SEM observations of nickel-titanium rotary endodontic instruments that fractured during clinical use
SEM observations of nickel-titanium rotary endodontic instruments that fractured during clinical use
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DOI：
10.1097/01.don.0000132301.87637.4a
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发表时间：
2005-01-01
影响因子：
4.2
通讯作者：
Daehn, GS
中科院分区：
文献类型：
--
作者：
Alapati, SB;Brantley, WA;Daehn, GS
通过扫描电子显微镜检查了从两个研究生牙髓诊所获得的许多废弃的 ProFile GT、ProFile 和 ProTaper 镍钛旋转器械。这些器械的临床使用历史未知，并且已经断裂或经历了相当大的永久性扭转变形而没有完全分离。失效过程通常表现出显着的延性特征，由凹坑断裂断裂面证明。对于一些样品，观察到了晶界和解理表面处的裂纹扩展，表明存在穿晶断裂。看来，制造过程中产生的氧化物颗粒充当了微孔的成核位点，导致凹坑破裂。还观察到了先前未报道的断裂模式，其中裂纹扩展近似平行于局部凹槽方向，连接表面上的凹坑区域。结合当前和以前对临床失效器械的扫描电子显微镜观察，提出了提高其抗断裂性的建议。
Numerous discarded ProFile GT, ProFile, and ProTaper nickel-titanium rotary instruments obtained from two graduate endodontic clinics were examined by scanning electron microscopy. These instruments had an unknown history of clinical use and had fractured or experienced considerable permanent torsional deformation without complete separation. The failure processes generally exhibited substantial ductile character, evidenced by a dimpled rupture fracture surface. Crack propagation at grain boundaries and cleavage surfaces indicative of transgranular fracture were observed for some specimens. It appeared that oxide particles from the manufacturing process served as nucleating sites for the microvoids, leading to dimpled rupture. A previously unreported fracture mode also was observed, in which crack propagation, approximately parallel to the local flute orientation, connected pitted regions on the surface. Combining present and previous scanning electron microscopy observations of clinically failed instruments, suggestions are offered for improving their fracture resistance.