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

在临床正畸中，必要时积极矫正下颌骨的位置。然而，下颌位置的改变是否对全身产生影响尚不清楚。本研究通过测量下颌在静止位置、咬合位置和咬合力作用下的重心随下颌的移动，探讨下颌位置的改变是否会影响身体调节，尤其是平衡调节的机制。得到了以下结果：在闭眼试验中，下颌骨被咬合、10%咬合力咬合和50%咬合力咬合时，重心移动的距离和速度比下颌骨保持静止或100%咬合力咬合时相对较小。2 .除1例被试在咬合、10%咬合力咬合和50%咬合力咬合时，下颌移位程度均趋向较小。重心总体上有向后侧偏移的趋势。下颌静止位置和咬合位置的轻微改变对重心移动无显著影响。结果表明，握拳通过刺激与握拳相关的下颌肌肉、牙周组织和颞下颌关节，进而影响身体尤其是躯体的调节机制，导致重心的移动，从而调节机体的平衡功能。

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.