2061支临床废弃手用ProTaper锉的损伤分析

Defects in 2061 discarded ProTaper handfiles after clinical use

目的:探讨手用ProTaper锉的损伤、断裂机制。方法:从临床采集2061支废弃的手用ProTaper镍钛锉,体视显微镜下观察锉刃损伤及塑性变形状况,对断锉进行微距数码摄影,Image-Pro Plus软件测量分析断点的位置。采用SPSS 11.0软件包对数据进行统计学分析。结果:166支锉锉刃发生塑性形变(8.2%),塑性形变类型包括解旋、紧致螺旋、塑性弯曲变形;581支锉发生器械分离,折断率为28.2%。F2锉组折断率最高(41.7%),而S X锉组断点水平最高,距离锉尖平均距离为(4.4±1.1)mm。结论:ProTaper手用锉预备根管时,直径较细的成形锉以及靠近锉尖端以扭转折断为主,直径较大的修形锉以及远离锉尖段以旋转疲劳断裂为主。掌握ProTaper手用锉的损伤类型,对根管治疗中避免器械分离具有重要意义。

PURPOSE： To explore the mechanism of failure of ProTaper NiTi handfiles during root canal preparation. METHODS： A total of 2061 discarded ProTaper handfiles were collected after clinical use. The files were studied under stero-mieroscope to determine the type of defect. The fractured files were photographed digitally and the pictures were analyzed by software Image-Pro Plus to measure the distance from the break point to the tip. The data were statistically analyzed by using SPSS 11.0 software package. RESULTS： Plastic deformation was observed in 166 files （8.2%）, and the types of defects included unwinding, winding flutes, and plastic bending. Instrument separation occurred in 581 files （28.2%）, and the fracture rate was the highest in the F2 file group （41.7%）. The Sx file group had the highest facture level, and the mean distance from the breakpoint to the file tip was （4.4±1.1） mm. CONCLUSIONS： For shaping files, especially at the apical level, the main cause of mental failure is overload of torque, whereas for finishing files, especially at the higher level, is cycle fatigue. Understanding the defect types of ProTaper handfiles is useful for avoiding file breakage during root canal therapy.