Papers by Keyword: Osteoconductivity

Abstract: The effects of electrically polarized HA microgranule/PRP compositeon new bone formation were examined. The composite gel was implanted into bone holes in rabbits. Histological examination was performed 3 and 6 weeks post-surgery. It was hypothesized that PRP alone could not induce new bone formation until 6 weeks after implantation. HA microgranules with or without electrical polarization/PRP composite, especially the former, activated osteogenic cells, resulting in enhanced bone formation. It was confirmed that electrical polarization treatment of HA microgranules can accelerate new bone formation and this effect is enhanced by forming a complex within PRP.

Abstract: Aim of the work was production of nanocomposite polymer fibres containing ceramic particles using the electrospinning method and characterisation of morphology and bioactivity of the produced materials. The first stage of investigations consisted in preparation of a series of poly-L-lactide (PLA) solutions in various solvents mixtures in order to reach viscosity which would allow formation of fibres by the electrospinning method. Ceramic nanoparticles such as tricalcium phosphate (TCP) and silica (SiO₂) were used as nanofillers of the polymer matrix. Their particle size distribution in the solvent solution as well as in the polymer suspension was determined by dynamic light scattering method (DLS). Morphology of the nanoparticles was observed using transmission electron microscopy (TEM). Distribution of the nanofillers in the nanocomposite fibres as well as diameter and morphology of the fibres was assessed using scanning electron microscopy with energy dispersive spectroscopy method (SEM/EDS). Effect of the nanofillers addition and the shaping method on the structure of the PLA matrix was investigated on the basis of the thermal analysis methods (TG/DSC) on the nanocomposite foils prepared by casting. It was revealed that the nanocomposite fibres showed apatite nucleation in in vitro conditions i.e. after incubation in SBF (37°C/ 3 days).

Abstract: In this study, anodizing of Ti in the various concentration of H₃PO₄ aqueous solutions gave TiO₂ films, and the osteoconductivity was examined using in vivo testing. In the anodizing treatment, anodizing potential of < 200 V was applied to the Ti substrate in H₃PO₄ aqueous solutions with the concentration of 0.1 to 14 M at 298 K. The coatings were evaluated using SEM, XRD, FT-IR and XPS. In in vivo testing, the coated samples were implanted in the rats’ tibia for 14 d to evaluate the osteoconductivity. In H₃PO₄ aqueous solutions with any concentration, anatase-type TiO₂ films were obtained on the Ti substrate by anodizing. The crystallinity of anodized TiO₂ films depended on the concentration of H₃PO₄ and sparking. In less than 2 M H₃PO₄, anatase with high crystallinity was formed. On the other hand, anodizing with sparking in more than 4 M H₃PO₄, gave low crystallinity anatase film. In in vivo testing, osteoconductivity of the coatings with low crystallinity anatase was much higher than that with high crystallinity.

Abstract: Titanium and Ti alloys are widely used as substitutional materials for natural bone because of their good biocompatibility, high strength, and high corrosion resistance. In our previous studies, TiO₂ coating on Ti with Ra (arithmetical means of roughness) < 0.1 μm formed by anodizing had much higher osteoconductivity than that of pure Ti. It can be expected that TiO₂ coating with fine surface can improve the osteoconductivity of Ti alloys. In this study, the effects on the osteoconductivity of TiO₂ coatings on different kinds of Ti alloys were investigated by in vivo study. TiO₂ coatings with Ra < 0.1 μm were formed on 4 kinds of Ti alloys (Ti-6Al-4V (Ti64), Ti-6Al-7Nb (Ti67), Ti-29Nb-13Ta-4.6Zr (TNTZ), Ti-13Cr-1Fe-3Al (TCFA)) using anodizing in H₃PO₄ aqueous solution. Surface properties of these coatings were evaluated using SEM, XRD, and XPS. In in vivo study, samples were implanted in rats’ tibia for 14 days, and then removed. Cross section of the sample was observed with optical microscope and bone-implant contact ratio (R_B-I) at the interface between body tissue and bone was used as a parameter of osteoconductivity. Anatase type TiO₂ coatings with Ra < 0.1 μm were uniformly formed on all of the Ti alloys by anodizing at low voltage. These oxide coatings contained the ions of other alloy elements. TiO₂ coatings on Ti64 and Ti67 indicated high osteoconductivity similar to that of TiO₂ coating on pure Ti. On the contrary, TiO₂ coating on TNTZ and TCFA showed low osteoconductivity. It was thought that ions of alloy elements brought bad influence on the osteoconductivity of TiO₂.

