Which caries is adjacent to an existing restoration, crown, or sealant?

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

Answer: (A)

The event being described is decay that forms right at the edge of an existing restoration, crown, or sealant. This is called secondary caries, also known as caries adjacent to restorations (CARS). It happens when margins are imperfect or breakdown occurs, allowing bacteria and acids to persist at the tooth-restoration interface or beneath the restoration. That location-specific nature is why this term fits best: it specifies decay that arises next to an existing restoration rather than on untouched tooth surfaces.

Primary caries is decay on surfaces that haven’t been restored before. Residual caries refers to decay that remains after an incomplete removal of decay during treatment, not specifically tied to the interface of a restoration. Smooth surface caries describes decay on exposed, smooth enamel areas away from any margins. So, for decay adjacent to a restoration, the correct term is secondary caries.