Until 2010, adults underwent surgical treatment for maxillary expansion; however, with the advent of micro-implant-assisted rapid maxillary expansion (MARME), the availability of less invasive treatment options has increased. Nevertheless, individuals with severe transverse maxillary deficiency do not benefit from this therapy. This has aroused interest in creating a new device that allows the benefit of maxillary expansion for these individuals. The aim of this study was to evaluate the efficacy of three MARME models according to tension points, force distribution, and areas of concentration in the craniofacial complex when transverse forces are applied using finite element analysis. Digital modeling of the three MARME models was performed. Model A comprised five components: one body screw expander and four adjustable arms with rings for mini-implant insertion. These arms have an individualized height adjustment that allows MARME positioning according to the patient’s palatal anatomy, thereby preventing body screw expander collision with the lateral mucosa in severe cases of maxillary deficiency. Model B was a maxillary expander with screw rings joined to the body, and model C was similar to model B, except that model C had open rings for the insertion of the mini-implants. Through the MEF (Ansys software), the stresses, distribution, and area of concentration of the stresses were evaluated when transverse forces of 7.85 N were applied. The three models maintained the following pattern: model C presented weak stress peaks with limited distribution and lower concentration area, model B obtained median stress peaks with better distribution when compared to that of model C, and model A showed better stress distribution and larger concentration area. In model A, tensions were located in the lateral lamina of the pterygoid process, which is an important site for maxillary expansion. The limitation of the present study was that it did not include the periodontal tissues and muscles in the finite element method evaluation. Model A showed the best stress distribution conditions. In cases of severe atresia, model A seems to be an excellent option.

中文翻译：

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三种不同类型的微种植体辅助快速上颌扩张 (MARME) 的应力分布和位移：三维有限元研究

直到 2010 年，成人接受上颌骨扩张手术治疗；然而，随着微种植体辅助快速上颌扩张 (MARME) 的出现，微创治疗方案的可用性增加了。然而，严重横向上颌骨缺损的个体不会从这种疗法中受益。这引起了人们对创造一种新装置的兴趣，该装置可以为这些人提供上颌扩张的好处。本研究的目的是使用有限元分析根据张力点、力分布和颅面复合体中的集中区域评估三种 MARME 模型的有效性。对三个 MARME 模型进行了数字建模。模型 A 包含五个组件：一个主体螺钉扩张器和四个可调节臂，带有用于微型种植体插入的环。这些臂具有个性化的高度调节，允许根据患者的上颚解剖结构进行 MARME 定位，从而防止在严重上颌骨缺损的情况下身体螺钉扩张器与外侧粘膜发生碰撞。B 型是一种上颌扩张器，螺钉环连接到身体上，C 型与 B 型相似，只是 C 型具有用于插入微型种植体的开口环。当施加 7.85 N 的横向力时，通过 MEF（Ansys 软件）评估应力、分布和应力集中区域。三个模型保持以下模式：模型C呈现弱应力峰，分布有限，集中区域较低，与模型C相比，模型B获得了分布更好的中值应力峰，模型A显示出更好的应力分布和更大的集中区域。在模型 A 中，张力位于翼突的外侧椎板，这是上颌扩张的重要部位。本研究的局限性在于它在有限元方法评估中没有包括牙周组织和肌肉。模型 A 显示了最佳的应力分布条件。在严重闭锁的情况下，模型 A 似乎是一个很好的选择。本研究的局限性在于它在有限元方法评估中没有包括牙周组织和肌肉。模型 A 显示了最佳的应力分布条件。在严重闭锁的情况下，模型 A 似乎是一个很好的选择。本研究的局限性在于它在有限元方法评估中没有包括牙周组织和肌肉。模型 A 显示了最佳的应力分布条件。在严重闭锁的情况下，模型 A 似乎是一个很好的选择。