Effects of antioxidants on the microleakage of composite resin restorations after external tooth bleaching

OBJECTIVE To compare the effects of three antioxidants (sodium ascorbate, sodium ascorbate combined with a surfactant, and catalase) on the microleakage of composite resin restorations after external tooth bleaching with 10% carbamide peroxide. MATERIALS AND METHODS Buccal cavities were prepared on the surface of 60 intact premolars, which were randomly divided into six groups. All cavities were filled with composite resin. In group 1, teeth were not bleached; in group 2, cavities were filled immediately after bleaching; in group 3, cavities were delay-filled for 3 weeks; in group 4, cavities were treated with sodium ascorbate after bleaching and then filled; in group 5, cavities were treated with sodium ascorbate combined with surfactant after bleaching and then filled; and in group 6, cavities were treated with catalase after bleaching and then filled. Microleakage of the restorations was measured from sections using a stereomicroscope. RESULTS Group 1 displayed the least amount of microleakage, while group 2 showed the greatest amount of microleakage (P < 0.05). Groups 3 and 4 were similar to group 2 (P > 0.05). However, groups 5 and 6 showed a significantly lower amount of microleakage compared to group 2 (P < 0.05). CONCLUSION Microleakage increased significantly after external bleaching with 10% carbamide peroxide, and decreased when the bleached teeth were treated with sodium ascorbate combined with Tween(®) 80, or with catalase. Catalase was more effective in decreasing microleakage, while delayed filling or treatment with sodium ascorbate alone did not effectively decrease the microleakage.