Leandro de Arruda Santos1, Javier Bayod López2, Estevam Barbosa de Las Casas3, Maria Guiomar de Azevedo Bahia4, Vicente Tadeu Lopes Buono5. 1. Department of Metallurgical and Materials Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil; Department of Structural Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. 2. Group of Structural Mechanics and Materials Modeling (GEMM), Aragón Institute of Engineering Research (I3A), Universidad de Zaragoza, Zaragoza, Spain. 3. Department of Structural Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. 4. Department of Restorative Dentistry, Faculty of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. 5. Department of Metallurgical and Materials Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. Electronic address: vbuono@demet.ufmg.br.
Abstract
AIM: To assess the flexibility and torsional stiffness of three nickel-titanium rotary instruments by finite element analysis and compare the numerical results with the experiment. METHODOLOGY: Mtwo (VDW, Munich, Germany) and RaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) size 25, .06 taper (0.25-mm tip diameter, 0.06% conicity) and PTU F1 (Dentsply Maillefer, Ballaigues, Switzerland) instruments were selected for this study. Experimental tests to assess the flexibility and torsional stiffness of the files were performed according to specification ISO 3630-1. Geometric models for finite element analysis were obtained by micro-CT scanning. Boundary conditions for the numerical analysis were based on the specification ISO 3630-1. RESULTS: A good agreement between the simulation and the experiment moment-displacement curves was found for the three types of instruments studied. RaCe exhibited the highest flexibility and PTU presented the highest torsional stiffness. Maximum values of von Mises stress were found for the PTU F1 file (1185MPa) under bending, whereas the values of von Mises stress for the three instruments were quite similar under torsion. The stress patterns proved to be different in Mtwo under bending, according to the displacement orientation. CONCLUSIONS: The favorable agreement found between simulation and experiment for the three types of instruments studied confirmed the potential of the numerical method to assess the mechanical behavior of endodontic instruments. Thus, a methodology is established to predict the failure of the instruments under bending and torsion.
AIM: To assess the flexibility and torsional stiffness of three nickel-titanium rotary instruments by finite element analysis and compare the numerical results with the experiment. METHODOLOGY: Mtwo (VDW, Munich, Germany) and RaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) size 25, .06 taper (0.25-mm tip diameter, 0.06% conicity) and PTU F1 (Dentsply Maillefer, Ballaigues, Switzerland) instruments were selected for this study. Experimental tests to assess the flexibility and torsional stiffness of the files were performed according to specification ISO 3630-1. Geometric models for finite element analysis were obtained by micro-CT scanning. Boundary conditions for the numerical analysis were based on the specification ISO 3630-1. RESULTS: A good agreement between the simulation and the experiment moment-displacement curves was found for the three types of instruments studied. RaCe exhibited the highest flexibility and PTU presented the highest torsional stiffness. Maximum values of von Mises stress were found for the PTU F1 file (1185MPa) under bending, whereas the values of von Mises stress for the three instruments were quite similar under torsion. The stress patterns proved to be different in Mtwo under bending, according to the displacement orientation. CONCLUSIONS: The favorable agreement found between simulation and experiment for the three types of instruments studied confirmed the potential of the numerical method to assess the mechanical behavior of endodontic instruments. Thus, a methodology is established to predict the failure of the instruments under bending and torsion.