Torsional properties and microstructures of miniscrew implants

Masahiro Iijima, Takeshi Muguruma, William A. Brantley, Miki Okayama, Toshihiro Yuasa, Itaru Mizoguchi

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Introduction: Titanium miniscrew implants are popular in orthodontics, but there is little information about their torsional performance. Methods: Four brands of miniscrew implants (A-D) with 1.6-mm diameters were compared, with miniscrew A implants also having diameters of 1.2 to 2.0 mm. Nominal compositions of the implants were determined by x-ray fluorescence (n = 8). The miniscrews were loaded to failure in torsion, and the mean moment and twist angle were determined for each group (n = 8). Data were compared by ANOVA and the Tukey multiple range tests. Micro x-ray diffraction (n = 3) was used to identify phases in the implants, and the phases were also examined in etched cross-sections with a scanning electron microscope. Results: Miniscrew A and C implants were pure titanium, whereas miniscrew B and D implants contained small amounts of vanadium, aluminum, iron, and manganese. Only alpha-titanium peaks were detected for all implants by micro x-ray diffraction, but beta titanium was observed in the microstructures of miniscrew B and D implants, which had significantly higher torsional moments at failure. Conclusions: Addition of small amounts of other elements to titanium yielded significantly improved torsional performance for miniscrew implants. Research to develop optimum compositions for mechanical properties and biocompatibility is needed.

Original languageEnglish
Pages (from-to)333.e1-333.e6
JournalAmerican Journal of Orthodontics and Dentofacial Orthopedics
Issue number3
Publication statusPublished - 2008 Sept


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