Crown Margin Types

Crown margin design affects fit, strength, and aesthetics. The shoulder margin (90-degree angle, 1-1.2mm wide) provides the best support for all-ceramic crowns and is the standard for anterior aesthetics. The chamfer margin (curved concavity, 0.5-0.8mm) is versatile, used for both metal-ceramic and all-ceramic crowns, and preserves more tooth structure. The knife-edge margin (feathered, minimal reduction) preserves maximum tooth structure but provides poor ceramic support and is mainly used for metal crowns. The beveled shoulder combines a shoulder with a metal bevel for precise metal-ceramic fit. Margin placement options include supragingival (above gum — easiest maintenance), equigingival (at gum line), and subgingival (below gum — hides margin but risks gum irritation). Modern trends favor supragingival or equigingival margins with tooth-colored ceramics.