Effect of heat treatment on transformation temperatures and bending properties of nickel-titanium endodontic instruments
Effect of heat treatment on transformation temperatures and bending properties of nickel-titanium endodontic instruments
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DOI：
10.1111/j.1365-2591.2009.01563.x
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发表时间：
2009-07-01
影响因子：
5
通讯作者：
Suda, H.
中科院分区：
文献类型：
--
作者：
Yahata, Y.;Yoneyama, T.;Suda, H.
为研究热处理对镍钛根管器械弯曲性能的影响，将镍钛超弹性合金丝（1.00mmO）加工成直径为0.30mm、锥度为0.06的圆锥形。将热处理温度设定在440或500摄氏度，持续10或30分钟。未热处理的试样用作对照。用差示扫描量热法研究了相变行为。采用单轴弯曲试验对试件的弯曲性能进行了评价。数据经方差分析和Tukey-Kramer检验（P = 0.05），各热处理条件下的相变温度均高于对照。对于在440 ℃下的热处理，观察到两个明显的热峰。在440 ° C下加热30分钟的试样表现出M（s）和A（f）的最高温度，随后在440 ° C下加热10分钟、500 ° C下加热30分钟、500 ° C下加热10分钟的试样和对照试样观察到较低的温度。在440 ℃下加热30分钟的样品在弹性范围（0.5 mm挠曲）和超弹性范围（2.0 mm挠曲）两者中具有最低弯曲载荷值（P <0.05）。热处理时间的影响小于热处理温度的影响，热处理改变镍钛合金的相变行为可能是提高镍钛根管器械柔韧性的有效途径。
To investigate the effect of heat treatment on the bending properties of nickel-titanium endodontic instruments in relation to their transformation behaviour.Nickel-titanium super-elastic alloy wire (1.00 mm O) was processed into a conical shape with a 0.30 mm diameter tip and 0.06 taper. The heat treatment temperature was set at 440 or 500 degrees C for a period of 10 or 30 min. Nonheat-treated specimens were used as controls. The phase transformation behaviour was examined using differential scanning calorimetry. A cantilever-bending test was used to evaluate the bending properties of the specimens. Data were analyed by anova and the Tukey-Kramer test (P = 0.05).The transformation temperature was higher for each heat treatment condition compared with the control. Two clear thermal peaks were observed for the heat treatment at 440 degrees C. The specimen heated at 440 degrees C for 30 min exhibited the highest temperatures for M(s) and A(f), with subsequently lower temperatures observed for specimens heated at 440 degrees C for 10 min, 500 degrees C for 30 min, 500 degrees C for 10 min, and control specimens. The sample heated at 440 degrees C for 30 min had the lowest bending load values (P < 0.05), both in the elastic range (0.5 mm deflection) and in the super-elastic range (2.0 mm deflection). The influence of heat treatment time was less than that of heat treatment temperature.Change in the transformation behaviour by heat treatment may be effective in increasing the flexibility of nickel-titanium endodontic instruments.