Seven-step tooth preparation for a gold onlay.

This article describes seven sequential steps for an onlay preparation: penetration and extension, axial reduction, cuspal reduction, supragingival shoulder, supragingival bevel, intracrevicular bevel, and finishing. Details and rationale of each step are reviewed, and the number of burs and diamond stones are minimized. The tooth preparation is designed to provide maximal retention with innocuous occlusal forces, esthetics, and preservation of tooth structure. The slip joint on the facial and lingual walls of the proximal boxes facilitates seating of single- or multiple-unit castings. These seven sequential clinical steps for a gold onlay have been successful.