A comparative study of ceramic crown margins constructed using different techniques

This study compares three variations of the direct lift-off technique utilizing porcelain materials with thermoplastic, modeling liquid, and visible light-cured resin carriers. Three commercially available materials were evaluated. Vita, Ducera, and Dentsply Spectrum. Measurements were made of the width of the marginal gap for three sites at each of four stages: (1) after the shoulder firing, (2) after the body-incisal firing, (3) after the glaze firing, and (4) after a correction firing. All techniques produced marginal gaps in the clinically acceptable range. Use of the Vita thermoplastic carrier porcelain material resulted in the smallest marginal gap at all but the body-incisal stage. Crowns done with the Ducera and Spectrum materials had statistically similar marginal gaps at all but the glaze stage, where the Ducera material crowns demonstrated the largest marginal gaps.