Abstract: The geometry of bone scaffolds plays a crucial role in bone tissue regeneration. This architecture, especially pore size and shape, determines the mechanical strength of the scaffold. A number of previous workers have indicated the parameters which are believed to be the main stimulus in the adaptive bone remodelling process. An ideal bone manufacturing system would deliver bone morphogenetic proteins (BMP) and provide adequate mechanical properties. The aim of this study was to design a highly osteoconductive and mechanically strong bone regeneration scaffold which can be successfully manufactured. Three porous architectures of scaffold were designed using Solid EdgeTM 3D solid modelling software. The equivalent trabecular structure model consisted of repeatable unit cells arranged in layers to fill the chosen scaffold volume. The three different unit cell structures examined include cubic, triangular, and hexagonal polyhedral. Designed scaffold’s pores were varied in this study to 120, 340 and 600µm. This range was selected to meet one of the requirements of the scaffold design – the macropores must be at least 100µm in diameter, so the cells can penetrate and proliferate within the structure. The strengths of each scaffold were determined using ANSYSTM finite element software. Trabecular scaffold designs were analysed independently and in connection with simulated cortical bone in order to investigate their stress-strain response. As well as providing useful information on strengths developed from these topologies, the models developed indicated geometric constraints in order to tailor scaffolds to specific patient needs.

Abstract: Metallic biomaterials such as stainless steel and Co-based alloys are corrosion resistant and possess excellent mechanical properties and hence can be used in load-bearing implants for human tissue repair. However, these materials are bioinert and some of them can cause concerns over their long-term implantation as they release cytotoxic metal ions to surrounding body tissues. Forming a bioactive coating on implantable metals combats these problems and makes these materials very attractive for medical applications. This paper gives an overview of our research work over the past decade on using a number of surface modification techniques (plasma spraying, spraying-and-sintering, ion beam assisted deposition, biomimetic deposition, etc.) to improve the osteoconductivity of metallic biomaterials (Ti, Ti-6Al-4V and NiTi SMA).

Abstract: The surface oxide films were prepared by Electron Cyclotron Resonance (ECR) plasma oxidation on Ti substrates. Octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) peaks were formed after calcification by supersaturated calcium and phosphate solutions. Calcification ability was enhanced with increasing the oxidation time and the total pressure of ECR plasma treatment during oxidation. The results demonstrated that the calcium phosphate nucleation and the deposition can be controlled by various ECR plasma conditions.

Abstract: We had investigated the biocompatibility, osteoconductivity, and biodegradability of a porous composite of hydroxyapatite (HA) and poly-DL-lactide (PDLLA) implanted into rabbit femoral condyles. It showed excellent osteoconductivity and biodegradability as a bone substitute. Newly formed bones were remodeled, and materials were resorbed almost completely at 78weeks after implantation. In consideration of its biocompatibility and degradability, we investigated its potential for use as a cellular scaffold and evaluated its osteoinductive property. On implantation to the rat dorsal subcutaneous tissue loaded with syngeneic bone marrow cells, osteogenesis with enchondral ossification was seen both on and in the material at 3 weeks after implantation. This osteogenesis in the HA/PDLLA tended to get mature and newly formed bone tissues were found in the material by 6weeks. To investigate the osteoinductive property material itself has, we attempted to implant this porous composite material to extra-osseous canine dorsal muscle. At 2months, osteogenesis was seen in the pores of the material. It indicated the material induced osteogenesis with intramembranous ossification process. Therefore, HA/PDLLA might be a desirable material for bone substitutes and cellar scaffolds with osteoconductive and osteoinductive property.

Abstract: Three types of polymethylmethacrylate (PMMA)-based composite cements containing 40− 56 wt% micron-sized titania (titanium oxide) particles, designated ST2-40c, ST2-50c, and ST2-56c, were developed as bone substitutes for vertebroplasty, and evaluated for their mechanical, setting, and biological properties. In animal experiments, ST2-50c and ST2-56c were implanted into rat tibiae and solidified in situ. Their biological properties were evaluated at 6 and 12 weeks after implantation. Compressive strength, bending strength, and bending modulus increased with increasing titania content. Peak temperature during the setting reaction decreased as the filler content increased. ST2-56c had direct contact with bone over larger areas than ST2-50c at 6 and 12 weeks. Data from the present study indicated that ST2-56c is a good candidate as a bone substitute for vertebroplasty.

Abstract: Alumina powder containing δ , δ crystal phases (designated δAP) showed osteoconductivity. δAP was manufactured by fusing pulverized alumina powder and quenching it. The purpose of the present study was to evaluate osteoconductivity of δAP using rat tibiae. Alumina powder containing αcrystal phase (designated αAP) was used as a reference material. These two types of alumina powder were packed into the intramedullary canals of rat tibiae to evaluate osteoconductivity, as determined by an affinity index. Rats were sacrificed at 4 and 8 weeks after surgery. The affinity index, equal to the length of bone in direct contact with the powder surface expressed as a percentage of the total length of the powder surface, was calculated for each alumina powder at each interval. At 4 and 8 weeks, the affinity indices for δAP were significantly higher than those for αAP. For both δAP and αAP, there were no significant differences between the values for 4 and 8 weeks. This study revealed that the osteoconductivity of δAP was due to the alumina’s δcrystal phases. δAP shows promise as a basis for developing a osteoconductive biomaterial.