Papers by Keyword: Bone Replacement

Abstract: Cobalt-based alloys have recently gained so much attention in the medical field due to their improved mechanical properties such as wear resistance and high thermal stability. However, limitations in the area of corrosion has posed a great challenge, leading to further studies being carried out on the corrosion resistance of these alloys. In this study, an investigation on the corrosion resistance of Co-Cr-Mo based alloys in 0.9 % NaCl solution was carried at 37 oC and pH of 7.4 using potentiodynamic polarization and chronopotentiometry electrochemical techniques. The surface analysis of the alloys before and after corrosion test was done using scanning electron microscope (SEM). The results obtained from the electrochemical tests showed sample without titanium (Ti) addition to be more resistance to corrosion in the salt solution compared to those containing Ti. It was observed that a decrease in Cr content in the alloys resulted in an increase in corrosion rate from 0.7868 to 1.3805 mpy. The SEM images confirmed the presence of Cr, Co and Mo in the alloys.

Abstract: We proposed a new biomaterial composed of solid and powder cubic compartments to exhibit isotropic or bone-mimic one-dimensional anisotropic mechanical properties. The raw material used was gas-atomized Ti-6Al-4V ELI powder comprising spherical particles with a diameter of approximately 80 μm. Cube-shaped products composed of 27 (3 × 3 × 3) unit cubic compartments occupied by solid or powder part were designed using three-dimensional CAD. The products were fabricated by electron beam melting (EBM) (Arcam AB, Sweden) according to the specifications shown in a CAD drawing. The residual unmelted powder in the products does not need to be removed to make the products more mechanically integrated. Moreover, the layout of the powder and solid compartments in the products were arranged to achieve isotropy resembling a face-centered cubic atomic arrangement or a long-bone-mimic mechanical anisotropy with square prismatic columns. The products demonstrate isotropic or anisotropic Young’s modulus, yield stress, and toughness, all of which can be changed by CAD design and EBM. In conclusion, novel powder/solid materials comprising solid cubic parts and functionalized powder particles between them were successfully developed, which could be useful in biomedical and industrial applications.

Abstract: Inorganic component of bone is not hydroxyapatite but carbonate apatite. Although pure carbonate apatite (CO₃Ap) has not been prepared due to the limited thermal stability of CO₃Ap, dissolution - precipitation method using precursor block allows fabrication of pure CO₃Ap. Fabrication of CO₃Ap, cell response, tissue response and improvement of CO₃Ap will be discussed.

Abstract: Localized antibiotic beads are often used for treating patients with osteomyelitis or infections of the bone by providing local, sustained and high concentrations of antimicrobial agents to the area of infection, without systemically exposing an individual to antibiotic levels that could result in numerous toxic side effects. In this study, antibiotic impregnated hydroxyapatite spheres were prepared aiming for a functional device of drug carrier and bone graft. Three types of antibiotics were employed including gentamicin, vancomycin and fosfomycin. Antimicrobial susceptibility of antibiotic impregnated beads were tested against two bacterial strains (Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923) by using modified agar diffusion assay. Differences in antimicrobial efficiency were observed and related with respect to differences in molecular weight, mechanism of action and spectrum of activity for each antibiotic. Cytotoxicity by serial extraction technique of all antibiotic impregnated beads were determined by MTT assay. No cytotoxic potential at all extraction periods was observed for vancomycin impregnated on beads. Gentamicin and fosfomycin impregnated beads showed cytotoxic potential only on day 1 extraction, but no cytotoxic potential on longer periods.

Abstract: Hydroxyapatite (HAp) is a major inorganic component of human hard tissues, such as bones and teeth, and its content determines their microstructures and physical properties. Artificial HAp shows strong biocompatibility and bioactivity and thus it has found broad applications in tissue engineering for replacing damaged hard tissues. The artificial HAp, however, suffers from its intrinsic low mechanical properties, so to meet mechanical requirements, HAp can be incorporated with stiff mineral phases (mullite, zirconia, alumina). The performance and long-term survival of these biomedical devices are also dependent on the presence of bacteria surrounding the implants. In order to reduce the incidence of implant-associated infections, several treatments have been proposed, e.g. introduction of silver or fluoride in the HAp. The objective of this research is the sintering of composites based on calcium phosphate, mainly HAp supported on zirconia, for bone replacement with better microstructural features. In fact the use of zirconia can enhance the mechanical properties of bioceramics. Moreover the introduction of small amounts of silver, which should improve the antibacterial properties, will be taken into consideration since it is expected also to further toughen the whole structure.

Abstract: The feasibility of processing glass-ceramics using the layer manufacturing technique, selective laser sintering (SLS), to produce parts with suitable biological and mechanical properties for use in bone replacement applications, has been investigated. Glass-ceramics derived from glasses based on several different systems have been considered. Initial experiments using an apatite-mullite glass-ceramic (4.5SiO2⋅3Al203⋅1.6P2O5⋅3CaO⋅2CaF2) demonstrated the ability to process glass-ceramic materials using this technique, creating parts with a strength similar to that of cancellous bone, and a porous structure that was shown in vivo to be suitable for the ingrowth of bone. Concerns over the inability of the apatite-mullite material to form an apatite layer on its surface when soaked in a simulated body fluid (SBF) has led to the development of Al2O3-free glasses based on the systems (50-x)CaO⋅45SiO2⋅5P2O5⋅xCaF2 and (48-x)CaO⋅45SiO2⋅5P2O5⋅2CaF2⋅xNa2O. These materials have demonstrated good in vitro bioactivity, and therefore have good potential as candidates for processing by an indirect SLS method for the production of custom-made bone implants.