Case: posterior open bite, and a lesion beneath a denture

Correct answer: C. Ankylosis of the primary molars

• A. Missing successors can delay exfoliation of a primary molar, but retention alone does not drop the tooth below the occlusal plane — ankylosis does.
• B. A thumb habit produces an anterior open bite, not a posterior one.
• C. Correct. An ankylosed primary molar is fused to bone and cannot follow the vertical growth of the alveolus, so the adjacent teeth erupt past it and it appears submerged — infraocclusion. A solid, high-pitched percussion note and loss of the PDL space confirm it.
• D. Primary failure of eruption affects permanent teeth that never erupt despite a clear path; here the primary teeth are present but submerged.

Correct answer: A. Inflammatory papillary hyperplasia

• A. Correct. Continuous denture wear plus poor hygiene and candidal colonisation produces this multinodular, papillary erythematous change of the hard palate — inflammatory papillary hyperplasia. It is benign and reactive.
• B. Erythroplakia is a velvety red patch with a high rate of dysplasia, but it is not confined to the denture outline and has no papillary texture.
• C. Median rhomboid glossitis is a rhomboid depapillated patch on the dorsum of the tongue, not the palate.
• D. Carcinoma would be expected to ulcerate, indurate and cross anatomic boundaries rather than mirror the denture outline exactly.

Note: First-line management is to stop nocturnal wear, disinfect the denture, and treat the candidiasis. Only tissue that persists after that is excised before a new prosthesis is made.