Janson Guilherme, Carvalho Paulo Eduardo Guedes, Cançado Rodrigo Hermont, de Freitas Marcos Roberto, Henriques José Fernando Castanha
Department of Orthodontics, Bauru Dental School, University of São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 2007 Jul;132(1):28-35. doi: 10.1016/j.ajodo.2005.07.024.
The purpose of this study was to cephalometrically compare the dentoskeletal and soft-tissue changes consequent to orthodontic treatment in patients with Class II subdivision malocclusion treated with asymmetric and symmetric extractions.
The sample included 54 patients with Class II subdivision malocclusion and full complement of permanent teeth, including first molars, at the beginning of treatment. Patients in group 1 (n = 27) were treated with the asymmetric extraction of 3 premolars and had initial and final mean ages of 14.07 and 16.71 years. Patients in group 2 (n = 27) were treated with the symmetric extraction of 4 premolars and had initial and final mean ages of 13.35 and 15.75 years. Lateral cephalometric radiographs were taken at pretreatment and posttreatment. T tests were used to compare the groups at pretreatment and the treatment changes between groups.
The results demonstrated that the asymmetric extraction group had significantly less mandibular incisor retraction, less soft-tissue retraction, and greater increases in mandibular incisor extrusion and mandibular molar asymmetry index than the symmetric extraction group.
It was concluded that the 3-premolar asymmetric extraction protocol in Class II subdivision malocclusions produces significantly less mandibular incisor and soft-tissue retraction than the 4-premolar extraction protocol.
本研究的目的是通过头影测量法比较不对称拔牙和对称拔牙治疗II类亚类错牙合患者正畸治疗后牙颌骨骼和软组织的变化。
样本包括54例II类亚类错牙合患者，治疗开始时恒牙列完整，包括第一磨牙。第1组（n = 27）患者采用不对称拔除3颗前磨牙进行治疗，初始平均年龄和最终平均年龄分别为14.07岁和16.71岁。第2组（n = 27）患者采用对称拔除4颗前磨牙进行治疗，初始平均年龄和最终平均年龄分别为13.35岁和15.75岁。在治疗前和治疗后拍摄头颅侧位片。采用t检验比较两组治疗前情况以及两组之间的治疗变化。
结果表明，与对称拔牙组相比，不对称拔牙组下颌切牙后移量显著更小，软组织后移量更小，下颌切牙伸长和下颌磨牙不对称指数增加更大。
得出的结论是，II类亚类错牙合采用3颗前磨牙不对称拔牙方案时，下颌切牙和软组织后移量显著小于4颗前磨牙拔牙方案。
