| Objective:To compare magnesium-substituted and pure hydroxyapatite coatings on the promotion of osteogenesis in vitro and on the osseointegration in vivo.Methods:Electrochemically deposited pure hydroxyapatite (HA) or electrochemically deposited magnesium-substituted hydroxyapatite (Mg-HA) coatings were formed on the surface of pure titanium disks. Observed the configuration of crystal and ingredient of thecoating by field-emiddion scanning electron microscope (FSEM), fourier transform infrared spectroscopy (FTIR), and X-ray diffraction apparatus (XRD). MC3T3-E1preosteoblasts were cultured on the HA and Mg-HA coating disks, and cell growth, alkaline phosphatase (ALP) activity, and osteocalcin secretion were measured at various time points. For studies on osseointegration,20roughened implants coated either with HA or Mg-HA (n=10for each coating) were implanted in the femurs of10NZW adult rabbits. Oxytetracycline hydrochloride, alizarin-complexon, and calcein green were respectively administered7,28,46and53d after the implantation. After eight weeks, femurs were retrieved and prepared for the fluorescence microscopy observation. We analyzed the bone mineral apposition rate (MAR), bone area ratio (BAR), and bone to implant contact (BIC) of the two groups.Results:MC3T3-E1cells cultured on Mg-HA coating disks showed increased cell number, ALP, and osteocalcin secretion compared with the HA coating disks at all time points (P<0.05for all). Peri-implant newly formed bone was observed in each group. From7th to53rd day after operation, the values of MAR and BAR in Mg-HA group were higher than those in HA group. However, no significant difference could be found (P>0.05). On7th and28th day, the BIC value of Mg-HA group was significantly higher than that of HA group (P<0.05).Conclusion:Compared with HA coating, Mg-HA coating could promote osteogenic differentiation of preosteoblasts in vitro and have more effect on enhancing peri-implant osseointegration. |
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