Prosthodontics & Occlusion · single question
The ideal crown-to-root ratio for a tooth to serve as a crown abutment is:
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Correct answer: C. 1:2 or greater
The ideal crown-to-root ratio for a tooth to serve as a crown or bridge abutment is 1:2 or better (i.e., the root is at least twice the length of the clinical crown). A 1:1 ratio is the minimum acceptable under normal occlusal loads. Ratios less than 1:1 (more crown than root) indicate poor prognosis for use as an abutment and greatly increase risk of failure under functional load.
- A. ❌ 1:1.5 is acceptable but 1:2 is the ideal target.
- B. ❌ 2:1 (crown greater than root) is unfavorable and would predict abutment failure.
- C. ✅ CORRECT – The ideal crown-to-root ratio is 1:2 or greater, meaning the root is at least twice the length of the clinical crown.
- D. ❌ A 1:1 ratio is the minimum acceptable, not the ideal.
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