颏部形态与正畸矫治拔牙设计的相关性研究

目的 探讨颏部突度对临界拔牙病例矫治设计的影响.方法 选取50例年龄15～18岁之间已完成正畸治疗的错牙合]畸形患者,男22名,女28名,平均年龄16.5岁.其中25例为拔牙矫治,拔除4个第一前磨牙,25例采用非拔牙矫治.矫治后侧貌良好,覆合覆盖正常,完成头影测量19项,并对50例临床牙牙合]畸形拔牙与非拔牙病例正畸治疗前牙颌面硬组织、及软组织治疗前后变化进行对比的回顾性研究,进行成组设计和配对设计t检验,并进行拔牙概率的回顾性分析.结果 治疗前拔牙组与非拔牙组在Pog-NB与L1-NB测量项目在两组之间存在显著性差异,Pog-NB与拔牙概率存在高度相关关系.拔牙组颏部突度明显小于非拔牙组,下切牙唇倾度明显大于非拔牙组.而上前牙突度、倾斜度及上下颌骨突度项目在两组间不存在显著性差异.治疗前、后软组织在两组病例无统计学意义的差异.结论 对于临界拔牙病例制定矫治计划时,为达到良好的侧貌,避免产生正畸面容,要综合考虑影响侧貌的鼻唇颏协调一致.颏部突度越大,拔牙的概率越小,下切牙可在一定程度上唇倾来调整患者侧面曲线使其更为协调.

Correlative study between the protrusion of chin and orthodontic treatment plan about extraction

Objective To determine the influence of chin on extraction in borderline cases.Methods Pre-treatment lateral cephalograms of 50 treated patients (25 first premolar extraction cases, 25 non-extraction cases) were collected and digitized. The average pre-treatment age was 16.5 years (15～18 years). 19 cephalometric parameters were used for assessment. Comparison was made between extraction and non-extraction orthodontic treatment in borderline cases. The correlation analysis, t-test and Logistic regression analysis were used. Results Significant hard tissue changes were found between extraction and non-extraction cases. Extraction cases had smaller chin prominence. Logistic regression analysis showed that the probability of orthodontic extraction was significantly correlated with Pog-NB. Conclusions The important factor in determining extraction in borderline cases was the prominence of the chin. The probability of orthodontic extraction decreased with the increasing chin prominence.