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This study investigated the in vivo osteoblast and osteoclast gene expression in the peri-implant bone tissue of the strontium (Sr)-incorporated microstructured Ti implants (SLA/Sr) in order to evaluate whether local Sr delivery to the implant surface as in the form of SrTiO3 also exerts original bone healing enhancement effect of Sr that take place through the dual modes of action of a stimulation of osteogenesis and an inhibition of osteoclastogenesis. The in vivo mRNA expression of osteoblast- and osteoclast-related genes in the peri-implant bone and removal torque forces of the SLA/Sr implants were compared with a chemically modified super-hydrophilic SLA implants (SLActive®) in rabbit cancellous bone after 2 weeks of implantation. There was no significant difference in the removal torque values between the two groups. Both the torque-tested SLA/Sr and SLActive implants exhibited a considerable quantity of bone attached to the surface. Real-time PCR analysis revealed notably increased mRNA expression of osteoblast genes (Runx2, osterix and osteocalcin) in the peri-implant bone of the SLA/Sr implants compared with the SLActive implants ( p < 0.05), whereas osteoclast phenotype gene (TRAP) expression was markedly decreased in the SLA/Sr implant ( p < 0.05). The results at the molecular level suggest that local Sr delivery as in the form of the Sr-incorporated Ti oxide layer favors early osseointegration of microrough Ti implants via a positive modulation of bone healing, that is, a promotion of osteoblast differentiation and suppression of osteoclastogenesis, in the bone-implant interface of cancellous bone. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A:298-306, 2013. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the surface characteristics and in vitro biocompatibility of a titanium (Ti) oxide layer incorporating calcium ions (Ca) obtained by hydrothermal treatment with or without post heat-treatment in the Ti–13Nb–13Zr alloy. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. In vitro biocompatibility of the Ca-containing surfaces was assessed in comparison with untreated surfaces using a pre-osteoblast cell line. Hydrothermal treatment produced a crystalline CaTiO3 layer. Post heat-treatment at 400°C for 2h in air significantly decreased water contact angles in the CaTiO3 layer (p <0.001). The Ca-incorporated alloy surfaces displayed markedly increased cell viability and ALP activity compared with untreated surfaces (p <0.001), and also an upregulated expression of various integrin genes (α1, α2, α5, αv, β1 and β3) at an early incubation time-point. Post heat-treatment further increased attachment and ALP activity in cells grown on Ca-incorporated Ti–13Nb–13Zr alloy surfaces. The results indicate that the Ca-incorporated oxide layer produced by hydrothermal treatment and a simple post heat-treatment may be effective in improving bone healing in Ti–13Nb–13Zr alloy implants by enhancing the viability and differentiation of osteoblastic cells. [Copyright &y& Elsevier]