Comparison of the formation ability of two types of machine⁃made nickel⁃titanium instruments in simulated curved root canals

Abstract

Objective To compare ProTaper Universal (PU) and M3⁃L instruments in preparing curved root canals and to provide a reference for clinical applications. Methods Twenty resin⁃simulated curved single root canals were randomly divided into two groups. Root canal preparation was performed with a PU nickel⁃titanium file or an M3⁃L nick⁃ el⁃titanium file. Root canal preparation time, root canal length before and after preparation and root canal deviation were recorded. Results In the M3⁃L group, the displacement measured at the 4th to 7th sites was less than that in the PU group (P 0.05); The length of the root canal before and after root canal preparation in the M3⁃L group was（14.90 ± 1.92） mm and（14.57 ± 1.13） mm, respec⁃ tively, and the difference between the two groups was not statistically significant (t＝3.18, P＝0.058). The root canal length before and after root canal preparation in the PU group was（14.53 ± 1.53） mm and（14.28 ± 1.39） mm, respec⁃ tively. The difference between the two groups was not statistically significant（t＝2.12， P＝0.124） ; The average prepara⁃ tion time of the M3⁃L group [（110.15 ± 10.43）s] was less than that in the PU group [（330.48 ± 12.62）s] (P < 0.05).Conclusion The M3⁃L nickel⁃titanium file has better central positioning ability and is less time⁃consuming than the PU nickel⁃titanium file in root canal bending preparation.

Keywords

• Root canal preparation
• Central positioning ability
• Nitinol
• ProTaper Universal
• M3⁃L