Shear bond strength of indirect resin to NiCr with different metal surface preparations

This study sought to evaluate the shear bond strength of indirect resin to nickel chromium (NiCr) after different surface preparations. Sixty-four metal samples were divided into four groups, according to surface preparation, and two layers of opaque resin and three layers of body resin were applied. Each group was divided into two subgroups based on storage period in distilled water at 37 degrees C. Mechanical shear testing was performed using a universal testing machine with 0.5 mm/minute of cross-head speed. Debonded areas were analyzed and classified according to different failure types, such as cohesive, adhesive, and mixed. The storage periods were compared using a student T-test (alpha = 0.05); Group T (that is, the tin electroplating group) showed the highest average after 24 hours. The macro retentions showed higher shear bond strength than the sandblasted samples (p < 0.05). Tin electroplating did not improve the shear bond strength of metal-resin bonding. The results were not affected by 30-day storage, with the exception of group T (p < 0.05).