Biomineralizacao de materiais de implante: estudos de molhabilidade.

The initial stages of the in vitro bio mineralization of implant materials for the replacement of hard tissues were investigated through surface analysis using static and dynamic contact angle measurements. The obtained results were complemented with XPS, SEM and EDS analysis. The biomaterials used in this work included titanium (T), two types of hydroxyapatite (commercial, HC, synthesized, HS), a glass ceramic of the CaO-P_2O_5-SiO_2-Mg O system (V C) and a biodegradable starch based polymer (starch/poly (ethylene vinyl alcohol), SEVA-C). The biological fluids were simulated using solutions of ionic composition similar to the blood plasma (Hanks Balanced Salt Solution, HBSS, and Kokubo's Simulated Body Fluid, SBF, the latter more supersaturated than HBSS and buffered with tris) and two proteins (albumin and fibronectin), The incubation in HBSS led to the precipitation of calcium phosphate on the surface of substrates, T, H S e V C, but not on H C. The results of the study with SBF (carried out only with H S and V C) were affected by the presence of the tris buffer, which played an inhibitor role on the mineralization process that was observed in its absence. The calcium phosphate films detected on the substrates prepared by incubation in SBF without tris and in HBSS were different. The addition of proteins to HBSS favoured or inhibited the mineralization, depending on the nature of the biome trials and on the fact of the protein molecules being adsorbed or in solution. Concerning the SEVA-C material, surface modifications due to several physical and chemical treatments were investigated. It was found that it is possible to improve significantly the adhesion between the substrates and the biological fluids through treatments with neopentyl (diallyl) oxytri(N-ethylene diamino)ethyl zirconate, KOH and UV radiation.Available from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1249-074 Lisboa, Portugal / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga