Schäfer E, Schlingemann R
Department of Operative Dentistry, University of Münster, Münster, Germany.
Int Endod J. 2003 Mar;36(3):208-17. doi: 10.1046/j.1365-2591.2003.00644.x.
To determine the cleaning effectiveness and the shaping ability of K3 nickel-titanium rotary instruments and stainless steel hand K-Flexofiles during the preparation of curved root canals in extracted human teeth.
A total of 60 root canals of mandibular and maxillary molars with curvatures ranging between 25 degrees and 35 degrees were divided into two groups of 30 canals. Based on radiographs taken prior to instrumentation with the initial instrument inserted into the canal, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared by K3 instruments using a crown-down preparation technique or by K-Flexofiles using a reaming motion up to size 35. After each instrument, the root canals were flushed with 5 mL of a 2.5% NaOCl solution and at the end of instrumentation with 5 mL of saline. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. After splitting the roots longitudinally, the amount of debris and smear layer were quantified on the basis of a numerical evaluation scale, using a scanning electron microscope. The data established for scoring the debris and the smear layer were separately recorded and analysed statistically using the Wilcox-on's test.
None of the stainless steel K-Flexofiles but 5 K3 nickel-titanium instruments separated. Completely clean root canals were never observed. For debris removal, K-Flexofiles achieved significantly better results (P < 0.001) than K3 instruments. The results for remaining smear layer were similar (P > 0.05). K3 instruments maintained the original canal curvature significantly better (P < 0.0001) than K-Flexofiles. No significant differences were detected between the instruments (P > 0.05) for the time taken to prepare the canals.
Under the conditions of this study, K-Flexofiles allowed significantly better removal of debris than K3 instruments. K3 files maintained the original curvature significantly better. A number of K3 instruments fractured.
确定K3镍钛旋转器械和不锈钢手动K-Flex锉在预备拔除的人牙弯曲根管时的清洁效果和根管塑形能力。
选取60个下颌和上颌磨牙的根管，根管弯曲度在25度至35度之间，分为两组，每组30个根管。根据在使用初始器械插入根管前拍摄的X线片，两组在根管弯曲角度和半径方面达到平衡。使用冠向下预备技术用K3器械预备根管，或用K-Flex锉以扩锉动作预备至35号。每个器械使用后，用5 mL 2.5%的次氯酸钠溶液冲洗根管，预备结束时用5 mL生理盐水冲洗。利用术前和术后的X线片，通过计算机图像分析程序确定根管弯曲度的矫正情况。将牙根纵向劈开后，使用扫描电子显微镜，根据数字评估量表对碎屑和玷污层的量进行量化。记录用于对碎屑和玷污层评分的数据，并使用Wilcox-on检验进行统计学分析。
不锈钢K-Flex锉均未分离，但有5支K3镍钛器械分离。从未观察到完全清洁的根管。在清除碎屑方面，K-Flex锉的效果显著优于K3器械（P < 0.001）。在剩余玷污层方面结果相似（P > 0.05）。K3器械在保持原始根管弯曲度方面显著优于K-Flex锉（P < 0.0001）。在预备根管所需时间方面，两种器械之间未检测到显著差异（P > 0.05）。
在本研究条件下，K-Flex锉在清除碎屑方面显著优于K3器械。K3锉在保持原始弯曲度方面显著更好。有若干K3器械发生折断。
