Schäfer E, Tepel J, Hoppe W
Poliklinik fuer Zahnerhaltung A, Muenster, Germany.
J Endod. 1995 Oct;21(10):493-7. doi: 10.1016/s0099-2399(06)80519-4.
The shaping abilities of nickel-titanium K-files, stainless steel reamers, K-files, and flexible stainless steel instruments with conventional cutting tips and with modified noncutting tips were investigated under standardized conditions using a computer-driven testing device simulating the clinical use of the instruments. Simulated root canals with a 42-degree curvature were sequentially enlarged from #15 to #35. Undesirable changes in the canal shape as a result of instrumentation occurred in all cases. None of the instruments were able to remove material on the whole length of the inner side of the curvature, whereas all instruments removed material on the whole length of the outer side of the curvature, resulting in slight to severe bulging. The extent of undesirable changes in the canal shape depended typically of the type of instrument used. Best instrumentation results were obtained with flexible instruments with noncutting tips.
在标准化条件下，使用模拟器械临床使用的计算机驱动测试装置，研究了镍钛K锉、不锈钢扩孔钻、K锉以及具有传统切割尖端和改良非切割尖端的柔性不锈钢器械的塑形能力。对具有42度弯曲度的模拟根管依次从15号扩大到35号。在所有情况下，器械操作均导致根管形状出现不良变化。没有一种器械能够去除弯曲内侧全长的材料，而所有器械都能去除弯曲外侧全长的材料，导致轻微到严重的鼓胀。根管形状不良变化的程度通常取决于所使用器械的类型。使用具有非切割尖端的柔性器械可获得最佳的器械操作效果。
