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目的 比较3种特殊热处理技术CM-丝、R-相和M-丝对镍钛根管锉相变行为、弯曲性能和抗疲劳折断性能的影响,为临床选择应用提供参考.方法 对3组经过特殊热处理的CM-丝镍钛锉Hyflex CM(25 mm长,25号/0.06锥度)、R-相镍钛锉TF(27 mm长,25号/0.06锥度)及M-丝镍钛锉ProTaper Next X2[25 mm长,25号/0.06锥度(尖段)]及2组传统镍钛锉Mtwo(25 mm长,25号/0.06锥度)、ProTaper F2[25 mm长,25号/0.08锥度(尖段)],每组选取5支新锉,用刻断钳将每支锉的螺纹部分截成2～3 mm长度段,电子分析天平称量(20±1) mg,使用差示扫描量热仪测量5组锉的相变行为;使用悬臂弯曲实验检测装置测量5组锉的弯曲性能(每组8支);使用金属模拟根管检测5组锉(每组10支)的抗疲劳折断性能.对各组相变开始温度和相变结束温度、相变热焓、弯曲载荷、疲劳折断圈数以及折断段长度数据采用单因素方差分析进行组间比较,以双侧P＜0.05为差异有统计学意义.结果 Hyflex CM和ProTaper Next的回复相变结束温度(Af)高于37℃,分别为(60.27±0.94)及(51.40±0.32)℃.加载3.0 mm形变对应载荷值,从低到高依次为Hyflex CM[(0.867±0.074)N]、TF[(1.275±0.146)N]、Mtwo[(2.281±0.426)N]、ProTaper Next[(3.104±0.252)N]、ProTaper[(4.227±0.483)N].疲劳折断圈数从高到低依次为Hyflex CM (582±99)、TF(427±85)、ProTaper Next(158±22)、Mtwo(129±32)、ProTaper (65±20).结论 3种特殊热处理技术对镍钛根管锉的相变行为产生重要影响,其弯曲性能和抗疲劳折断性能均显著优于传统镍钛锉.

Objective To compare the phase transformation behavior,bending property and cyclic fatigue resistance of CM-wire,R-phase and M-wire nickel-titanium endodontic files treated by 3 heat treatment techniques.Methods Hyflex CM (25 mm,25#/0.06) made from CM wire,TF (25 mm,25#/0.06) made from R-phase heat treatment,ProTaper Next X2 (25 mm,tip size 25#/0.06) made from M-wire,Mtwo (25 mm,25#/0.06) and ProTaper F2 (25 mm,tip size 25#/0.08) made from conventional nickel-titanium wire were chosen.Five of each files were chosen for differential scanning calorimetric (DSC) evaluation (n=5).The specimens were prepared from adjacent portions of the shaft.The weight and length were typically (20± 1) mg and 2-3 mm.Another eight of the 5 nickel-titanium files were undergone cantilever-bending test,respectively (n=8).Further ten of the 5 instruments were submitted to the cyclic fatigue test by using a simulated metal root canal (n=10).The data of Ms,Mf,As,Af,△H,bending load,number of cyclic fatigue (NCF),fragment length were analyzed using one-way analysis of variance at a significance level of P＜0.05.Results The Af of Hyflex CM [(60.27±0.94) ℃] and ProTaper Next [(51.40±0.32) ℃] were higher than body temperature of 37 ℃.The bending load values at 3.0 mm deflection of Hyflex CM [(0.867±0.074) N],TF [(1.275±0.146) N],Mtwo [(2.281±0.426) N],ProTaper Next [(3.104±0.252) N] and ProTaper [(4.227± 0.483) N] increased gradually and significantly.The NCF of Hyflex CM (582±99),TF (427±85),ProTaper Next (158 ± 22),Mtwo (129 ± 32) and ProTaper (65 ± 20) decreased gradually.Conclusions The 3 heat treatment techniques exert tremendous influence on the phase transformation behavior and mechanical characteristics of the files,which demonstrate improved bending property and cyclic fatigue resistance than the conventional ones.