An elderly patient has a zirconia crown on a maxillary molar with root caries extending subgingivally below the crown margin. The lesion is not restorable without significant surgical exposure and the patient has limited dexterity and multiple medical comorbidities. What is the most appropriate management?

Correct answer: A. Apply silver diamine fluoride (SDF) to arrest the lesion

• A. Correct. SILVER DIAMINE FLUORIDE (38%) is specifically indicated for arresting active root caries in elderly or medically complex patients when definitive restoration is not feasible. The silver is antibacterial and the fluoride promotes remineralisation; arrest rates for root caries are high. The patient must be counselled that treated dentine turns black.
• B. Incorrect. An active subgingival lesion left untreated will progress to pulpal involvement and tooth loss. SDF offers a minimally invasive way to intervene.
• C. Incorrect. Desensitisers address dentine hypersensitivity — they do not arrest an active carious lesion.
• D. Incorrect. Fluoride varnish alone is preventive and helps early non-cavitated lesions, but it is substantially less effective than SDF at ARRESTING established, cavitated root caries.

Note: SDF is a caries-arresting medicament, not a restoration. Follow-up at 6 months and reapplication is standard; the black staining is permanent on the affected dentine.