Lesion becomes triangular with apex toward dentino-enamel junction in what kind of caries?

• A. Proximal
• B. Occlusal
• C. Root
• D. Recurrent

Answer: (A)

Proximal caries show up between teeth and advance in a wedge-like fashion along the interproximal surface. Because the decay starts at the contact area and works inward toward the dentinoenamel junction, the remaining sound enamel tapers as it approaches the junction. That pattern creates a triangular radiolucency with the narrow apex pointing toward the DEJ. In other words, the lesion grows deeper toward dentin from the outer enamel surface, giving that characteristic shape.

Occlusal caries tend to spread from pits and fissures on the chewing surface and don’t produce that interproximal, apex-toward-DEJ wedge. Root caries involve exposed root surfaces and have a different progression, while recurrent caries occur at restoration margins and are irregular in shape.