Effect of bromelain enzyme on the microleakage of composite resin restorations after external tooth bleaching: An in vitro study

AIMS: The aim of this study is to evaluate in vitro the effect of application of bromelain enzyme on the microleakage of composite resin restorations after external tooth bleaching using spectrophotometric evaluation. SUBJECTS AND METHODS: Buccal Class V cavities were prepared on the surface of fifty intact premolars, which were randomly divided into five groups. All cavities were filled with composite resin. Group I: Teeth were not bleached but restored (n = 10). External bleaching with 35% hydrogen peroxide was carried out for the rest of the specimens. Group II: Cavities were restored immediately after bleaching (n = 10). Group III: Cavities were restored after a delay of 3 weeks (n = 10). Group IV: Cavities were treated with sodium ascorbate after bleaching and then restored (n = 10). Group V: Cavities were treated with bromelain enzyme solution after bleaching and then restored (n = 10). Microleakage was assessed by the dye extraction method using a spectrophotometer. STATISTICAL ANALYSIS USED: The data were analyzed statistically by comparison of mean microleakage and post hoc test using SPSS 2.0 software. RESULTS: Group I displayed the least amount of microleakage, whereas Group II showed the greatest amount of microleakage (P < 0.05). Groups III, IV, and V showed a significantly lower amount of microleakage compared to Group II (P < 0.05). There was no statistically significant difference between Groups IV and V. CONCLUSIONS: Microleakage increased significantly after external bleaching with 35% hydrogen peroxide, and decreased when the bleached teeth were treated with antioxidants. Ten percent bromelain enzyme was effective in decreasing microleakage; however, its efficacy was similar to 10% sodium ascorbate.