青春前期不同深度下颌角前切迹Ⅱ类错(牙合)患者的颅面形态

Dimensional Differences in Craniofacial Morphologies of Prepubescence Class Ⅱ Patients with Deep and Shallow Mandibular Antegonial Notching

目的初步探讨下颌角前切迹深度不同的安氏Ⅱ类错(牙合)患者在青春前期出现的颅面形态差异以及与Ⅱ类错(牙合)形成的关系。方法选择ANB≥5°的35例青春前期患者为研究对象,按照下颌角前切迹深度分为两组:深切迹组18例,切迹深度≥3mm;浅切迹组17例,切迹深度≤1mm。所有患者治疗前均拍摄头颅侧位定位片并进行描记测量,测量17项角度指标及11项线距指标,比较两组患者的颅面形态差异。结果深切迹组上、下颌骨矢状方向(Ptm-A、Go-Pg)的发育小于浅切迹组,相对于前颅底的位置(SNA、SNB)也更加靠后(P<0．05),但两组ANB的差异无统计学意义(P>0．05);在垂直高度上,深切迹组SN-GoGn、ANS-Me大于浅切迹组(P<0．05),上后牙槽高度 (U6-PP)增加、下颌升支生长不足,同时下颌骨体顺时针旋转。结论青春前期骨性Ⅱ类错(牙合)患者颅面形态已出现差异,深切迹组患者较浅切迹组上下颌骨呈现出明显的垂直生长趋势,而水平向发育不足,这种差异可能由于各自的生长型造成,但在Ⅱ类骨性矢状关系上的严重程度基本相似。

Objective To identify certain craniofacial characteristics of untreated prepubescence Class Ⅱ patients with deep and shallow mandibular notching. Methods 18 untreated preadolescent Class Ⅱ patients with deep mandibular notching and 17 untreated preadolescent Class Ⅱ patients with shallow mandibular notching were selected. Each subject＇s pretreatment lateral cephalogram was traced. Seventeen angular and eleven linear measurements were made. The means and standard deviations were calculated for each parameter. The significance of difference between mean values was evaluated by the Independent-Samples T test. Differences were considered statistically significant when the P value was 0.05 or less. Results There was no difference in ANB between two groups, but deep notch cases had more retrusive maxillary and mandibles with shorter maxillary and corpus. In vertical direction, subjects with a deep mandibular notch had a longer lower facial height and more vertically directed mandibular plane angle than did shallow notch cases, these may be caused by the increasing of alveolar height of maxillary, smaller ramus height and greater gonial angle. Conclusion There were some differences in the craniofacial morphologies between deep and shallow notching groups of preadolescent Class Ⅱ patients. Compared with shallow notching group, the mandibles with the deep notching rotated downward and backward and have more vertical directed tendency, but there have no obviously difference in horizontal relationship of maxillary and mandible between two groups.