Effect of Chlorhexidine and Ethanol on Push-out Bond Strength of Fiber Posts under Cyclic Loading

Purpose: To investigate the effects of pretreatment with 2% chlorhexidine in a gel base (CHX) and 100% ethanol (EtOH) on the bond strength between fiber posts relined with resin composite and root dentin under cyclic loading. Materials and Methods: Forty bovine incisor roots were divided into four groups after phosphoric acid etching: group 1 (control), irrigation with physiological saline solution; group 2, 5 min pretreatment with CHX; group 3, 1 min pretreatment with EtOH; group 4, 5 min pretreatment with CHX followed by 1 min with EtOH. Fiber posts relined with resin composite were cemented with RelyX ARC and the etch-and-rinse adhesive system Scotchbond Multi-Purpose. Each group was randomly divided into two subgroups: 24 h of storage (immediate groups) and cyclic loading (loading groups) with 250,000 cycles in a controlled chewing simulator. All roots were sectioned transversely and push-out tests were performed. Failure modes were observed and the bond strength means were analyzed using ANOVA and Tukey's test (alpha = 0.05). Results: The mean values for the bond strength test (MPa) in immediate groups were: group 1, 5.44 +/- 1.48; group 2, 5.57 +/- 1.41; group 3, 5.49 +/- 1.48; group 4, 5.57 +/- 1.42. Immediate groups showed similar bond strength values (p > 0.05). In the cyclic loading groups, the bond strength values were: group 1, 2.80 +/- 0.79; group 2, 4.02 (1.30); group 3, 4.50 +/- 1.67; group 4, 4.97 +/- 2.00. After cyclic loading, a significant decrease in the control group was observed (p 0.05). Conclusion: Chlorhexidine and/or ethanol pretreatment preserved the bond strength of the fiber post after cyclic loading.1618792FAPERGS grant [2010/00100-7]FAPERGS grant [2010/00100-7