Marginal adaptation of porcelain margins in metal ceramic restorations

The purpose of this study was to evaluate the marginal adaptation of all-porcelain labial margin metal ceramic crowns using a porcelain shoulder material containing a light-polymerizing resin and one that used a direct-lift technique. Conventional metal margin restorations served as controls. Scanning electron micrographs were made of a 1-mm mesiodistal width of the margin at midfacial and midlingual reference marks. Image processing and analysis techniques were accomplished using a computer. Statistical evaluation indicated that the mean labial marginal discrepancy of the control group was significantly less than that of either of the two porcelain shoulder methods.