What is the most common cause of gagging with a complete maxillary denture?

This question covers the same clinical scenario as Q8. Overextension of the posterior palatal seal is the most common cause of gagging with a complete maxillary denture. The posterior border of the maxillary denture must terminate at or just anterior to the vibrating line (the junction of the hard and soft palate). When this border extends too far posteriorly, it stimulates the gag reflex. Treatment involves relieving the posterior border of the denture. Psychological factors and poor adaptation also contribute, but mechanical overextension is the most common and treatable cause.