β-metastable titanium alloys with high strength to Young’s modulus ratio have been developed by different authors aiming their use as biomaterials for hard tissue replacement. However, it is not easy to combine low elastic modulus with high mechanical strength. In this work, a β-Ti alloy (Ti-10Mo-20Nb) was produced by arc-melting, then homogenized, cold swaged and aged in order to obtain fine α-Ti precipitates in a β-Ti matrix. The microstructures were characterized by transmission electron microscopy and X-ray diffraction. Mechanical properties characterization was based on Vickers microhardness tests and Young’s modulus measurements. The cold swaged material subjected to an ageing treatment at 500 °C for 4 h showed the highest hardness/ Young’s modulus ratio, associated to very fine α phase precipitates in a β-Ti matrix.

The objective of this study was to evaluate how silver can be inserted into hydroxyapatite (HA) via two distinct processes: co-doping with CO32- via precipitation in an aqueous medium and immersion of preformed HA crystals into Ag+ solutions. It was concluded that although Ag+ and Ca2+ have different radii, the accommodation of Ag+ ions in the Ca2+ sites of the hydroxyapatite lattice can be explained by the models proposed for inserting monovalent ions such as Na+. In this case, because Ag+ ions are larger than Ca2+ ions and have a different charge, the Ag+ ions are stabilized in the HA structure by co-substitution with CO32- ions in both the A- and B-type sites. This simultaneous insertion of Ag+ and CO32- appears to thermally stabilize the HA phase because no phase transformation is observed after calcination. In addition, the doping of HA with Ag+ ions can clearly occur via two routes: co-precipitation in the presence of these ions or diffusion in preformed hydroxyapatite crystals. This result appears to indicate the possibility of doping HA with Ag+ using less complex routes at ambient temperature and with prefabricated implants or biomaterials, which reduces the costs of producing devices with antibacterial effects.

Ti-doped carbon coatings were deposited on TiAlV alloys by reactive dc-magnetron sputtering in Ar/CH4 mixed gas. When Ar flow increases the incorporation of Ti into films raises while the concentration of C decreases. The formed nanometric TiC crystals were more noticeable for coatings deposited with higher Ar flows. Hardness (H) and elastic modulus (E) of coatings were measured by nanoindentation. H values were in the range of 8.8-15.9 GPa and E of 53.4-113.7 GPa. Higher values for H and E were obtained for films containing larger amount of TiC-phase. The presence of TiC crystals increased the coefficient of friction (COF) from 0.07 to 0.28 in scratch tests. Tribological experiments were carried out by using a pin-on-disk apparatus in air and in liquid. COF values ranged from 0.10 to 0.50 for tests in air. Despite of presenting higher COF, tests performed in liquid resulted in less pronounced wear tracks.

The incorporation of zinc onto biomaterials may improve their biological properties, since it is an essential trace element, involved on important steps of bone remodeling. The aim of this work was to evaluate the in vivo biocompatibility of previously characterized hydroxyapatite granules incorporated with 5% zinc (ZnHA), through a subcutaneous grafting test. Granules produced from powders of ZnHA or stoichiometric HA were subcutaneously grafted onto Balb/c mice, and histomorphometrical analysis was performed at 7, 14, 21, 28 or 60 days after grafting. HA and ZnHA induced a similar foreign body reaction, with formation of granulome and the presence of a fibrous capsule. Granulocytes were virtually absent, and agranulocytes decreased with time. ZnHA treated samples presented faster reduction on multinucleated giant cells and increase on observed angiogenesis, as compared to HA. It could be concluded that ZnHA granules are biocompatible. Further study should better address its potential use for bone therapy.

