a Full Professor, Department of Orthodontics, University of North Parana, Londrina, PR, Brazil.
Angle Orthod. 2013 Nov;83(6):937-42. doi: 10.2319/022813-170.1. Epub 2013 Jun 7.
To compare the efficiency in anchorage preservation of conventional and self-ligating brackets after the extraction of first maxillary premolars using differential moment mechanics.
Thirty-eight patients requiring extraction of maxillary first premolars and maximum anchorage during space closure were evaluated based on bracket type. Group 1, comprising 23 patients, was bonded with preadjusted conventional brackets (CBs) with a slot of 0.022-inch × 0.030-inch. Group 2 comprised 15 patients who were bonded with 0.022 inch preadjusted self-ligating brackets (SLBs). Patients in both groups received a nickel titanium (NiTi) intrusion arch and a 150 g NiTi closing coil spring for separate canine retraction, followed by a continuous mushroom loop archwire to retract the incisors. Lateral cephalograms were available at the start of treatment (T1) and at the completion of space closure (T2). Statistical comparisons were performed with paired and unpaired Student's t-tests.
No significant differences were found between the groups in maxillary molars anchorage loss (3.87 ± 1.35 mm and 3.65 ± 1.73 mm for the CB and SLB groups, respectively). Only the mean vertical movement of the tip of the incisor was significantly different between the groups (CB = -0.92 ± 1.46 mm; SLB = 0.56 ± 1.65 mm).
There were no significant differences in the amount of anchorage loss of the maxillary first molars between SLB and CB systems during space closure using differential moments.
通过差动力矩比较上颌第一磨牙拔牙后传统和自锁托槽的保持效率。
根据托槽类型，评估了 38 例需要上颌第一前磨牙拔牙和最大支抗关闭的患者。第 1 组包括 23 例患者，使用 0.022 英寸×0.030 英寸槽的预调整传统托槽（CB）粘结。第 2 组包括 15 例患者，使用 0.022 英寸预调整自锁托槽（SLB）粘结。两组患者均接受镍钛（NiTi）压入弓和 150 g NiTi 闭合圈簧，用于单独的尖牙后移，然后用连续蘑菇型圈丝弓将切牙收回。治疗开始时（T1）和空间关闭完成时（T2）均有侧位头颅侧位片。采用配对和非配对学生 t 检验进行统计学比较。
在磨牙支抗丧失方面，两组之间无显著差异（CB 组为 3.87±1.35mm，SLB 组为 3.65±1.73mm）。仅切牙尖的垂直移动平均值在两组之间存在显著差异（CB 组为-0.92±1.46mm；SLB 组为 0.56±1.65mm）。
在使用差动力矩进行间隙关闭时，SLB 和 CB 系统对上颌第一磨牙的支抗丧失量无显著差异。
