To assure clinical success, the following minimum material thickness is recommended.
Preparation
Anterior Crown
1.5 - 2.0 mm incisal reduction
1.0 - 1.5 mm labial and lingual reduction
Round the internal line angles
Chamfer margin
Posterior Crown
1.5 - 2.0 mm occlusal/incisal reduction
1.0 - 2.0 mm axial reduction
Round the internal line angles
Chamfer margin
Preparation
The optimal preparation is a shoulder or chamfered preparation
with a circumferential step or chamfer which must be applied
at an angle of >5° (horizontal). The angle of the preparation
(vertical) should be 4° or larger. The inside angle of
the shoulder preparation must be given a rounded contour.
Chamfered Preparation
Shoulder Preparation
Contraindication
We do not recommend a feather edge, as it does not provide adequate reduction for the porcelain buildup, or the trough (or gutter) shoulder because the
outermost edge may not be detected when scanned.
