Biocompatibility of the titanium-based implant surfaces: Еffect of the calcium dihydrogen phosphate on osteoblast cells

Investigated was the influence of the presence of calcium dihydrogen phosphate in acidic media on titanium-based implant surfaces (Ticer), used in clinical practice, and its white form (Ticer white), on osteoblast cells. Novel surfaces, denoted M1 and M2, were obtained by immersing Ticer and Ticer white surfaces in calcium dihydrogen phosphate solution at pH 3.5. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) investigations were performed to characterize the surfaces. Comparative results of interaction between investigated surfaces and human osteoblast cells from indirect biocompatibility (MTT and SRB assays), proliferation (DAPI assay) and mode of cell death (acridine orange/ethidium bromide (AO/EB) double staining) were found to be in good agreement, as well as findings from osteocalcin (OC) and bone sialoprotein (BSP) expression. Surfaces obtained by employing anodic plasma-electrochemical oxidation with spark discharges, without subsequent surface modifications were found to be more compatible. Soaking Ticer and Ticer white in phosphate solution resulted in toxic materials (M1 and M2) which induced apoptosis and secondary necrosis in osteoblast cells.