A complete-denture patient's prosthesis repeatedly dislodges. Panoramic films and casts show severely resorbed ridges. The most likely cause of poor retention is:

Correct answer: A. Severely resorbed residual ridges

• A. Correct. Severe alveolar ridge resorption reduces the supporting/retentive area, undermining stability and retention of a complete denture.
• B. Short flanges can reduce the seal, but the dominant finding here is the markedly resorbed ridge.
• C. Saliva quantity/quality affects retention but is secondary to the resorbed-ridge anatomy described.
• D. A high palatal vault can aid retention; it is not the cause of dislodgement here.