How does moderate occlusal caries appear on radiographs?

• A. Narrow radiolucent line in enamel
• B. Broad, bowled-shaped radiolucent zone in dentin; enamel mostly unchanged
• C. Radiopaque area in dentin
• D. No radiolucency

Answer: (B)

Moderate occlusal caries show dentin involvement with the enamel largely intact. On radiographs this appears as a broad, bow-shaped radiolucent zone in the dentin beneath the occlusal enamel surface. The enamel itself stays mostly unchanged on the image at this stage, which is why you don’t see a radiolucent line limited to enamel. If it were only an early enamel lesion, you’d expect a narrow radiolucent line within enamel; caries are radiolucent, not radiopaque; and absence of radiolucency would mean no detectable lesion. So the characteristic pattern is a broad, bow-shaped radiolucent area in dentin with enamel largely unaffected.