Which hand scaling tool is used only on the crown?

• A. Scaler
• B. Curette
• C. Periodontal probing
• D. Polisher

Answer: (A)

The key idea here is differentiating hand instruments by where they’re used on the tooth. A scaler is specifically designed to remove calculus from the crown, i.e., the supragingival surfaces above the gumline. Its design targets the exposed tooth surfaces without going beneath the gingiva, which is why it’s the instrument you’d use for crown debridement.

A curette, in contrast, is built for subgingival work and root surface scaling; its shape and beveling allow access under the gingival margin, so it isn’t limited to the crown. Periodontal probing isn’t a scaling tool at all—it's used to measure pocket depths and assess periodontal health. A polisher is used after scaling to smooth and polish tooth surfaces, not to remove calculus.

So the tool used only on the crown is the scaler.