Effects of porcelain application procedures on two noble alloys

✍ Scribed by M. Bagby; S. J. Marshall; G. W. Marshall Jr.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1990
• Tongue: English
• Weight: 637 KB
• Volume: 1
• Category: Article
• ISSN: 1045-4861
• DOI: 10.1002/jab.770010106

✦ Synopsis

Abstract

Distortion of ceramometal restorations during porcelain application is often attributed to mismatch of thermal expansion coefficients. Little attention has been paid to treatment the metal receives after casting. Oxide formation, lattice parameter changes, and macroscopic distortion were studied for flat specimens of two ceramometal alloys, a high Pd alloy and a high Au alloy. SnO~2~ and In~2~O~3~ formed on the surface of the high Au alloy after the oxidation firing, while SnO~2~ and CuGa~2~O~4~ formed on the high Pd alloy. Lattice parameter changes reflected the loss of base metal elements in the formation of surface oxides. The edges of specimens distorted toward the ground side. Such distortion can be explained by the induction of residual stress in the metal surface during grinding and subsequent surface stress annealing accompanied with subsurface elastic recovery during firings. Oxide formation was not related to specimen distortion. This study suggests a relationship between surface preparation and specimen distortion during porcelain application procedures.