Which caries is not adjacent to an existing crown or restoration?

• A. Primary caries
• B. Secondary caries/CARS
• C. Residual caries
• D. Smooth surface caries

Answer: (A)

Caries types are often defined by their relationship to restorations. Primary caries occur on surfaces that have never been restored before, so they are not associated with any crown or filling. The other terms describe decay that is linked to a restoration: secondary (recurrent) caries form at the margin of an existing restoration; residual caries are remaining decay left after removal during cavity prep near a restoration; smooth surface caries refers to decay on smooth surfaces and can occur away from restorations, but the question’s focus is on adjacency to a crown or restoration. Therefore, primary caries is the best answer because it by definition is not adjacent to any existing crown or restoration.