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

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.