安氏Ⅱ类1分类错不同拔牙模式对青少年颏部形态变化的影响

Effect of different extraction modes on morphology of chin in adolescents with Class Ⅱ Division 1 malocclusion

目的:通过对安氏Ⅱ类1分类错青少年患者拔牙矫治前、后X线头影测量分析矫治前、后颏部形态的变化,为临床治疗提供参考.方法:选择安氏Ⅱ类1分类错青少年患者74例,其中上下颌拔除四颗第一前磨牙(第1组)20例,上颌拔除两颗第一前磨牙,下颌拔除两颗第二前磨牙(第2组)20例,上颌仅拔除两颗第一前磨牙,下颌不拔牙(第3组)20例以及义诊普查资料中未进行矫治者(对照组)14例.经X线头影测量分析,比较矫治前、后各组颏部形态的变化,对所得数据采用SPSS14软件进行统计学分析.结果:颏高度、颏前点处颏厚度及颏倾斜度各组均无明显改变.颏突度各组均有增加.采用双颌拔牙矫治组(第1,2组)颏凹陷、下齿槽座点处颏厚度、根尖点处颏厚度、颏弯曲度和颏唇沟深度显著减小,而采用上颌拔牙矫治组(下颌不拔牙)无显著变化.结论:颏部形态的改变与下颌拔牙有关,与下颌拔牙的位置无明显联系.应根据患者颏部形态选择适当的拔牙模式,以利于患者面型的改善.

AIM： To investigate the effects of extractions on the morphology of chin in adolescents with Class Ⅱ Division 1 malocclusion. METHODS： A total of 74 subjects were divided into 4 groups ： Group 1 of extracting 4 first premolars, Group 2 of extracting upper first premolars and lower second premolars, Group 3 of extracting upper first premolars only, and control group of nonextraction. Pre- and post-treatment changes of chin were compared by cephalometric analysis and statistical analysis was performed with SPSS14 software. RESULTS： No significant difference was found in the height of chin, the tilt angle of chin, and the thickness of chin at Po point in all groups. Proptosis degree of chin increased significantly in all groups. Significant decreases were found in the fossa of chin, the thickness of chin at B point and root tip, the curve of chin, and the depth of mentolabial furrow in groups treated with bimaxillary extraction, but no significant difference was found in maxillary extraction group. CONCLUSION： Changes of morphology of chin are affected by mandibular teeth extraction but the site of mandibular extraction does not seem to have obvious effect on the changes. Orthodontists should choose proper extraction modes to achieve the best results.