Effects of cleaning, chemical disinfection, and sterilization procedures on the mechanical properties of endodontic instruments

The aim of this study was to test and compare the values of torsional moment, torsional angular deflection, bending moment, and permanent angular deflection of three designs of root canal files (Unifile, Flexofile, and H-File) before and after cross-infection treatment procedures, according to ANSI/ADA specification no. 28. An increase in value for all mechanical properties tested was observed after the treatment procedures, with the exception of Flexofile wherein a decrease in permanent angular deflection was evident. Unifile showed a decrease in torsional moment and bending moment. The changes in mechanical properties after treatment procedures ranged from 0.1 to 63% from the control groups. Generally, the changes in values observed were insignificant and still well within ANSI/ADA specification no. 28. Thus, they do not have any clinical significance.