What radiographic pattern would you expect to see if an occlusal caries has advanced into dentin?

• A. A diffuse radiolucent shadow
• B. A radiopaque shadow
• C. A sharp radiolucent line at the CEJ
• D. A narrow radiopaque line along the enamel

Answer: (A)

When occlusal caries has advanced into dentin, the radiograph shows a diffuse radiolucent shadow under the occlusal enamel. This happens because dentin is less mineralized than enamel and carious demineralization creates an irregular, spread-out area of increased radiolucency that lacks a sharp, well-defined border. The lesion tends to extend irregularly within dentin, often along the fissure, producing a broader, fuzzy radiolucent appearance rather than a crisp line.

In contrast, other patterns don’t fit this scenario: a radiopaque shadow would indicate calcified material or a restorative obstacle, not caries; a sharp radiolucent line at the CEJ would suggest cervical caries rather than occlusal involvement; and a narrow radiopaque line along enamel would point to a sealant or restoration, not dentinal caries.