Bone integration capability of a series of strontium-containing hydroxyapatite coatings formed by micro-arc oxidation.
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 Sr(y)HA [Sr(y)Ca(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 Sr(y)HA/Sr(y)HA-Sr(x)Ca(1-x)TiO3/Sr(x)Ca(1-x)TiO3-TiO2 multilayers, in which the outer Sr(y)HA and intermediate Sr(y)HA-Sr(x)Ca(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.
Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, No. 145 West Changle Road, Xi'an 710032, China.
Jun
J
Yan
Ji-Feng
JF
Sun
Paul K
PK
Chu
Yong
Y
Han
Yu-Mei
YM
Zhang
D000818:Animals; D001696:Biomechanical Phenomena; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008422:Materials Testing; D008856:Microscopy, Fluorescence; D016348:Osseointegration; D010084:Oxidation-Reduction; D019736:Prostheses and Implants; D011817:Rabbits; D013499:Surface Properties; D014025:Titanium; D014961:X-Ray Diffraction; D055114:X-Ray Microtomography
D020099:Coated Materials, Biocompatible; C509320:strontium-containing hydroxyapatite; D017886:Durapatite; D014025:Titanium
Sr-doped hydroxyapatite; coating; in vivo implantation; micro-arc oxidation; osseointegration; titanium