Abstract:

Abstract：Objective To investigate the skeletal and dental changes produced by the Twin-block appliance excluding the influence of natural growth in order to reflect the treatment effect more objectively and accurately. Methods The study consisted of 30 children with class Ⅱ1 malocclusion and retrognathic mandible. One group （averaged 11.5 years） was treated with Twin-block appliance for an average of 14 months；the other group （averaged 11 years old） was observed for 13 months without treatment. The cephalometric data of two groups before and after treatment or control was analyzed with Pancherz statistically. Results After treatment ， the mandible unit length，the ramus height and the mandibular body length increased by 4.95 mm，4.03mm and 1.67 mm respectively，excluding the influence of natural growth. The SNB angle increased by 2.39°. The anterior facial height and posterior facial height increased obviously， but the angle of mandibular plane was stable. The upper incisor retroclined and the lower incisor proclined； overjet and molar relationship was corrected by 4.76 mm and 5.22 mm in the treatment group， of which 61% and 75% was due to dental effect， 39% and 25% due to skeletal effect. Conclusion Deep overbite， deep overjet， and molar relation can be improved greatly by the Twin-block appliance. It can promote the mandibular growth sagitally and vertically；the correction of ClassⅡ skeletal relation can be achieved.

Key words: Pancherz analysis, Twin-block appliance, cephalometric, Class Ⅱ1 malocclusion, functional treatment

摘要：

目的 了解排除了自然生长因素后，Twin-block矫治器治疗青少年安氏Ⅱ1错牙合引起的硬组织改变，从而更为真实、准确地评价该矫治器的矫治效能。方法 于2008年9月至2010年9月在河北医科大学附属口腔医院正畸科门诊选择30例手腕骨片为FG-G期的安氏Ⅱ1下颌后缩患者。治疗组15例，平均年龄11.5岁，采用Twin-block矫正器治疗，平均治疗及保持时间14个月； 对照组15例，平均年龄11岁，作为自然生长对照，平均观察时间13个月。对治疗及观察前后头颅X线侧位片的32项硬组织项目进行Pancherz测量分析，评价矫治疗效。结果 排除了自然生长因素的影响，治疗组在采用Twin-block矫治器矫治后，下颌全长、升支高度及下颌体长分别净增加了4.95、4.03和1.67 mm， SNB角（蝶鞍中心、鼻根点及下齿槽座点所构成的角）增加了2.39°； 全面高、下面高及后面高均明显增加，但下颌平面保持稳定；上切牙舌倾、下切牙唇倾。在4.76 mm的覆盖减少量和5.22 mm的磨牙关系改善中，牙齿效应分别占61%和75%，骨骼效应占39%和25%。结论 Twin-block矫治器使发育期安氏Ⅱ1错牙合患者覆牙合覆盖、磨牙关系均得到改善，有效促进了下颌骨矢状方向上的生长发育，Ⅱ类骨面型趋于好转。

关键词: Pancherz分析法, Twin-block矫治器, 头影测量, 安氏Ⅱ1错牙合, 功能矫治