## 4 Discussion
\begin{table}
\begin{tabular}{c c c} \hline  & **Mean Operative Torque** & **Mean Average Peak Torque** \\  & **(MOT)** & **(MAPT)** \\ \hline Saline Solution & \(0.52\pm 0.04\)\({}^{\text{ABC}}\) & \(23.01\pm 3.48\)\({}^{\text{ABC}}\) \\ Sodium Hypoclorite & \(0.47\pm 0.08\)\({}^{\text{ADE}}\) & \(22.79\pm 3.51\)\({}^{\text{ADe}}\) \\ Ethylenediaminenetetraacetate (EDTA) & \(0.29\pm 0.07\)\({}^{\text{BDf}}\) & \(12.11\pm 4.45\)\({}^{\text{BDf}}\) \\ Hydrogen Peroxide (RC PREP) & \(0.42\pm 0.07\)\({}^{\text{Cef}}\) & \(20.04\pm 2.61\)\({}^{\text{cef}}\) \\ \hline \end{tabular}
\end{table} 
Table 1: Mean values of operative torque test and average peak torque mean values (Ncm). One-way ANOVA (\(p<0.05\)) and a Bonferroni post hoc test were performed. The superscript uppercase letter shows that the post hoc test was significant otherwise the superscript lowercase shows a non-significant post hoc test. the instruments. Furthermore, since one of the main issues of operative torque is that its measurement is influenced by factors, such as time and technique used, the above-explained concept of APT could be proposed as a possible solution to this problem. In the literature, the role of irrigants regarding the torque generated during intracanal instrumentation has been poorly evaluated. The role of different irrigants on torque developed during ex vivo instrumentation has never been evaluated before. Figure 3: Peak values representation. On the axes are the torque values reached during instrumentation (Ncm) and the instrumentation time (1/10 s). The red arrows indicates peak values. Figure 2: Operative torque test graphical evaluation. According to the in vitro studies of [PERSON] et al. (2005) and [PERSON] et al. (2007), the paste-type lubricants showed significantly more torque accumulation during simulated root-canal instrumentation than the aqueous irrigants [22; 23]. The method of torque calculation used in the two above-mentioned papers is really different from the current experimental condition. Indeed, both [PERSON] et al. (2005) and [PERSON] et al. (2007) take into account maximum torque reached as the only torque value. Despite that, their results seem to confirm the findings of the present study. [PERSON] et al. (2012) showed that there is an increased risk of failure of Ni-Ti rotary files without irrigation [35]. The result of the present study showed statistically different values regarding the different irrigants, partially in agreement with the in vitro previously published studies. Indeed, as shown in Table 1, mean operative torque test results showed a significant difference comparing saline solution and NaOCl or RC PREP. On the other hand, using the mean APT evaluation, the differences were not significant between saline solution and NaOCl or RC PREP. This difference could be related to the influence of inward progression time on the mean operative torque values. Anyway, both evaluations performed in the present study MOT and MAPT showed a significant reduction in torque generated using aqueous EDTA. Therefore, it could be stated that the primary role in the reduction in torque stresses is played by the chelating action of the ethylenediaminetetraacetate, while the aqueous form seems to only slightly influence the stress generation during RCT.