Referred odontogenic pain via trigeminal convergence — ORE Part 1 MCQ

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HardApplied Dental SciencesReferred odontogenic pain via trigeminal convergenceORE Part 1

A patient reports pain in an upper molar, but testing shows the upper teeth are normal. A lower molar has deep caries, lingering cold pain and percussion tenderness. The patient struggles to localise the pain accurately across the jaw. What is the correct anatomical and physiological explanation?

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Correct answer: B — Convergence of trigeminal afferents can cause referred dental pain

The correct answer is B. This scenario exemplifies referred odontogenic pain caused by central convergence of trigeminal afferents. The lower molar (true source) shows clear signs of pulpitis (lingering cold pain, percussion tenderness, caries), but the patient perceives pain in the upper molar due to convergence: nociceptive inputs from both teeth converge onto shared second-order neurons in the trigeminal subnucleus caudalis, causing inaccurate pain localisation. Option C is incorrect: the trigeminal nerve (CN V), not facial nerve (CN VII), innervates dental pulp. Option A is incorrect: maxillary teeth are supplied by the trigeminal nerve's maxillary division, not the vagus nerve. Option D is incorrect: dental pulp contains nociceptors and mechanoreceptors, not proprioceptors; moreover, referred pain results in *poor*, not precise, localisation. Option E is incorrect: the optic nerve is unrelated to the mandibular canal or dental innervation.

Reference: Convergence of cutaneous, tooth pulp, visceral, neck and muscle afferents onto nociceptive and non-nociceptive neurones in trigeminal subnucleus caudalis (medullary dorsal horn) and its implications for referred pain. Pain. 1986;27:219–235. https://pubmed.ncbi.nlm.nih.gov/3797017/