Bioceramics 20

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Authors: Flavia Mendonça, Luis Henrique Leme Louro, Jose B. de Campos, Marcelo Henrique Prado da Silva
Abstract: The present work suggests a modified gel casting process, including polyethylene wax spheres addition to the suspension with the objective of creating uniform and interconnected pores in the body of samples. In the present study, apatite powders were synthesized at pH 10 and pH 12 in order to give rise to biphasic and triphasic bioceramics after sintering.
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Authors: Takahisa Anada, Akihiro Araseki, Shou Matsukawa, Tomokazu Yamasaki, Shinji Kamakura, Osamu Suzuki
Abstract: Our previous studies suggested that synthetic octacalcium phosphate (OCP) enhances bone regeneration more than hydroxyapatite (HA). However, the molecular mechanisms to induce osteogenic phenotype in osteoblast by OCP have not been identified. OCP tended to convert into an apatite structure in vivo and in vitro, and its process was accompanied by calcium consumption from the surrounding solution and the release of phosphate ions into the solution at a physiological condition. The present study was designed to investigate whether the dissolution of ionic products of OCP affects on proliferation and differentiation of mouse bone marrow stromal ST-2 cells in vitro. The number of cells treated with OCP-conditioned medium was slightly decreased in comparison to that of control at day 7. On the other hand, the level of alkaline phosphatase activity increased in OCP-conditioned medium. These results demonstrated that OCP is capable of inducing osteoblastic cell differentiation in ST-2 cells.
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Authors: Joerg Brandt, Sven Henning, Goerg Michler, Matthias Schulz, Anke Bernstein
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Authors: Serge Baroth, Xavier Bourges, Borhane H. Fellah, G. Daculsi
Abstract: The purpose of this study ass to investigate the addition of round 80-200m granules shape radiopaque agents (RA) to synthetic Injectable Bone Substitute to improve contrast performance for minimal invasive surgery MIS. Composites were obtained by mixing BaSO4, Bi2O3, Lu2O3 or GdPO4 with calcium deficient apatite CDA which decompose during sintering process in BCP (60% HA, 40% β-TCP). Each composite was characterized: by XRD, FTIR. Biocompatibility was tested in vitro and in vivo in bony site (3 weeks implantation in rats). Primary results show that the suitable radiopaque BCP/RA composite (radiopacity intensity, biological responses) appeared to be BCP/Ba. Next works will complete the current studies on biological performance in association with different kind of resorbable injectable bone substitute as suspension, gel or calcium phosphate cements.
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Authors: Racquel Z. LeGeros, Dindo Q. Mijares, Fang Yao, Samar Tannous, Gary Catig, Qing Xi, Renata Dias, John P. LeGeros
Abstract: Osteoporosis is a ‘silent’ disease characterized by thinning cortical bone and disorganized trabecular architecture causing bone fragility leading to fracture. Osteoporosis results when the rate of bone resorption far exceeds the rate of bone formation. Current pharmaceutical interventions (estrogen therapy, bisphosphonate-based drugs) focus on inhibiting bone resorption. However, some of these therapies have serious side effects (e.g., cancer risk from estrogen therapy; osteonecrosis of the jaw and delayed fracture healing from bisphosphonate-based drugs). The long term objective of the study was to develop a novel material for potential osteoporosis therapy, prevention and fracture repair. This novel material MZF-CaP or synthetic bone mineral, SBM) incorporates Mg, Zn and F ions in a calcium phosphate matrix. Separately, magnesium (Mg), zinc (Zn) and fluoride (F) ions have been associated with biomineralization and osteoporosis therapy in human and in animals. MZF-CaP or SBM was prepared by a modified hydrolysis method previously described and characterized using x-ray diffraction, FT-IR spectroscopy, inductive coupled plasma and dissolution in acidic buffer. Separately, male and female Sprague-Dawley rats were randomly assigned to the following groups depending on the diet: GA: normal on basic diets; GB: on mineral deficient diets (md); GC: on md + Mg-CaP; GD: on md + Zn-CaP; GE: md+F-CaP; and GF: md+MZF-CaP. The rats were sacrificed after 3 months and the femur bones separated, cleaned of extraneous soft tissues and stored until needed for analyses. Femur bones were analyzed using microradiography (Faxitron), scanning electron microscopy (SEM) and microCT. Results: SEM, Faxitron and microCT analyses showed thinning of cortical bone and disorganized trabecular bone architecture for osteoporotic rats on mineral deficient diet (GB) and prevention of bone loss in rats receiving the supplemented diets (GC,GD,GE,GF). Conclusion: These results indicate that the novel material, MZF-CaP or SBM had a potential for osteoporosis therapy and prevention. Studies to demonstrate the use of SBM in reversing (recovering) bone loss are in progress.
