Objective This study was to investigate the mechanical properties of thermodynamic nickel-titanium (NiTi) archwires of different brands under controlled temperature and in artificial saliva to provide some reference for its clinical application. Methods Using a modified partial dental arch bending system, four types of thermodynamic NiTi archwires were tested under controlled temperature (25, 33, 37, 60℃) and in artificial saliva. An Instron Universal Testing Machine was used to apply 3 mm deflections of archwires in the lateral incisor area. The load-deflection curves were determined from the passive position to deflections of 3 mm. The following variables from unloading curves were calculated: Stiffness between 2.5 mm UDP (unloading deflection point) to 0.5 mm UDP after unloading. Any statistically significant differences in these variables for the different brands, temperature and moments levels were analyzed using one-way analysis of variance. Results Unloading values of four types thermodynamic nickel-titanium archwires' increased with controlled temperature rising. The unloading stiffness of the same brand archwires were approximate at 25, 33, 37 °C, while their unloading stiffness increased obviously at 60 °C. Conclusion Different brands thermodynamic NiTi archwires demonstrated different mechanical behaviours, but all of them exhibited super elasticity and practical shape memory effect. The four thermodynamic NiTi archwires displayed temperature sensitivity at the four test temperatures.%目的 研究温控型镍钛弓丝在不同温度人工唾液环境下的力学性能变化,为临床合理、有效地使用温控型镍钛弓丝提供参考.方法 利用Instron万能材料力学实验机在25、33、37、60℃人工唾液中对4种温控型镍钛弓丝进行改良部分牙弓托槽弯曲实验.将4种温控型镍钛弓丝加载挠曲至3 mm后卸载,绘制弓丝卸载的载荷-挠曲曲线,计算卸载至2.5 mm与0.5 mm之间的卸载刚度,结果采用单因素方差分析法进行统计分析.结果 随着温度的升高,4种弓丝的卸载力值均有不同程度的升高；同种弓丝的卸载刚度在25、33、37℃时十分接近,而在60℃时卸载刚度均有明显增大.结论 在本实验条件下,4种温控型镍钛弓丝表现出不同的力学性能,但均表现出临床所需的超弹性与形状记忆效应,也均表现出明显的温度敏感性.
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