A mother travels 1.5 hours to reach your clinic with her child, who is from a marginalized community. The child has poor oral hygiene, multiple carious lesions, and is only moderately cooperative. What is the most appropriate intervention at this FIRST visit?

Correct answer: B. Silver diamine fluoride applied to the active carious lesions

• A. Conventional restorations in a moderately uncooperative child at a first visit invites a negative experience that can entrench dental fear for years. Restorative care is the eventual goal, not the opening move; disease control comes first.
• B. CORRECT. Silver diamine fluoride is the intervention that matches every constraint in this stem at once. The child is only moderately cooperative, so operative care is likely to fail behaviourally. The family faces a substantial travel burden, so the number of visits must be minimised and each visit must accomplish something durable. And the lesions are already cavitated and active, so prevention alone is not enough. SDF arrests active caries with a painless brush-on application in under a minute, requires no anaesthesia and no rotary instrumentation, and buys time for behaviour to mature and for a definitive plan to be arranged.
• C. Topical fluoride gel in trays requires cooperation with trays and suction for four minutes, carries an ingestion risk in a young or uncooperative child, and — like varnish — does not arrest established cavitated lesions.
• D. Fluoride varnish is excellent for preventing new lesions and remineralising early non-cavitated ones, but it does not reliably arrest lesions that are already cavitated and active. It leaves this child's existing disease untreated.

Note: This is an access-to-care question dressed as a treatment question. The 1.5-hour travel and the marginalized background are not decoration — they are telling you that a multi-visit conventional plan will not be completed. SDF is the flagship of the 'interim therapeutic' approach for exactly this population.