How does a D3 interproximal caries compare in dentin vs enamel?

• A. Enamel lesion is more extensive than dentin lesion
• B. Dentin lesion is more extensive than enamel lesion
• C. Dentin and enamel lesions are equal
• D. There is no enamel involvement

Answer: (B)

In this stage, the caries has reached dentin, so the damage is deeper than in enamel. Enamel is very highly mineralized and acts as a strong surface barrier, but once the lesion breaks into dentin, it typically becomes more extensive because dentin has tubules and is less mineralized, allowing easier and faster spread of decay. This is why the dentin involvement is greater than enamel at this point. It’s not correct to say there’s no enamel involvement or that dentin and enamel are equally affected at this stage, since the hallmark of this depth is that dentin is now the predominant, more extensive tissue involved.