Schäfer E, Erler M, Dammaschke T
Department of Operative Dentistry, University of Münster, Münster, Germany.
Int Endod J. 2006 Mar;39(3):196-202. doi: 10.1111/j.1365-2591.2006.01074.x.
To compare the shaping ability of Mtwo instruments with K3 and RaCe instruments. Part 1 of this two-part report describes the efficacy of these nickel-titanium instruments in simulated curved root canals.
Simulated canals with 28 degree and 35 degree curves in resin blocks were prepared with Mtwo instruments using a single length technique and with K3 and RaCe instruments using a crowndown preparation technique (n = 20 canals in each case). Pre- and post-instrumentation images were recorded and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 20 measuring points, beginning 1 mm from the endpoint of preparation. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were also recorded. The data were analysed statistically using ANOVA and Student-Newman-Keuls test.
On an average, canals prepared with Mtwo instruments remained better centred compared with those enlarged with K3 or RaCe instruments. Six RaCe instruments, four K3 files and none of the Mtwo instruments fractured during preparation (P > 0.05). In both of the canal types, Mtwo was significantly faster (P < 0.001). It was possible with all types of instruments to control working length as well.
Mtwo instruments prepared curved canals rapidly, respected original canal curvature well and were safe to use.
比较Mtwo器械与K3和RaCe器械的根管预备能力。本两部分报告的第一部分描述了这些镍钛器械在模拟弯曲根管中的效果。
在树脂块中制备具有28度和35度弯曲的模拟根管，使用Mtwo器械采用单一长度技术，使用K3和RaCe器械采用逐步深入法预备（每种情况n = 20个根管）。记录预备前和预备后的图像，并使用计算机图像分析程序完成根管形态评估。在距预备终点1 mm处开始，在20个测量点测量材料去除量。还记录根管偏移发生率、预备时间、工作长度变化和器械折断情况。使用方差分析和Student-Newman-Keuls检验对数据进行统计学分析。
平均而言，与使用K3或RaCe器械扩大的根管相比，使用Mtwo器械预备的根管保持更好的中心定位。预备过程中，6支RaCe器械、4支K3锉折断，Mtwo器械无一折断（P > 0.05）。在两种根管类型中，Mtwo器械的预备速度均明显更快（P < 0.001）。所有类型的器械都能够控制工作长度。
Mtwo器械能快速预备弯曲根管，很好地保留原始根管弯曲度，且使用安全。
