Distortion of ceramometal fixed bridges by heat treatment

Abstract

Notable distortion and displacement of the ceramometal fixed bridge frame occur in presoldering and degassing phases through laboratory procedures. In porcelain-fused-to-precious-metal crown, heat treatment before grinding is said to prevent marginal distortion. There is no research, however, on this heat treatment to make ceramometal fixed bridges or to assemble them by pre-sol dering.The author studied the heat treatment effects on distortion and displacement of ceramometal fixed bridges compared with ones not treated by heat. The frames were measured three-dimensional deviations after the indexing for the heat treatment, pre-soldering, surface grinding of the frame, degassing, opaque porcelain firing, body-incisor porcelain firing and glazing.The results were as follous:1. In pre-soldering and degassing phases, the heat-treated frames produced significantly smaller distortion and displacement than not heat-treated ones.2. In opaque porcelain firing, body-incisor porcelain firing and glazing phases, the heat-treated frameworks were not significantly different from ones not treated by heat.3. It was therefore explicated that the heat treatment before grinding is the effective method of producing ceramometal bridges in decreasing distortion and displacement expected in labolatory procedures.