Fatigue and mechanical properties of nickel-titanium endodontic instruments
Fatigue and mechanical properties of nickel-titanium endodontic instruments
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DOI：
10.1097/00004770-200210000-00009
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发表时间：
2002-10-01
影响因子：
4.2
通讯作者：
Jordan, L
中科院分区：
文献类型：
--
作者：
Kuhn, G;Jordan, L
形状记忆合金在复杂循环变形的超弹性条件下得到了越来越广泛的应用。在这些应用中，很难根据理论规律来预测其使用寿命。本文利用差示扫描量热仪(DSC)和力学性能测试(弯曲试验)对NiTi发动机驱动的回转体的疲劳性能进行了表征。采用差示扫描量热法(DSC)进行了精密相变的测量。用差示扫描量热法和力学性能测试相结合的方法研究了复合材料的弯曲变形程度。在这些冷加工文件中，高的位错密度影响重定向过程和裂纹扩展。一些热处理促进了力学性能和相变特征的变化。400℃左右的热处理效果很好；恢复率允许在R期萌发所需的足够密度和限制这些仪器脆性的低密度之间进行折衷。在临床使用中，重要的是要考虑不同的根管形状。可以建议，对于非常弯曲的渠道，只需使用几次循环就是安全的，但对于笔直的渠道，则应遵循制造商的建议。
Shape memory alloys are increasingly used in superelastic conditions under complex cyclic deformation situations. In these applications, it is very difficult to predict the service life based on the theoretical law. In the present work, fatigue properties of NiTi engine-driven rotary files have been characterized by using differential scanning calorimetry (DSC) and mechanical testing (bending). The DSC technique was used to measure precise transformation. The degree of deformation by bending was studied with combined DSC and mechanical property measurements. In these cold-worked files, the high dislocation density influences the reorientation processes and the crack growth. Some thermal treatments are involved in promoting some changes in the mechanical properties and transformation characteristics. Annealing around 400degreesC shows good results; the recovery allows a compromise between an adequate density for the R-Phase germination and a low density to limit the brittleness of these instruments. In clinical usage, it is important to consider different canal shapes. It could be proposed that only few cycles of use is safe for very curved canals but to follow the manufacturer's advise for straight canals.