The E2 caries base orientation is located at which surface?

• A. Proximal surface
• B. Distal surface
• C. Enamel surface
• D. Dentin

Answer: (A)

The question tests where this enamel-appearing caries is oriented on the tooth. E2 caries refers to a lesion that sits on a proximal surface—the side of the tooth that faces the neighboring tooth. Proximal surfaces are between teeth, where plaque tends to accumulate and cleaning is harder, so caries often develop there first. The base of the lesion is directed toward that interproximal surface, which is why the proximal surface is the correct location. The other options describe surfaces or tissues that aren’t the typical orientation for this lesion type: the distal surface is the opposite side, enamel surface is too general, and dentin describes depth rather than the surface facing another tooth.