AN ANALITICAL EVALUATION OF PERIODONTAL TISSUE CHANGE WITH DAMPED OSCILLATION OF TEETH.

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In particular, the measurement of tooth mobility is concidered a majior technique for demonstrating the conditions and functions of periodontal tissue directly.The aim of this study is to establish a new method to evaluate periodontal tissue characteristics objectively, including tooth mobility. In advance of clinical study, it used artificial tooth model with adjustable root tapers and thickness of a shock-absorbing material around the root. Factors investngated included individual damped oscillation, elastic constants, viscositic constants and the ratio of the elastic and viscositic constant. The data were used to explore whether they contribute to objective evaluation of the characteristics of periodontal tissue. The results were as follows :(1) These were obtained from analysis of the wave forms selected on an accelemeter when the tooth model was loaded horizontally and vertically.(2) A theoretical formula of the accelation was derived, and the elastic and viscositic constants were considered with regard to clinical use.(3) In cases of both horizontal and vertical loding, individual damped oscillation, elastic constants, viscositic constants and the ratio of the elastic and viscositic constants showed a tendency to decrease as the taper of the root increased.(4) In case of vertical loding, the value of individual damped oscillation, elastic constants, viscositic constants and the ratio of the elastic and viscositic constants decreased as the thickness of the shock absorbing material on the botom of root increased.