Comparative in-vitro Microscopic Evaluation of Vertical Marginal Discrepancy, Microhardness, and Surface Roughness of Nickel-chromium in New and Recast Alloy

Abstract

Abstract In the restoration of the partial dentition the casting alloy plays a major role. The alloys used require the long term stay in oral cavity exposed to a wet environment, so they must have good wear resistance, biocompatibility, and mechanically good strength. The objective of the study is to evaluate the vertical marginal discrepancy, surface roughness and microhardness of the new and recast nickel-chromium (base metal) alloys. 125 wax patterns were fabricated from a customized stainless steel master die with a heavy chamfer cervical margin divided into 5 groups. Each group had 25 samples. Group A: twenty five wax patterns were cast using 100% by weight of new alloy, Group B: casting was done by using 75% new alloy and 25% alloy by weight, Group C: wax patterns were cast using 50% new alloy and 50% alloy, Group D: 25% new alloy and 75% alloy and Group E: 100% recast alloy. Induction castings were finished and seated on the die. The vertical marginal discrepancy was measured by analytical scanning microscope, microhardness were tested on universal testing machine and surface roughness on tester of surface roughness. The maximum vertical marginal discrepancy and surface roughness was found in group E while minimum was in group A. The mean maximum microhardness was found in group C while minimum was in group B (p < 0.001). Castings produced using new alloy were better than those obtained with recast alloy. This indicated that recasting of (Ni–Cr) can be used as a good alternative for the new alloy from an economical point of view.