This study has investigated the niobium (Nb) additions effect on both microstructure and heat-treated Ti-10Mo-xNb (x = 3, 6 and 9) alloys mechanical properties. The microstructures were characterized by optical microscopy, X-ray diffraction and transmission electron microscopy. The mechanical characterization was carried out by Vickers microhardness test and Young's modulus measurements. The outcomes show that the addition of Nb in alloys decreased the proportion of ω and α' phases. The Ti-10Mo-3Nb alloy presented the best hardness and elastic modulus combination among the three developed alloys and also with respect to Ti-6Al-4V alloy and commercially pure Ti.

Calcium phosphate salts, or more specifically hydroxyapatite, are products of great interest in the fields of medical and dental science due to their biocompatibility and osteoconduction property. Deproteinized xenografts are primarily constituted of natural apatites, sintered or not. Variations in the industrial process may affect physicochemical properties and, therefore, the biological outcome. The purpose of this work was to characterize the physical and chemical properties of deproteinized xenogenic biomaterials, Bio-Oss (Geistlich Biomaterials, Wolhuser, Switzerland) and Gen-Ox (Baumer S.A., Brazil), widely used as bone grafts. Scanning electron microscopy, infrared region spectroscopy, X-ray diffraction, thermogravimetry and degradation analysis were conducted. The results show that both materials presented porous granules, composed of crystalline hydroxyapatite without apparent presence of other phases. Bio-Oss presented greater dissolution in Tris-HCl than Gen-Ox in the degradation test, possibly due to the low crystallinity and the presence of organic residues. In conclusion, both commercial materials are hydroxyapatite compounds, Bio-Oss being less crystalline than Gen-Ox and, therefore, more prone to degradation.

Este estudo comparou in vivo a performance de implantes orais rosqueáveis fabricados em titânio comercialmente puro (Ti cp) e implantes recobertos com hidroxiapatita (HA) estequiométrica pelo processo de eletroforese. A camada recoberta foi caracterizada por microscopia eletrônica de varredura, espectroscopia de energia dispersiva e espectroscopia de infravermelho com transformada de Fourier. Foram obtidas camadas de carbonato-apatita bem aderidas ao substrato metálico, com espessura variando de 4 a 8 µm. Testes in vivo foram realizados por meio da inserção de implantes em tíbias de coelho por períodos de 8 ou 12 semanas. A análise histomorfométrica foi realizada quantificando-se imagens obtidas em microscopia eletrônica de varredura e com o auxílio de um software de processamento de imagens. Os resultados mostraram que a porcentagem de contato direto osso-implante foi significativamente maior para os implantes recobertos (p<0,05) do que para os implantes de titânio cp. A comparação da quantidade de osso no interior das roscas não mostrou diferença significativa para os dois tipos de implantes (p>0,05), embora os implantes de titânio cp tenham apresentado valores de porcentagem numericamente maiores que os implantes recobertos. Concluiu-se que os implantes recobertos com hidroxiapatita tiveram melhor performance em relação à área de contato osso-implante que os implantes de titânio cp. O processo de eletroforese parece ser uma alternativa simples e viável para se recobrir implantes de titânio com material osteocondutivo, como a hidroxiapatita.

This study compared in vivo the performances of commercially pure titanium (cp Ti) screw dental implants either uncoated or coated with synthetic hydroxyapatite (HA) by electrophoresis. The HA coating was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS) and Fourier-transform infrared (FT-IR) spectroscopy. Well-adhered carbonated-hydroxyapatite layers (4- to-8-µm-thick) were obtained. In vivo tests were carried out by insertion of both uncoated and HA-coated implants into rabbit tibiae for 8 or 12 weeks. Histomorphometric analysis was performed by scanning electron microscopy with the aid of image-processing software. Results showed significantly greater bone-implant contact for HA-coated implants (p<0.05) than cp Ti implants. Comparison of bone content inside the screw implants showed no significant differences (p>0.05) between both types of implants, although cp Ti had numerically higher percentage of bone content than HA-coated implants. In conclusion, the HA-coated implants had better performance regarding the bone-implant contact area than the uncoated implants; coating by electrophoresis proved to be a valuable process to coat metallic implants with an osteoconductive material such as hydroxyapatite.