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To evaluate the bending and torsional properties of four nickel-titanium endodontic files, we simulated and compared WaveOne (R) primary size 25 with 0.07 taper, WaveOne Gold (R) primary size 25 with 0.07 taper, Reciproc (R) primary size 25 with 0.08 taper, and Reciproc Blue (R) primary size 25 with 0.08 taper. Three-dimensional models were created using computer-aided design software and numerically analyzed in ANSYS (R) Workbench. Boundary conditions for the numerical analyses were based on the ISO 3630-1 specifications. The highest stress levels were recorded for WaveOne (R) and Reciproc (R). Numerical results of the bending test showed that WaveOne Gold (R) is 86% more flexible than WaveOne (R) with a deflection of 3 mm. Reciproc Blue was 42.31% more flexible than Reciproc (R) file with a deflection of 3 mm. The WaveOne (R) instrument withstood the highest stress under the torsion test, followed by Reciproc (R), then Reciproc Blue (R) files. The stress under torsion in the WaveOne (R) and WaveOne Gold (R) files is reduced in a 51%. Regarding Reciproc (R) and Reciproc Blue (R) files, the stress under torsional moments remains very similar. Our results exposed a considerable difference in terms of stress tolerance between WaveOne (R) and WaveOne Gold (R). However, Reciproc (R) files demonstrated a similar stress distribution. The results obtained through finite element analysis suggest that thermal treatment of files might improve their flexibility, increasing resistance during the preparation of highly curved canals. Also, the values obtained regarding the improvement of flexibility were in accordance with the manufacturer claims.