歯及び歯周組織の周波数測定について

ユニットパルス加振と高速フーリエ変換機による解析

抄録

The purpose of this study was to clarify the mechanism of the tooth mobility by measuring the frequency of a tooth and its surrounding tissue. A unit pulse technique was used to vibrate the tooth by hitting it with a hammer with plastic tip. The frequency range from 0Hz to 5, 925Hz was given in a moment to the examined tooth. An accelerated pick up (NP-501s: BBN, U. S. A.) was used for detection of frequency from a tooth and its surrounding tissue. It was adhesived to the palatal surface of a maxillary central incisor. Analysis of data was perfomed by FFT (Fast Fourier Transformer, CF-400; ONO SOKKI Co., Tokyo, Japan).
Tooth mobility was measured in visco-elastical model and extracted teeth, and then 41 maxillary central incisors of the patients with healthy periodontal condition and with early to advanced periodontal disease.
As the results, two components of frequency were fonud in visco-elastical model and in the patient. One was below 1, 000Hz (Peak 1: P. 1) and the another was above 1, 000Hz (Peak 2: P. 2). From the result obtained from extracted teeth, the characteristic frequency value of the maxillary central incisor was 2, 255.4Hz, which was average frequency of five teeth. This value was corresponded with the frequency of P. 2. The frequency of P. 1 was caused mainly by vibrating its surrounding tissue.
The frequency value of P. 1 and the frequency spectrum of P. 2 were found to relate with the destruction of periodontal tissue. The frequency value of P. 1 decreased according to the progress of periodontal destruction.
The frequency spectrum of P. 2 became wider according to the advance of destruction.
The shapes of wave of P. 2 was classified into 4 types. There were Bell-type, Voigt-type, Maxwell-type and Mixed Voigt-Maxwell-type. Healthy periodontum showed Bell-type. According to an advance of periodontal disease, the shape of wave of P. 2 change to show a tendency to appear Maxwell-type.