Is 200,000 rpm too slow for high speed preps?
It is correct that an air-driven high-speed runs much faster (350,000 – 400,000 rpm) than an electric-driven high-speed. However, as soon as an air-driven high-speed touches the tooth, the speed will drop to under 200,000 rpm, making it much more difficult to create an accurate margin. The electric will cut steadily with 200,000 rpm.