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Endodontics · single question

Each of the following teeth has an oval endodontic access shape EXCEPT one. Which is the EXCEPTION?

  1. Mandibular second premolar
  2. Mandibular canine
  3. Maxillary central incisor
  4. Maxillary first premolar
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Correct answer: C. Maxillary central incisor

Endodontic access shapes by tooth: Maxillary first premolar = oval/hexagonal (two canals, wide buccolingually). Mandibular second premolar = oval (single canal, wider BL). Mandibular canine = oval (single canal). Maxillary CENTRAL INCISOR = TRIANGULAR access (the pulp chamber is triangular with rounded corners, wider incisally and narrower apically). The maxillary central incisor is the exception as it has a TRIANGULAR, not oval, access shape.
  • A. INCORRECT. Mandibular second premolar typically has an oval access shape for its single canal.
  • B. INCORRECT. Mandibular canine has an oval access shape for its single, often oval cross-section canal.
  • C. CORRECT. Maxillary central incisor has a TRIANGULAR access shape (widest at the incisal edge, narrowing toward the apex), not oval. The triangle mirrors the cross-sectional shape of the pulp chamber.
  • D. INCORRECT. Maxillary first premolar has an oval (or figure-8) access shape to accommodate its two-canal anatomy (one buccal, one palatal).

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