A Study of the Relationship between the Development of Skeletal Malocclusion and the Tooth Crowding in Posterior Part of Dentition

为探讨骨性错牙合畸形的发生与后牙-义齿基托不齐引起磨牙萌出的关系，本研究采用猕猴模型进行实验研究。制作金属全冠，固定在实验动物的左右上颌第一磨牙上，以增加咬合垂直距离。在固定第一冠1个月后重复此程序，并提供总共增加2 mm的垂直尺寸。生长动物表明，下颌骨的向前位移和随后的髁状突生长与磨牙高度的增加有关。下颌骨的这种反应引起了前牙反牙合。而成年动物则表现为下颌骨向后旋转，提供前牙开牙合。这些结果表明，磨牙过萌，由于后方的差异是一个重要的病因发展的骨性错，如骨性III类和骨性开牙合。

In order to clarify the relationship between the development of skeletal malocclusion and the over eruption of molars due to posterior tooth -to-denture base discrepancy, a model experiment using monkeys have done in this study. Metal crowns were made and fixed on the right and left maxillary first molars of experimental animals to increase the vertical dimension of occlusion. This procedure was duplicated after one month of fixing the first crown and providing the increasing 2mm of the vertical dimension totally.Growing animal indicated that the forward displacement of the mandible followed by the condylar growth was associated with increasing the molar height. This response of the mandible induced the anterior cross bite of occlusion. However, adult animal showed that the backward rotation of mandible was induced by the increasing vertical dimension, providing the anterior open bite occlusion. These findings are suggesting that the molar over eruption due to posterior discrepancy is one of the important etiologic factors in the development of skeletal malocclusion such as skeletal class III and skeletal open bite.