title: Relationship between the metallurgical structure of experimental titanium miniscrew implants and their torsional properties.
abstract: The aims of this study were to investigate the torsional properties of three experimental titanium miniscrew implants for orthodontic anchorage and to determine the relationship between the torsional properties and metallurgical structures. Experimental miniscrew implants with a diameter of 1.4 mm were fabricated from commercially pure (CP) titanium (alpha-titanium), Ti-4Al-4V (duplex alpha-beta-titanium), and Ti-33Nb-15Ta-6Zr (beta-titanium). Micro-X-ray diffraction (XRD) was performed to identify phases, and microstructures of etched cross-sections were obtained with scanning electron microscopy (SEM). Implants were loaded in torsion (n = 5), and mean moments and twist angles at fracture were statistically compared using the Kruskal-Wallis and Mann-Whitney U-tests. Cyclic torsional moment for fracture of starting square wires (2 × 2 × 30 mm) was measured (n = 3). At fracture, the Ti-4Al-4V and Ti-33Nb-15Ta-6Zr implants demonstrated significantly higher mean torque than the CP titanium implant, while the Ti-33Nb-15Ta-6Zr implant had a significantly higher mean twist angle than the other two implants. The CP titanium and Ti-33Nb-15Ta-6Zr implants displayed good fatigue performance and excellent ductility. Ti-33Nb-15Ta-6Zr beta-titanium alloy is suitable for manufacturing miniscrew implants since it has excellent torsional properties.
authors.affiliation: Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muguruma
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iijima
authors.forename: William A
authors.initials: WA
authors.lastname: Brantley
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yuasa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ohno
authors.forename: Itaru
authors.initials: I
authors.lastname: Mizoguchi
mesh_terms: D001863:Bone Screws; D003722:Dental Alloys / Q000737:chemistry*; D015921:Dental Implants; D003799:Dental Stress Analysis; D008422:Materials Testing / Q000295:instrumentation; D008669:Metallurgy; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D010784:Photomicrography; D018709:Statistics, Nonparametric; D014025:Titanium / Q000737:chemistry*; D054159:Torsion, Mechanical; D014961:X-Ray Diffraction
chemical_list: D003722:Dental Alloys; D015921:Dental Implants; C023988:beta titanium; D014025:Titanium