Papers by Keyword: Bioresorbable

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Authors: Z. Yang, E.S. Thian, Serena Best, Ruth Cameron
Abstract: α-tricalcium phosphate (α-TCP) was prepared by a wet precipitation reaction between calcium hydroxide and orthophosphoric acid solutions. The as-synthesised powder was then characterised using a Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectroscope (EDS), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscope (FTIR). Analyses revealed that a phase-pure powder with a Ca/P ratio of 1.5 was produced. In addition, nanosized α-TCP particles of diameter ~ 70 nm were agglomerated to form larger particles of 10μm in diameter. It was found that by the combination of attritor milling and solution evaporation, the agglomerates of α-TCP nanoparticles could be broken down, and distributed evenly within the poly(D,L-lactic-co-glycolic acid) (PLGA) matrix. Thus, a α-TCP/PLGA nanocomposite was successfully produced by a modified solution evaporation method at room temperature followed by hot pressing at 150 °C. The achievable ceramic loading was approximately 38 wt.%, which was confirmed by thermal gravimetric analysis (TGA).
Authors: Argyrios Kasioptas, Veronica Sandell, Eva Lidén, Oskar Börjesson, Malin Nilsson
Abstract: The hydration of α−tricalcium phosphate (α−TCP) is known to lead to the formation of an interlinked calcium−deficient hydroxyapatite (CDHA) framework. This apatite resembles the composition and structure of physiologic bone mineral, making it a good candidate for bone reconstruction. The additional presence of a calcium sulfate phase, which has a faster resorption rate than apatite, gives a gradual creation of porosity in the cement. This may in turn enhance bone ingrowth. The aim of this study was to gain deeper understanding of the main characteristics and properties of a bi−phasic α−TCP/α−CSH cement, prepared with an X−ray contrast medium.Isothermal calorimetry has been used to follow the course of the hydration reaction over time as it involves traceable exothermic events with possible contributions from both the calcium phosphate and calcium sulfate components. This was done in an attempt to identify and differentiate the role of each reactive phase. Additionally, the total produced heat from the cement has been used to estimate the degree of conversion and this result has been verified by X−ray diffraction analysis.Furthermore, compressive strength of the α−TCP/α−CSH cement has been measured over time to investigate the possible connection to its thermal evolution signature. Also, the impact of the surrounding environment on the α−TCP and α−CSH conversion was investigated by comparing XRD results between samples that had been kept dry or wet.
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