中文摘要：

目的：比较TFA与TF、K3XF、K3镍钛根管锉的疲劳折断性能。方法：取新的27 mm长、#25/0.06锥度的TFA和TF各15支,25 mm长、#25/0.06锥度的K3XF和K3各15支。使用60°弯曲角度、3.5 mm弯曲半径的模拟金属根管进行疲劳性能研究。记录疲劳折断时间、疲劳折断圈数;测量折断段长度,并对断端进行SEM观察。结果：疲劳折断圈数TFA 465±97,显著大于TF（371±110）、K3XF（194±52）、K3（129±40）（P〈0.05）;断段长度4组相比无显著差异（P〉0.05）,断端口均呈现典型的疲劳折断特征。结论：TFA抗疲劳折断性能优于TF、K3XF和K3。

英文摘要：

AIM： To compare the cyclic fatigue resistance of Twisted File Adaptive（ TFA） with that of Twisted File（ TF）,K3 XF and K3. METHODS： Size 25,0. 06 taper,27 mm- long TFA and TF,as well as size25,0. 06 taper 25 mm- long K3 XF and K3 were selected（ n = 15） for the cyclic fatigue test and a simulated metal root canal with curvature of 60° and 3. 5 mm radius was used. The time till fracture and the number of rotations per second to obtain the number of cycles to failure were recorded. The length of fractured fragment was measured. The topographic features of the fractured surfaces were observed by SEM. The data were analyzed using the One- Way ANOVA. RESULTS： The number of cycles to failure of TFA was 465 ± 97,significantly more than those of TF（ 371 ± 110）,K3XF（ 194 ± 52） and K3（ 129 ± 40）,respectively（ P〈0. 05）. Among the 4 instruments,no significant difference was identified for the length of fractured fragments（ P〉0. 05）,and the SEM observation demonstrated typical fatigue features in all the groups. CONCLUSION： TFA exhibits better cyclic fatigue resistance than TF,K3 XF and K3.