The effect of recasting on biological properties of Ni-Cr dental alloy

Introduction Increases in market prices of gold over the last 20 years have led to expansion of basic dental alloys, which, primarily due to their good mechanical properties and acceptable prices, have found their place in everyday dental practice. However, within the procedure of making dental prosthetic restorations, the alloys are melted and cast, which leads to changes in their physical, mechanical and biological properties. Objective The objective of the study was to test biocompatibility of a Ni-Cr dental alloy (WIRON 99) depending on the number of melting and casting processes. Methods The working method included the testing of cytotoxicity of the alloy obtained by casting after one, after four, and after eight successive processes of melting. Cytotoxicity of samples was tested by means of a 24-hour and a three-day cytotoxicity test, done on L929 fibroblasts. Results A repeatedly melted and cast alloy shows a reduced biocompatibility and causes specific responses of the tissues in the surrounding area. Since the cytotoxic effect is more significant in the extended contact with the culture cells, a three-day cytotoxicity test showed discrete changes which were the indicator of cell growth inhibition in the cell culture. Conclusion The obtained results confirm the working hypothesis that repeated alloy melting and casting will decrease biocompatibility of dental alloys and will lead to specific responses of the tissue in the surrounding area