Bone Abstracts

Purpose: The aims of this study were (1) to assess the topographical and chemical changes of Ca and Mg ion implantation procedures using plasma immersion ion implantation and deposition (PIIID) technique and (2) to evaluate cellular response of human bone marrow-derived mesenchymal stem cells (hBMMSCs) to Ca and Mg ion-implanted titanium surface, compared with resorbable blast media (RBM)-treated titanium surface by observing cell attachment, proliferation and gene expression of the osteoblastic phenotype.

Material and methods: Three different titanium surfaces were analyzed: RBM surface (hydroxyapatite grit blasted), Ca-implanted surface, and Mg-implanted surface. Ca and Mg ion implantation onto surface were performed by PIIID technique. The surface characteristics were evaluated by scanning electron microscopy (SEM), surface roughness tester, X-ray diffractometer (XRD), and Auger electron spectroscopy (AES). hBMMSCs were cultured on three different surfaces for evaluation of cellular response. Initial cell attachment was evaluated by SEM, and MTT assay was used to determine cell proliferation. Real-time PCR was used for quantitative analysis of osteoblastic gene expression (Runx2, Type I collagen, alkaline phosphatase, osteocalcin).

Results: In SEM, surface roughness (Ra) and XRD analysis, there were no changes of surface topography after ion implantation procedure by PIIID technique. In AES depth profile analysis, the concentration of Ca, Mg, oxygen, carbon and titanium varied gradually from the outermost surface to the bulk. Mg ion was present in deeper layers than Ca ion. In cell attachment, Ca- and Mg-implanted surface showed greater quantity and quality of initial cell attachment after 4- and 24-h cultivation. In cell proliferation, there was no statistical difference between three different surfaces. In real-time PCR analysis after 6 days cultivation, expression of Runx2 was higher in Mg-implanted surface and expression of osteocalcin was lower in Ca-implanted surface.

Conclusion: Ca- and Mg-implanted surface showed greater initial cellular attachment. Ion implantation using PIIID technique changed the surface chemistry without topographical change.