アブストラクト（26巻2号：The Bulletin of Kanagawa Dental College）

The Bulletin of Kanagawa Dental College

English

Title　： An Attempt to Reduce Discomfort from High Frequency Noises in the Air Turbine Handpiece
Subtitle　： BKDC CLINICAL AND RESEARCH TOPICS : Bioadaptives of Dental Materials
Authors　： Taiji Sohmura1), Koji Ikuta2), Kohji Masuda2), Keiji Kawai3), Junzo Takahashi1)
Authors（kana）　：
Organization　： 1)Department of Dental Materials Science and Technology, Faculty of Dentistry, Osaka University, 2)Department of Micro System Engineering, Nagoya University Graduate School, 3)Department of Conservative Dentistry, Faculty of Dentistry, Osaka University
Journal　： The Bulletin of Kanagawa Dental College
Volume　： 26
Number　： 2
Page　： 83-91
Year/Month　： 1998 / 9
Article　： Report
Publisher　： Kanagawa Odontological Society
Abstract　： [Abstract] High frequency noises generated from the air turbine handpiece cause much discomfort to patients, and hinder dental treatment. The noises are thought to originate from a mixture of sound formed from the impact of the turbine blade on the air, the vibration of the turbine shaft and the handpiece body, and so on. In the present study, the sound pressure vs frequency analyses of the noises were carried out initially to identify the characteristic frequency which causes the uncomfortable noises. Considering that the audible sound frequency for a human being is distributed between 20Hz and 20kHz, two groups of noise peaks generated between 5kHz and 15kHz are responsible for the uncomfortable noises, where the first corresponds to the number of revolutions in the turbine, and the second to its harmonic sound frequency. The air turbine handpiece has holes and clearance on the head, and the noises are emitted from them with the air. Then, the size and shape of the holes and clearance were examined, and a reduction in the intensity of the uncomfortable noises was accomplished. That is, in the case of a ball bearing handpiece, when fitting with an upper lid with two 0.5 mmφ and one 1.0 mmφ holes and a lower lid with a 2 mmφ hole, the second characteristic peak almost disappeared, while the first peak still remained and the uncomfortable noise was decreased to a certain degree. On the other hand, in the case of an air bearing handpiece, when fitting with an upper lid with four 0.5 mmφ holes and a lower lid with a 2 mmφ hole, the intensity in both characteristic peaks and the uncomfortable noises decreased considerably.
Practice　： Dentistry
Keywords　： Air turbine, Noise, Reduction in the high frequency noise