Objective. This study evaluated the biomechanical effects of a metallic orthodontic mini-implant (OMI) covered with various types of angled revolving cap on the peri-OMI bone and the canine periodontal ligament (PDL) by finite element (FE) analyses. Materials and Methods. Three-dimensional FE models included comprised cortical bone and cancellous bone of the maxilla, and the OMIs were created. The forces (0.98 N) pulled in both the canine hook and the revolving cap, pulling towards each other in both directions as loading conditions. The upper surface of the maxilla was fixed as a boundary condition. Results. The bone stresses were increasing in the models by using OMI covered with a revolving cap as compared with that in the conventional model (in which only the OMI was placed). However, no obvious differences in bone stresses were observed among the models with various types of angled revolving cap. The minimum principal strain in the canine PDL was highest for condition 180T, followed by condition 180L. However, the maximum differences in the values between each experimental model and the conventional model were around 5%. Conclusion. This study showed no obvious effects in decreasing or increasing stress/strain in bone and PDL by using various types of angled revolving cap covered metallic mini-implant in orthodontic treatment of canine retraction.

中文翻译：

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不同角度旋转帽覆盖金属正畸微型种植体（OMI）正畸治疗犬齿回缩的生物力学效应

客观。本研究通过有限元 (FE) 分析评估了金属正畸微型种植体 (OMI) 对 OMI 周围骨和犬牙周韧带 (PDL) 的各种类型的倾斜旋转帽的生物力学影响。材料和方法。三维有限元模型包括上颌骨皮质骨和松质骨，并创建了OMI。力（0.98 N）拉动犬钩和旋转帽，在两个方向上相互拉动作为加载条件。上颌骨的上表面被固定为边界条件。结果. 与传统模型（仅放置 OMI）相比，使用旋转帽覆盖的 OMI 模型中的骨应力增加。然而，在不同类型的带角度旋转帽的模型中，没有观察到骨应力的明显差异。犬 PDL 的最小主应变在 180T 条件下最高，其次是 180L 条件。然而，每个实验模型与传统模型之间的值的最大差异约为 5%。结论。本研究表明，在尖牙回缩的正畸治疗中，使用各种类型的带角度旋转帽覆盖的金属微型种植体对减少或增加骨骼和 PDL 的应力/应变没有明显效果。