Papers by Keyword: Tricalcium Phosphate

Abstract: In this work, a simple, reproducible and low-cost synthesis method for the preparation of ß-tricalcium phosphate (ß-TCP) was developed. ß-TCP was prepared via wet mechanochemical treatment using calcium oxide and calcium hydrogen phosphate as raw materials. XRD and FTIR analysis indicated that the as-treated precursor was non-stoichiometric, poorly-crystallized carbonated hydroxyapatite (CHA) resulting from the mechanochemical reaction, and the crystalline ß-TCP powder was obtained by calcining the precursor at 800°C for 2 hours. SEM observation showed that the addition of surfactants could eliminate the agglomeration of the powder and well-dispersive ß-TCP powder with a particle diameter between 0.1 and 2.0 2m can be obtained.

Abstract: Biomaterials have been developed and used for bone grafting. Here, we study a fabrication of composite for bone tissue engineering by combining tricalcium phosphate and collagen. This tricalcium phosphate and collagen composite material may be applicable for use as a bone substitute. The β-tricalcium phosphate (β-TCP) is the one of the most investigated biomaterials due to its biocompatibility and good bioactivity. The β-TCP is used in a filling purpose to the bone defect region such as bone fractures. It is known that β-TCP substitutes it for a self bone in the body. The ingredient of the real bone is made of hydroxyapatite and collagen. In this study, the purpose was at giving the mechanical property and biological property which were near to a bone with β-TCP and collagen this time. We evaluate what kind of action collagen addition.

Abstract: We have previously reported that the carbonate apatite (CAP) foam that has similarities in both inorganic chemical composition and morphology to cancellous bone could be prepared from α-tricalcium phosphate (α-TCP) foam by the hydrothermal treatment with Na2CO3 at 200°C for 24 hrs. However, the crystallinity of the CAP foam was much higher than that of bone. In order to prepare CAP foam similar to cancellous bone in crystallinity as well as its inorganic composition and morphology, this study attempted to prepare CAP foam at lower temperature. Hydrothermal treatment at 100°C allowed low-crystalline CAP foam whereas longer period was imposed for complete conversion of α-TCP foam into CAP foam.

Abstract: In many in-vivo and in vitro studies, the behavior of calcium phosphate ceramics like β - tricalcium phosphate in biological environments has been reported to be predictive and positive. In terms of bone tissue growth, this ceramic can be more attractive presenting a porous microstructure. To obtain biomaterial quality ceramics, in this investigation β- TCP porous ceramics were prepared by a special consolidation method with albumin as a foam generating agent. This technique enables preparation a variety of formats with complex geometries. To obtain porous samples using albumin, heat had to be introduced into the system during the consolidation stage. After consolidation, the samples were sintered at 1250oC for 30 minutes and characterized using X-ray diffractometry, scanning electron microscopy and mercury porosimetry. The foams that were obtained by this method exhibited spherical and interconnected pores, characteristics desirable in biomedical implants.

Abstract: Effect of added α-tricalcium phosphate (α-TCP) and β-TCP was investigated to understand the setting reaction of apatite cement consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA). Addition of TCP delayed the initial setting time because TCP was not involved in the initial setting reaction and resulted in the decreased initial mechanical strength. After the initial setting of the cement due to the conversion of TTCP and DCPA into apatite, α-TCP dissolved to supply calcium and phosphate ions and they were consumed for crystal growth of apatite. Therefore, mechanical strength of the apatite cement containing α-TCP was increased. In contrast, added β-TCP showed no reactivity in the cement and thus result in the decreased mechanical strength.

Abstract: The effect of composition on the reactivity of a calcium phosphate cement (CPC) made of tricalcium phosphate (TCP) – water mixtures was investigated by isothermal calorimetry at 37°C. The parameters of interest were the mean particle size of the powder, the use of small amounts of nanosized hydroxyapatite powder, and the phosphate concentration and the pH of the aqueous solution. The results could be well explained by theoretical considerations. The main parameter controlling CPC reactivity was TCP particle size.

Abstract: In this work a new kind of CaSiO3-doped α-Ca3(PO4)2 ceramic materials, with compositions lying outside the field of the Ca3(PO4)2 solid solution in the system Ca3(PO4)2- CaSiO3, were obtained and some of their properties, relevant for bone repairing, were studied in vitro. Crystalline α-Ca3(PO4)2 solid solution and minor amounts of non-equilibrium residual glass were the only phases in the materials containing 2 and 5 wt% of CaSiO3. α-Ca3(PO4)2, crystalline eutectic-like phase and residual glass were observed for sample containing 15 and 20 wt% of CaSiO3. The mechanical strength improved for all the doped ceramics with regard to un-doped Ca3(PO4)2. The release of ionic Ca and Si in simulated physiological conditions increased with the content of CaSiO3 and favored α-Ca3(PO4)2 surface transformation. The soluble components extracted from the CaSiO3-doped α-Ca3(PO4)2 bioceramics were not cytotoxic to human fibroblastlike cells. Initial cell adhesion onto the surface of the materials seemed to be partially hindered by surface reactivity and remodeling, however those cells adhered to the experimental bioceramics were viable and proliferated normally.

Abstract: On this paper, methods to obtain Mg-free reagents for synthesizing pure phase Sistabilized α-TCP were established. The Mg contents of synthesized reagents were considerably lower than those in commercially available reactants. Pure Si-doped (2.5 at.-% of P by Si substitution) α-TCP was obtained by solid state reaction from synthetic reagents at temperature as low as 1200°C. When commercial reagents were employed for the solid state synthesis, a mixture of α- and β-TCP was obtained even when the solid state reaction was conducted at 1300 °C.

Abstract: Comparison of two experimental techniques of silicon-contained and/or silica-substituted calcium phosphate preparation from Ca(NO3)2·4H2O, NH4H2PO4, fumed silica and aqueous solution of NH4OH was performed. The first technique was a traditional one, in which the final product was synthesized in an aqueous solution by the well-known sol-gel process, followed by phase separation, washing off, drying and high-temperature sintering. An environmentally friendly direct preparation route was the second technique, in which the initial chemicals were mixed in the necessary proportions inside a crucible, followed by a high-temperature sintering of the entire mixture. The sintered powders were analyzed by the standard measurement techniques. Intentional variations from the stoichiometry within ±10% of the amounts of the mixed chemicals were employed to compare the vulnerability of both preparation techniques to random fluctuations of the processing parameters. The results revealed a better reproducibility and a higher yield of the direct preparation technique but the traditional sol-gel technique was found to be able to compensate accidental technological imperfections.