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

在临床正畸治疗中，下颌骨的位置在必要时会得到肯定的矫正。然而，下颌位置的改变是否会对整个身体产生影响仍是个未知数。本研究通过测量在静止、咬合和咬合时下颌重心的移动，探讨下颌位置的改变是否会影响身体的调节机制，特别是平衡调节机制。结果表明：1.闭眼测试中，咬合、咬合力为10%、咬合力为50%时重心移动的距离和速度均较静止或100%咬合力咬合时小。咬合力为10%的咬合，咬合力为50%的咬合力。3.重心总体上有向后移动的趋势。4.下颌静止位置和咬合状态的轻微变化对重心的移动没有明显的影响。5.咬合似乎将刺激传导到咬合相关的颌肌、牙周组织和颞下颌关节，进而影响身体，特别是躯体的调节机制，导致重心移动，从而调节身体的平衡功能。

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.