[Effect of catalase on marginal microleakage of resin restoration after external bleaching].

PURPOSE: To investigate the effect of catalase on marginal microleakage of resin restoration after external tooth bleaching with 10% carbamide peroxide. METHODS: Forty extracted human premolars, both intact and health, were randomly divided into 4 groups: group 1, direct composite resin filling without bleaching; group 2, composite resin filling immediately after external bleaching; group 3, immersed in artificial saliva for 3 weeks after external bleaching ,then filling with composite resin; group 4 ,cavity treated with catalase after external bleaching and then filled with composite resin. After 2000 thermal cycles, the teeth were immersed in 2% methylene blue for 24 hours, then the microleakage of interface of resin restorations was observed under stereomicroscope. The data were analysed with SPSS17.0 software package. RESULTS: Group 1 displayed the least amount of microleakage, while group 2 showed the greatest amount of microleakage, group 3 behaved similarly as group 2, having great amount of microleakage, with no significant difference (P>0.05); the microleakage of group 4 decreased significantly (P<0.05) compared to group 2. CONCLUSIONS: The microleakage increases significantly after external bleaching with 10% carbamide peroxide, then decreases if cavities are treated with catalase, but delay filling can not improve microleakage effectively.