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Radiology · single question

A panoramic radiograph shows an inverted (reverse) smile line with downward curvature of the occlusal plane. What is the patient positioning error?

  1. Patient moved during exposure
  2. Patient's chin was tilted too far UP (hyperextended — head tilted back)
  3. Patient was positioned too far forward in the focal trough
  4. Patient's chin was tilted too far DOWN (depressed)
Show answer and explanation

Correct answer: B. Patient's chin was tilted too far UP (hyperextended — head tilted back)

  • A. Incorrect. Patient movement causes motion blur across the image — not specifically an inverted smile.
  • B. Correct. When the chin is tipped UP (hyperextended), the hard palate projects onto the root apices of the upper teeth, creating a DOWNWARD (inverted/reverse) smile curve on the panoramic image. The condyles may also appear at the top edges of the film.
  • C. Incorrect. Incorrect focal trough positioning causes blurring/widening or narrowing of teeth, not an inverted smile arc.
  • D. Incorrect. Chin TOO LOW (depressed) creates an exaggerated upward curve (pronounced smile arc) on the panoramic image.

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