Can an E2 interproximal caries reach the DEJ?

• A. It always penetrates into dentin
• B. No, it stays within enamel
• C. Yes, it may extend to the DEJ
• D. It stops at the outer enamel surface

Answer: (C)

An E2 interproximal caries is an inner-enamel lesion, still confined to enamel depth but near the boundary with dentin. Caries progress through enamel before dentin, so the deepest part of an E2 lesion can reach the dentinoenamel junction without yet invading dentin. Hitting the DEJ means it’s at the boundary; once dentin is involved, the classification would shift to a dentin lesion (D1 or deeper). So, it may extend to the DEJ, which is why that option is the best choice.