中文摘要：

目的：比较镍钛锉在模拟根管预备后相变行为的变化.方法：（1）选取30#/0.06锥度的TF和K3镍钛锉,制备样本（n=5）,使用差示扫描量热仪测量相变行为.（2）以上两种镍钛锉,每套预备10个树脂S形弯曲模拟根管,预备过程模拟临床使用条件.收集其中30#/.06锥度的器械,制备样本（n=5）,测量相变行为.分析模拟根管预备后,两种器械相变行为的变化.使用Student＇s t-test检验.结果：两种锉的相变温度和相变热焓均显著下降（P＜0.05）.结论：镍钛锉模拟根管预备后,呈现显著的工作硬化现象,是疲劳折断的微观组织基础.

英文摘要：

Objective： To compare the changes of phase transformation behaviors of nickel-titanium rotary instruments after simulated clinical use. Methods： （1） TF and K3 with taper .06 and tip size 30 were prepared to undergo differential scanning calorimetric （DSC） examination （n=5）. （2） Two nickel-titanium instruments were used to prepare l0 simulated S-shaped canals in resin blocks in accordance with clinical procedures. The #30/0.06 instrument in each set of instruments were collected and prepared to undergo DSC evaluation （n=5）. Student＇s t-test was used. Results： The phase transformation temperatures and heat flow of both TF and K3 were significantly decreased （P〈0.05）. Conclusions： Significant work hardening was identified in two nickel-titanium instruments after simulated clinical use, which may be the microstructural mechanism of fatigue fracture clinically.