2% CHX may provide residual antimicrobial activity against E faecalis.