What is the finish line in crown preparation?

• A. The occlusal plane
• B. The proximal contact area
• C. The crown margin boundary
• D. The tooth apex

Answer: (C)

The finish line is the crown margin boundary—the edge where the prepared tooth ends and where the crown margin will sit. It defines the seating area for the restoration and the seal between tooth and crown. Getting this boundary right ensures a snug fit, proper margin placement, and healthy gums around the crown. The other terms aren’t about where the crown ends: the occlusal plane refers to the chewing surfaces’ alignment, the proximal contact area is where adjacent teeth touch, and the tooth apex is the root tip.