Papers by Keyword: Bioceramic

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: Globular-shaped beta-tricalcium phosphate (β-TCP) granules were synthesized using a unique dropping slurry method and the biological response was analyzed by implantation into the rat femur. Two kinds of globular-shaped β-TCP granules, composed of either rod-shaped particles or conventional non-rod-shaped particles were synthesized, implanted into the left femurs of 8-week-old female Wistar rats, and analyzed histologically. Commercially available β-TCP granules composed of conventional non-rod-shaped particles were also implanted as a control experiment. Four weeks after the operation, part of each implant was already resorbed and the resorbed area was replaced by newly formed bone tissue and bone marrow. Eight weeks after the operation, the resorption and replacement were advanced in each implant. At 12 weeks after the operation, residual globular-shaped β-TCP granules composed of rod-shaped particles were resorbed into compact petrotic bone tissue almost completely. The formation of less compact petrotic bone tissue was observed in specimens implanted with globular-shaped β-TCP granules composed of conventional non-rod-shaped particles. Commercially available β-TCP granules composed of conventional non-rod-shaped particles were mostly resorbed into trabecular bone and the formation of compact petrotic bone tissue was rarely observed. These data suggested that both the unique spherical shape and microstructure of β-TCP particles affected bone-forming activity after the operation.

Abstract: Molluscan shell possesses excellent strength, stiffness and fracture toughness that are closely related to its exquisite microstructure. SEM observation of a clam’ shell showed that the shell is a kind of bioceramic composite consisting of aragonite and protein layers parallel with the surface of the shell. The observation also showed that the aragonite layers are composed of long and thin aragonite sheets. Many aragonite sheets are of curving shape at the center of the shell. The higher fracture toughness of the shell was analyzed based on the representative model of the curving aragonite sheets and the concept of the maximum pullout force that is related to the fracture toughness of the shell. The analytical result showed that the maximum pullout force of the curving aragonite sheet is larger than that of straight aragonite sheets, which may effectively enhance the fracture toughness of the shell.

Abstract: Two different injectable materials, intended for use in vertebroplasty (VP) treatments of fractured vertebras, were tested in an in vitro bone model. The materials tested were an experimental bioceramic material based on calcium aluminate manufactured by Doxa AB, and Vertebroplastic, a PMMA based material manufactured by DePuy Acromed. The model was earlier developed by others and has been found valid for testing of materials intended for PVP. The model offers alternative data to traditional compressive and diametral tensile testing by adding the infiltration of material into synthetic cancellous bone. Five different synthetic bones with different porosity and pore structure were tested. The results show that for the PMMA the infiltration pattern of the different bones tested seems to have no influence. The material deforms plastically and displays about the same strength in all bones tested. For the bioceramic, linear elastic, material however there is a difference. In the more porous bones, where the material infiltrate the pores and creates a test body with a large amount of crack initiation points, the material displays lower strength compared to that of the more solid bones.

Abstract: Microporosity and granules size are important parameters for the development of suspension, composites and injectable bone substitutes. In this experimental study performed in a rat bone model of critical size defects, were have determined the kinetics of bioceramic resorption and bone ingrowth. Two kinds of granules (1mm in diameter) of Biphasic Calcium Phosphate BCP (60/40 HA/TCP ratio) with 20% and 40% microporosity of less of 5 microns in size, were used. Higher bone ingrowth was observed for low porosity (LP) at 3 weeks versus high porosity (HP); the contrary was measured after 6 weeks. About the kinetics of BCP resorption, significant difference between the 2 porosities was noticed, the higher for high microporosity. High porosity on time, promotes more bone ingrowth at the expense of the bioceramic than lower microporosity.

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: Calcium is generally determined by EDTA titration after separation of phosphate radicals, and the phosphorus is determined by weigh method. This traditional analytical process is time consuming and unfavourable for quality controlling. In contrast, the ICP-AES is simple and fast, and can simultaneously determine multielements. In this paper, the ICP-AES method was used to simultaneously determine calcium and phosphorous in calcium phosphate based bioceramics, and wavelengths of 317.933 nm and 213.618 nm were selected for the measuring of the calcium and phosphorus, respectively. The results obtained by ICP-AES are well consistent with the results determined by the traditional EDTA titration and weigh method, and suggest that the ICP-AES analysis is a simple, fast and accurate method for simultaneous determination of calcium and phosphorous in calcium phosphate based bioceramics.

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.

Abstract: Dense bioceramics made of pure hydroxyapatite (HA) was prepared and characterized. The cylindrical samples were compacted from HA powders of diverse pretreatments; namely, from spray-dried HA, calcined HA and mixtures thereof. The samples were prepared by a hydraulic press under different compaction loads both with and without auxiliary compounds (a binder and a lubricant). Both the total mass and geometrical dimensions of the prepared cylinders were measured. Then, the cylindrical samples were sintered at 1200 °C for 4 hours. After cooling down to ambient temperature, the sintered cylinders were weighed and their geometrical dimensions were measured once again. Mass decreasing and the shrinkage degree were calculated as a result. Afterwards, the compression strength of the sintered cylinders was measured by an Instron 5587 machine. Preparation of dense HA bioceramics possessing the highest possible compression strength was the purpose of this study. The necessary processing parameters were discovered.