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

为了阐明由于后牙与义齿基托不一致导致的磨牙过度萌出与骨骼错颌发展的关系，本研究采用猴子模型实验。制作金属冠固定在实验动物的左右上颌第一磨牙上，增加咬合的垂直尺寸。在第一个冠固定一个月后重复这个步骤，并提供垂直尺寸增加2mm。生长动物表明，下颌向前移动后髁突生长与磨牙高度增加有关。下颌骨的这种反应引起了前交叉咬合。然而，成年动物显示，下颌骨的向后旋转是由于垂直尺寸的增加而引起的，提供了前开咬合。这些结果提示，由于后牙差异导致的磨牙过露是导致骨III类和骨开咬等骨错牙合发生的重要原因之一。

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.