coronal microleakage of three different dental biomaterials as intra-orifi ce barrier during nonvital bleaching

background: this study was designed to assess the microleakage of glass-ionomer (gi), mineral trioxide aggregate (mta), and calcium-enriched mixture (cem) cement as coronal orifi ce barrier during walking bleaching. materials and methods: in this experimental study, endodontic treatment was done for 70 extracted human incisors without canal calcifi cation, caries, restoration, resorption, or cracks. the teeth were then divided into three experimental using “simple randomization allocation” ( n = 20) and two control groups ( n = 5). the three cements were applied as 3-mm intra-orifi ce barrier in test groups, and bleaching process was then conducted using a mixture of sodium perborate powder and distilled water, for 9 days. for leakage evaluation, bovine serum albumin marker was traced in a dual-chamber technique with bradford indicator. the kruskal-wallis and mann-whitney tests were used for statistical analysis. results: the mean ± standard deviation leakage of samples from negative control, positive control, gi, mta, and cem cement groups were 0.0, 8.9 ± 0.03, 0.47 ± 0.02, 0.48 ± 0.02, and 0.49 ± 0.02 mg/ml, respectively. statistical analysis showed no signifi cant difference between three experimental groups ( p > 0.05). conclusion: it is concluded that gi, mta, and cem cements are considered as suitable intra-orifi ce barrier to provide coronal seal during walking bleaching. key words: calcium enriched mixture cement, coronal barrier, nonvital bleaching, rmgic,wmta