OBJECTIVES The aim of this study is to investigate and compare the characteristics of as received and retrieved NiTi archwires at a constant temperature by plotting their load/deflection graphs and quantifying three parameters describing the discharge plateau phase. MATERIALS AND METHODS Two hundred four NiTi archwires, traditional and heat-activated, of various cross sections, were obtained from 5 different manufacturers. Specimens prepared from the selected wires were subjected to a three-point bending test where 92 were retrieved through an in vivo retrieval protocol (crowding group C1 and group C2), 56 went through an in vitro retrieval protocol, and 56 were as received. The in vitro retrieval protocol was performed by a gear motor connected to a stainless steel support that performed fatigue cycles to the bent wires in artificial saliva. The load/deflection graphs of as received and retrieved wires were described through three parameters and the results were analyzed with classification and regression trees (CART) and analysis of variance (ANOVA). RESULTS Statistically significant differences between as received and retrieved wires were found only for the parameter plateau slope which represents the constancy of force expressed by the wire. CONCLUSIONS The aging of NiTi archwires influences the force constancy expressed. The behavior of the wires changes depending on the size, brand, and type of retrieval protocol. In terms of performance, the poorest is represented by all wires retrieved in vitro and in vivo group C2 (moderate to severe crowding).

中文翻译：

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接收和回收的镍钛正畸弓丝的力学行为。

目的本研究的目的是通过绘制负载/挠度图并量化描述放电平稳阶段的三个参数，来研究和比较在恒定温度下接收和回收的镍钛弓丝的特性。材料和方法从5个不同的制造商处获得了244根不同截面的传统和热活化NiTi弓丝。对从选定电线制备的标本进行三点弯曲测试，其中通过体内取回规程（拥挤组C1和C2组）取回92个，通过体外取回规程取回56个，按原样接收56个。通过连接到不锈钢支架的齿轮电动机执行体外取回协议，该齿轮支架对人造唾液中的弯曲金属丝进行疲劳循环。通过三个参数描述了接收和回收导线的载荷/挠度图，并使用分类和回归树（CART）和方差分析（ANOVA）对结果进行了分析。结果仅对于参数平稳斜率发现了接收到的导线和回收的导线之间的统计上的显着差异，该参数代表了导线所表达的力的恒定性。结论NiTi弓丝的老化会影响所表达的力恒定性。导线的行为会根据检索协议的大小，品牌和类型而变化。在性能方面，最差的代表是体外和体内C2组（中度到严重拥挤）回收的所有电线。