快速腭扩展对牙颌横向矫治作用的研究

目的：探讨快速腭扩展对牙颌各结构的横向矫正作用。方法：对12例恒牙期上颌狭窄病例用Hyrax扩弓器行快速腭扩展矫治。通过矫治前后研究模型分析,头颅后前位定位X线片头影测量分析评价腭扩展效果。结果：快速腭扩展使上腭中缝打开,上颌牙齿及牙槽基骨颊向移动,支抗磨牙位移最大,平均4.84mm。牙槽突点（alm）侧移大于上颌点（mx）。全鼻高侧移过程中以鼻高中1/2水平（bn50）侧移量最大,平均2.74mm。上颌中线两侧牙齿,牙槽骨及颌骨位移值的变化无统计学差异。结论：上颌快速腭扩展在打开腭中缝解除上牙弓狭窄时,上颌牙齿、牙槽基骨发生了颊向移动,基骨位移量大于牙齿位移量,上颌牙槽突发生了形变。鼻上颌复合体整体位移效果呈三角形,中线两侧基本对称。

A study on transverse effects of dentonmxillary structuresby rapid palatal expansion

Objective:The purpose of this study was to evaluate the transverse changes of the dentomaxillary structures by means of rapid palate expansion. Method:12 patients with constrict maxillary arch had been treated by Hyrax expander with 2 turns per day for two weeks. The changes of dentomaxillary structures were evaluated before and after expansion via study models and posteroanterior cephalometric analysis. Result:The palate suture was opened,the teeth and the alveolar crest moved buccally. The most buccal movement occurred at the anchorage molar(mean 4.84 mm). The ALM point moved more than MX point. Change most were witnessed at BN50 in the nasal template(mean 2.74 mm). The changes of two maxillary sides appeared with no significance differences statistically. Conclusion:The constrict maxillary arch was corrected by RPE through opening palate suture. The maxillary alveolar crest moved more than those of teeth. Modification of alveolar crest was observed and morphological changes of nasomaxillary complex were attained with symmetric triangular shape on coronal plane.