Effect of sterilization on cyclic fatigue of rotary nickel-titanium endodontic instruments
Effect of sterilization on cyclic fatigue of rotary nickel-titanium endodontic instruments
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DOI：
10.1016/s0099-2399(98)80015-0
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发表时间：
1998-12-01
影响因子：
4.2
通讯作者：
Carnes, DL
中科院分区：
文献类型：
--
作者：
Mize, SB;Clement, DJ;Carnes, DL
使用280件40号Lightspeed器械，评价了高压灭菌导致的热处理通过减少循环疲劳效应延长镍钛旋转牙髓器械寿命的能力。器械在人工根管内循环，曲率角为30度，曲率半径为2 mm或5 mm。在一项初步研究中，对手术工具进行灭菌或未灭菌，并循环至失效，以获得每组的平均失效循环值。在第一个实验方案中，将手术工具循环至初步研究中确定的平均失效循环限值的25%、50%或75%，然后在循环至失效之前灭菌或不灭菌。在第二个实验方案中，将手术工具循环至初步研究中确定的平均失效循环次数的25%，并进行灭菌或未灭菌。重复循环至预定失效循环限值的25%，然后灭菌，直至器械失效。当在相似半径下对器械进行评价时，对于任一实验方案，未观察到组间失效循环次数显著增加。仅当在半径为2 mm的人工髓腔内循环至失效的器械与在半径为5 mm的人工髓腔内循环至失效的器械进行比较时，才观察到失效循环次数的显著差异。扫描电子显微镜照片显示，所有手术工具在循环至预定失效循环限值的百分比时均出现裂纹萌生和扩展。可以得出结论，高压蒸汽灭菌导致的热处理不会延长镍钛器械的使用寿命。
The ability of heat treatment as a result of autoclave sterilization to extend the life of nickel-titanium rotary endodontic instruments by reducing the effect of cyclic fatigue was evaluated using 280 size 40 Lightspeed instruments. Instruments were cycled in artificial canals with angles of curvature of 30 degrees and either 2 or 5 mm radii of curvature. In a pilot study, instruments were sterilized or not sterilized and cycled to failure to obtain mean cycles-to-failure values for each group. In the first experimental protocol, instruments were cycled to either 25%, 50%, or 75% of the mean cycles-to-failure limit determined in the pilot study, then sterilized or not sterilized before being cycled to failure. In the second experimental protocol, instruments were cycled to 25% of the mean cycles-to-failure determined in the pilot study, and sterilized or not sterilized. This sequence of cycling to 25% of the predetermined cycles-to-failure limit followed by sterilization was repeated until the instruments failed. No significant increases in cycles to failure were observed between groups for either experimental protocol when instruments were evaluated at a similar radius. Significant differences in cycles to failure were only observed when instruments cycled to failure in the artificial canal with 2 mm radius were compared with instruments cycled to failure in the artificial canal of 5 mm radius. Scanning electron microscopic photos showed crack initiation and propagation in all instruments that were cycled to a percentage of the predetermined cycles-to-failure limit. It is concluded that heat treatment as a result of autoclave sterilization does not extend the useful life of nickel-titanium instruments.