G. Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Acta Bioeng Biomech. 2020;22(1):31-39.
Most of the orthodontic archwires used in the clinical practice nowadays contain nickel (Ni), however, many patients, especially kids, are allergic to Ni. One possible Ni-free alternative is the Titanium-Niobium (Ti-Nb) archwire. Unfortunately, there is not enough information about its mechanical properties in the literature, especially after clinical usage. Therefore, the aim of this work was to investigate and compare the mechanical properties, chemical composition, structure and morphology of as received and used in clinical practice Ti-Nb orthodontic archwires.
We investigated and compared as received and clinically retrieved after 4 and 6 weeks respectively Ti-Nb archwires with dimensions 0.43 × 0.64 mm (0.017 in. × 0.025 in.). The following methods were used: instrumented indentation testing (nanoindentation), X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.
The nanoindentation investigations of as received and used Ti-Nb archwires revealed a decreasing in their indentation hardness with increased periods of use in the patient's mouth. Moreover, an increasing of the concentration of Ti in the content of the TiNb alloy was associated with an increased period of use in the oral cavity. The SEM analysis showed changes in surface morphology with increasing the period of use of the archwires.
The results showed that there are slight changes in the mechanical and physicochemical properties of the investigated wires after their use in the patient's mouth. That is why we do not recommend them for recycling.
现今临床应用中的大多数正畸弓丝都含有镍（Ni），然而，许多患者，尤其是儿童，对 Ni 过敏。一种可能的无 Ni 替代品是钛-铌（Ti-Nb）弓丝。不幸的是，文献中关于其力学性能的信息并不多，尤其是在临床使用后。因此，本研究旨在调查和比较原始状态和临床使用 4 周和 6 周后的 Ti-Nb 正畸弓丝的力学性能、化学成分、结构和形态。
我们分别对尺寸为 0.43×0.64mm（0.017 英寸×0.025 英寸）的原始和临床回收的 Ti-Nb 弓丝进行了调查和比较。使用的方法包括：仪器压痕测试（纳米压痕）、X 射线衍射、扫描电子显微镜、能谱分析和 X 射线光电子能谱。
对原始和使用中的 Ti-Nb 弓丝的纳米压痕研究表明，随着在患者口腔中使用时间的增加，其压痕硬度逐渐降低。此外，TiNb 合金中 Ti 浓度的增加与在口腔中使用时间的增加有关。SEM 分析显示，随着弓丝使用时间的增加，表面形貌发生了变化。
结果表明，在患者口腔中使用后，所研究的弓丝的力学和物理化学性能有轻微变化。这就是为什么我们不建议回收利用的原因。
