What is the maximum time an ultrasonic scaler can be on one tooth?

• A. 15 seconds
• B. 8 seconds
• C. 20 seconds
• D. 60 seconds

Answer: (B)

A key idea here is protecting the tooth from heat buildup while cleaning with an ultrasonic scaler. The tip’s rapid vibration can generate enough heat to injure the dental pulp if left on a single tooth surface for too long, even with water spray. To minimize this risk, you limit the time the scaler stays on one tooth surface and take short, intermittent passes, allowing cooling between passes.

Eight seconds per tooth surface is a commonly taught maximum in veterinary dentistry because it provides a safe window to remove plaque and calculus while allowing heat to dissipate. If you push beyond this, the risk of thermal injury to the pulp increases, which can lead to pulpitis or other damage. Longer durations, such as fifteen, twenty, or sixty seconds, are not advisable for that reason, even with cooling.

In practice, you work in brief strokes, continuously move the tip to a new area, and rely on steady coolant flow to help manage heat. If a tooth needs more cleaning, you’ll cover it in additional short passes rather than a prolonged single pass.