How can caries be classified by proximity to a restoration?

• A. All of the above
• B. Primary caries
• C. Secondary caries/CARS
• D. Residual caries

Answer: (A)

Caries can be described by how close they are to a restoration, which includes three forms: primary caries on surfaces that have no restoration, secondary (recurrent) caries that develop at the margin of an existing restoration due to factors like marginal leakage, and residual caries that remain after partial caries removal. Because this classification spans all three scenarios, the best answer is the one that includes primary, secondary, and residual caries. The other options would miss one of these forms, whereas all three together fully describe proximity-related classifications.