MC3T3-E1 cell response to microporous tantalum oxide surfaces enriched with Ca, P and Mg.

The formation of a porous oxide surface doped with osteoconductive elements, Ca, P and Mg, to enhance osseointegration, was achieved through micro arc oxidation. Micro arc oxidation parameters, such as electrolyte composition, concentration and applied voltage, were studied to understand their effect on the morphology and chemical composition of the samples surface. Considering the optimum atomic concentration reported in literature for each osteoconductive element, microporous Ta anodic oxide samples treated with calcium acetate (CaA) and ß-glycerophosphate (ß-GP) revealed that an increase of ß-GP molarity in the electrolyte boosts Ca incorporation, as well as, increasing the porosity. In adding magnesium acetate (MgA) to the electrolyte, when composed by CaA + ß-GP, both addition and variation of MgA did not affect the surface morphology along the samples, being incorporated into the oxide layer for 0.1 M. Finally, in vitro tests were carried out to study the biocompatibility of Ta, to verify the cytotoxicity of the samples and their behavior towards cells, by performing adhesion and differentiation tests with the MC3T3-E1 cell line. Cytotoxicity tests revealed that the samples were non-toxic. Despite none of the samples having been raised up through cell adhesion tests, cell differentiation revealed promising results for the Ta-CaP.

Bioactivity response of Ta1-xOx coatings deposited by reactive DC magnetron sputtering.

The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft-hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar+O2 atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates.