In Situ Formation of Hydroxyapatite - Alpha Tricalcium Phosphate Biphasic Ceramics with Higher Strength and Bioactivity
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Date
2012
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
Abstract
Synthetic bone grafts based on hydroxyapatitealpha tricalcium phosphate (HA/a-TCP) biphasic system are preferred for their higher resorbability and bioactivity. In this work, a viable method is suggested to produce HA/a-TCP systems with enhanced bioactivity and mechanical strength, through the in situ conversion of calcium-deficient apatite precursor. A homogeneous precipitation technique was used to produce the precursor powder. It was heat-treated to study the phase conversion using XRD and FTIR. The precursor got converted HA/beta-TCP system above 762 degrees C, which further transformed to HA/a-TCP system after 1165 degrees C. The sintering temperature was optimized at 1175 degrees C. It is the net Ca/P ratio of the precursor which decides the ratio of the phases in the final ceramic. The precursor with Ca/P = 1.585 gave a biphasic ceramic containing 47% a-TCP. The flexural strength of this sample was more than 2.5 times higher compared to the biphasic ceramic made by sintering HA/a-TCP powder mix. The internal microstructure of the ceramic revealed the formation of a-TCP in sheet-like morphology. Preferential dissolution of the a-TCP from the sample surface in aqueous and acidic environment was confirmed quantitatively. Biomimetic growth technique in simulated body fluid has been used to assess the bioactivity in vitro.
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Materials Science
Citation
95 ,3;915-924