Division of Oral Health Sciences, Departments of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Division of Oral Health Sciences, Departments of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
J Endod. 2017 Oct;43(10):1706-1710. doi: 10.1016/j.joen.2017.05.010. Epub 2017 Jul 20.
The purpose of the present study was to compare 2 modes of reciprocal movement (torque-sensitive and time-dependent reciprocal rotation) with continuous rotation in terms of torque and apical force generation during nickel-titanium rotary root canal instrumentation.
A custom-made automated root canal instrumentation and torque/force analyzing device was used to prepare simulated canals in resin blocks and monitor the torque and apical force generated in the blocks during preparation. Experimental groups (n = 7, each) consisted of (1) torque-sensitive reciprocal rotation with torque-sensitive vertical movement (group TqR), (2) time-dependent reciprocal rotation with time-dependent vertical movement (group TmR), and (3) continuous rotation with time-dependent vertical movement (group CR). The canals were instrumented with TF Adaptive SM1 and SM2 rotary files (SybronEndo, Orange, CA), and the torque and apical force were measured during instrumentation with SM2. The mean and maximum torque and apical force values were statistically analyzed using 1-way analysis of variance and the Tukey test (α = 0.05).
The recordings showed intermittent increases of upward apical force and clockwise torque, indicating the generation and release of screw-in forces. The maximum upward apical force values in group TmR were significantly smaller than those in group CR (P < .05). The maximum torque values in clockwise and counterclockwise directions in groups TqR and TmR were significantly smaller than those in group CR (P < .05).
Under the present experimental conditions using TF Adaptive instruments, both torque-sensitive and time-dependent reciprocal rotation generated significantly lower maximum torque and may have advantages in reducing stress generation caused by screw-in forces when compared with continuous rotation.
本研究的目的是比较两种往复运动模式（转矩敏感和时间依赖的往复旋转）与连续旋转在镍钛根管器械预备过程中产生的转矩和根尖力的差异。
使用定制的自动化根管预备和转矩/力分析装置，在树脂块中预备模拟根管，并监测块中预备过程中产生的转矩和根尖力。实验组（n=7，每组）包括（1）转矩敏感的往复旋转与转矩敏感的垂直运动（组 TqR），（2）时间依赖的往复旋转与时间依赖的垂直运动（组 TmR），和（3）连续旋转与时间依赖的垂直运动（组 CR）。使用 TF Adaptive SM1 和 SM2 旋转锉（SybronEndo，Orange，CA）对根管进行预备，并在预备过程中测量 SM2 时的转矩和根尖力。使用单向方差分析和 Tukey 检验（α=0.05）对平均和最大转矩和根尖力值进行统计分析。
记录显示向上的根尖力和顺时针转矩间歇性增加，表明产生和释放了旋入力。组 TmR 的最大向上根尖力值明显小于组 CR（P<0.05）。组 TqR 和 TmR 中顺时针和逆时针方向的最大转矩值明显小于组 CR（P<0.05）。
在本实验条件下使用 TF Adaptive 器械，转矩敏感和时间依赖的往复旋转产生的最大转矩明显较低，与连续旋转相比，可能在减少旋入力引起的应力产生方面具有优势。
