Mousavi Sayed Ali, Kargar-Dehnavi Vida, Mousavi Sayed Amir
Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran.
Dent Res J (Isfahan). 2012 May;9(3):281-7.
Nickel-titanium (Ni-Ti) rotary instrument files are important devices in Endodontics in root canal preparation. Ni-Ti file breakage is a critical and problematic issue and irrigation techniques were applied to decrease risk of file failure root. The aim of the present study was to compare the temperature gradient change of different irrigation solutions with Ni-Ti rotary instrument system during root canal preparation and also to define their effects on the file failure.
A novel computerized instrumentation was utilized and thirty standard (ProFile #25/.04) files were divided into three groups and subjected to a filing in the root canal test. Changes in temperature on teeth under constant instrumental conditions with custom-designed computerized experimental apparatus were measured by using a temperature sensor bonded to the apical hole. A rotary instrument for canal preparation in three series of solution was used and the changes in temperature after each solution were compared. Finally, the file failure results were mentored according to each step of test. Comparisons were performed between group status clinically by using ANOVA (t) test, once the sample showed up normal and differences of P<0.01 were considered significant. All data collected were computerized and analyzed for frequency, distribution, and statistical description.
There was a decrease in the temperature of the instruments, which were immersed in 5% NaOCl, when compared with the water group (P<0.01). There was also a decrease in the temperature of the instruments immersed in water, when compared with the no solution group (P<0.01). Test results showed that sodium hypochlorite, water, or air of root canals does alter the properties of gradual temperature change and contributes to the failure of the instruments.
By immersing the file in 5% NaOCl, the temperature gradient decreased and instrument failure was reduced.
镍钛（Ni-Ti）旋转器械锉是根管治疗中根管预备的重要器械。镍钛锉折断是一个关键且有问题的情况，应用冲洗技术以降低锉在根管内折断的风险。本研究的目的是比较根管预备过程中不同冲洗液与镍钛旋转器械系统的温度梯度变化，并确定它们对器械折断的影响。
使用一种新型计算机化器械装置，将30根标准（ProFile #25/.04）锉分为三组，并在根管测试中进行锉削。使用粘结到根尖孔的温度传感器，通过定制设计的计算机化实验装置，在恒定器械条件下测量牙齿上的温度变化。使用一种用于在三种冲洗液系列中进行根管预备的旋转器械，并比较每种冲洗液后的温度变化。最后，根据测试的每个步骤记录器械折断结果。当样本显示正常时，通过方差分析（t检验）在临床组状态之间进行比较，P<0.01的差异被认为具有统计学意义。收集的所有数据进行计算机化处理，并分析频率、分布和统计描述。
与水组相比，浸泡在5%次氯酸钠中的器械温度降低（P<0.01）。与无冲洗液组相比，浸泡在水中的器械温度也降低（P<0.01）。测试结果表明，根管内的次氯酸钠、水或空气确实会改变温度逐渐变化的特性，并导致器械折断。
将锉浸泡在5%次氯酸钠中，温度梯度降低，器械折断减少。
