Influence of Chlorhexidine Application Time on the Bond Strength between Fiber Posts and Dentin

Introduction: The aim of this study was to investigate the effects of chlorhexidine (CHX) application time on the bond strength and durability of the adhesion of fiber posts relined with resin composite to the root dentin. Methods: Eighty bovine incisor roots were divided into 4 groups after root preparation: control group (irrigation with physiological solution) and experimental groups, CHX for 30 seconds, CHX for 60 seconds, and CHX for 120 seconds. Fiber posts relined with resin composite were cemented with RelyX ARC. The Scotchbond Multi-Purpose total-etching adhesive system was used in half of the samples of each group, and the Clearfil SE Bond self-etching adhesive system was used in the other half. The samples were randomly divided into 2 subgroups, 24 hours of storage and 12 months of storage. All roots were sectioned transversely, and push-out tests were performed. Bond strength means were analyzed by analysis of variance and Tukey test (alpha = 0.05). Failure mode was determined by examining specimen's surfaces under scanning electron microscope, and its distribution was evaluated by using x(2) test (alpha = 0.05). Results: CHX pretreatment resulted in homogeneous bond strength values at 24 hours and 12 months of storage, irrespective of the CHX application time and adhesive system (P < .05). A significant bond strength decrease was noticed after 12 months of storage when irrigation was performed with physiological solution in the control groups (P> .05). Significant differences were observed for fracture patterns (P < .001). Conclusions: The use of CHX pretreatment could preserve the bond strength of the fiber post relined with resin composite to root dentin for 12 months, irrespective of the CHX application time and adhesive system used.