Papers by Keyword: α-Tricalcium Phosphate (α-TCP)

Abstract: Stearic acid was utilized to modify biphasic alpha-tricalcium phosphate (α-TCP)/hydroxyapatite (HA) powders in the ethanol. The results showed that the dispersion of biphasic α-TCP/HA powders (BCPs) in non-polar matrix improved. And the released content of Ca2+ and PO4 3- of the BCPs soaked in the NaAc-HAc buffer solution (pH 5.0) was almost same as that before modification. Stearic acid could modify the suface properties of BCPs and would not obviously affect their biological characteristics, which affords a good groundwork of application of calcium phosphates powders.

Abstract: The aim of this study is to explore the effects of quenching and milling processing on setting property of calcium phosphate cement (CPC). For this purpose, non-quenched α-tricalcium phosphate (α-TCP) and quenched α-TCP were synthesized and their corresponding cement systems were prepared. The particle size of α-TCP powder was introduced as a variable. Then, setting properties of these CPC systems were estimated. By a comparison between non-quenched CPC and the quenched one, it is found that milling processing mainly influences the initial setting stage by decreasing reactant particle size whereas the quenching treatment affects the final setting stage by changing α-TCP content, which supports that CPC setting initially depends on the surface area of reactants and subsequently on the diffusion through the hydrated layer formed around the reactants.

Abstract: An amorphous calcium phosphate precursor way was utilized to prepare submicron biphasic α-tricalcium phosphate (TCP)/hydroxyapatite (HA) powders. The results showed that the addition of carbonate during the precipitation reaction could eventually lead to the formation of HA phase in the resulting powders, and even determine the relative content of HA to the range from 0 percent (pure α-TCP) to 100 percent (pure HA). Similarly, the particle size of the resulting biphasic powders depended on the carbonate content, ranging from 100nm to 500nm. The biphasic Ca phosphate with tailored α-TCP/HA ratio could be a new combination of calcium phosphate for promoting early bone formation.

Abstract: Composite material composed of hydroxyapatite (HAp) and structural proteins, such as type I collagen or cross-linked gelatins, were synthesized at 37.4°C by hydrolysis of alpha tricalcium phosphate (α-TCP) in the presence of these protein structures. X-ray diffraction (XRD)and isothermal calorimetry were used as tools to evaluate the rate of HAp formation. Rates of HAp formation depend on protein structure. Gelatin enhances HAp formation while collagen delays it. Changes in pH during the hydrolysis α-TCP are unlikely to have an aggressive effect on the surrounding tissue. The presence of the protein improves the ductility of the HAp/protein composite but it decreases the tensile strength.

Abstract: Carbonate apatite form that has three-dimensional fully interconnected pore was prepared based on so-called ceramics form preparation method. First, a-tricalcium phosphate (a-TCP) form was prepared by immersing polyurethane form into a-TCP powder suspension. The form was heated in an electronic furnace for sintering a-TCP as well as for burning out of the polyurethane form. Then hydrothermal treatment was preformed at 200 degrees in the presence of saturated sodium bicarbonate for 24 hours. Although the mechanical strength of the carbonate apatite form was poorer when compared with a-TCP form, we found that the hydrothermal treatment of a -TCP form result in the formation of B-type carbonate apatite form without changing the ideal morphology of a -TCP form.

Abstract: Calcium phosphate (CaP) ceramics possessing an interconnecting porosity network in the appropriate size range for vascularisation offer the possibility of providing a structural matrix for replacement of diseased or damaged bone. Such bioceramics must possess sufficient mechanical strength to avoid failure whilst offering a bioactive surface for bone regeneration. The objective of the current study was to produce a hydroxyapatite/tricalcium phosphate (HA/TCP) bioceramic that imitated the orientated trabecular structure found in cancellous bone. The structure-property relationship of these bioceramics was then analysed. It was hypothesised that the mechanical properties would be linked to the shape of the pore structure due to the orientation of the open porous scaffolds (OPS) produced. OPS bioceramics possessed an interconnected macroporosity network of 40-70% by volume with bending strengths of 0.30MPa ± 0.01MPa and apparent densities of 0.35g/cm3 ± 0.05g/cm3. Typically, pore sizes in the range of 150-300µm were produced. The fabrication of CaP OPS resulted in a wide range of macroporosity in the correct size range for osseointegration to occur. Elongating the pore structure did not affect the total porosity of the bioceramics. Strengths were low due to microcrack formation on sintering and not due to the shape of the pores present in the scaffold as initially hypothesised.

Abstract: Porous a-tricalcium phosphate (a-TCP) ceramics are attractive as a novel bioresorbable material for bone repair, since they can be easily fabricated through conventional sintering of b-TCP at high temperature. However, the solubility of a-TCP is too high to keep its body until the bone defect is repaired completely. Coating of the a-TCP porous body with organic polymer is a way to reduce the degradation rate. In the present study, biodegradation of a-TCP porous body coated with silk sericin was evaluated in vivo. Bone repair at the defect made in rabbit tibia was nearly completed after 4 weeks. Higher density of cortical bone was estimated for a-TCP coated with sericin than for mere a-TCP. The a-TCP porous body coated with sericin is expected as a material that show less degradation than mere a-TCP, and may result in suitable bone repair.