PFM Crown Preparation — NDEB AFK MCQ
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Correct answer: C — 1.5 mm
The facial (labial/buccal) surface of a metal-ceramic crown preparation requires approximately 1.2-1.5 mm of tooth reduction to accommodate the metal substructure (~0.3-0.5 mm), opaque porcelain layer (~0.2-0.3 mm), and body/enamel porcelain (~0.5-0.7 mm). Insufficient reduction results in overcontoured restorations, poor aesthetics, or thin porcelain prone to fracture. The lingual surface requires 0.5-1.0 mm for metal only. The occlusal surface requires 1.5-2.0 mm for functional cusps.
Reference: Shillingburg – Fundamentals of Fixed Prosthodontics, 4th ed., 2012