Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 2011 Jun;139(6):768-74. doi: 10.1016/j.ajodo.2009.10.044.
The maxillary anterior teeth are the most important to facial esthetics because they are the first to show on a smile. Therefore, stability of the maxillary anterior teeth alignment is an important issue. The objective of this study was to compare the stability of maxillary anterior tooth alignment in Class I and Class II Division 1 malocclusions.
The sample comprised dental casts of 70 patients with Class I and Class II Division 1 malocclusions and a minimum of 3 mm of maxillary anterior crowding measured by an irregularity index. The patients were treated with extractions and evaluated at pretreatment and posttreatment and at least 5 years after treatment. The sample was divided into 3 groups: group 1, Class I malocclusion treated with 4 first premolar extractions comprising 30 subjects, with an initial age of 13.16 years and 8.59 mm of initial maxillary irregularity; group 2, Class II malocclusion treated with 4 first premolar extractions comprising 20 subjects, with an initial age of 12.95 years and 11.10 mm of maxillary irregularity; and group 3, Class II malocclusion treated with 2 first maxillary premolar extractions comprising 20 subjects, with an initial age of 13.09 years and 9.68 mm of maxillary irregularity.
The decrease in the maxillary irregularity index was significantly greater in group 2 than in group 1 during treatment. The stability of maxillary anterior alignment was 88.12% over the long term; 77% of the linear displacement of the anatomic contact points tended to return to their original positions.
Stability of maxillary anterior alignment between the 3 groups was similar. The stability of maxillary anterior alignment was high over the long term, but a high percentage of teeth tended to return to their original positions.
上颌前牙对于面部美观至关重要，因为它们是笑容中最先展现的牙齿。因此，上颌前牙排列的稳定性是一个重要问题。本研究的目的是比较 I 类和 II 类 1 分类错颌中上颌前牙排列的稳定性。
样本包括 70 名 I 类和 II 类 1 分类错颌患者的牙模，且用不整齐指数测量上颌前牙有至少 3mm 的拥挤。这些患者接受拔牙治疗，在治疗前、治疗后和治疗后至少 5 年进行评估。样本分为 3 组：第 1 组，I 类错颌，4 颗第一前磨牙拔牙，共 30 例，初始年龄为 13.16 岁，上颌不整齐初始值为 8.59mm；第 2 组，II 类错颌，4 颗第一前磨牙拔牙，共 20 例，初始年龄为 12.95 岁，上颌不整齐初始值为 11.10mm；第 3 组，II 类错颌，2 颗上颌第一前磨牙拔牙，共 20 例，初始年龄为 13.09 岁，上颌不整齐初始值为 9.68mm。
治疗期间，第 2 组的上颌不整齐指数下降显著大于第 1 组。上颌前牙排列的长期稳定性为 88.12%；解剖接触点的线性位移有 77%倾向于回到原始位置。
3 组间上颌前牙排列的稳定性相似。上颌前牙排列的长期稳定性较高，但很大比例的牙齿有回到原始位置的趋势。