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Authors: Satoshi Hayakawa, Akiyoshi Osaka, Kanji Tsuru, Eiji Fujii, Kouji Kawabata, Kanae Ando, Christian Bonhomme, Florence Babonneau
Abstract: Nano-crystalline Mg-containing hydroxyapatite (Mg·HAp) were prepared by a wet chemical method, for which selective adsorption of proteins was examined, taking bovine serum albumin (BSA) and a pathogenic protein β2-microglobulin (β2-MG) as the model proteins. Increase in the Mg content led to smaller crystallites and larger specific surface area (SA) of Mg·HAps as well as zeta potential, while the amount both of BSA and β2-MG adsorption on Mg·HAp particles. It is thus concluded that the adsorption of BSA and β2-MG on Mg•HAp was associated with surface charges.
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Authors: Aurelie Billon Chabaud, Christian Merle, Jean Michel Bouler
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Authors: D.J. Hadden, J.M.S. Skakle, Iain R. Gibson
Abstract: Silicon-substituted hydroxyapatite (SiHA) bioceramics are widely used as bone replacement materials. There are various synthesis methods used to produce SiHA samples using different sources of silicon. This study aims to investigate the role of tetraethyl orthosilicate (TEOS) as the silicon source in the precipitation reaction synthesis of silicate-substituted HA. Four different synthesis methods were studied by changing the order of addition of the TEOS solution during the precipitation reaction. XRD and QXRD were used to determine the phase purity of the prepared samples. FTIR and SSNMR were used to assess silicon/silicate substitution in the prepared materials. Of the initial four methods used, only one resulted in a sample that was phase pure. The other three syntheses, which produced biphasic compositions, were modified and a further single phase sample was prepared. Results showed that the final composition is strongly dependant on how and when the TEOS was added during the precipitation reaction.
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Authors: Masanobu Kamitakahara, Takashi Kurauchi, Masao Tanihara, Koji Ioku, Chikara Ohtsuki
Abstract: Si-containing tricalcium phosphate (TCP) ceramics are expected to be useful biodegradable bone substitutes that enhance bone regeneration because TCP is a biodegradable ceramic and Si is the trace element that enhances bone formation. We successfully synthesized the Si-containing TCP with different Si contents through a wet process. The Si addition lowered the temperature of phase transition from β-TCP to α-TCP. After the sintering the compacts of Si-containing TCP powders at 1400 oC, the sintered ceramics showed higher density than those of Si-free TCP. The Si addition was effective to promote the sintering of TCP.
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Authors: Tomoko Kanaya, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka, Eiji Fujii, Kouji Kawabata, Georgiana Gasqueres, Christian Bonhomme, Florence Babonneau
Abstract: Hydroxyapatite (HAp) and Si-containing hydroxyapatite (SiHAp) particles were synthesized by a wet chemical method. Local structures around Si, P and H in the hydroxyapatites were analyzed by solid-state magic-angle spinning nuclear magnetic resonance spectroscopy. In vitro solubility of those SiHAp particles was evaluated by soaking them in acetic acid/acetate buffer solution (pH=4.0) at 36.5°C. As the Si content increased, the in vitro solubility of the SiHAp particles increased, while their crystallite size changed little.
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