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Bone integration capability of a series of strontium-containing hydroxyapatite coatings formed by micro-arc oxidation

Authors

  • Jun Yan,

    1. Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an 710032, China
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  • Ji-Feng Sun,

    1. State-Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
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  • Paul K. Chu,

    1. Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong, China
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  • Yong Han,

    Corresponding author
    1. State-Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
    • Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an 710032, China
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  • Yu-Mei Zhang

    Corresponding author
    1. Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an 710032, China
    • State-Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
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Correspondence to: Y. Han; e-mail: yonghan@mail.xjtu.edu.cn or Y.-M. Zhang; e-mail: wqtzym@fmmu.edu.cn

Abstract

Strontium-containing hydroxyapatites (Sr-HA) combine the desirable bone regenerative properties of hydroxyapatites (HA) with anabolic and anti-catabolic effects of strontium cations. In the present work, a series of SryHA [SryCa(10−y)(PO4)6(OH)2; y = 0, 0.5, 1, 2] coatings on titanium are produced by micro-arc oxidation (MAO), and the effects of the in vivo osseointegration ability of the coatings are investigated by using a rabbit model. All samples are subjected to biomechanical, surface elemental, micro-CT and histological analysis after 4 and 12 weeks of healing. The obtained results show that the MAO-formed coatings exhibit a microporous network structure composed of SryHA/SryHA–SrxCa(1-x)TiO3/SrxCa(1-x)TiO3–TiO2 multilayers, in which the outer SryHA and intermediate SryHA–SrxCa(1-x)TiO3 layers have a nanocrystalline structure. All Sr-HA coated implants induce marked improvements in the behavior of bone formation, quantity and quality of bone tissue around the implants than the control HA implant and in particular, the 20%Sr-HA coating promotes early bone formation as identified by polyfluorochrome sequential labeling. The bone-to-implant contact is increased by 46% (p < 0.05) and the pull-out strength is increased by 103% over the HA group (p < 0.01). Extensive areas of mineralized tissue densely deposit on the 20%Sr-HA coating after biomechanical testing, and the greatest improvement of bone microarchitecture are observed around the 20%Sr-HA implant. The identified biological parameters successfully demonstrate the osteoconductivity of 20%Sr-HA surfaces, which results not only in an acceleration but also an improvement of bone–implant integration. The study demonstrates the immense potential of 20%Sr-HA coatings in dental and orthopedic applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 2465–2480, 2013.

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