Tailor-made implant surfaces : the effects of surface roughness and calcium phosphate coating

Contains fulltext : 19095.pdf (publisher's version ) (Open Access)In order to be able to design medical implants that elicit a specific tissue response, extensive knowledge of the interaction of an implant material with its surrounding tissue is essential. The surface characteristics of the material, as well as the cellular characteristics of the tissue govern the precise interaction of a material with the tissue. Although many implant materials show a favorable bone response, the mechanisms involved in this bone response are still poorly understood. The studies described in this thesis are aimed at elucidating the mechanisms by which RF magnetron sputtered calcium phosphate (CaP) coatings and implant surface roughness affect the bone response. The studies showed that CaP coating crystallinity has a clear effect on osteogenic cell growth and differentiation. Amorphous CaP coatings inhibited cell growth and differentiation. This was probably due to the extensive dissolution shown by these coatings. On the other hand, crystalline CaP coatings enhanced osteogenic cell growth and differentiation compared to titanium substrates. Surface roughness also affected the osteogenic cells, but not as much as the effect of the presence of a crystalline coating. In subsequent studies, the effect of crystalline CaP coating and surface roughness on osteogenic cell attachment, spreading and integrin expression was studied. We found that differences in substrate characteristics can affect cell attachment and spreading, although the precise effect was cell-type dependent. Integrin expression was also influenced by the substrate surface, but the effect was limited. We have to notice that different methods to generate CaP coatings will lead to coatings with completely different characteristics, which can markedly influence the tissue reaction. Further, different methods of measuring surface roughness can result in different data. A standardized method for measuring and describing surface roughness will have to be developed. Also, complete characterization in terms of chemical composition, crystallinity, but also method of manufacturing is very important when developing and reporting about CaP coated implants. The goal of these and subsequent studies is to get more insight into the bone-biomaterial response. This will enable the manufacturing of tailor-made implants that generate a predicted tissue response149 p