Inlay and Onlay Prep: Traditional inlay and onlay prep is recommended. Taper the cavity walls 5-6 degrees to the long axis of the preparation. Do not undercut. Internal edges should be rounded. Incisal/occlusal reduction should be at least 1.0 mm below the bottom of the fissure and at least 1.5 in the area of the isthmus or cusps.
Veneer Prep: Reduction of the labial surface should be at least 0.6 mm and 0.4 mm at the gingival. The reduction of the incisal, labial-lingual angle should be 0.5 to 1.5 mm. Margins for the veneers should be in the enamel and above the gingival tissues. Create a chamfer or rounded shoulder. Proximal extensions should be made far enough into the proximal region so that margins do not show and have no proximal-gingival undercuts.
Crown Prep: Axial reduction should be at least 1.0 mm at bottom of the fissure and at least 1.5 mm in the area of the cusps with a 5-6 degree taper. Incisal/occlusal reduction should be 1.5 to 2 mm clearance in centric occlusion and all excursions. Shoulders must extend at least 0.8 mm from the lingual to the proximal contact area. Non-beveled shoulder finish lines are recommended. All line angles should be rounded and surfaces should be smooth.