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Endodontics · single question

In the maxillary first molar, which root is MOST likely to have TWO canals?

  1. Mesiobuccal root
  2. Palatal root
  3. All roots are equally likely
  4. Distobuccal root
Show answer and explanation

Correct answer: A. Mesiobuccal root

  • A. Correct. The MESIOBUCCAL (MB) ROOT has a second canal (MB2) in approximately 60–80% of cases. Missing the MB2 is the most common cause of endodontic failure in the maxillary first molar and a frequent INBDE question.
  • B. Incorrect. The palatal root typically has one large, wide canal. Two palatal canals are rare (<10%).
  • C. Incorrect. The three roots are NOT equally likely — the mesiobuccal root is distinctly the most likely to have two canals.
  • D. Incorrect. The distobuccal root almost always has only ONE canal.

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