RESUMO
BACKGROUND: Tooth bleaching has become a routine treatment due to patients' esthetic demands. PURPOSE: The aim of this study was to evaluate how prerestorative home-bleaching affected microleakage of resin composite restorations bonded with etch-and-rinse and self-etch adhesives. MATERIALS AND METHODS: Fifty extracted human premolar teeth were used. The bleaching agent (10% carbamide peroxide) was applied to the buccal surface of each tooth for 6 hours a day for 2 weeks. The lingual surfaces of the same teeth received no application (control). The teeth were stored in artificial saliva. After 14 days, standardized Class V cavity preparations (2 mm high, 3 mm wide, and 2 mm deep) were made on the buccal and lingual surfaces with all margins in the enamel. They were randomly divided into five groups according to the adhesive systems: an etch-and-rinse adhesive (Single Bond [SB]), two two-step self-etch adhesives (Adper SE Plus [ASE] and One Coat [OC]), and two one-step self-etch adhesives (Adper Easy One [EO] and G-Bond [GB]). All adhesives were applied according to the manufacturers' instructions. The preparations were then restored using the same hybrid composite (Filtek Z250) in one increment and light-cured. The teeth were thermocycled (5/55 degrees C, 1,000x) and immersed in dye, then sectioned, and dye penetration was scored. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Although statistically significant differences were found between the adhesive systems in the bleached teeth, no differences were observed in the control groups (non-bleached teeth). There were significant differences between SB/GB, SB/EO, SB/OC, and GB/ASE in the bleached teeth (p < 0.05). When comparing bleached and non-bleached teeth within each adhesive system, only SB and EO produced higher leakage scores when bleaching was applied. The other groups showed no difference in terms of bleaching (p > 0.05). CONCLUSION: Prerestorative home-bleaching had an adverse effect on microleakage of SB and EO. CLINICAL SIGNIFICANCE: The effect of prerestorative home-bleaching agents on microleakage of composite resin restorations differs according to the type of adhesive material used.
