目的

评价反复高压灭菌对两种镍钛锉抗扭力性能和切割效率的影响。

方法

新的ProTaper F1 锉和Mtwo 20^#锉各60 支，分为3 组:对照组（未高压灭菌）、A 组（连续高压灭菌7 次）和B 组（连续高压灭菌14 次）。 分别随机取3 组中ProTaper F1 锉和Mtwo 20^#锉各10支进行抗扭力性能试验，测定其在同转速和同扭距下的折断时间；分别取3 组中ProTaper F1 锉和Mtwo 20^#锉另外各10 支进行切割效率测定。

结果

A、B 组与对照组的ProTaper F1锉和Mtwo 20^#锉在扭力作用的折断时间差异均无统计学意义（P ＞0.05）；与对照组相比，A 组的ProTaper F1 锉和Mtwo 20^#锉切割力分别下降20.34%和15.34%，B 组的ProTaper F1 锉和Mtwo 20^#锉切割力分别下降46.39%和35.89%。

结论

高压灭菌并未增加镍钛锉折断的可能性，但可以降低镍钛锉的切割效率。

Objective

To evaluate the torque resistance and cutting efficiency of two different types of nickel-titanium rotary instruments under repeated sterilization cycles.

Methods

60 new ProTaper F1 and 60 new Mtwo 20^# were divided into 3 groups.Each group has 20 ProTaper F1 and 20 Mtwo 20^# respectively.Samples in group A were exposed to 7 consecutive sterilization cycles in a steam autoclave.Samples in group B were exposed to 14 consecutive sterilization cycles； the control group samples were not sterilized.The torque resistance and cutting efficiency of ProTaper F1 and Mtwo 20^# of each group were tested.

Results

Compared with the control group， the time of fracture of instruments under repeated sterilization cycles was shortened， but there is no significant difference （P ＞0.05， ANONA test）； the cutting efficiency of ProTaper F1 and Mtwo 20^# in group A were decreased by 20.34% and 15.34% respectively， while those in group B were decreased by 46.39% and 35.89% respectively.Each of these differences was statistically significant （P ＜0.05，ANONA test）.

Conclusions

Repeated sterilization in autoclave does not increase the likelihood of instrument fracture， but reduces the cutting efficiency of nickel-titanium rotary instruments.