Experimental Study of the Effects on Alteration of Vertical Dimension Involving the Mandibular Movement

在临床矫正学中，必要时下颌骨的位置被积极地矫正。本研究通过测量下颌骨在静止位、咬合状态和咬合力作用下的重心移动，探讨下颌骨位置改变是否影响人体的生理调节机制，尤其是平衡调节机制。结果表明：1.在闭眼测试中，下颌骨咬合时，重心移动的距离和速度相对较小，咬合力10%和50%时的咬合力比下颌静止位和100%时的咬合力高咬合力。2.除了一个受试者，当下颌骨被咬合时，用10%咬合力握紧，用50%咬合力握紧结果表明：（1）下颌骨在静止状态和咬合状态下的位置变化对重心的移动无显著影响，（2）下颌骨在静止状态和咬合状态下的位置变化对重心的移动无显著影响5.咬合刺激可传递到与咬合相关的颌骨肌肉、牙周组织和颞下颌关节，进而影响机体的生理调节机制，尤其是躯体调节机制，使调节机体平衡功能的重心发生偏移。

In clinical orthodontics, the position of the mandible is positively corrected when necessary. However, it still remains unknown whether the alteration of mandibular position exerts an influence on the whole body.In this study, the shifting of gravity center with mandible at resting position, in occlusion and in clenching with voluntary occlusal force was measured to investigate whether or not the mechanism of physical adjustment, especially adjustment of equilibrium, was affected by the alteration of mandibular position. The following results were obtained.1.In the testing with eyes closed, the distance and velocity of the shifting of gravity center tended to be relatively smaller, when the mandible was occluded, clenched with 10% occlusal force and clenched with 50% occlusal force than when the mandible was kept at resting position or clenched with 100% occlusal force.2.The extent of shifting tended to be smaller except in one subject, when the mandible was occluded, clenched with 10% occlusal force and clenched with 50% occlusal force.3.The center of gravity tended to be displaced on the whole toward the posterior direction.4.Slight alteration of mandibular position at rest and in occlusion produced no signficant differences in the shifting of gravity center.5.It seemed that clenching transmitted stimulation to clenching-associated jaw muscles, periodontium and temporomandibular joints, which in turn affected the mechanism of physical, especially somatic, adjustment to result in the shifting of gravity center which regulates the equilibrium function for the body.