Analysis of Noise Frequency of High-speed Air Turbine Dental Handpiece

Noise of high-speed air turbine dental handpiece is one of the serious noise pollution sources in dental clinic and laboratories which may harm the dentists' health and bring dental anxiety to many patients. However because of its small size, special working conditions and too high frequency noise, noise cancellation of high-speed air turbine dental handpiece becomes a so difficult problem that has not been solved yet. In order to solve this problem, as a preliminary study, frequency spectrum and influence of cutting tissues on main frequency of noise of high speed air turbine dental handpiece were studied. 50 cow teeth were used. Each tooth was flat before milling and then milled 3 to 4 through slots in an automatic handpiece system designed to keep the feed rate and air pressure constant. Real time sound, feed displacement and air pressure were collected simultaneously and analyzed. After milling, use micro ct to scan the milled tooth and gray scale of milled slot got were used to represent tissues of different positions of the milled slot. It was concluded that the high noise level of air turbine dental handpiece is mainly caused by sound signal related with rotational frequency and the main frequency of sound is closely related to properties of cutting tissues.