A patient presents with generalized erythema of the palatal mucosa confined precisely to the area covered by the maxillary denture. Which organism is responsible?

Correct answer: D. Candida albicans

• A. ❌ S. mutans is cariogenic and plays no role in mucosal disease.
• B. ❌ S. aureus contributes to angular cheilitis alongside Candida but does not cause the palatal erythema.
• C. ❌ Actinomyces causes cervicofacial actinomycosis with sulfur granules — a completely different clinical picture.
• D. ✅ CORRECT — Denture stomatitis (chronic atrophic candidiasis) is caused by CANDIDA ALBICANS colonizing the fitting surface of the denture. The tissue is erythematous, typically asymptomatic, and demarcated exactly by the denture outline — the acrylic itself is the reservoir.

Note: Treatment must address BOTH surfaces: antifungal for the mucosa AND disinfection of the denture, plus removing it at night. Treating only the tissue guarantees relapse from the untreated prosthesis.