Which statement is true about coronal caries surface layer?

• A. The surface layer is always absent
• B. The surface layer is always present
• C. The surface layer may be present
• D. The surface layer dissolves rapidly

Answer: (C)

In coronal caries, there is an outer surface zone of the enamel lesion that can remain relatively mineralized, forming a surface layer. This layer doesn’t always exist—it depends on the lesion’s activity and the balance between demineralization and remineralization. When caries is arrested or remineralization occurs, this surface layer may be present and remain intact. When the lesion is active and demineralization outpaces remineralization, the surface layer can be absent. Because of this variability, the accurate statement is that the surface layer may be present. The idea that it is always absent or always present doesn't fit the range of lesion behavior, and there isn’t an inherent rule that it dissolves rapidly in all cases.