The influence of three heat sources of casting on the cervical adaptation of total metal crowns

Abstract

Considering the existing difficulties of making cast metal restorations, where the minimal cervical discrepancy leads to serious clinical problems, this study examined the fit of total metal crowns of AglPd and PdlAg alloys, with three different margin configurations on the stainless steel dies: a shoulder, a 20-degree bevel shoulder and a 45-degree chamfer. Three heat sources were used for casting: acetyleneoxygen, gas-oxygen and electric resistance. After casting, the specimens were seated on the dies, with a static load of9 kg. The readings ofthe diel crown interface were made in a microscope, using a digital micrometer. The statistical analysis showed that the Pd/Ag alloy (Pors-on 4), the acetylene/oxygen heat source and both the 20-degree bevel shoulder and 45-degree chamfer showed the highest cervical discrepancy means. It was concluded that the Ag/Pd (Pall iag-rn) al loy; both, the electric resistance and the gas/oxygen heat sources; and the shoulder provided the better cervical fit means. Keywords:metal casting, margin configuration, heat source.