effect of smear layer on the push-out bond strength of two endodontic biomaterials to radicular dentin

introduction : this in vitro study was designed to evaluate the effect of smear layer removal on push-out bond strength of white mineral trioxide aggregate (wmta) and calcium-enriched mixture cement (cem). materials and methods: dentin discs with 3 mm thicknesses were divided into 4 groups ( n =15): group 1: irrigation of the canal with normal saline and filling with wmta; group 2: irrigation with sodium hypochlorite (naocl) and ethylenediaminetetraacetic acid (edta), and then filling with wmta; group 3: same as group 1 but the lumens were filled with cem; group 4: same as group 2 but the lumens filled with cem. the samples were incubated at 37 ° c for 3 days after wrapping in gauze pieces moistened with distilled water. the push-out bond strengths were then measured by the universal testing machine and the failure modes were examined under a stereomicroscope at 40× magnification. data were analyzed using two-way anova and post-hoc tukey’s test for bond strength. statistical significance was set at p <0.05. results: the greatest and lowest mean standard deviation for push-out bond strength were observed for groups 4 (3.13±1.46 mpa) and group3 (1.44±0.96 mpa), respectively. the effect of smear layer removal on push-out bond strength of cem was significant ( p =0.01), however, it was not significant for wmta ( p =0.52). the failure mode for all the groups was of mixed type. conclusion: under the limitations of this study, smear layer removal is recommended for cem in order to gain higher push-out strength.