Castability of crown and bridge alloys.

A special saucer-shaped wax pattern was designed to evaluate the castability of five casting machines and four casting alloys. The casting machines used included one broken arm unit, one induction unit, one resistance unit, and two vacuum air pressure units. The alloys included one base metal alloy, two high-fusing noble metal alloys, and one type III gold alloy. Results of analysis of variance showed that at the 95% confidence level there was a significant difference among casting machines and alloys, the casting machines had a stronger effect on castability. No attempt was made to evaluate the fit quality of the castings with regard to surface roughness or porosity.