Restorative & Materials · single question
A patient presents with a fractured mandibular molar that has minimal remaining tooth structure, and is known to have bruxism. Which crown material is MOST appropriate?
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Correct answer: C. Zirconia
Zirconia is the ideal material for a posterior molar in a bruxism patient with minimal remaining tooth structure because: (1) it has the highest fracture strength of all-ceramic materials, (2) it does not require a metal substructure, (3) it preserves more tooth structure than PFM, and (4) it is biocompatible and has good esthetic properties. PFM risks porcelain fracture from bruxism; feldspathic porcelain alone is too brittle.
- A. All-porcelain/feldspathic ceramic has the lowest fracture resistance of ceramic options and is contraindicated for posterior teeth in bruxism patients.
- B. Stainless steel crowns are used in pediatric dentistry for primary teeth — not appropriate for adult permanent molars in this context.
- C. CORRECT. Zirconia has exceptional fracture toughness (900–1200 MPa flexural strength), making it the best choice for a posterior molar with limited tooth structure in a bruxism patient who needs maximum strength.
- D. PFM is durable but the porcelain veneer is susceptible to chipping and fracture under heavy bruxism forces, making it suboptimal for this high-load scenario.
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