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Pathology · patient case with 2 questions

Painful mandibular deviation on opening

Patient: Adult with temporomandibular symptoms

Chief complaint: Pain and restricted mouth opening.

Background: No relevant medical history reported.

Current findings: On opening, the mandible deviates to the RIGHT and remains deviated. Opening is limited and painful.

Question 1

What is happening to the articular disc?

  1. The right articular disc is displaced anteriorly WITH reduction
  2. The left articular disc is displaced anteriorly without reduction
  3. The left articular disc is displaced anteriorly with reduction
  4. The right articular disc is displaced anteriorly WITHOUT reduction
Show answer and explanation

Correct answer: D. The right articular disc is displaced anteriorly WITHOUT reduction

  • A. With reduction, the disc recaptures with an audible click and opening then returns to normal, producing DEFLECTION that corrects — an S-shaped path rather than persistent deviation, and opening is not limited.
  • B. The side is wrong. Deviation is toward the restricted side, which is the right.
  • C. Both the side and the mechanism are wrong.
  • D. CORRECT. The mandible DEVIATES TOWARD THE AFFECTED SIDE, because the restricted condyle cannot translate forward while the healthy side does. Persistent deviation to the right with limited, painful opening indicates a RIGHT disc displaced anteriorly WITHOUT reduction — closed lock. The disc obstructs translation and never recaptures, so there is no click.

Note: Distinguish the terms: DEVIATION is a persistent shift toward the affected side that does not correct (without reduction). DEFLECTION is a transient shift that corrects as the disc recaptures (with reduction). Limited opening around 25–30 mm suggests closed lock.

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Question 2

Which imaging modality best evaluates the bony condyles in this patient?

  1. Cone beam computed tomography
  2. Lateral cephalometric radiograph
  3. Panoramic radiograph
  4. Periapical radiograph
Show answer and explanation

Correct answer: A. Cone beam computed tomography

  • A. CBCT provides three-dimensional, distortion-free imaging of the condylar bony morphology, and is the modality of choice for assessing erosion, flattening, osteophytes and degenerative change.
  • B. A lateral cephalogram is used for skeletal and orthodontic analysis, not condylar detail.
  • C. A panoramic view is a useful screening image but superimposes structures and distorts the condyle, so subtle bony change is readily missed.
  • D. A periapical film cannot image the joint at all.

Note: Important qualification: CBCT images BONE. If the question concerns the DISC or other soft tissue, MRI is the modality of choice.

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