1996 Volume 40 Issue 1 Pages 141-146
The marginal fit of twenty-nine collarless metal ceramic restorations was measured in vivo with the Margin-Checker Type I, by which both the marginal gap and the horizontal discrepancy can be measured intraorally. All collarless metal ceramic crowns were fabricated with the direct-lift technique when using porcelain material with visible light-cured resin carrier.
Over 80% of single crowns showed marginal gaps of less than 80 micrometers. In comparison with conventional metal ceramic margins, however, collarless porcelain margins showed greater marginal gaps, especially in case of abutments for fixed partial denture.
To investigate the marginal characteristics of collarless metal ceramic crowns, marginal seals were evaluated on facial and lingual surfaces of embedded and sectioned specimens with the SEM micrograph. The exhibited characteristics of porcelain margins were rounder edges and greater marginal gaps than conventional metal ceramic crowns. It was suggested to improve the method for making porcelain margins because of an increasing demand for dental restorations with high esthetic qualities
