Abstract
Ultrasonic dental scalar is the instrument to remove dental calculus using ultrasonic vibration of a transducer. The transducer is used in resonant condition. However, it's resonance frequency change with value of input voltage to the transducer and condition of contact with a tooth or gum, so we produced the system that traces change of resonance frequency and generates driving signal at the frequency. In addition, we proposed to diagnose dental abnormality using the system and transducer. This paper reveals its possibility.