Papers by Keyword: Bioactive

Abstract: Colloidal processing was used to cast zirconia and hydroxyapatite materials. The cast materials reached densities around 99% when sintered at 1500°C and 1200°C respectively. By controlling the colloidal process the sintered density of hydroxyapatite was also reduced to around 80% when the same sintering condition was used. The casting process was combined with free form fabrication to prepare designed scaffolds with identical macroporosity. These scaffolds were used to evaluate the early bone tissue response in rabbit femur. After six weeks of implantation the bone area in scaffolds of zirconia and hydroxyapatite were compared. In scaffolds of hydroxyapatite the bone area was roughly three times larger compared to corresponding scaffolds of zirconia. When the scaffolds of hydroxyapatite also contained an open microporosity of around 20% the amount of bone was even more pronounced. The results showed the importance of the material composition and the microstructure on the bone regenerating performance of scaffolds.

Abstract: Two series of bioactive and biodegradable composite materials consisting of particulate β-tricalcium phosphate (β-TCP) and polyhydroxybutyrate (PHB) and its copolymer polyhydroxybutyrate-co-hydroxyvalerate (PHBV) were produced and investigated for bone tissue repair. A manufacturing route employing injection moulding was established for producing the biomedical composites. In the process, plates of composites containing 10%, 20%, 30% or 40% by volume of micro-sized TCP particles were successfully injection moulded for both TCP/PHB and TCP/PHBV composites. Thermal properties of as-produced TCP/PHB and TCP/PHBV composites were systematically evaluated using differential scanning calorimetry (DSC). The mechanical performance of TCP/PHB and TCP/PHBV composites was assessed using dynamic mechanical analysis (DMA).

Abstract: In this paper, the hydration product of calcium phosphate cement with bioactive glass containing Si was used to investigate the effect of chemical composition on its bioactivity. The variation of concentrations of Ca2+, P and Si in TE solution complemented with electrolytes typical for plasma (TEE) and the formation of amorphous calcium phosphate layer on the surface of the materials were investigated by immersing the designed materials in TEE solution in vitro. The results showed that the composition of the bioactive composite CPC greatly affected its behavior in the solution and the formation of bioactive apatite. After immersed in TEE solution, the Ca ions were uptaken for all the samples, showing the decreases of Ca concentration during the entire duration, but the concentration of P ions increased sharply at the initial stage, and then decreased due to the formation of amorphous calcium phosphate layer on the surface of the materials. FTIR revealed that the layer was poorly crystallized Ca-deficient carbonate apatite. The thickness of the layer was more than 12 um, which layer was composed of rod-like apatite with directional arrangement. All the data obtained would be useful for the design and optimization of the orthopedic degradable implant inorganic materials.

Abstract: Biocompatibility of metallic implants and bone in orthopaedic surgery plays an important role in long-term survivor of the prosthetic implant fixation. However, titanium and its alloys do not bond to bone in the early stage of implantation (<6 months). On the other hand, titanium alloy undergoes electrochemical exchange and releases metallic ions in the physiological environment, which is believed to be the cause of implant failure. Cathodic electrolytic deposition is an important method in ceramic processing. In this paper, the nanocrystalline BaTiO3 coating were prepared by electrolytic deposition process. According to the XRD results, we can clearly identified that electrolytic deposition Barium titanate hydrate gel annealed at 350°C for 1 hr will form to BaTiO3, and its grain size about 4.85 nm. From dynamic cyclic polarization tests, we can found that dense BaTiO3 coated effective improved corrosion resistance of Ti substrate than untreated. From immersion tests, we can found that BaTiO3 exhibited excellent bioactive.

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: Poly methyl methacrylate(PMMA) with mar resistant or poly ethtylene(PE) substrates were surface-treated by applying plasma discharge or alkaline solution. Ceramic thin film comprised of silicon oxide, titanium oxide and zirconium oxide was formed on these surface treated substrates respectively from an aqueous solution, and after the formation of ceramic thin film, titanium oxide thin film was also coated on them from aqueous solution at ordinary temperature and pressure. The thin film coated polymer material was tested in mechanical property. The thin film was hard and the adhesion strength to the organic polymer substrate was very high. The substrate was soaked in SBF and apatite was formed on the substrate. This method is promising for developing hard and soft tissue implants with various mechanical properties as well as high bioactivity.

Abstract: Enhanced bioactivity has been observed for amorphous CaO-SiO2 sol-gels with 30mol% CaO, and several structural techniques have recently been used to investigate the structural basis for this bioactivity. The current work presents the first detailed atomic model of (CaO)0.3(SiO2)0.7 solgel after heat treatment at 600°C, produced using molecular dynamics. The model contains 1056 atoms in cubic box with length 24.1Å, and specifically incorporates hydroxyl groups which are characteristic of the sol-gel. The model is in good agreement with experimental X-ray and neutron diffraction results. Inspection of the model shows a network of SiO4 tetrahedra with an average connectivity of approximately 3. Ca have coordination of NCaO=5.3, in agreement with experimental results. On average, each Ca is surrounded by 4 other Ca, and visual inspection shows several large clusters of Ca. These clusters should influence the dissolution of Ca, and hence the bioactivity of (CaO)0.3(SiO2)0.7 sol-gel.

Abstract: In this study, chemical methods were used to treat NiTi for the purpose of preparing bioactive NiTi implants. The surface of the bioactive NiTi alloy was investigated by XRD and ESEM. The biocompatibility and bioactivity of the bioactive NiTi samples were evaluated by in vivo implantation experiments. The results show that a Ca-P layer composed mainly of hydroxyapatite (HA) with a trace amount of other apatites and a Ca/P ratio of 1.59 covers the surface of the bioactive NiTi alloy. In vivo tests show that osteoblasts actively proliferated on the bioactive NiTi implants after 6 weeks implantation. A large amount of new bone directly in contact with the host bone was observed after 13 weeks implantation. These revealed the excellent biocompatibility and bioactivity of the prepared bioactive NiTi alloy.

Abstract: This study aimed to investigate the effects of hydroxyapatite on bonding strength between dental luting cement and human teeth. In the previous study, bonelike forming ability by mixing hydroxyapatite with several bone cements was reported in a protein-free acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. Therefore in this experiment, we assumed that if bonelike apatite layer could form between dental luting cement and human teeth, the bonding strength between the two would improve. In addition, we expected the HA mixed dental luting cement to improve the physical properties. Fuji I glass ionomer and Relyx™ glass ionomer cement were the selected dental luting cements and the film thickness, setting time and compressive strength were measured mixing various concentrations of hydroxyapatite. Glass ionomer cement with the most superior physical properties(Fuji I ; 20% hydroxyapatite, Relyx™ ; 15% hydroxyapatite) was immersed in the simulated body fluid for three weeks and the surface was observed under SEM after measuring the bonding strength. As the concentration of HA increased, the film thickness of hydroxyapatite-glass ionomer cement decreased, the setting time increased, and the compressive strength increased. The most noteworthy results were that bonding strength increased, and that bonelike apatite formed on the tooth surface when observed under SEM.