Background and objective

Mini-implants have been developed and effectively used by clinicians as anchorage for orthodontic tooth movement. The objective of this study was to elucidate the stress response of orthodontic forces on the periodontal system, bone tissues, mini-implant and the bracket-enamel interface.

Methods

Computer tomography images of a commercially available mini-implant, an orthodontic bracket bonded to a central incisor, and jawbone section models were used to reconstruct three dimensional computer models. These models were exported and meshed in an ABAQUS^Ⓡ finite-element package. Material properties, multi-segment interactions, boundary and loading conditions were then applied to each component. Finite-element analyses were conducted to elucidate the effect of orthodontic force on the equivalent von Mises stress response within the simulated orthodontic system.

Results

The highest stress values in the orthodontic system were predicted at the mini-implant neck, at the interface of the cortical bone, and gradually decreased in the internal apical direction of the miniscrew. On the alveolar bone, the maximum stress values were located in the alveolar cortical bone near the cervical areas of the mini-implant, which is in line with clinical findings of area where bone loss was found post orthodontic tooth treatment. Another peak of von Mises stress response was found in the enamel bracket junction with a maximum up to 186.05 MPa. To ensure good bonding between the enamel and bracket, it is vital to select carefully the type and amount of bonding materials used in the bracket-enamel interface to assure an appropriate load distribution between the teeth and alveolar bone. The results also revealed the significance of the periodontal ligaments, acting as an intermediate cushion element, in the load transfer mechanism.

Conclusions

This study is sought to identify the stress response in a simulated orthodontic system to minimize the failure rate of mini-implants and bracket loss during orthodontic treatment.

中文翻译：

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应力在模拟治疗负荷下对正畸系统组件的影响。

背景和目标

微型植入物已被开发并被临床医生有效地用作正畸牙齿移动的固定物。这项研究的目的是阐明正畸力对牙周系统，骨组织，微型植入物和托槽-牙釉质界面的应力响应。

方法

商业上可买到的微型植入物的计算机断层扫描图像，结合到中切牙的正畸托槽以及颚骨切片模型用于重建三维计算机模型。这些模型已导出并使用^ABAQUSⓇ有限元软件包进行了网格^划分。然后将材料特性，多段相互作用，边界和加载条件应用于每个组件。进行了有限元分析，以阐明正畸力对模拟正畸系统内等效von Mises应力反应的影响。

结果

正畸系统中的最高应力值是在微型植入物颈部，皮质骨界面处预测的，并在微型螺钉的内顶点方向逐渐减小。在牙槽骨上，最大应力值位于微型种植体子宫颈区域附近的牙槽皮质骨中，这与在正畸牙齿治疗后发现骨质流失区域的临床发现一致。在搪瓷托槽连接处发现了另一个冯·米塞斯应力响应峰，最大峰值为186.05 MPa。为了确保牙釉质和托槽之间的良好粘结，至关重要的是，仔细选择托槽-牙釉质界面中使用的粘结材料的类型和数量，以确保牙齿和牙槽骨之间的适当载荷分布。

结论

本研究旨在确定模拟正畸系统中的应力反应，以最大程度地减少在正畸治疗过程中微型植入物的失败率和支架丢失。