Delayed fracture of beta titanium orthodontic wire in fluoride aqueous solutions

Kazuyuki Kaneko, Ken'ichi Yokoyama*, Keiji Moriyama, Kenzo Asaoka, Jun'ichi Sakai, Michihiko Nagumo

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    76 Citations (Scopus)


    Hydrogen embrittlement of a beta titanium orthodontic wire has been examined by means of a delayed-fracture test in acid and neutral fluoride aqueous solutions and hydrogen thermal desorption analysis. The time to fracture increased with decreasing applied stress in 2.0% and 0.2% acidulated phosphate fluoride (APF) solutions. The fracture mode changed from ductile to brittle when the applied stress was lower than 500MPa in 2.0% APF solution. On the other hand, the delayed fracture did not occur within 1000h in neutral NaF solutions, although general corrosion was also observed similar to that in APF solutions. Hydrogen desorption of the delayed-fracture-tested specimens was observed with a peak at approximately 500°C. The amount of absorbed hydrogen was 5000-6500 mass ppm under an applied stress in 2.0% APF solution for 24h. It is concluded that the immersion in fluoride solutions leads to the degradation of the mechanical properties and fracture of beta titanium alloy associated with hydrogen absorption.

    Original languageEnglish
    Pages (from-to)2113-2120
    Number of pages8
    Issue number12
    Publication statusPublished - 2003 May


    • Beta titanium
    • Delayed fracture
    • Fluoride
    • Hydrogen embrittlement
    • Orthodontic wire
    • TMA

    ASJC Scopus subject areas

    • Biotechnology
    • Bioengineering
    • Biomedical Engineering


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