Principles of Tooth Preparation

Principles of Tooth Preparation

1. Preservation of tooth structure
2. Retention and resistance
3. Structural durability
4. Marginal integrity
5. Preservation of the periodontium

Amounts of Tooth Preparation

Metal crown 修磨量：

1. Occlusal reduction
• functional cusp-- 1~1.5 mm
• nonfunctional cusp-- 0.5~1 mm
2. Axial reduction-- 0.5~1 mm
3. Supragingival margin-- 0.5 mm

PFM (Porcelain Fused to Metal) crown 修磨量：

1. Occlusal reduction
• functional cusp-- 1.5~2 mm
• nonfunctional cusp-- 1~1.5 mm
2. Axial reduction
• buccal side-- 1.2~1.5 mm
• lingual (palatal) side-- 0.5 mm 
• proximal area-- 0.5 to 1.2 mm (lingual to buccal)
3. Subgingival margin-- 0.5~1 mm

All-Ceramic crown 修磨量：

1. Occlusal reduction
• functional cusp-- 2.0 mm
• nonfunctional cusp-- 1.5 mm
2. Incisal reduction-- 1.5~2 mm
3. Axial reduction-- 1.0~1.5 mm
4. Subgingival margin--0.5~1 mm (use rounded shoulder or heavy chamfer bur)