Date

2015

Author

Khoshsima, Sina

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The aim of this study was to investigate the microstructure, mechanical and biological properties of pure hydroxyapatite and composites of hydroxyapatite with zirconia, boron oxide and lanthanum oxide. Hydroxyapatite was synthesized via precipitation method and sintered at 1100°C for 1 h. It was observed that relative density of the sintered composites including zirconia was increased while the density of composites including boron oxide decreased. For physical and structural analysis, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, mercury intrusion porosimetry and Fourier transform infrared spectroscopy examinations were performed. Due to boron oxide and zirconia substitution, small amounts of β-TCP phase were detected besides hydroxyapatite. Scanning electron microscopy results revealed that addition of composite powders resulted in smaller grains for zirconia group and bigger grain size for boron oxide group. Presence of different atoms and their corresponding weight ratios were determined by energy dispersive X-ray spectroscopy. Mercury intrusion porosimetry test showed the percent porosity of the composites. In Fourier transform infrared spectroscopy analysis, in vi addition to the characteristic bands of hydroxyapatite, novel bands indicating the substitution of zirconia, boron oxide and Lanthanum oxide were observed in samples. The microhardness test revealed that zirconia had a positive effects on the mechanical properties of the samples up to a certain amount, while substitution of the boron oxide had a negative effect on their mechanical properties. In order to evaluate the biocompatibility, in vitro cytotoxicity tests were performed using Saos-2 cells. PrestoBlue® assay viability test was used to analyze cell proliferation on the surface of samples. It was observed that composites including zirconia have a better biocompatibility and higher cell attachment rate than those including boron oxide. Scanning electron microscopy images were examined to observe morphology of the cells on the surface of the samples and it was observed that in all samples, the surface of the pellets were covered with cell layers showing perfect cell-material interaction.

Subject Keywords

Hydroxyapatite., Zirconium oxide., Boron oxide., Lanthanum oxide., Biocompatibility., Biomedical materials.

URI

http://etd.lib.metu.edu.tr/upload/12618514/index.pdf
https://hdl.handle.net/11511/24422

Collections

Graduate School of Natural and Applied Sciences, Thesis