Effect of internal bleaching agents on the bond strength of glass fiber posts to root dentine

Abstract

Objective: This study evaluated the effect of internal bleaching agents on the bond strength of glass fiber posts to root dentine. Methods: Seventy bovine teeth were divided into 7 experimental groups (n=10) according to the bleaching agent used: SpH - sodium perborate + 20% hydrogen peroxide; SpW - sodium perborate + distilled water; Cp37 - 37% carbamide peroxide; Cp16 - 16% carbamide peroxide; Cp10 - 10% carbamide peroxide; H - 35% hydrogen peroxide; C - no bleaching agent (control). After bleaching, posts were cemented with a self-Adhesive resin cement (RelyX U100) and the roots were crosssectioned to obtain two discs from each third. The posts underwent micropush-out testing, and bond strength values (MPa) were analyzed using ANOVA in a split-plot arrangement and the Tukey test (p<0.05). Failure mode was evaluated under confocal microscopy. Results: There were no significant differences between the control and bleaching agent groups. Bond strength was greater in the cervical third of the 16% carbamide peroxide (Cp16) group than in the sodium perborate + 20% hydrogen peroxide (SpH) group. The cervical third had a higher bond strength than the apical third in the 10% carbamide peroxide (Cp10), 16% carbamide peroxide (Cp16) and sodium perborate + distilled water (SpW) groups, and no significant differences in the other groups. Adhesive cement-dentine failure was prevalent in all groups. Conclusion: The use of internal bleaching agents did not decrease the bond strength of glass fiber posts to root dentin.