Efficacy of MTwo-R Compared with M3-RT re-treatment files in Removing Obturation Material from Moderated Curved Root Canals: An ex-vivo Micro–Computed tomography study

Abstract Background: Comparing the advantages and drawsback of MTwo-R and M3-RT re-treatment files in root canal fillings removal in terms to provide references for clinical application. Methods: After Twenty-eight mesial root canal with moderate curvature of extracted first mandibular permanent molar were collected, M3-PRO preparation files were used for root canal glide path and shaping preparation. All the samples were then underwent root canal obturation. MTwo-R and M3-RT re-treatment files were used to remove the root canal fillings. Micro-CT scan was used before and after the removal of root canal fillings. All data including time required and clearance rate of root canal fillings removal, apical transportation and deformation of re-treatment files were recorded. Independent sample t-test and chi-square testwere used to compare the differences between groups. Results: M3-RT group exhibited a higher efficiency and clearance rate in root canal fillings removal; Apical transportation occurred at apical 1mm, 3mm and 5mm in both M3-RT and MTwo-R groups; MTwo-Rgroup exhibited a higher instruments deformation rate in re-treatment files. Conclusion: M3-RT re-treatment files showed higher efficiency and clearance rate in root canal fillings removal, as well as the lifespan and safety coefficientwhen compared with MTwo-R system. Thus, M3-RT is more suitable for root canal fillings removal in moderate curved root canals when apical transportation rate is not significant.