RESEARCH OF TOOTH MOBILITY CHANGE DURING AND AFTER ORTHODONTIC TOOTH MOVEMENT

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The authors followed the change of the mechanical impedance of maxillary canines and their periodontium during orthodontic treatment with the mechanical impedance measuring device. The measurements of the mechanical impedance of these canines and their periodontium decreased following the active tooth moving manipulation during the initial tooth moving period, and these measurements showed increasing tendency during retention period after the orthodontic tooth movement. From the result, it was found that the degree of the periodontal tissue changes with orthodontic treatment could be estimated from these measurements of the mechanical impedance. The feasibility of this method for clinical use was also suggested.The authors made major reform of this mechanical impedance measuring device after the first stage of this research to observe and to measure much wider and higgher frequency domain. We employed new theoretical model of the tooth and periodontium for new device. New device could … More analyze the resonance phenomena of the periodontium could be done clearer and easier.To investibate the fumdamental sufficiency of this new device, maxillary and mandibular incisors were measured (20 times continuously, 30 second intervals). From each measurement of each tooth, three parameters (elastic coeffiicient, viscous coefficient and dynamic mass) were calculated respectively. Each parameter of these three remained almost constant respectively and this phenomenon indicated that the repetition of the measurements made no significant effects on the measurements. The variations of these three that were obtained from same tooth were small. This new device showed the sufficiency that matched up to the old one. There were significant differences between the measured parameters of the maxillary and mandibular central incisors. It was suggested that the differences of the tooth mass, the length of the root, and other factors might have some influence on the measurement.At the end, the new device we developed could be used not only for the humans but also for the experimental animals. This new device will provide the effective research method for basic studies to establish the clinical application of the tooth mobility measuring method. Less