Barbagallo Laura J, Jones Allan S, Petocz Peter, Darendeliler M Ali
Discipline of Orthodontics, Faculty of Dentistry, University of Sydney, Sydney, Australia.
Am J Orthod Dentofacial Orthop. 2008 Feb;133(2):218-27. doi: 10.1016/j.ajodo.2006.01.043.
Orthodontic treatment with clear sequential removable thermoplastic appliances (TAs) is gaining popularity as an alternative to treatment with fixed appliances. The amount of orthodontically induced inflammatory root resorption generated by such appliances has not been investigated. In this prospective randomized clinical trial, we used x-ray microtomography to quantify resorption generated by treatment with ClearSmile appliances (ClearSmile, Woollongong, Australia) and compared the effects with those of heavy and light conventional orthodontic forces and no force.
The sample consisted of 54 maxillary first premolars in 27 patients who required bilateral extractions as part of their planned orthodontic treatment. The subjects were randomly assigned to 3 groups, each with 9 subjects. A split-mouth design was used, and forces were applied to the first premolars. In group 1, TAs were used to move teeth on 1 side in a buccal direction at a rate of 0.5 mm every 2 weeks (TA movement); the contralateral teeth were not moved and served at controls. In group 2, TA movement was used on 1 side. A buccal force of 225 g from a beta-titanium alloy cantilever spring (heavy force) was used on the contralateral side. In group 3, TA movement was used on 1 side. A buccal force of 25 g from a cantilever spring (light force) was used on the contralateral side. The treatment duration was 8 weeks (56 days +/- 1 day). The TAs were changed every 14 days, and each patient used 4 appliances. The springs were not reactivated. At the end of the study period, the teeth were extracted according to a strict protocol to prevent root damage. Resorption was measured with an x-ray microtomograph (1072, SkyScan, Aartselaar, Belgium). Software analysis determined quantity, location, and distribution of root resorption craters.
The control teeth had the least amount of resorption. The light-force teeth had approximately 5 times more resorption than the control teeth (P <.001). The TA teeth had similar but slightly greater resorption than the light-force teeth, or approximately 6 times greater than the control teeth (P <.001). The heavy-force teeth had the most resporption, about 9 times greater than the controls (P <.001).
Clear removable TAs have similar effects on root cementum as light (25 g) orthodontic forces with fixed appliances.
使用透明连续可摘热塑性矫治器（TA）进行正畸治疗作为固定矫治器治疗的替代方法正越来越受欢迎。此类矫治器所产生的正畸诱导性炎性牙根吸收量尚未得到研究。在这项前瞻性随机临床试验中，我们使用X线显微断层扫描技术对ClearSmile矫治器（ClearSmile，澳大利亚卧龙岗）治疗所产生的吸收进行量化，并将其效果与重度和轻度传统正畸力以及无矫治力的情况进行比较。
样本包括27例患者的54颗上颌第一前磨牙，这些患者因计划中的正畸治疗需要双侧拔牙。受试者被随机分为3组，每组9名受试者。采用双侧对照设计，对第一前磨牙施加矫治力。在第1组中，使用TA使一侧牙齿向颊侧移动，移动速度为每2周0.5毫米（TA移动组）；对侧牙齿不移动作为对照。在第2组中，一侧采用TA移动。对侧使用β钛合金悬臂弹簧施加225克的颊向力（重度力组）。在第3组中，一侧采用TA移动。对侧使用悬臂弹簧施加25克的颊向力（轻度力组）。治疗持续时间为8周（56天±1天）。每14天更换一次TA，每位患者使用4副矫治器。弹簧不再重新激活。在研究期结束时，按照严格方案拔牙以防止牙根损伤。使用X线显微断层扫描仪（1072，SkyScan，比利时阿尔茨拉尔）测量吸收情况。软件分析确定牙根吸收坑的数量、位置和分布。
对照牙的吸收量最少。轻度力组牙齿的吸收量约为对照牙的5倍（P<.001）。TA移动组牙齿的吸收情况与轻度力组相似但略多，约为对照牙的6倍（P<.001）。重度力组牙齿的吸收量最多，约为对照牙的9倍（P<.001）。
透明可摘TA对牙根牙骨质的影响与固定矫治器施加的轻度（25克）正畸力相似。
