Journal ArticleDOI
Comparison of in vivo dissolution processes in hydroxyapatite and silicon-substituted hydroxyapatite bioceramics
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TLDR
High-resolution transmission electron microscopy observations confirmed that defects, in particular those involving grain boundaries, were the starting point of dissolution in vivo and may help to explain the mechanism by which silicate ions increase the in vivo bioactivity of pure HA.About:
This article is published in Biomaterials.The article was published on 2003-11-01. It has received 391 citations till now. The article focuses on the topics: Bioceramic.read more
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In vitro studies of degradation and bioactivity of aliphatic polyesther composites
Abstract: IN VITRO STUDIES OF DEGRADATION AND BIOACTIVITY OF ALIPHATIC POLYESTER COMPOSITES by Georgia Chouzouri In spite of numerous publications on the potential use of combinations of aliphatic polyester composites containing bioactivity fillers for bone regeneration, little information exists on the combined in vitro mechanisms involving simultaneously diffusion for polymer degradation and bioactivity through nucleation and growth of apatite in simulated body fluid (BF) solution. The objective of this study is to contribute to the understanding of the fundamentals in designing nonporous, solid materials for bone regeneration, from experimental data along with their engineering interpretation. Bioactivity, in terms of apatite growth, was assessed through several experimental methods such as scanning electron microscopy (SEAM), energy dispersive X-ray analysis (EDX), X-ray-diffraction (CORD) and changes in ion concentration. In the case of the six neat fillers evaluated, the filler shape, form and chemical structure showed significant differences in bioactivity response. Bioglass and calcium silicate fillers showed faster nucleation and growth rates in the screening experiments. Aomposites at 30 % by weight filler were prepared by solution and/or melt mixing. Polycaprolactone (PAL) composites containing five different fillers were evaluated. Solution processed PCL/calcium silicate (AS) samples showed faster bioactivity, as determined by apatite growth, compared to melt mixed samples. The onset time for bioactivity was different for all PAIL composites. The limited bioactivity in the PAL composites over longer periods of time could be attributed to the PAL hydrophobicity leading to a slow polymer degradation rate, and also to the lack of BF replenishment. For both polylactic acid (PLA) composites containing AS and biomass significant growth was observed after one week and in the case of AS was still evident after four weeks immersion. However, at prolonged time periods no further bioactive was observed, although ion release results indicated a faster release rate that would eventually lead to a faster polymer degradation and possibly continuing bioactivity. The presence of silicate fillers enhanced the hydrolytic degradation rate of both PAIL and PLA as shown from kinetic data calculations based on molecular weight measurements. Unfilled PLAN samples showed significant embattlement after two weeks immersion, whereas for the AS filled system more significant changes could be observed in the compressive strength and modulus after the same time period. Experimental data were also fitted into an equation proposed to calculate erosion number; in the case of unfilled PLAN predictions were found to agree with literature results suggesting bulk erosion. By assuming impermeable, randomly dispersed mass flakes, water transport in a composite system, prior to significant polymer degradation could be modeled. However, modeling of transport in the case of the composite consisting of a degrading polymer and a reactive decaying filler was challenging, particularly in the case of directional bioactivity reinforcements, due to the occurrence of simultaneous time dependent diffusion phenomena that altered the integrity of the sample. IN VITRO STUDIES OF DEGRADATION AND BIOACTIVITY OF ALIPHATIC POLYESTER COMPOSITES by Georgia Chouzouri A Dissertation Submitted to the Faculty of New Jersey Institute of Technology In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering Otto H. York Department of Chemical Engineering May 2007 Copyright © 2007 by Georgia Chouzouri ALL RIGHTS RESERVED APPROVAL PAGE IN VITRO STUDIES OF DEGRADATION AND BIOACTWITY OF ALIPHATIC POLYESTER COMPOSITES Georgia Chouzouri Dr. Marino Xanthos, Dissertation Advisor Date Professor, Otto H. York Department of Chemical Engineering, NJIT Dr. Treena Liviττgstοn Arinzeh, Committee Member Date Associate Professor, Biomedical Engineering, NJIT Dr. Michael Jaffe, • ' ittee Member Date Research Profess • , ' iomedical Engineering, NJIT Dr. ÍJaυrent Simon, Cómmittee Member l Date Assistant Professor, Otto H. York Department of Chemical Engineering, NJIT Dr. Jing Wu, Committee Member Date Assistant Professor, Otto H. York Department of Chemical Engineering, NJIT
Journal ArticleDOI
In vitro angiogenesis in response to biomaterial properties for bone tissue engineering: a review of the state of the art
TL;DR: An overview of the available literature on scaffolds for BTE, and trends are extracted on the relationship between architectural features, biochemical properties, co-culture parameters and angiogenesis as discussed by the authors .
Silikon İkameli Hidroksiapatitte Biyoaktivite Ve Kemik Oluşumu
TL;DR: In this paper, the authors investigated the bioactivity and successful bone formation in silicon-substituted hydroxyapatite bone grafts by using scanning electron microscopy and electron dispersive x-ray spectroscopy.
Book ChapterDOI
Mechanism of ceramic coatings degradation
TL;DR: The coating of the ceramic layer gives a major solution to some of the problems posed by the metallic orthopedic implant, which mainly eradicate the threat of brittle fracture due to the high toughness of metals as discussed by the authors .
Journal ArticleDOI
Investigation of Surface Layers on Biological and Synthetic Hydroxyapatites Based on Bone Mineralization Process
TL;DR: In this article , the structural and surface properties of hydroxyapatite (HA, Ca10(PO4)6(OH)2) have been analyzed for effective bone formation and regeneration mechanisms.
References
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Book
Theory of Dislocations
John Price Hirth,Jens Lothe +1 more
TL;DR: Dislocations in Isotropic Continua: Effects of Crystal Structure on Dislocations and Dislocation-Point-Defect Interactions at Finite temperatures.
Journal ArticleDOI
Bioactive ceramics: the effect of surface reactivity on bone formation and bone cell function
Paul Ducheyne,Qing-Qing Qiu +1 more
TL;DR: This review describes some of the current concepts regarding the surface reactivity of bone bioactive materials and its effect on attachment, proliferation, differentiation and mineralization of bone cells.
Journal ArticleDOI
Silicon: A Possible Factor in Bone Calcification
TL;DR: Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone and is suggested to be associated with calcium in an early stage of calcification.
Journal ArticleDOI
The effect of calcium phosphate ceramic composition and structure on in vitro behavior. II. Precipitation.
TL;DR: The dissolution behavior of the CPCs studied was found to vary over a wide range, and the dissolution rate of the monophase CPCs increased in the order of stoichiometric hydroxyapatite, calcium deficient hydroxyicarbonate, oxyhydroxyapatites, beta-tricalcium phosphate, alpha-tricals calcium phosphate, and tetracalcium phosphate.
Journal ArticleDOI
Chemical characterization of silicon-substituted hydroxyapatite.
TL;DR: Chemical analysis confirmed the proposed substitution of the silicon (or silicate) ion for the phosphorus (or phosphate) ion in hydroxyapatite and demonstrated that phase-pure silicon-substituted hydroxyAPatite may be prepared using a simple precipitation technique.