Which visual sign indicates an active carious lesion?

• A. Chalky when dried
• B. Rough with explorer
• C. Opaque
• D. Covered in plaque

Answer: (B)

Understanding active caries hinges on surface texture and softness. An active lesion is still breaking down mineral, so its surface is soft, porous, and often rough. When you probe with a sharp explorer, the surface catches and feels rough, and you may sense some give or slight penetration. That tactile feedback—roughness under probing—shows the lesion is currently progressing and demineralization is ongoing.

Other signs can be misleading by themselves. A chalky appearance after air-drying can occur in demineralized areas but doesn’t reliably indicate ongoing activity. An opaque surface can accompany demineralization but isn’t a definite indicator of activity. Plaque coverage shows biofilm presence, which is necessary for caries but does not prove that the lesion is actively advancing.

So, the best cue that a lesion is active is the rough, catchable texture revealed by probing, reflecting ongoing mineral loss and lack of remineralization.