title: Structural characterisation and mechanical FE analysis of conventional and M-Wire Ni-Ti alloys used in endodontic rotary instruments.
abstract: The purpose of this study is to understand how the M-Wire alloy conditions the mechanical flexibility of endodontic rotary files at body temperature.Two different rotary instruments, a Profile GT 20/.06 and a Profile GT Series X 20/.06, were selected due to their geometrical similarity and their different constituent alloy. GT series X files are made from M-Wire, a Ni-Ti alloy allegedly having higher flexibility at body temperature. Both files were analysed by X-Ray Diffraction and Differential Scanning Calorimetry to investigate phase transformations and the effects of working temperature on these different alloys. Mechanical behaviour was assessed by means of static bending and torsional Finite Element simulations, taking into account the nonlinear superelastic behaviour of Ni-Ti materials. It was found that GT files present austenitic phase at body temperature, whereas GT series X present R-phase at temperatures under 40 °C with a potential for larger flexibility. For the same load conditions, simulations showed that the slight geometrical differences between the two files do not introduce great disagreement in the instruments' mechanical response. It was confirmed that M-Wire increases the instrument's flexibility, mainly due to the presence of R-phase at body temperature.
authors.affiliation: School of Engineering and Technology, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK.
authors.forename: Diogo
authors.initials: D
authors.lastname: Montalvão
authors.affiliation: The Dental Implant and Gingival-Plastic Surgery Centre, 717 Christchurch Road, Bournemouth, Dorset BH7 6AF, UK.
authors.forename: Francisca Sena
authors.initials: FS
authors.lastname: Alçada
authors.affiliation: CENIMAT/I3N, Materials Science Department, Faculty of Science and Technology, New University of Lisbon, Campus of Caparica, 2829-516 Caparica, Portugal.
authors.forename: Francisco Manuel
authors.initials: FM
authors.lastname: Braz Fernandes
authors.affiliation: CENIMAT/I3N, Materials Science Department, Faculty of Science and Technology, New University of Lisbon, Campus of Caparica, 2829-516 Caparica, Portugal ; Department of Endodontics, School of Dental Medicine, University of Pennsylvania, 3451 Walnut Street, Philadelphia, PA 19104, USA.
authors.forename: Sancho
authors.initials: S
authors.lastname: de Vilaverde-Correia
mesh_terms: D001831:Body Temperature; D003722:Dental Alloys / Q000737:chemistry*; D004548:Elasticity; D004708:Endodontics / Q000295:instrumentation; D009532:Nickel / Q000737:chemistry*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium