| Summary: | 碩士 === 國立成功大學 === 口腔醫學研究所 === 98 === Recently, the implants coated with hydroxyapatite (HA) by plasma spraying were widely used in orthopaedic applications. In previous study, HA has excellent biocompatibility and ability for bone tissue directly bonding and fixation. Because of the low bone density for the patients with osteoporosis, it was hard to achieve the great HA-bone tissue integration. There is 98 percent of strontium in the human’s normal bone. It had been investigated that strontium could promote the bone cell to differentiation, inhibit the bone absorption, and reduce the rate of bone loss. In the clinical usage, strontium can be used to cure osteoporosis. The Calcium atoms on HA can be substituted by strontium to form strontium substituted HA (Sr-HA). It was found that Sr-HA bone cement has the ability to bone aggregation in animal models. The aim of the study is to coat Sr-HA on the surface of metal implant, and it could be used for patients with osteoporosis. In this study, we plasma sprayed Sr-HA layers on titanium alloy substrate to observe the osteoblast cell morphology, proliferation, and differentiation in vitro. We formed the powders of different concentration of strontium (0, 1, 3, 5and 10 mole% Sr). Then the powders were coated on titanium alloy by plasma spraying. The samples were analyzed by X-ray Diffraction (XRD), Transmission Electron Microscope (TEM), Inductively coupled plasma-atomic emission spectrometer (ICP-AES), Scanning Electron Microscope/ Energy Dispersive Spectrometers (SEM/SEI/EDS), Thermal Differential / Thermal Gravimetric Analyzer (DTA/TGA) and etc. We formed the powders of different concentration of strontium. In the XRD for the phase of the powders, it was similar to HA pattern, and the peak shift was to low angle with Sr increase. The lattice constant and volume increase and grain size decrease with Sr increase. For TEM observation, the morphology of Sr-HA was resembled to HA. The interatomic distance increase with Sr increase. By ICP-AES, the CaSr/P was close to ideal value. Then, the Sr-HA layer was coated by plasma-spraying on titanium alloy. For SEM observation, the morphology of Sr-HA was has un-melted. particle, melted pellet, microcrack and pore. The XRD result showed the Sr-HA has mixed phase and the content increase with Sr increase. Then it was observed the mineralization level by the SBF immersion test. The result showed the apatite produced quickly with the content increase of Sr. Then we will to evaluate the influence of biocompatibility by HA of different Sr content substituted.
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