Influence of different oxide coatings on Ti-Substrates on osteoblast behaviour

Objectives: To improve osteointegration of dental implants, we developed specific techniques for surface coatings and applied four biocompatible oxides TiO2, SiO2, Nb2O5, (Ti,Si)O2. Methods: Mirror-like polished specimens of cp-Ti with an average roughness value (Ra) of 10 nm were coated using the sol-gel process. After drying and annealing, the purity, thickness and topography of the layers were characterized by IR-spectroscopy, ellipsometry, HRSEM and AFM, and surface energy. MC3T3-E1 osteoblasts were used for the biological tests: roliferation, vitality, adhesion kinetics, morphology, and cytochemical immune-labelling of actin and vinculin. Results: IR-spectroscopy approved the absence of organic residues within the layers. Ellipsometry determined the layer thickness of approximately 100 nm. HRSEM and AFM investigations revealed a nanoporous structure of the TiO2 and Nb2O5 layers whereas the SiO2 and (Ti,Si)O2 layers appeared very smooth. The Ra values, determined by white light interferometry, ranged from 20–50 nm. The surface energy was evaluated by using the drop contact angle formed on the sample surfaces with liquids of different polarity, it revealed the highest polar component for SiO2 (30.7 mJ/m2) and the lowest for cp-Ti and 316L (6.7 mJ/m2). The highest rates of proliferation and cell vitality were found for (Ti,Si)O2 = Nb2O5 > TiO2 > cp-Ti with respect to TCPS controls, the lowest for pure Ni and 316L as positive controls. TiO2 induced also the quickest immediate cell adhesion. A special interest is given to Nb2O5, which induced the most important cell spreading with normal actin stress fibres and a well developed network of focal adhesion contacts. Conclusion: The Nb2O5 seems to be the most interesting process to improve the biological Material-Biosystem interactions. The surface energy measurements didn't reveal any correlation with the biological results, and we conclude that the surface topography and composition influence more importantly the biological response than the surface energy.