A patient who recently received new complete upper and lower dentures reports a persistent gag reflex. Which of the following could be responsible?

Correct answer: D. An overextended or thick posterior palatal border, or an increased vertical dimension of occlusion

• A. Relief over the incisive papilla prevents pressure on the nasopalatine bundle. Excessive relief may reduce the seal anteriorly, but it does not cause gagging.
• B. The posterior palatal seal must be placed in the DISPLACEABLE SOFT TISSUE just anterior to the vibrating line. A seal cut into unyielding hard palate produces poor retention and soreness, but it is not the classic cause of gagging.
• C. Insufficient VDO produces overclosure, angular cheilitis, and an aged appearance — not gagging.
• D. CORRECT. Gagging in a new denture wearer is usually MECHANICAL. An OVEREXTENDED posterior border, a border placed past the vibrating line onto mobile soft palate, or an excessively thick and bulky distal edge stimulates the sensitive soft palate and pharyngeal mucosa. An INCREASED VDO compounds the problem by holding the mandible open, crowding the tongue posteriorly and reducing tongue space.

Note: Work through the causes in order: check extension against the vibrating line, thin the distal border, verify VDO, then consider psychogenic factors and desensitisation. Never simply trim the border blindly — retention will be lost.