Department of Orthodontics and Dentofacial Orthopedics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Angle Orthod. 2013 Sep;83(5):749-57. doi: 10.2319/083012-698.1. Epub 2013 Jan 17.
To verify the hypothesis that appropriate acquisition of masticatory function and normal growth of the mandible are modified by malocclusion.
Eighteen Jcl:ICR mice were divided into two groups. In one group we shifted the mandible laterally using an occlusal guidance appliance, creating a posterior crossbite at 5 weeks of age. The other group served as control. After 10 weeks, three-dimensional jaw movements and muscle activities were recorded simultaneously during mastication. Microcomputed tomography scans were obtained in vivo to evaluate morphometric changes in the mandible.
(1) The jaw movement pattern in the sagittal plane showed significantly less anteroposterior excursion in the malocclusion group during the late-closing phase (power phase). (2) Electromyography showed significantly less masseter activity in the malocclusion group. (3) The condylar width and mandibular bone mineral density (BMD) were significantly reduced in the malocclusion mice compared to the normal mice.
These findings suggest that optimization of the chewing pattern and acquisition of appropriate masticatory function is impeded by malocclusion. Altered mechanical loading to the mandible may cause significant reduction of condylar width and mandibular BMD.
验证以下假设，即错颌畸形会改变咀嚼功能的正常获得和下颌的正常生长。
将 18 只 Jcl：ICR 小鼠分为两组。一组在 5 周龄时使用咬合引导装置将下颌侧向移位，造成后牙反颌。另一组作为对照。10 周后，在咀嚼过程中同步记录下颌的三维运动和肌肉活动。通过小动物活体 microCT 扫描评估下颌的形态变化。
（1）在矢状面，错颌组在闭合后期（力闭合相）的前伸运动明显减少。（2）肌电图显示，错颌组的咬肌活动明显减少。（3）与正常组相比，错颌组的髁突宽度和下颌骨骨密度（BMD）显著降低。
这些发现表明，错颌畸形会阻碍咀嚼模式的优化和获得适当的咀嚼功能。下颌受到的机械负荷改变可能导致髁突宽度和下颌骨 BMD 显著减少。
