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Pathology · single question

TMJ with no clicking, no sound, pain on opening limited to 20mm. What is the diagnosis?

  1. Myofascial pain syndrome
  2. Osteoarthritis
  3. Bruxism
  4. Anterior disc displacement without reduction (closed lock)
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Correct answer: A. Myofascial pain syndrome

  • A. MYOFASCIAL PAIN SYNDROME (muscle pain disorder, formerly MPD) is characterized by: muscle pain and tenderness (not joint sounds), LIMITED OPENING (~20mm due to pain/spasm), no joint clicking or crepitation, and trigger points in the muscles of mastication (especially masseter and temporalis). It is the most common TMJ disorder. Contrast with disc displacement (with clicking), arthritis (with crepitation), and ankylosis (rigid, no movement).
  • B. Osteoarthritis typically presents with CREPITATION (grinding sounds) — not the silent, painful limited opening described.
  • C. Bruxism is a parafunctional habit — it may coexist with myofascial pain but is not itself a TMJ diagnosis. It doesn't explain the limited opening.
  • D. Closed lock (anterior disc displacement without reduction) would give limited opening and NO clicking — BUT it is distinguished from myofascial pain by joint-based origin (condyle blocked by displaced disc) vs. muscle spasm.

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