Which instrument is most commonly used to detect subgingival calculus?

• A. Curette
• B. Explorer
• C. Scaler
• D. Periodontal probe

Answer: (D)

Subgingival calculus is located below the gum line, so it’s detected during a careful periodontal examination as you explore the sulcus. The periodontal probe is designed to be inserted into the sulcus and glide along the root surface, allowing you to measure pocket depths and feel for surface irregularities. When calculus sits beneath the gingival margin, it creates a rough, uneven area that the probe can detect by tactile feedback as you trace the root. This combination of access to subgingival areas and the ability to note irregularities while recording probing depths makes the periodontal probe the most practical and reliable tool for detecting subgingival deposits in routine exams. Scalers and curettes are mainly for removing calculus, not detection, while explorers are good for tactile exploration but are not used as systematically to map subgingival calculus during probing.