Dental high-speed cutting of four cast alloys.

The purpose of this study was to evaluate dental high-speed cutting behaviour of four cast alloys, namely Ag-Pd-Cu-Au alloy, Ag-Zn-In-Sn alloy, Ni-Cr alloy and Ti. Weight-load cutting tests were conducted on four cast alloys, using two rotary cutting instruments, namely a diamond point and a carbide bur, both driven by an air-turbine handpiece. While the constant transverse load of 80 g was applied on the workpiece for 5s, the handpiece speed was measured during cutting as well as the volume of workpiece removal which took place. The cutting tests were repeated 10 times. We found that the cutting volumes of soft Ag-Pd-Cu-Au alloy and Ag-Zn-In-Sn alloy were considerably larger than those of hard Ni-Cr alloy and Ti. It was also clarified that the cutting effectiveness of the carbide bur was generally superior to that of the diamond point. With continuing use, however, the cutting capability of the carbide bur tended to decline while that of the diamond point remained quasi-constant.