安氏Ⅱ类2分类错颅颌面形态及牙弓宽度的特征分析

The study of cephalometric and arch width characteristics of class Ⅱ division 2 malocclusions

目的:通过对颅颌面形态和牙弓宽度的联合研究,探讨安氏Ⅱ类2分类错患者的特征及发病机制。方法:选取50例13～18岁(安氏Ⅱ类2分类错患者26例和个别正常者24例)未正畸治疗患者取记录模型和拍摄头颅侧位片。在记录模型上用电子游标卡尺测量牙弓宽度和牙冠宽度,计算Pont指数;头颅侧位片采用WinCeph 8.0软件系统测量相关的15项骨性指标,对测量结果采用SPSS.13.0 for Windows统计软件进行两个独立样本的t检验。结果:模型测量显示安氏Ⅱ类2分类错组患者的上下颌尖牙段和前磨牙段的宽度均明显小于个别正常组(P<0.05),同时安氏Ⅱ类2分类错组的前磨牙Pont指数明显大于个别正常组(P<0.05)。头颅侧位片分析显示∠SNB,A.P.D.I.ANS-Me,ANS-Me/N-Me(%)小于个别正常组,O.D.I.和Pog-NB大于个别正常组(P<0.05)。结论:安氏Ⅱ类2分类错患者上下颌尖牙及前磨牙段牙弓宽度发育不足,下颌牙槽骨及面下1/3发育不足而颏部发育正常。

Objective：The aim of this compound cephalometric and arch-width study was to determine arch-width and skeletal differences between subjects with Class Ⅰ normal and with Class Ⅱ division 2 malocclusions.Methods：50 untreated patients＇dental models and lateral cephalograms were selected;arch width and tooth width measurements were carried out on study models using a calibrated digital caliper.The radiographs were digitized and processed using WinCeph 8.0 Imaging software,and an independent sample T-test was carried out in order to compare the two groups.Results：The statistically significant differences between the groups for the study model measurements were in maxillary and mandibular intercanine,and interpremolar width.The cephalometric results revealed that ∠SNB and A.P.D.I.ANS-Me,ANS-Me/N-Me（%）,O.D.I.and Pog-NB were different between the two groups.Conclusion：Class Ⅱ division 2 malocclusion patients＇ maxillary and mandibular intercanine,and interpremolar width are smaller and they show similar chin prominent,but compared with the Class Ⅰ normal group,the Class Ⅱ division 2 malocclusion patients exhibit mandibular restriction.