Instruments are susceptible to deformation and/or fracture, which may represent a failure in endodontic treatment. This study assessed the mechanical properties of nickel-titanium rotary instruments through cyclic fatigue, buckling resistance, and 45° bending tests.

One hundred and twenty rotary instruments were divided into three groups: Super Flexi Files Blue (SFB; 20/.04), TruNatomy Small (TN; 20/.04), and ProTaper Ultimate Shaper (PTU; 20/.04). They underwent cyclic fatigue tests at fixed and manufacturer-specified speeds, along with buckling and bending tests. SFB files exhibited the greatest cyclic fatigue resistance with the longest time to fracture and highest number of cycles to failure (NCF), followed by TN and PTU. For PTU and TN, reducing rotation speed increased time to fracture and NCF, while SFB showed reduced values with speed increase.

TN exhibited the highest buckling resistance, whereas PTU had superior performance in the bending test. Rotation speed significantly affected cyclic fatigue resistance, with SFB being the most resistant overall. TN demonstrated notable buckling resistance and flexibility.

The rotational speed significantly affects the resistance of instruments to cyclic fatigue and that the SFB file is the most resistant file to cyclic fatigue. The TN file proved to be the most resistant and flexible.

Full Study: Rocha AR, et al. Multimethod Analysis of a Novel NiTi Rotary System. Eur J Dent. 2025.
European Journal of Dentistry (efirst)
DOI: 10.1055/s-0045-1806949
Licensed under CC BY 4.0.