Effects of Internal Bleaching on Microtensile Bond Strength of a Former Veneer Composite to Tooth Enamel

Abstract

Background: At present, combined provision of direct composite restorations and dental bleaching has become increasingly popular to meet the esthetic demands of patients. This study aimed to assess the effect of internal bleaching on microtensile bond strength of composite to freshly veneered enamel. Methods: In this in vitro experimental study, 50 sound extracted human premolars were randomly divided into five groups (n=10). All teeth received composite veneers. Two groups underwent no further intervention and were subjected to measurement of microtensile bond strength of composite to enamel 24 hr and one week after the veneering. The remaining three groups underwent internal bleaching. Group 3 underwent bleaching one month after the veneering, and microtensile bond strength was measured after 24 hr. In groups 4 and 5, bleaching was performed immediately after the veneering. Microtensile bond strength was measured after 24 hr in group 4 and after one month in group 5. Data were analyzed using one-way ANOVA. Results: All the groups were not significantly different regarding the mean bond strength (p=0.110), but they were significantly different in terms of the mode of failure (p=0.01) such that the mode of failure was mainly adhesive in the three bleached groups. Conclusion: Internal bleaching after composite veneering has no significant effect on microtensile bond strength of composite to the enamel.