Department of Endodontics, Sapienza University of Rome, Rome, Italy.
Med Sci Monit. 2012 Jun;18(6):MT41-5. doi: 10.12659/msm.882887.
The aim of the present study was to evaluate the cyclic fatigue resistance of Mtwo NiTi rotary instruments after clinical use by 1 experienced and 1 novice operator.
MATERIAL/METHODS: Cyclic fatigue testing of instruments was performed on tapered artificial canals with a 5 mm radius of curvature and 60° angle of curvature. Twenty Mtwo instruments for each size were selected and divided into 2 groups: group A consisted of 10 instruments of each size used for shaping 10 root canals in molar teeth of patients by an experienced operator; group B consisted of 10 instruments of each size used for shaping 10 root canals in molar teeth of patients by a novice operator. Instruments were rotated until fracture occurred and the numbers of cycles to failure (NCF) were recorded. Data obtained were subjected to an independent sample t-test to determine statistical differences. The significance was determined at a 95% confidence level.
No statistically significant difference (P<0.05) was noted between the instruments of groups A and B for all sizes. More instruments with visible signs of plastic deformation were identified for the novice operator.
The clinical use of Mtwo NiTi rotary instruments by a novice operator did not significantly affect the cyclic fatigue resistance when compared with the control group of the same instrument sizes used by an experienced operator. It can be concluded that novice operators can use these instruments safely under the recommended technical guidelines.
本研究的目的是评估 1 名经验丰富的操作者和 1 名新手操作者在临床使用后 Mtwo 镍钛根管锉的抗疲劳性能。
材料/方法：在半径为 5mm、弯曲角度为 60°的锥形人工根管上进行器械的循环疲劳测试。选择每种尺寸的 20 根 Mtwo 器械，并将其分为 2 组：A 组由 10 根每种尺寸的器械组成，用于由经验丰富的操作者成形 10 颗磨牙的根管；B 组由 10 根每种尺寸的器械组成，用于由新手操作者成形 10 颗磨牙的根管。器械旋转至断裂，记录失效的循环次数（NCF）。对获得的数据进行独立样本 t 检验，以确定统计学差异。显著性水平设定为 95%置信度。
对于所有尺寸，A 组和 B 组的器械之间没有统计学上的显著差异（P<0.05）。新手操作者使用的器械中，有更多的器械出现明显的塑性变形迹象。
与经验丰富操作者使用的相同器械尺寸的对照组相比，新手操作者在临床使用 Mtwo 镍钛根管锉时，其循环疲劳阻力没有显著影响。可以得出结论，新手操作者可以在推荐的技术规范下安全地使用这些器械。
