The effect of various methods of trimming of a stone die on the margins of a cast gold crown.

Four common methods of trimming a die and the effects on the contour of the wax pattern have been described. Carving of the wax pattern may be facilitated by trimming of the die as a continuation of the unprepared portion of the tooth. When the finishing line is apical to the cervical line only the contour of the adjacent teeth and a knowledge of dental anatomy can guide the technician in reaching an acceptable contour. When part of the unprepared tooth is not reproduced in the impression the die should be trimmed at an angle or more than 180 degrees to the long axis of the preparation to provide a prominent cavo-surface angle and a guiding contact surface for the wax carving instrument.