University of Sapienza, Rome, Italy.
J Endod. 2012 Oct;38(10):1408-11. doi: 10.1016/j.joen.2012.05.019. Epub 2012 Jun 29.
The purpose of this study was to evaluate cyclic fatigue fracture resistance of engine-driven nickel-titanium (K3XF) instruments under reciprocating movement in various angles.
Fifty K3XF size 40 taper 0.06 nickel-titanium instruments were divided randomly into 5 groups of 10 each. All instruments were subjected to cyclic fatigue tests. Instruments in groups 1-4 were tested by using different reciprocating motions, whereas instruments of group 5 (control group) were used in continuous rotation. All instruments were rotated or reciprocated until fracture occurred. Time to fracture was recorded, and data were statistically analyzed by using one-way analysis of variance, followed by Tukey honestly significant difference test for comparison between different groups.
All reciprocating groups (groups 1-4) showed a significant increase in time to failure when compared with group 5 (continuous rotation) (P < .05). Mean time was significantly higher in group 1, followed by group 2. No significant difference was found between groups 3 and 4 (P = .251). Increasing the clockwise angle of reciprocation and consequently increasing the angle of progression for each reciprocation cycle reduced the resistance to cyclic fatigue.
Movement kinematics (reciprocating movements in various angles) had a significant influence on the cyclic fatigue life of the tested nickel-titanium instruments.
本研究的目的是评估在不同角度下往复运动中引擎驱动的镍钛（K3XF）器械的循环疲劳断裂阻力。
将 50 个 K3XF 尺寸 40 锥度 0.06 的镍钛器械随机分为 5 组，每组 10 个。所有器械均进行循环疲劳测试。器械 1-4 组采用不同的往复运动进行测试，而器械 5 组（对照组）则连续旋转。所有器械均旋转或往复运动，直至发生断裂。记录断裂时间，采用单向方差分析对数据进行统计学分析，然后采用 Tukey Honestly Significant Difference 检验进行组间比较。
与器械 5 组（连续旋转）相比，所有往复组（组 1-4）的失效时间均显著延长（P<.05）。组 1 的平均时间显著升高，其次是组 2。组 3 和组 4 之间无显著差异（P=.251）。增加往复运动的顺时针角度，从而增加每个往复循环的递进角度，会降低器械的循环疲劳阻力。
运动运动学（不同角度的往复运动）对测试镍钛器械的循环疲劳寿命有显著影响。
