Peters Ove A, Roehlike Jan O, Baumann Michael A
Division of Endodontics, Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, CA 94143, USA.
J Endod. 2007 May;33(5):589-93. doi: 10.1016/j.joen.2007.01.007. Epub 2007 Mar 12.
This study investigated the effect of immersion in sodium hypochlorite (NaOCl) on torque and fatigue resistance of two nickel-titanium files. Size 25 .04 ProFile and RaCe files were immersed in 5.25% NaOCl for 1 or 2 hours at temperatures of 21 degrees C and 60 degrees C. Torque and angle at failure were measured according to ISO 3630-1. Resistance to cyclic fatigue was determined by counting rotations to breakage in a 90 degrees curve with a 5-mm radius. Data were analyzed by 2-way analysis of variance. Torsional resistance of both rotaries was not significantly affected by immersion in NaOCl, except after 2 hours of immersion at 60 degrees C. Resistance to cyclic fatigue decreased significantly for ProFile and RaCe instruments after immersion in NaOCl. Spontaneous fractures occurred in 28 of 160 files during immersion in NaOCl. In conclusion, nickel-titanium rotaries have reduced resistance to cyclic fatigue after contact with heated NaOCl and may then be considered single-use instruments.
本研究调查了次氯酸钠（NaOCl）浸泡对两种镍钛锉的扭矩和抗疲劳性能的影响。25.04规格的ProFile锉和RaCe锉在21摄氏度和60摄氏度下于5.25%的NaOCl中浸泡1或2小时。根据ISO 3630-1标准测量失效时的扭矩和角度。通过计算在半径为5毫米的90度弯曲中折断所需的旋转次数来确定抗循环疲劳性能。数据采用双向方差分析。除了在60摄氏度下浸泡2小时后，两种旋转锉的抗扭性能均未受到NaOCl浸泡的显著影响。ProFile锉和RaCe器械在浸泡于NaOCl后，其抗循环疲劳性能显著下降。在浸泡于NaOCl的过程中，160根锉中有28根发生了自发性折断。总之，镍钛旋转锉在与加热的NaOCl接触后抗循环疲劳性能降低，因此可被视为一次性器械。
