Fabrication of calcite-coated rough-surface titanium using calcium nitrate

Although Ti bone scaffolds are widely used clinically as various hard-tissue scaffolds including dental implants, their limited initial osseointegration property is a significant disadvantage, which should be improved. A rough surface and the allied Ca ion release capability might improve initial osteointegration by enhancing the activity of osteoblasts, which dominates osseointegration. In this study, a calcite-coating method, as a Ca ion releaser, is introduced onto rough surfaces of the Ti scaffold by heat carbonation using calcium nitrate as the Ca source below the α-to-β phase transition temperature (~880 °C) of Ti. After this treatment, the Ti scaffolds become whiter with increasing the concentration of the calcium nitrate solution. X-ray diffraction (XRD) and spectroscopic measurements demonstrate that calcite is formed on the Ti scaffold after the treatment. Scanning electron microscopy (SEM) observations show numerous rhombohedral crystals with a size of several micrometers, densely covering the surface of the Ti scaffold, maintaining its rough surface structure. Optimization of the initial calcium nitrate solution concentration controls the amount of calcite coating onto the desired regions on the surface of the Ti scaffolds. The coating strength of the fabricated calcite is ~20 MPa, which is sufficient to resist implanting strength.