Which instrument is used below the gumline?

• A. Scaler
• B. Curette
• C. Ultrasonic
• D. Explorer

Answer: (B)

The instrument used below the gumline is chosen for its ability to access beneath the gingival margin and debride the root surfaces without harming soft tissue. A curette is designed specifically for subgingival work: it has a rounded toe and a curved blade that can be inserted into the sulcus or pocket and gently adapted to the root surface for both scaling and root planing. This design enables effective removal of subgingival calculus and smoothing of the root while minimizing tissue trauma.

In contrast, scalers are typically angled for supragingival calculus on crowns and are less suitable for subgingival work without risking tissue injury. Explorers are diagnostic tools used to detect calculus and irregularities rather than for removal. Ultrasonic scalers can do subgingival cleaning as well, but the instrument most classically associated with subgingival debridement and root planing is the curette.