Defects in Nickel-Titanium Instruments after Clinical Use. Part 2: Fractographic Analysis of Fractured Surface in a Cohort Study
Defects in Nickel-Titanium Instruments after Clinical Use. Part 2: Fractographic Analysis of Fractured Surface in a Cohort Study
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DOI：
10.1016/j.joen.2008.10.013
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发表时间：
2009-01-01
影响因子：
4.2
通讯作者：
Haapasalo, Markus
中科院分区：
文献类型：
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作者：
Shen, Ya;Cheung, Gary Shun-pan;Haapasalo, Markus
本研究旨在研究临床使用期间分离的三种品牌镍钛（NiTi）手术工具（ProTaper [Dentsply Maillefer，Ballaigues，Switzerland]、ProTaper for Hand Use [Dentsply Maillefer]和K3 [SybronEndo，橙子，CA]）的失效模式。在16个月的时间里，从三家根管诊所总共收集了79件断裂器械。通过扫描电子显微镜检查每个碎片的断裂表面。大多数旋转器械（78%的K3和66%的ProTaper）因疲劳断裂而失效，而91%的NiTi手动器械因剪切而失效（p < 0.01）。两种临床类型的ProTaper预备锉折断方式存在差异（p < 0.05）。疲劳断裂的所有表面（n = 47）显示存在一个或两个裂纹源。绝大多数（86%）K3疲劳失效有两个裂纹源，不仅在切割边缘，而且在沿着凹槽的不同位置也有，而ProTaper只有28%显示多个裂纹源（p < 0.01）。后者在81%的疲劳成形锉中显示出一个裂纹起源，而在精加工锉中仅为37%（p < 0.01）。本研究结果表明，镍钛器械的失效模式与制备技术有关。（J Endod 2009;35：133-136）
The purpose of this study was to investigate the mode of failure of three brands of nickel-titanium (NiTi) instruments (ProTaper [Dentsply Maillefer, Ballaigues, Switzerland], ProTaper for Hand Use [Dentsply Maillefer], and K3 [SybronEndo, Orange, CA]) that separated during clinical use. A total of 79 fractured instruments were collected from three endodontic clinics over 16 months. The fracture surface of each fragment was examined by scanning electron microscope. Most of the rotary instruments (78% of K3 and 66% of ProTaper) failed because of fatigue fracture, whereas 91% of NiTi hand instruments failed as a result of shear (p < 0.01). The fracture mode of shaping files in rotary ProTaper was different between two different clinics (p < 0.05). All surfaces with fatigue fracture (n = 47) revealed the presence of either one or two crack origins. The vast majority (86%) of K3 fatigue failure had two crack origins that could be found not only at the cutting edge but also at various places along the flute compared with only 28% of ProTaper showing multiple crack origins (p < 0.01). The latter showed one crack origin in 81% of the fatigued shaping files but only 37% for finishing files (p < 0.01). The results of this study indicated that the failure mode of NiTi instruments is related to preparation technique. (J Endod 2009;35:133-136)