Evaluation of the surface characteristics of nickel–titanium rotary instruments after clinical use: An atomic force microscope study

Aim: This study aimed to compare the surface roughness of two rotary nickel–titanium instrument systems before and after clinical use using atomic force microscope (AFM). Methods: Sixteen instruments of two rotary nickel–titanium systems were used in this study. Eight MTwo (VDW, Munich, Germany) instruments and eight Neoendo flex rotary files (Orikam Healthcare, India) were evaluated. New and the used rotary files of the two experimental groups were evaluated. Instruments were analyzed on a point at a 5-mm section from the tip of the instrument. Quantitative measurements according to the topographical deviations were recorded. The data were statistically analyzed with paired t-test and independent samples t-test. Results: The mean root mean square (RMS) values for new and used MTwo 25.06 files were 1.23 ± 0.176 nm and 1.58 ± 0.284 nm, respectively, and the difference between them was statistically significant (P < 0.05). The mean RMS values for new and used NeoEndo Flex Files 25.06 were 0.96 ± 0.34 nm and 1.76 ± 0.414 nm, respectively; the difference between them also was statistically significant (P < 0.05). Conclusion: According to the AFM analysis, the instruments underwent surface deterioration after clinical use and MTwo had better surface quality than NeoEndo Flex Files.