PORCELAIN MARGIN PREPARATION GUIDE For Porcelain Fused To Metal Crowns The Porcelain Margin can be an integral part of a premium restoration, maximizing esthetics and oral health. The porcelain margin helps avoid metal visibility, tissue discoloration and possible over-building of the gingiva. PREPARATION NOTES • Where a porcelain margin is desired, the crown preparation must be either a 90 degree shoulder (preferred) or a deep chamfer (Figs.1 & 2). • All preparations should be smooth and display no sharp line angles. • As in all other fixed prosthodontic procedures, any undercuts must be blocked out on the die. • Axial reduction should be a minimum of 1.3 - 1.5 mm for porcelain (0.5 mm for metal lingual). (Fig. 3) • For porcelain margins; beveled margins, knife-edge margins, feather-edge margins, slice preparations and light chamfers should be avoided. •All margins must be clean and well recorded in the impression so that all margins on the dies are clearly visible.