RESUMO
Composite restoration microleakage has been reported following bleaching treatment. The purpose of this study was to assess the in-vitro effect of sodium ascorbate gel on microleakage of class V restorations on bleached teeth. Forty-eight premolar teeth were randomly divided into 4 equal groups. Class V cavities were prepared on the buccal surfaces of group 1 teeth [negative control] and they were restored. In groups 2-4, bleaching was applied by using 9.5% hydrogen peroxide gel. In group 2 [positive control] and group 3, [delayed bonding] teeth were restored immediately and one week later, respectively. In group 4, 10% sodium ascorbate gel was applied, rinsed and restored. After thermocycling, samples were immersed in fushin and then, sectioned. Leakage was assessed and penetration of dye was scored. Data were analyzed using Kruskal-Wallis and Dunn's tests. There were significant differences in terms of microleakage between group 2 and other groups [P<0.05]. Groups 1, 3 and 4 exhibited similar leakage patterns, and all groups demonstrated less leakage values than group 2. Regarding marginal microleakage, there were significant differences between enamel and dentinal margins. Applying sodium ascorbate gel or 7-day delay following bleaching technique may improve the marginal integrity of composite class V restorations