Central Interdisciplinary Ambulance in School of Dentistry, University of Münster, Münster, Germany.
Int Endod J. 2011 May;44(5):447-57. doi: 10.1111/j.1365-2591.2011.01850.x. Epub 2011 Jan 28.
To compare the cleaning effectiveness and shaping ability of Mtwo, PVD-coated and uncoated EasyShape nickel-titanium rotary instruments 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° and 35° were divided into three groups of 20 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 using a low-torque control motor according the single-length technique. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Preparation time, changes of working length and instrument failures were also recorded. These data were analysed statistically using ANOVA and Student-Newman-Keuls test. The amounts of debris and smear layer were quantified on the basis of a numerical evaluation scale. The data established for scoring the debris and the smear layer were recorded separately and analysed statistically using the Kruskal-Wallis test.
During preparation, one coated and two uncoated EasyShape files fractured. Completely clean root canals were never observed. All instruments maintained the original canal curvature well with no significant differences between the different instruments (P > 0.05). Instrumentation with Mtwo files was significantly faster than with the two other instruments (P < 0.05). For debris removal Mtwo instruments achieved significantly better results (P < 0.001) than the two EasyShape instruments. The use of coated EasyShape files resulted in significantly less debris compared to instrumentation with uncoated EasyShape instruments (P < 0.05). The results for remaining smear layer were similar and not significantly different for the coronal, middle and apical third of the canals (P > 0.05) but in summary significantly less smear layer was observed following instrumentation with Mtwo (P < 0.01).
Under the conditions of this study, all instruments maintained the original canal curvature well. The use of Mtwo instruments resulted in good canal cleanliness. PVD-coating of EasyShape instruments had no impact on their shaping ability but improved their cleaning effectiveness.
比较 Mtwo、PVD 涂层和未涂层的 EasyShape 镍钛根管预备器械在预备弯曲根管时的清洁效果和成形能力。
将 60 个下颌和上颌磨牙的根管分为 3 组，每组 20 个。根据初始器械插入根管前的影像学检查，平衡了每组根管的角度和曲率半径。使用低扭矩控制马达根据单长度技术进行根管预备。使用预备前后的影像学检查，使用计算机图像分析程序确定根管曲率的拉直情况。记录预备时间、工作长度的变化和器械故障。使用方差分析和 Student-Newman-Keuls 检验对这些数据进行统计学分析。根据数值评价量表对碎屑和玷污层的量进行量化。分别记录用于评分的碎屑和玷污层的数据，并使用 Kruskal-Wallis 检验进行统计学分析。
在预备过程中，有 1 个涂层和 2 个未涂层的 EasyShape 文件断裂。从未观察到完全清洁的根管。所有器械都很好地保持了原始的根管曲率，不同器械之间没有显著差异（P > 0.05）。与其他两种器械相比，Mtwo 器械的操作速度明显更快（P < 0.05）。在去除碎屑方面，Mtwo 器械的效果明显优于两种 EasyShape 器械（P < 0.001）。与使用未涂层的 EasyShape 器械相比，使用涂层的 EasyShape 文件产生的碎屑明显更少（P < 0.05）。对于剩余的玷污层，根管冠、中、根尖三分之一的结果相似，无显著差异（P > 0.05），但总体而言，Mtwo 器械预备后观察到的玷污层明显较少（P < 0.01）。
在本研究条件下，所有器械均能很好地保持原始根管的曲率。使用 Mtwo 器械可获得良好的根管清洁度。EasyShape 器械的 PVD 涂层对其成形能力没有影响，但提高了其清洁效果。
