Final answer:
The ultrasonic scaler is designed to clean subgingival calculus from a specific tooth surface by using high-frequency sound waves.
Step-by-step explanation:
The instrument designed to clean subgingival calculus from a specific tooth surface is the ultrasonic scaler. An ultrasonic scaler uses high-frequency sound waves to remove calculus and plaque from the teeth and gums. This device produces ultrasonic vibrations that create bubbles in the cleaning solution, and when the bubbles collapse, they generate shockwaves that help in removing the deposits.