One week after delivery of a cast metal removable partial denture, the patient returns with erythema, soreness and pain confined to the mucosa beneath the major connector. What is the most likely cause?

Correct answer: D. An allergic contact reaction to a component of the alloy

• A. Nicotinic stomatitis is a keratotic white palatal change with inflamed, elevated minor salivary duct openings in a heavy smoker. It has no relationship to a newly delivered prosthesis.
• B. Denture stomatitis is a chronic candidal infection producing diffuse erythema over the whole denture-bearing area, typically in a patient who wears the appliance overnight. It develops over weeks to months and is usually asymptomatic or mildly burning, not acutely painful within a week.
• C. Primary herpetic gingivostomatitis presents with fever, malaise, lymphadenopathy and widespread vesicles and ulcers across keratinised and non-keratinised mucosa — not a lesion mapped to a metal framework.
• D. CORRECT. Three features point to allergy. The reaction is confined precisely to the tissue contacting the metal, it appeared about a week after delivery — the expected latency of a type IV delayed hypersensitivity response — and it is painful rather than merely erythematous. Nickel is the commonest culprit, present in nickel-chromium alloys, and cobalt and chromium sensitisation also occur. This is a cell-mediated reaction, not an immediate IgE one, which is exactly why it takes days rather than minutes to appear.

Note: The diagnostic principle: when a mucosal lesion reproduces the OUTLINE of a restoration or appliance, think contact allergy. Confirm with patch testing (nickel, cobalt, chromium, palladium) through a dermatologist.