Zinelis Spiros, Pandis Nikolaos, Al Jabbari Youssef S, Eliades George, Eliades Theodore
Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Greece.
Dental Biomaterials Research and Development Chair, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
Eur J Orthod. 2018 Apr 6;40(2):126-131. doi: 10.1093/ejo/cjx045.
The aim of this study was to evaluate the elemental and mechanical alterations of stainless steel (SS) multistranded orthodontic wires used in fixed retention after intraoral ageing.
Two types of 0.022-inch, seven-stranded wires, Lingual Retainer Wire (LRW) and Tru-Chrome (TCH), from the same manufacturer (Rocky Mountain Orthodontics, Denver, Colo, USA) were tested. Thirty-three samples from LRW group and thirty-seven from TCH were collected, whereas three unused wires from each package were used as controls. The median ageing time for LRW was 7.4 years and 8.4 for TCH. All samples were subjected to scanning electron microscope/X-ray energy dispersive spectroscopy analysis. Three spectra were taken from the surface of each wire and then all samples were used for the assessment of Martens hardness, indentation modulus (EIT), and elastic index (ηIT) with the instrumented indentation testing method (IIT). The intraoral ageing time was statistically compared between the two groups by Mann-Whitney rank sum test and the compositional and mechanical properties were compared by unpaired t-test. The Spearman correlation between elemental content and ageing time was carried out for all elements (a = 0.05).
No significant differences were found for both the elemental content and for the mechanical properties between the wires tested. Spearman analysis revealed no correlation between elemental content and intraoral time while two groups share statistically equal intraoral ageing times (P > 0.05).
Both wires seemed to maintain their mechanical and elemental integrity within a period of 14-year intraoral exposure, whereas no measurable ionic release could be identified.
本研究旨在评估口腔内老化后用于固定保持的不锈钢多股正畸丝的元素和力学变化。
测试了来自同一制造商（美国科罗拉多州丹佛市的落基山正畸公司）的两种0.022英寸七股丝，即舌侧保持丝（LRW）和特鲁铬丝（TCH）。收集了LRW组的33个样本和TCH组的37个样本，而每个包装中未使用的三根丝用作对照。LRW的中位老化时间为7.4年，TCH为8.4年。所有样本均进行扫描电子显微镜/ X射线能量色散光谱分析。从每根丝的表面获取三个光谱，然后使用仪器压痕测试方法（IIT）对所有样本进行马氏体硬度、压痕模量（EIT）和弹性指数（ηIT）的评估。通过曼-惠特尼秩和检验对两组之间的口腔内老化时间进行统计学比较，并通过不成对t检验比较成分和力学性能。对所有元素进行元素含量与老化时间之间的Spearman相关性分析（α = 0.05）。
测试的丝在元素含量和力学性能方面均未发现显著差异。Spearman分析显示元素含量与口腔内时间之间无相关性，而两组的口腔内老化时间在统计学上相等（P>0.05）。
在14年的口腔内暴露期间，两种丝似乎都保持了其力学和元素完整性，而未发现可测量的离子释放。
