Twin block applianceによる顎運動時の顎顔面軟組織の動態解析

概要

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The purpose of the present study was to elucidate the kinetics of facial soft tissue affected by use of a twin block appliance (TBA) to determine the optimum amount of construction bite. The subjects were 10 adult males with Class II division 1 malocclusion (Class II group) and 10 adult males with Class I malocclusion (Class I group). Individual TBAs were prepared by registering the construction bite vertically after being raised by 2 mm at the incisors. The mandible was advanced stepwise to 4 protruding positions of 0, 2, 4, and 6 mm, and the 3-dimensional positions of 18 markers whose coordinates were converted from 3 forehead points were determined in the directions of the x, y, and z axes using a optical motion capture system. As for the task, tapping at 2 Hz was performed. The movement distance of the upper lip in the transverse direction was significantly less in the Class II group without a TBA than in the Class I group without a TBA. Further, that of the upper lip in the transverse and vertical direction was significantly greater in the Class II group at the 4mm protruding position than in the Class II group without a TBA. Our results indicate that an optimum construction bite by the mandible was obtained at the 4mm protruding position.