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Despite the increasing progress achieved in the last 20 years in both the fabrication of porous dental implants and the development of new biopolymers for targeting drug therapy, there are important issues such as bone resorption, poor osseointegration, and bacterial infections that remain as critical challenges to avoid clinical failure problems. In this work, we present a novel microtechnology based on polycaprolactone microspheres that can adhere to porous titanium implant models obtained by the spacer holder technique to allow a custom biomechanical and biofunctional balance. For this purpose, a double emulsion solvent evaporation technique was successfully employed for the fabrication of the microparticles properly loaded with the antibacterial therapeutic agent, rose bengal. The resulting microspheres were infiltrated into porous titanium substrate and sintered at 60 °C for 1 h, obtaining a convenient prophylactic network. In fact, the sintered polymeric microparticles were demonstrated to be key to controlling the drug dissolution rate and favoring the early healing process as consequence of a better wettability of the porous titanium substrate to promote calcium phosphate nucleation. Thus, this joint technology proposes a suitable prophylactic tool to prevent both early-stage infection and late-stage osseointegration problems. [ABSTRACT FROM AUTHOR]

Titanium and its alloys are reference materials in biomedical applications because of their desirable properties. However, one of the most important concerns in long-term prostheses is bone resorption as a result of the stress-shielding phenomena. Development of porous titanium for implants with a low Young's modulus has accomplished increasing scientific and technological attention. The aim of this study is to evaluate the viability, industrial implementation and potential technology transfer of different powder-metallurgy techniques to obtain porous titanium with stiffness values similar to that exhibited by cortical bone. Porous samples of commercial pure titanium grade-4 were obtained by following both conventional powder metallurgy (PM) and space-holder technique. The conventional PM frontier (Loose-Sintering) was evaluated. Additionally, the technical feasibility of two different space holders (NH4HCO3 and NaCl) was investigated. The microstructural and mechanical properties were assessed. Furthermore, the mechanical properties of titanium porous structures with porosities of 40% were studied by Finite Element Method (FEM) and compared with the experimental results. Some important findings are: (i) the optimal parameters for processing routes used to obtain low Young's modulus values, retaining suitable mechanical strength; (ii) better mechanical response was obtained by using NH4HCO3 as space holder; and (iii) Ti matrix hardening when the interconnected porosity was 36–45% of total porosity. Finally, the advantages and limitations of the PM techniques employed, towards an industrial implementation, were discussed. [ABSTRACT FROM AUTHOR]

Medical grade of both titanium (Ti) and Ti6Al4V alloy are recognized as the metallic biomaterials with the better outcomes for clinical repair of bone tissue thanks to their suitable mechanical properties and corrosion resistance. However, those Ti advantages are not enough to avoid failure risks of bone implants; between 5 and 10% of Ti implants fail due to a deficient osseointegration, within 5 years of post-implantation. Most of these failures indicate the necessity of getting a better biomechanical-biofunctional balance. Microstructural and tribo-mechanical characterizations were performed on Ti6Al4V samples obtained by selective laser melting and subjected to different surface treatments (thermal stress relief, acid etching, chemical treatment and thermo-chemical treatment). Scanning electron microscopy and X-ray diffraction were used for detailed characterization of the elemental composition, phase analysis and surface morphology. Micro-hardness and scratch tests were employed to evaluate the tribo-mechanical properties, which were improved after consecutive surface treatments. Protuberances with spherical morphology, as a remainder of the original powder, were present on the surface. The resulting modified surfaces were constituted by rutile (major phase) and anatase (minor phase). Submicro-nano-topographies were obtained after the chemical and thermochemical treatments. [ABSTRACT FROM AUTHOR]

Bone resorption and further failure of titanium implants are often associated to stress-shielding phenomenon. This problem of mechanical incompatibility is even worst due to anisotropy of bone tissue to be replaced. In this work, different samples with gradient longitudinal porosity by using space-holder technique were fabricated and characterized. Main results of this work indicated that: 1) Experimental procedure for space-holder elimination was effective, feasible and reproducible, with better results for a compaction pressure of 800 MPa, and for highest salt contents; 2) 3-D images by micro-CT and images analysis of optical micrographs showed that initial designs were reasonably repeatable; this was observed in terms of both porosity and interfaces quality; and 3) Designs of 30/40/50 and 30/50/30, allowed to solve stress shielding without any important effect on mechanical strength, from the cortical bone point of view. [ABSTRACT FROM AUTHOR]

