Chlorhexidine Preserves Dentin Bond <i>in vitro</i>

TLDR

Hybrid layer degradation, partly driven by matrix metalloproteinases, compromises resin‑dentin bond stability. The study tested whether chlorhexidine, an MMP inhibitor, slows resin‑dentin bond loss. Specimens from extracted third molars were split, with one half receiving standard adhesive/composite and the other half treated with 2 % chlorhexidine after etching; both groups were stored in artificial saliva (± protease inhibitors) and evaluated by microtensile bond strength and SEM failure analysis immediately and after 6 months. After 6 months, chlorhexidine significantly preserved bond strength and reduced hybrid layer failures, while protease inhibitors had no effect, indicating chlorhexidine may help maintain dentin bond strength.

Abstract

Loss of hybrid layer integrity compromises resin-dentin bond stability. Matrix metalloproteinases (MMPs) may be partially responsible for hybrid layer degradation. Since chlorhexidine inhibits MMPs, we hypothesized that chlorhexidine would decelerate the loss of resin-dentin bonds. Class I preparations in extracted third molars were sectioned into two halves. One half was customarily restored (etch-and-rinse adhesive/resin composite), and the other was treated with 2% chlorhexidine after being acid-etched before restoration. Specimens were stored in artificial saliva with/without protease inhibitors. Microtensile bond strengths and failure mode distribution under SEM were analyzed immediately after specimens’ preparation and 6 months later. With chlorhexidine, significantly better preservation of bond strength was observed after 6 months; protease inhibitors in the storage medium had no effect. Failure analysis showed significantly less failure in the hybrid layer with chlorhexidine, compared with controls after 6 months. In conclusion, this in vitro study suggests that chlorhexidine might be useful for the preservation of dentin bond strength.