Medical School of Chinese People's Liberation Army, Beijing, China; Outpatient Department of 32087 Troops, People's Liberation Army, Beijing, China.
Department of Stomatology, Air Force Medical Center, People's Liberation Army, Beijing, China.
Am J Orthod Dentofacial Orthop. 2020 May;157(5):641-650. doi: 10.1016/j.ajodo.2019.05.019.
Nonsurgical mandibular expansion has been increasingly performed in recent years because it can effectively expand the mandibular dental arch. However, many types of mandibular expanders have been used in previous studies. No relevant studies have compared the biomechanical responses of different designs of mandibular expansion appliances with screws. Therefore, the purpose of this study was to analyze the stress distribution and displacement of the dentoalveolar structures according to different designs of mandibular screw expanders.
Cone-beam computed tomography scans were used for 3-dimensional reconstruction of the mandibular finite element model. Four different designs of mandibular expanders, 1 removable expander (type A) and 3 fixed expanders (types B, C, and D), were added to the finite element models. Expanders were activated transversely for 0.2 mm. The initial tooth displacement and von Mises stress distribution were evaluated.
All the expanders enlarged the arch dimensions. In types A and B, the stress was mainly concentrated in the region of the anterior teeth, along with greater tooth displacement, whereas in types C and D, greater stress and displacement occurred in the region of the posterior teeth. Type A showed the greatest amount of transverse displacement. Type D was more efficient in the region of the posterior teeth.
Types A and B should be used with great caution in the clinic because of their incompatible expansion pattern. Type D is the recommended mandibular expansion appliance because of its appropriate expansion pattern.
近年来，非手术下颌扩张术越来越多地应用于临床，因为它可以有效地扩展下颌牙弓。然而，在以前的研究中已经使用了许多类型的下颌扩张器。目前尚无相关研究比较不同设计的带有螺丝的下颌扩张器的生物力学反应。因此，本研究旨在分析根据不同设计的下颌螺丝扩张器的牙牙槽结构的应力分布和位移。
使用锥形束 CT 扫描对下颌有限元模型进行三维重建。将 4 种不同设计的下颌扩张器（1 种可摘式扩张器[类型 A]和 3 种固定式扩张器[类型 B、C 和 D]）添加到有限元模型中。扩张器横向扩张 0.2mm。评估初始牙齿位移和 von Mises 应力分布。
所有的扩张器都扩大了牙弓的尺寸。在类型 A 和 B 中，应力主要集中在前牙区域，同时牙齿位移较大，而在类型 C 和 D 中，后牙区域的应力和位移较大。类型 A 显示出最大的横向位移。类型 D 在后部牙齿区域更为有效。
由于其不兼容的扩展模式，类型 A 和 B 在临床上应谨慎使用。类型 D 是推荐的下颌扩张器，因为它具有适当的扩展模式。
