TMJ Dysfunction — ORE Part 1 MCQ

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ModerateOral MedicineTMJ DysfunctionORE Part 1

A patient presents with sudden onset of limited mouth opening (25 mm) following a previous history of TMJ clicking. The clicking has now stopped. What is the most likely diagnosis?

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Correct answer: B — Anterior disc displacement without reduction

Explanation lettering: C = shown as A · A = shown as B · E = shown as C · B = shown as D · D = shown as E

The clinical history of prior TMJ clicking that has now ceased, combined with sudden-onset severe limitation of mouth opening, is pathognomonic for anterior disc displacement without reduction (ADDwoR). In anterior disc displacement with reduction (ADDR), the displaced disc relocates as the condyle translates during mouth opening, producing an audible click. When the disc remains anteriorly positioned and fails to reduce during opening, the disc mechanically blocks forward condylar translation, preventing normal opening and eliminating the clicking sound. This represents progression along the internal derangement spectrum. Trismus (B) presents acutely with systemic infection signs; coronoid hyperplasia (C) develops gradually over years; ankylosis (D) involves bony fusion without prior clicking; myofascial pain (E) explains pain but not the specific mechanical pattern of clicking cessation with blocked opening.

Reference: Katsura et al. (1986) Clinical and radiological study of patients with anterior disc displacement of the temporomandibular joint. PubMed PMID: 6576492; corroborated by Alsayed et al. (2023) Role of Dynamic 3 Tesla MRI in the Evaluation of Temporomandibular Joint Dysfunction. PMC10126526. https://pubmed.ncbi.nlm.nih.gov/6576492/