Effect of cement film thickness on shear bond strengths of two resin cements.

Abstract

Objective: The purpose of this study was to determine the effect of cement thickness on the shear bond strength of two commercial adhesive resin cements, Panavia-F and Super-Bond C&B when used to bond nickel-chromium alloy to bovine dentine. Materials and methods: Ni-Cr alloy discs, Ø5x3 mm and bovine teeth (120 pairs) were bonded together by two different resin cements (Super Bond C&B and Panavia F) at four different film thicknesses (50, 100, 150 and 200 micrometers). After bonding, they were stored in 37°C water for 24 h. Shear bond test at a crosshead speed of 0.5mm/min was performed. The fracture surfaces of the specimens were observed by scanning electron microscope. Results: Panavia F showed the shear bond strength ranged from 4.02±1.44 MPa to 9.32±2.40 MPa, whereas Super Bond C&B showed a shear bond strength ranging from 5.01±1.38 MPa to 7.10±2.70 MPa. Both cements showed maximum shear bond strength to Ni-Cr alloy at 100 micrometers. In general, Panavia F showed higher bond strength than Super Bond C&B. Both cement thickness and cement type, and their interaction were found to have an effect on the shear bond strength of nickel-chromium alloy to bovine dentine. No significant differences were found when the film thickness was less than 150 micrometers for Panavia F (P>0.05) while those of Super Bond C&B were not significantly different at any film thickness (P>0.05). When the thickness of cement increased, more voids in the cement were found especially in Super Bond C&B. Conclusions: Within the limitations of this study, the shear bond strength between 50 and 150 micrometers was not significantly affected by the cement thickness.