拔牙与非拔牙矫治安氏Ⅱ~1错对下颌第三磨牙影响研究

Position change of mandibular third molar after extraction or non-extraction orthodontic treatment in patients with Class Ⅱ~1 malocclusion

目的探讨拔牙和非拔牙矫治对安氏Ⅱ1错患者下颌第三磨牙的影响。方法随机选择2005年1月至2007年12月云南省第二人民医院口腔正畸门诊收治的安氏Ⅱ1错患者27例,分为拔牙组15例(矫治拔除4个双尖牙)和非拔牙组12例(保存全牙列矫治),均采用Edgwise矫治技术治疗。对患者治疗完成时的全颌曲面断层片进行各指标测量及比较分析。结果治疗结束后,拔牙组和非拔牙组下颌第三磨牙萌出间隙(BX)均较治疗前分别平均增加2.6mm和0.71mm,组间比较差异有统计学意义(P<0.05);拔牙组下颌第三磨牙近中倾斜角(θ)平均减小4.36°,而非拔牙组则平均增大0.41°,组间比较差异有统计学意义(P<0.01);拔牙组BX与下颌第三磨牙牙冠宽度之比(BX/MD)虽有明显变化,但与非拔牙组比较差异无统计学意义(P>0.05)。结论对于生长期安氏Ⅱ1错患者,拔牙矫治更有利于下颌第三磨牙的正常萌出。

Objective To study the impact with extraction or non-extraction orthodontic treatment on mandibular third molar. Methods Twenty-seven patients of Class Ⅱ1 malocclusion in 2002—2005 were chosen randomly,and they were divided into two groups according to their extraction or non-extraction orthodontic treatment. Their panoramic radiographs of pretreatment and post-treatment were analysed. Results After orthodontic treatment, eruption space of mandibular third molar（BX） increased in the two groups;changes were statistically significant（P 0.05）. Mesioclination angle of mandibular third molar decreased in the extraction group, but increased in the non-extraction group;difference between the two groups was also statistically significant（P 0.01）. Though changes of mandibular third molar eruption space with mandibular third molar crown width ratio（BX/MD）were significant in the extraction group,but changes of the ratio of the two groups had no statistical significance when compared. Conclusion For Class Ⅱ1 patients who are in the growing period,extraction orthodontic treatment is more conducive to mandibular third molar’s eruption.