Tensile strength of Ni-Cr copings subjected to inner surface sandblasting using different cementing agents: An in vitro study

Abstract

Objectives. To evaluate the effect of thermal cycling and inner surface treatment with aluminum oxide at different granulations on the tensile strength of Ni-Cr copings cemented with different cementing agents. Materials and methods. Ninety-six metal copings were manufactured and divided into two groups: before and after thermal cycling (n = 48). The copings of both groups were internally treated by sandblasting with aluminum oxide particles of 100 (n = 24) and 320 (n = 24) mesh. The copings were cemented on previously manufactured metal cores using zinc phosphate (n = 8), conventional glass ionomer (CGIC) (n = 8) and resin-modified glass ionomer (RMGIC) (n = 8) cements. The tensile strength before and after thermal cycling was then determined (Newtons). Results. The tensile strength before and after thermal cycling was significantly higher in copings cemented with RMGIC compared to CGIC (p < 0.05) and was similar to that for zinc phosphate (p > 0.05). Thermal cycling and sandblasting of the inner surface of the metal copings with different granulations did not influence retention (p > 0.05). Conclusions. Zinc phosphate cements and RMGIC showed similar retention. Additionally, the retention of the cements was not influenced by either thermal cycling or the particle size of the aluminum oxide.