In this work, the mechanical and bio-functional behavior of a TiNbTa alloy is evaluated as a potential prosthetic biomaterial used for cortical bone replacement. The results are compared with the reference Ti c.p. used as biomaterials for bone-replacement implants. The estimated mechanical behavior for TiNbTa foams was also compared with the experimental Ti c.p. foams fabricated by the authors in previous studies. A TiNbTa alloy with a 20–30% porosity could be a candidate for the replacement of cortical bone, while levels of 80% would allow the manufacture of implants for the replacement of trabecular bone tissue. Regarding biocompatibility, in vitro TiNbTa, cellular responses (osteoblast adhesion and proliferation) were compared with cell growth in Ti c.p. samples. Cell adhesion (presence of filopodia) and propagation were promoted. The TiNbTa samples had a bioactive response similar to that of Ti c.p. However, TiNbTa samples show a better balance of bio-functional behavior (promoting osseointegration) and biomechanical behavior (solving the stress-shielding phenomenon and guaranteeing mechanical resistance). [ABSTRACT FROM AUTHOR]

Although titanium is widely used as biomaterial, the control of the interface properties between its surface and the surrounding physiological environment (like bone, other tissues or biofluids) results crucial to achieve a successful osseointegration and good biomechanical and functional performance. In this work, commercially pure titanium (Grade IV) discs obtained by conventional powder metallurgy were coated with 1–3 µm of Ti6Al4V (Grade V) alloy using DC-pulsed or high-power impulse magnetron sputtering (HiPIMS) technique with the aim of improving their biomedical performance. SEM, confocal microscopy, X-ray diffraction, nanoindentation and wetting measurements are used to evaluate the bio-interface role of the titanium-coated implants. Conformal Ti6Al4V coatings with controlled nano-roughness can be deposited with enhanced mechanical (H = 5–8 GPa; E = 140–160 GPa) and hydrophobic properties thanks to a dense columnar structure. The increased Ti-O bonding at the interface helps to prevent the corrosion due to the formation of a surface passivation layer. Particularly in the case of the HiPIMS process, the surface modification of titanium implants (chemistry, morphology and structure) appears as an effective strategy for satisfying the biomedical requirements and functionality, with enhanced mechanical properties and nanostructuration for prevention of bacteria colonization. [Display omitted] • The bio-interface of titanium specimens was tuned by pulsed magnetron sputtering. • Conformal adherent Ti6Al4V coatings with controlled nanoroughness values below 50 nm. • A surface TiO 2 layer ensures a good corrosion protection to biological media. • The mechanical properties were improved in the case of the novel HiPIMS technology. • Hydrophobic surfaces thanks to surface nanostructuring and chemical functionalization. [ABSTRACT FROM AUTHOR]

The design of bone implants with proper biological and mechanical properties remains a challenge in medical implantology. The use of bioactive coatings has been shown to improve the biocompatibility of the implant surface. In this study, a new approach including porous scaffolds, β-Ti alloys and nanocoatings to design new bone implants is presented. Porous Ti-Nb-Ta-xMn alloys (x: 2, 4, and 6 wt%) substrates were obtained by powder metallurgy and the effect of the porosity and Mn content on mechanical properties was studied. CVD single-layer graphene was transferred onto the porous substrates that presented the best mechanical response (x: 4 wt%) for further evaluation of in vitro cell behavior (biocompatibility and cell adhesion). Cytotoxicity and biocompatibility tests confirmed that cell adhesion and proliferation were successfully achieved on graphene-coated porous substrates, confirming these systems are potential candidates for using in partial bone tissue replacement. • Ti-based alloy foam is proposed and studied for bone implant applications. • Porous TiNbTaMn samples were obtained by powder metallurgy and space holder technique. • 4 wt% Mn content favors the presence of Ti β-phase and lower Young's modulus. • CVD-grown graphene coating was used to improve the biocompatibility of Ti alloy. • Graphene coating promotes cell growth and adhesion on Ti-35Nb-29Ta-4Mn substrate. [ABSTRACT FROM AUTHOR]