Which instrument is sharp on three sides?

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

Answer: (C)

The instrument designed with three sharp edges is the scaler because its blade has a triangular cross-section that provides three grinding surfaces: two cutting edges on the sides and a sharp tip. This configuration lets the scaler efficiently remove supragingival calculus from various surfaces and line angles while staying precise and minimally aggressive to surrounding tissue.

In contrast, a curette has a rounded toe and back with two cutting edges on the curved blade but not a sharp tip, so it’s sharp on two sides. An explorer is mainly a pointed instrument with a sharp tip used for detecting calculus and irregularities, not for planing surfaces, and a probe is non-cutting and blunt for measurements.