Which term describes carious tissue that was not completely excavated prior to placing a restoration?

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

Answer: (A)

In minimally invasive dentistry, when a cavity is prepared and not all decayed tissue can be removed without risking damage to the tooth or pulp, the carious tissue that remains is called residual caries. This term specifically describes decay left behind after attempting excavation and is the reason a restoration is placed over some decayed dentin. It is distinct from primary caries, which is decay that exists on a tooth that has not yet been treated; secondary caries refers to new decay that forms at the margins of an already placed restoration; and smooth surface caries describes the location of decay rather than what happened during preparation. Recognizing residual caries helps guide treatment decisions, such as sealing the remaining decay with adhesive materials or planning staged removal, depending on the tooth’s risk and pulp status.