Shear bond strength of aesthetic materials bonded to Ni–Cr alloy

Objectives. This study was undertaken to evaluate the shear bond strength of four materials used as aesthetic material bonded to Ni–Cr alloy. Methods. Sixty-eight alloy discs were prepared and divided equally into four groups, and received four treatments for veneering: conventional feldspathic porcelain (Noritake EX-3) and three light-cured prosthodontic composite resins (Artglass, Solidex and Targis). The aesthetic materials were applied after metal structure conditioning in accordance with the manufacturersʹ recommendations. The specimens were stored in distilled water at 37 °C for 7 days. A universal testing machine was used to measure the shear bond strength of the specimens at a cross head speed of 0.5 mm/min. Fractured specimens were examined by using both optical and scanning electron microscope. Results. The analysis of variance and Tukeyʹs test showed that the strongest mean shear bond was obtained with Noritake EX-3 (mean shear bond strength 42.90±7.82 MPa). For composites, the highest mean shear bond strength was observed for Targis (12.30±1.57 MPa); followed by Solidex (11.94±1.04 MPa) and Artglass (10.04±0.75 MPa). Optical analysis of the fractured surfaces indicated that for Targis and Noritake EX-3 all failures were a mixture of both cohesive and adhesive patterns. As for Artglass and Solidex, the fractures were mainly adhesive in nature. Conclusions. The Solidex system was equivalent to the Targis system in bond strength and exhibited greater strength than the Artglass system. The porcelain fused-to-metal showed considerably higher shear bond strength than the three metal–resin bonding techniques.