Which dental instrument operates at 400,000 rpm to cut and prepare the tooth?

The high-speed handpiece is designed to operate at speeds of around 400,000 revolutions per minute (rpm), making it highly effective for cutting through tooth structure, preparing cavities, and shaping teeth during restorative procedures. The high speeds allow the dentist to efficiently remove enamel and dentin with precision, minimizing heat generation and discomfort for the patient due to advanced engineering and design features of the handpiece.

In contrast, slow-speed handpieces operate at significantly lower speeds, generally in the range of 10,000 to 40,000 rpm, which are more suited for polishing and finishing rather than cutting. Ultrasonic scalers, employed primarily for periodontal treatment and calculus removal, utilize vibrations rather than high rotational speeds for their function and thus do not meet the required rpm for cutting. Lastly, electric handpieces can also vary in speed but are not typically associated with the high-speed range of cutting procedures at 400,000 rpm like traditional high-speed handpieces. Thus, the unique characteristics of the high-speed handpiece make it the correct choice for precisely cutting and preparing the tooth.