正畸治疗中磨牙的拔除和保留(四十四)——骨性Ⅲ类错畸形拔除下颌磨牙矫治后追踪观察

A follow-up study of treatment of skeletal class Ⅲ malocclusion following mandibular molar extractions

目的:观察恒牙期骨性III类错拔除下颌磨牙矫治及矫治后4年牙、、面形态的变化。方法:恒牙期骨性III类错病例22例(男6例、女16例)。年龄12.1～16.9岁,平均14.2±1.6岁。均拔除下颌第一或第二磨牙后采用直丝弓矫治器进行掩饰性治疗,并在矫治结束后追踪观察2.8～7.5年,平均4.3±2.2年。治疗前(T0)、治疗后(T1)及追踪期末(T2)头颅侧位片以Pancherz头影测量方法进行分析。结果:治疗结束后上下颌前牙覆盖增加5.37mm(P<0.001),i-i/Olp减少4.67mm(P<0.001),ii/Olp-Pg/Olp减少3.15mm(P<0.01);LL/Olp减少2.18mm(P<0.01),UL/Olp-LL/Olp减少2.47mm(P<0.001)。在追踪期内前牙覆盖减少1.73mm(P<0.001),ii/Olp增加2.85mm(P<0.01);A/Olp增加1.07mm(P<0.05),Pg/Olp增加1.97mm(P<0.05)。将追踪期末的数据与治疗期间比较,虽有复发但与治疗前比较仍有显著改善。结论:恒牙期骨性III类错畸形患者在拔除下颌第一或第二磨牙矫治后下颌切牙的内收使前牙反覆盖得以纠正。在追踪期内随着内收切牙的复发及下颌矢状向生长,前牙覆盖显著减小,与治疗前相比有显著增加。在软组织方面,下唇凸点在治疗期间的后退导致上下唇凸点间的距离显著减小,从而患者的软组织侧貌得以改善,在追踪期末患者仍然维持良好的软组织侧貌。在治疗期及追踪期内患者前下面高增加并在观察期末出现下颌平面角的增大。

Objective： The purpose of this investigation was to evaluate dento-skeletal and soft-tissue profile changes in skeletal Ⅲ patients after treated orthodontically with mandibular molar extractions and at a four-year follow-up. Method： Twenty two patients with skeletal class Ⅲ malocclusion were included in the study. All patients were treated with straight wire fixed appliances after mandibular molar extractions. Lateral cephalograms obtained before and after active treatment and at four-year follow-up were analyzed using Pancherz analysis. Result： The immediate treatment results showed that overjet increased 5.37 mm （P〈0.001）, from -2.02 mm at the beginning of treatment to 3.35 mm after active treatment, ii/Olp decesesed 4.67 mm （P〈0.001）and ii/Olp-Pg/Olp decreased 3.15 mm （P〈0.01） ;LL/Olp decreased 2.18 mm （P〈0.01）and UL/ Olp- LL/Olp decreased 2.47 mm （P〈0.001）. During the four-year follow-up, overjet decreased 1.73 mm （P〈0.001）, ii/Olp increased 2.85 mm （/9〈0.01）; A/Olp increased 1.07 mm （P〈0.05）and Pg/Olpincreased 1.97 mm （P〈0.05）. The long-term treatment outcome was that at the four-year follow-up all 22 patients still maintained a positive overjet or edge-to-edge incisal relationship. Conclusion： In skeletal Ⅲ patients after treated orthodontically with mandibular molar extractions, the anterior erossbite was corrected because of lingual movement of the lower incisors. The overjet relapsed significantly during the follow-up period, but still maintained a positive value or edge-to-edge relationgship at the end of follow-up. With the backward movement of the lower lip, the distance between the most convex points of upper lip and lower lip to Olp decresed dramticlly and resulted in a remarkable improvement of soft-tissue profile. At the end of follow-up, the soft-tissue change ramained stable.