Which VISUAL finding best indicates a carious occlusal surface?

Correct answer: D. A change in the translucency of the enamel

• A. The sharp explorer is a TACTILE test, not a visual one — and current guidance actively discourages forcing an explorer into a fissure, because it can cavitate a remineralisable lesion, transfer cariogenic bacteria between sites, and gives poor diagnostic accuracy (a 'stick' often reflects fissure anatomy rather than caries).
• B. Deep, sharply defined fissure anatomy is an anatomical RISK FACTOR that indicates a sealant is appropriate — it is not itself evidence that caries is present.
• C. Brown STAINING alone is unreliable. Arrested caries and simple extrinsic or dietary stain in a fissure are both brown and both hard on probing. Colour without opacity or surface texture change does not establish an active lesion.
• D. CORRECT. The question specifies a VISUAL examination, and the earliest reliable visual sign of occlusal demineralisation is a CHANGE IN ENAMEL TRANSLUCENCY — the surface loses its normal glassy translucency and becomes opaque, chalky or white on a cleaned, dried tooth. This forms the basis of the ICDAS system, which grades occlusal caries visually from a white or brown opacity visible only after drying (ICDAS 1) through to frank cavitation (ICDAS 5-6).

Note: Note from the contributor: the version of this question seen on their exam offered 'change in enamel translucency' as an option, and that is the answer that is defensible for a strictly VISUAL examination. Method: clean the tooth, dry it thoroughly for 5 seconds (drying is essential — early lesions become visible only when the water in the porous subsurface is displaced by air), and examine under good light with magnification.