Janson Guilherme, Cruz Karina Santana, Woodside Donald G, Metaxas Angelos, de Freitas Marcos Roberto, Henriques José Fernando Castanha
Department of Orthodontics, Bauru Dental School, University of São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 2004 Oct;126(4):451-63. doi: 10.1016/S0889540604004482.
The objective of this study was to evaluate the dentoskeletal changes consequent to orthodontic treatment in subjects with Class II subdivision malocclusions, treated with asymmetric extractions, compared with a normal-occlusion control group. The sample consisted of 3 groups, with 30 subjects in each: normal-occlusion subjects (group 1), untreated Class II subdivision subjects (group 2), and Class II subdivision patients treated with asymmetric extractions (group 3). All subjects had a full complement of permanent teeth at the beginning of treatment. The average ages of the subjects were 22.42, 15.76, and 18.57 years, respectively, in groups 1, 2, and 3. Measurements of relative differences in the spatial position of dental and skeletal bilateral landmarks were obtained from the submentovertex and posteroanterior cephalometric (PA) radiographs. The t test for independent samples was used to compare group 1 with groups 2 and 3 at different times. Results from the submentovertex radiograph showed that asymmetric extractions in Class II subdivision malocclusions will maintain the differences in the anteroposterior positions of right and left, maxillary and mandibular first molars, as would be expected with the treatment protocols used. There were no significant skeletal changes that could be attributed to the treatment approaches investigated or transverse collateral effects with the asymmetric mechanics used. It was also demonstrated that treatment of Class II subdivision malocclusions with asymmetric extractions produced corrections of maxillary and mandibular dental midline deviations with the midsagittal plane, without canting the occlusal plane or any other investigated horizontal plane, as seen in the PA radiograph. Treatment of Class II subdivision malocclusions with asymmetric extractions constitutes a beneficial approach to this problem.
本研究的目的是评估采用不对称拔牙治疗的安氏II类亚类错牙合患者正畸治疗后的牙颌面变化，并与正常牙合对照组进行比较。样本包括3组，每组30名受试者：正常牙合受试者（第1组）、未经治疗的安氏II类亚类受试者（第2组）和采用不对称拔牙治疗的安氏II类亚类患者（第3组）。所有受试者在治疗开始时均有完整的恒牙列。第1、2、3组受试者的平均年龄分别为22.42岁、15.76岁和18.57岁。从颏顶位和正位头影测量（PA）X线片上获取牙齿和骨骼双侧标志点空间位置的相对差异测量值。采用独立样本t检验在不同时间比较第1组与第2组和第3组。颏顶位X线片结果显示，安氏II类亚类错牙合的不对称拔牙将维持左右上颌和下颌第一磨牙前后位置的差异，这与所采用的治疗方案预期一致。没有显著的骨骼变化可归因于所研究的治疗方法或所使用的不对称力学的横向附带效应。PA线片显示，采用不对称拔牙治疗安氏II类亚类错牙合可使上颌和下颌牙中线相对于矢状面的偏差得到矫正，而不会使牙合平面或任何其他所研究的水平面倾斜。采用不对称拔牙治疗安氏II类亚类错牙合是解决该问题的一种有益方法。
