Zhang Yaqiu, Keilig Ludger, Dörsam Istabrak, Bourauel Christoph
Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany.
J Mech Behav Biomed Mater. 2023 May;141:105764. doi: 10.1016/j.jmbbm.2023.105764. Epub 2023 Mar 14.
Temporomandibular joint disorder (TMD) often coincides with malocclusion, and in some cases TMDs are reported after orthodontic treatment. Intermaxillary elastics (also known as orthodontic elastics, OE) are a common way to apply force during orthodontic treatment, and they might cause mechanical effects on the temporomandibular joint (TMJ), thereby lead to joint remodeling. It is still a controversial topic whether the adapted remodeling of the TMJ or of the alveolar bone is the main cause for the alteration of occlusion after treatment with OEs. It was the aim of this study to analyze whether variations of OEs would develop harmful effects on the healthy TMJ. A TMJ model with a masticatory system based on Hill-type muscle actuators was established. Mouth opening and closure with and without OEs were simulated, and maximum principal stresses in the disc and condylar cartilage as well as the displacement of the mandible were analyzed. We found no considerably difference in the mandibular movement without and with symmetrical OEs during mouth opening and closing. At full mouth opening, stresses in the disc and condylar cartilage of some models with OEs were much smaller than without OEs, but we did not find consistency in the results from the left and right sides of the same model (e.g. the lowest compressive stress on the left side of disc from the model with Class II OEs is much smaller than without OEs, -17.3 MPa compared with -28.2, while on the right side, there was no obvious difference). Hence, we could not conclude that OEs would develop deleterious effects on the healthy TMJ.
颞下颌关节紊乱病（TMD）常与错牙合畸形同时出现，在某些情况下，正畸治疗后会出现TMD。颌间弹力牵引（也称为正畸弹力牵引，OE）是正畸治疗中常用的施力方式，可能会对颞下颌关节（TMJ）产生机械作用，从而导致关节重塑。在用OE治疗后，TMJ适应性重塑还是牙槽骨适应性重塑是导致咬合改变的主要原因，这仍然是一个有争议的话题。本研究的目的是分析OE的变化是否会对健康的TMJ产生有害影响。建立了一个基于Hill型肌肉驱动器的咀嚼系统的TMJ模型。模拟了有无OE时的张口和闭口情况，并分析了关节盘和髁突软骨中的最大主应力以及下颌骨的位移。我们发现在张口和闭口过程中，有无对称OE时下颌运动没有显著差异。在最大张口时，一些有OE的模型中关节盘和髁突软骨的应力比没有OE时小得多，但我们没有在同一模型的左右两侧结果中发现一致性（例如，II类OE模型关节盘左侧的最低压应力比没有OE时小得多，-17.3MPa对比-28.2MPa，而右侧没有明显差异）。因此，我们不能得出OE会对健康的TMJ产生有害影响的结论。
