［关键词］ AngleⅡ类错牙合；正畸治疗；稳定性
Long-term stability of Angle class Ⅱ malocclusion after orthodontic treatment
［Abstract］ Objective To evaluate the trend of change in Angle's Ⅱmalocclusion after orthodontic treatment,and to analyze some possible factors which may predict or affect these changes,providing some reference for the clinical practice.Methods The sample consisted of 60 patients with Angle class Ⅱmalocclusion between 10～26 years,the patients before 16 years were divided into Group A,those after 16 years were divided into Group B.To evaluate the study models of pre-treatment,post-treatment and out of retention,ten variables were chosen to evaluate the change of occlusion paired T test,analysis of variance,correlation analysis were applied to the data. Results The dental relationship tend to return toward their pretreatment values after treatment,while still remaining a major part of the correction.The values have significant differences between the group A and B. Conclusion The early treatment is stable;the maxillary intercuspid width tended to be more stable than the mandibular one. The mandibular intercuspid width decreased significantly accompanied by the relapse of mandibular crowding.
［Key words］ Angle'sⅡmalocclusion;orthodontic treatment;stability
随着现代矫治技术的不断改进，矫治后的效果也越来越让患者满意，然而患者所得到的矫治效果能终生维持吗？这不仅是患者所关心的问题，同样也是正畸医师关注的焦点。
AngleⅡ类错牙合在错牙合畸形中占的比例要略多于AngleⅢ类错牙合，而且AngleⅡ类错牙合更易出现覆盖、覆牙合的复发。本课题将选择10项模型测量指标对60例AngleⅡ类错牙合患者的牙牙合模型进行研究，探讨其复发规律及寻求解决的办法。
1 资料与方法
1.1 样本选择 本研究选择1998～2004年我院口腔正畸科门诊治疗完成的AngleⅡ类错牙合患者60例，且治疗前后模型完整，病例均由正畸科医师提供，为尽量减小病例选择的偏倚，对医师提供病例的要求为只需资料完整，病例选择标准如下：（1）患者年龄在10～26岁，平均为16.46岁，男28例，女32例。（2）正畸治疗前诊断为安氏Ⅱ1类错牙合畸形。（3）其中19例患者在替牙期开始戴功能矫治器，包括twin-block、activator等，恒牙早期继续Ⅱ期固定矫治。（4）均采用固定矫正器非拔牙治疗，且正畸结束后时间为2～6年，平均为52.79个月。（5）固定正畸治疗前为恒牙列，固定正畸治疗后至随访时第一磨牙前无牙齿缺失，无外伤史。（6）保持方式均为Hawley保持器，完全停戴保持器后平均时间为29.56个月。（7）治疗完成后未进行牙龈纤维环切术。（8）正畸治疗效果良好：上下颌牙齿排列整齐，无扭转，无倾斜；前牙覆牙合、覆盖正常；尖牙与磨牙为中性关系，后牙咬牙合关系良好，为正中牙合关系。
1.2 研究方法 使用精确度为0.01 mm的游标卡尺测量牙牙合模型各项数据，并输入计算机，以下是主要测量指标：（1）上前牙不齐指数（UIRR）:上颌6个前牙相邻解剖邻接点之间的距离之和；（2）下前牙不齐指数（LIRR）：下颌6个前牙相邻解剖邻接点之间的距离之和；（3）覆牙合（OB）；（4）覆盖（OJ）；（5）上颌尖牙间宽度（U3W）；（6）下颌尖牙间宽度（L3W）；（7）上颌磨牙间宽度（U6W）；（8）下颌磨牙间宽度（L6W）；（9）左侧磨牙关系（LULM）；（10）右侧磨牙关系（RULM）。