Design has an important influence on mechanical response of endodontic instruments made of shape memory alloys. The experimental and numerical prediction of their thermomechanical response is necessary to improve their behavior during operating inside root canal. Due to the curved and tapered shape of the dental canal, endodontic files are subjected to rotating bending during the root canal preparation phase. These rotative bending could ever be combined with torsion when the instruments are engined in the root canal. Bending and torsion tests available in the standard ISO 3630-1 do not take into account this combined loading leading to a response different from the one obtained by superposition of separated bending and torsion loadings. This article details the design and the realization of bending–torsion testing device particularly adapted to shape memory alloy endodontic files. It allows to control the torsion and the bending rotations in a separate or a combined way. Qualification tests using this bending–torsion testing device on NiTi wires showed a good agreement between the experimental and the simulated responses. Finally, this bending–torsion testing device allowed to analyze the response of various NiTi endodontic files, currently used in endodontics, subjected to bending, torsion, and combined bending–torsion loadings. Obtained results showed clearly that combined bending–torsion loading changes significantly the shape memory alloy file response.

中文翻译：

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用于表征形状记忆合金牙髓锉的弯曲-扭转组合测试装置

设计对形状记忆合金制成的牙髓器械的机械响应具有重要影响。它们的热机械响应的实验和数值预测对于改善它们在根管内操作期间的行为是必要的。由于牙管的弯曲和锥形形状，牙髓锉在根管准备阶段会受到旋转弯曲。当器械在根管内加工时，这些旋转弯曲可能与扭转相结合。标准 ISO 3630-1 中可用的弯曲和扭转测试没有考虑这种组合载荷，该载荷导致的响应不同于通过单独的弯曲和扭转载荷叠加获得的响应。本文详细介绍了特别适用于形状记忆合金牙髓锉的弯扭测试装置的设计和实现。它允许以单独或组合的方式控制扭转和弯曲旋转。使用这种弯曲扭转测试设备对 NiTi 丝进行的鉴定测试表明，实验和模拟响应之间具有良好的一致性。最后，这种弯曲-扭转测试设备允许分析目前用于牙髓病学的各种 NiTi 牙髓锉在弯曲、扭转和弯曲-扭转组合载荷下的响应。获得的结果清楚地表明，组合弯曲 - 扭转载荷显着改变了形状记忆合金文件响应。它允许以单独或组合的方式控制扭转和弯曲旋转。使用这种弯曲扭转测试设备对 NiTi 丝进行的鉴定测试表明，实验和模拟响应之间具有良好的一致性。最后，这种弯曲-扭转测试设备允许分析目前用于牙髓病学的各种 NiTi 牙髓锉在弯曲、扭转和弯曲-扭转组合载荷下的响应。获得的结果清楚地表明，组合弯曲 - 扭转载荷显着改变了形状记忆合金文件响应。它允许以单独或组合的方式控制扭转和弯曲旋转。使用这种弯曲扭转测试设备对 NiTi 丝进行的鉴定测试表明，实验和模拟响应之间具有良好的一致性。最后，这种弯曲-扭转测试设备允许分析目前用于牙髓病学的各种 NiTi 牙髓锉在弯曲、扭转和弯曲-扭转组合载荷下的响应。获得的结果清楚地表明，组合弯曲 - 扭转载荷显着改变了形状记忆合金文件响应。目前用于牙髓病学，承受弯曲、扭转和组合弯曲 - 扭转载荷。获得的结果清楚地表明，组合弯曲 - 扭转载荷显着改变了形状记忆合金文件响应。目前用于牙髓病学，承受弯曲、扭转和组合弯曲 - 扭转载荷。获得的结果清楚地表明，组合弯曲 - 扭转载荷显着改变了形状记忆合金文件响应。