Antioxidants reduce microleakage of resin-based composite fillings and the associated toxicity after bleaching human teeth

Background: Bleaching teeth is popular because the discoloration is a major people’s concern. This study aimed to compare the effect of three antioxidants on the microleakage of composite resin filling after bleaching teeth with 35% H2O2, thus minimizing the potential clinical toxicity of filling materials entering patients’ body. Methods: Sixty-six extracted intact teeth were included in this study. After preparation of a ClV cavity on the buccal surface, the teeth were randomly divided into six groups (n=11, each). Except for group A (control), all others were bleached. Cavities in group A were filled with composite resin.  In group B, the samples were immediately restored after bleaching while in group C, the filling was delayed for two weeks after bleaching. In groups D, E, and F, the cavities were treated with either sodium ascorbate, ascorbic acid, or vitamin C, and the filling restored. Teeth were sectioned and the microleakages examined microscopically, and the data were analyzed statistically. Results: Group A showed the least amount of microleakage. In Group B, there was a significant increase in the microleakage when the samples were filled immediately after bleaching. The microleakages among groups of C, D, E, and F were similar to those in group A.  Conclusions: The microleakage increased significantly after bleaching with 35% H2O2, while treating dental cavities with the antioxidants effectively reduced the microleakage. Thus, delayed filling is a useful approach to minimize the microleakage. The findings help reduce or prevent the clinical toxicity arising from the microleakage of filling materials.