The posterior palatal seal of a maxillary complete denture is determined primarily by which factor?

Correct answer: A. The displaceability (resilience) of the soft tissue along the posterior palate

• A. CORRECT. The posterior palatal seal is created by placing the denture border into slightly displaced tissue, so its position, width and depth are dictated by TISSUE RESILIENCE. Displaceability is mapped clinically with a T-burnisher or mouth mirror handle and varies with palatal form and glandular tissue thickness. Correctly executed, the seal maintains a partial vacuum, compensates for polymerisation shrinkage of the acrylic and prevents air ingress.
• B. The incisive papilla is an anterior landmark used for tooth positioning and as a guide to the incisive foramen — it must be relieved, not sealed.
• C. The uvula lies on the movable soft palate BEYOND the seal area and is not part of it.
• D. The tuberosities are relevant to retention and to the buccal extension of the denture, but they do not determine the posterior seal.

Note: The seal runs between the two hamular notches, passing through or just anterior to the fovea palatinae, along the vibrating line — the junction between the immovable hard palate and the movable soft palate, demonstrated by having the patient say 'ah' briefly.