Chung Chooryung J, Jung Kil-Young, Choi Yoon Jeong, Kim Kyung-Ho
a Associate Professor, Department of Orthodontics, Gangnam Severance Hospital, The Craniofacial Deformity Institute, College of Dentistry, Yonsei University, Seoul, South Korea.
Angle Orthod. 2014 Sep;84(5):878-84. doi: 10.2319/092613-703.1. Epub 2014 Mar 3.
To analyze morphological variations of retrieved orthodontic miniscrews and to evaluate the mechanical properties that may adversely affect relocation of miniscrews.
Retrieved miniscrews were classified with scanning electron microscopy according to the degree of morphological deformation of the tip. To evaluate the differences in mechanical characteristics during reinsertion, changes in insertion torque, insertion time and differences in successful insertion load were compared between unused controls and retrieved miniscrews. In addition, surface composition analysis of retrieved miniscrews was performed using energy-dispersive x-ray spectroscopy.
Significant tip deformation was evident in the majority (>84.5%) of retrieved miniscrews. Initial conditions such as insertion site or duration of insertion were not associated with the presence of tip deformation. Insertion load for successful bone penetration increased in proportion to the degree of tip deformation; however, serial changes in insertion torque were similar to those of the controls. Deposited debris such as carbon, calcium, and phosphorus was noted on the retrieved miniscrews.
Miniscrews retrieved after primary insertion exhibited decreased cutting ability due to deformation of the tip structure, as well as surface contamination.
分析回收的正畸微螺钉的形态变化，并评估可能对微螺钉重新植入产生不利影响的机械性能。
根据尖端形态变形程度，利用扫描电子显微镜对回收的微螺钉进行分类。为评估重新植入过程中机械特性的差异，比较了未使用的对照微螺钉和回收微螺钉在插入扭矩、插入时间的变化以及成功插入负载方面的差异。此外，使用能量色散X射线光谱对回收的微螺钉进行表面成分分析。
大部分（>84.5%）回收的微螺钉存在明显的尖端变形。诸如插入部位或插入持续时间等初始条件与尖端变形的存在无关。成功穿透骨质的插入负载随着尖端变形程度的增加而增加；然而，插入扭矩的系列变化与对照微螺钉相似。在回收的微螺钉上发现了诸如碳、钙和磷等沉积碎片。
初次植入后回收的微螺钉由于尖端结构变形以及表面污染而表现出切割能力下降。
