Prosthodontics & Occlusion · single question
A patient presents with hissing speech (difficulty with 's' sounds). What is the most likely anatomical cause?
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Correct answer: B. Spacious (large) antero-superior arch space
Hissing speech (difficulty with sibilant sounds /s/, /z/) is caused by an enlarged anterosuperior arch space — too much air escapes through an open space between the tongue and palate during sibilant production. This is often seen with anterior open bite, missing upper anterior teeth, or inadequate denture palate contour. A large antero-superior space does not allow the tongue to properly approximate the palate/teeth to direct airflow for correct /s/ production.
- A. INCORRECT. Labial incompetence (inability to close the lips completely) causes difficulty with bilabial sounds (/p/, /b/, /m/) and lip sounds — not specifically hissing sibilant sounds.
- B. CORRECT. Hissing speech is caused by excessive anterior superior arch space — the tongue cannot adequately approximate the palate/anterior teeth for sibilant sounds, allowing air to escape with a hissing quality.
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