EFFECT OF 2 OPAQUING TECHNIQUES AND 2 METAL-SURFACE CONDITIONS ON METAL-CERAMIC BOND STRENGTH

The optimal conditions for opaquing techniques during porcelain applic ation have not been confirmed. In this study the metal-ceramic bond st rength was measured among one porcelain and three dental alloys, namel y a gold-platinum-palladium alloy, a silver-free gold-palladium alloy, and a base metal alloy, with two opaquing techniques (a single maskin g layer versus a thin overfired layer followed by a second masking lay er). In addition, the opaque porcelain was fired over an oxidized and nonoxidized alloy surface for the silver-free gold-palladium alloy. No significant differences in bond strength were recorded between the tw o opaquing techniques with the gold-platinum-palladium and base metal alloys. There were no substantial differences between the two opaquing techniques when opaque was applied over an oxidized gold-palladium al loy surface and bond strengths were substantially greater over an oxid ized surface. However, when the opaque was applied to a nonoxidized go ld-palladium surface the two-layer technique created a significantly g reater bond strength.