Upper Molar Dual Innervation — ORE Part 1 MCQ

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ModeratePharmacology & TherapeuticsUpper Molar Dual InnervationORE Part 1

A patient requires treatment of an upper first molar. A posterior superior alveolar block and greater palatine block have produced soft-tissue anaesthesia, but the tooth remains sensitive to pulp testing. What is the most likely explanation?

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Correct answer: B — The mesiobuccal root has middle superior alveolar nerve supply

**A is correct.** The upper first molar has variable pulpal innervation: its mesiobuccal root may be supplied through the middle superior alveolar distribution, whereas a posterior superior alveolar block more reliably covers the remaining molar supply. The greater palatine block contributes palatal soft-tissue anaesthesia; it does not reliably address accessory buccal pulpal supply. Therefore, persistent sensitivity despite both blocks is best explained by the mesiobuccal root requiring supplementary buccal infiltration. **B** reverses the role of the greater palatine nerve. **C** is incorrect because the PSA block is used for maxillary molar pulpal anaesthesia, not solely palatal tissue. **D** is implausible because maxillary bone generally permits effective infiltration. **E** is incorrect: supplementary local anaesthetic techniques are appropriate when anaesthesia is incomplete.

Reference: Velasco I, Soto R. Anterior and middle superior alveolar nerve block for anesthesia of maxillary teeth using conventional syringe. Dent Res J (Isfahan). 2012. https://pubmed.ncbi.nlm.nih.gov/23559916/