MB2 Canal — MFDS Part 1 MCQ

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ModerateAnatomy (Head & Neck)MB2 CanalMFDS Part 1

During endodontic access, an additional canal orifice is sought palatal to the main mesiobuccal orifice within the same root. In which permanent tooth is this second mesiobuccal canal (MB2) most characteristically and most frequently encountered?

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Correct answer: A — Maxillary first molar

The correct answer is A, the maxillary first molar. Its mesiobuccal root commonly contains two canals, designated MB1 and MB2. A systematic review of CBCT studies found an MB2 canal in approximately 69.6% of maxillary first molars, compared with 39.0% of maxillary second molars. The MB2 orifice is commonly sought palatal to MB1 along the developmental groove. Although the maxillary second molar may also contain an MB2 canal, it is encountered less frequently. Mandibular molars commonly have separate mesiobuccal and mesiolingual canals in a mesial root, rather than the canal being designated MB2. Maxillary first premolars often have two canals but do not possess a mesiobuccal root with the characteristic MB1–MB2 arrangement.

Reference: Martins JNR et al. Second mesiobuccal root canal in maxillary molars—A systematic review and meta-analysis of prevalence studies using cone beam computed tomography. Archives of Oral Biology. 2020;113:104589. https://pubmed.ncbi.nlm.nih.gov/31735252/