This study was conducted to develop novel ceramic bone substitute that resembles the autologous bone behavior when used as graft material. Solid-state reaction at 1100°C was performed to synthesize β-tricalcium phosphate (β-TCP) and biphasic calcium phosphate (BCP). The ceramics were further analyzed to characterize phase composition, microstructural properties, cytocompatability and then challenged to regenerate critical bone defects in the parietal bone of rabbits. X-ray diffraction analysis confirmed the production of β-TCP and indicated the synthesis of novel BCP composed of β-TCP and silicocarnotite (calcium phosphate silicate mineral). The cytocompatibility test with human osteoblast cell line revealed enhanced cell proliferation on the BCP ceramic. The novel BCP induced the filling of about 73% of the bone defect with a newly formed bone tissue and an almost complete degradation after 12 weeks of healing. This novel ceramic resembles the autologous bone properties of complete degradation and efficient enhancement of bone formation, making it promising as bone graft material.
Rdsum& Le comportement rhrologique de sols d'acide silicique a 6t6 examin6 au cours du temps fi des pH compris entre 6 et 8 fi la concentration de 10 g. 1-1 de silice, et pH = 8 fi des concentrations variant entre 0,5 et 10 g. 1-1. Les courbes d'rcoulement rrvrlent un comportement rhrologique complexe. L'analyse des rhrogrammes en fonction du temps, du pH et de la concentration contribue fi la connaissance de l'rtat structural du polymrre au cours de la formation du gel. I1 ressort que le comportement initialement rhrorpaississant aux faibles concentrations correspondant ~ l'rtat d'une solution colloidale, laisse place fi un 6coulement rh~ofluidifiant dans les conditions favorables fi la polymrrisation de l'acide silicique. La transition sol-gel est marqure par un breakpoint; en prolongeant les mesures on observe un comportement plastique dfi l'apparition d'agrrgats sous l'effet du cisaillement. Tous les processus rhrologiques se trouvent exacerbres fi pH = 8.Abstract: The rheological behaviour of silicic acid in aqueous solutions was studied over a period of time for pH values between 6 and 8 at the concentration 10 g. 1-2 and at pH = 8 for different concentrations varying from 0.5 to 10 g. 1-1. The shear stress-shear rate curves indicate a very complex character of theological behaviour. Its analysis with respect to the infuence of time, pH and concentration contributes to the knowledge of the structure of the polymer during the process of gel formation. It is shown that the inital shear-thickening behaviour of the colloidal sol at low concentrations is followed by a shear-thinning behaviour under conditions of polymerization of the silicic acid. The sol-gel transition is marked by a breakpoint. When measurements pass beyond this point, plastic flow behaviour is observed because of the shear induced formation of amorphous silicic aggregates. All rheological processes of silicic acid sols are intensified at pH = 8.
Calcium phosphate materials (CPM) are widely used in dentistry and maxillofacial surgery. The presence of microbial biofilms and external infections is responsible for the failure of many procedures of dental implants and bone grafts. In an attempt to reduce the percentage of these infectious processes antibiotics have been associated with CPM improving certain conditions. For instance, antibiotics administered orally or intravenously have less effect and the blood flow in relation to this is poor near implants and grafts. Tissue engineering (TE) has employed CPM as a local drug delivery vehicle to be more effective and efficient in bone infections. This review is presented to describe current antibiotics used and the physical and chemical properties of scaffolds.
Porous ceramics doped with silicon and pure β-TCP were analyzed in terms of internal microstructure, cell behavior, and the percentage of newly formed bone. Additionally the materials were tested to determine which of the two had better properties to load and release vancomycin hydrochloride. Internal pore distribution and porosity were determined through high pressure mercury porosimetry and the specific surface area was measured by the Brunauer Emmet-Teller method. The proliferation and viability of the human osteoblast-like cell line MG-63 was studied to validate both materials. The materials were tested on eight New Zealand rabbits which created defects, 10 mm in diameter, in the calvaria bone. After 8 and 12 weeks a histological and histomorphometric analysis was performed. Si-β-TCP showed a higher porosity and specific surface area. The cytocompatibility test revealed acceptable results in terms of proliferation and viability whereas the percentage of new bone was higher in Si-β-TCP with a two-time study being statistically significant with 12 weeks of healing (p < 0.05).The vancomycin loaded within the ceramic scaffolds were burst released and the material had the ability to inhibit bacterial growth. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2307-2315, 2018.
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