Authors: Wei Chang Xue, Chuan Xian Ding, Cong Cao, Yuqi Dong
Abstract: A new bioceramic coating based on diopside was prepared by plasma spraying. The
surface and cross-section microstructure of the coating were examined by scanning electron microscopy. The thermal expansion coefficient of the diopside coating measured by a dilatometer adapted to that of titanium alloy. The bond strength of the coating was about 32.5 MPa, which is higher than that of HA coatings used in orthopedics and dentistry. The bioactivity of diopside coating was evaluated in vitro. After 15 days soaking in simulated body fluid, an apatite layer was
formed on the surface of the coating. The cytocompatibility was investigated by studying the behaviour of human osteoblast cultured directly onto the surface of the coating. MTT assay was performed to assess the influence of the coating on cell proliferation. The morphologies of the cell were observed by SEM after incubation for 1 and 7 days. The results obtained indicated that plasma sprayed diopside coating may be a suitable candidate for bone and dental implant.
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Authors: Xiao Bing Zhao, Xuan Yong Liu, Chuan Xian Ding
Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying using commercial nano-powders. Then, as-sprayed coatings were treated using 10% hydrofluoric acid (HF) at room temperature for 30 seconds. As-sprayed and HF-treated titania coatings were soaked in simulated body fluid to investigate the formation of apatite on their surface. Field-emission
scanning electron microscopy was used to observe the surface morphologies, and the phase composition of the as-sprayed coating and apatite were analyzed by X-ray diffraction and energy-dispersive X-ray spectrometry. As-sprayed titania coating is composed of rutile, anatase, and a small quantity of Ti3O5. It exhibited excellent adhesion between the TiO2 coatings and titanium alloy substrates, and the bonding strength was about 38 MPa. After in vitro experiment, a new substance containing calcium and phosphate was formed on the surface of HF-treated TiO2 coatings
after being soaked in SBF, while the new substance was not formed on the surface of as-sprayed TiO2 coatings. The results indicated that the bioactivity can be induced to the surface of plasma sprayed TiO2 coatings by hydrofluoric acid treatment.
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Authors: Sen Yang, Hau Chung Man
Abstract: To accelerate the bone growth around a metallic implant and to achieve the mechanical
characteristics needed for biomedical applications, a HA/Ti composite coating was produced on NiTi
alloy substrate by laser cladding. The chemical compositions, microstructures and surface
morphology of the cladded layer were analyzed using energy dispersive X-ray spectroscopy (EDX),
scanning electron microscopy (SEM), and X-ray diffractometry (XRD). The experimental results
showed that an excellent metallurgical bonding between the coating and the substrate was obtained.
Owing to decomposition of HA under irradiation of high power laser, the microstructures in
bioceramics coating were mainly composed of CaO, CaTiO3, Ti4P3, and HA phases. In vitro
experimental result showed that HA/Ti composite coating made the bioactivity of NiTi alloy improve
remarkably, which would promote the bone growth and could restrain Ni ion releasing from NiTi
alloy.
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Authors: Xue Bin Zheng, Yi Zeng, Chuan Xian Ding, Soo Wohn Lee, Zi Yuan Zhu, Fu Qiang Zhang
Abstract: Vacuum plasma sprayed (VPS) hydroxyapatite (HA) coatings with silver-loaded
zirconium phosphate antimicrobial have been prepared on titanium substrate. Antibacterial effects
of the coatings were studied by bacteria culturing using Porphyromonas gingivalis (Pg),
Fusobacterium nucleatum (Fn) and Actinobacillus actinomycetemcomitans (Aa) as microorganisms.
Simulated body fluid (SBF) test was carried out to evaluate the bioactivity of the coatings as well.
The results obtained showed that the coatings exhibited a marked antibacterial effect against Pg, Fn
and Aa when the content of antimicrobial was equal to or more than 5%. The antibacterial
capability of the coatings decreased in the following order: Pg, Fn, Aa. Bone-like apatite layer was
formed on the silver-containing HA coatings after immersed in SBF, suggesting that their
bioactivities were not affected obviously by the addition of silver-zirconium phosphate
antimicrobial. This study indicated that silver-containing VPS HA coating is a prospective candidate
as dental material.
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Authors: Yun Cang Li, Jian Yu Xiong, C.S. Wong, Peter D. Hodgson, Cui E Wen
Abstract: In the present study, titanium (Ti) samples were surface-modified by titania (TiO2), silica (SiO2) and hydroxyapatite (HA) coatings using a sol-gel process. The bioactivity of the film-coated Ti samples was investigated by cell attachment and morphology study using human osteoblast-like SaOS-2 cells. Results of the cell attachment indicated that the densities of cell attachment on the surfaces of Ti samples were significantly increased by film coatings; the density of cell attachment on HA film-coated surface was higher than those on TiO2 and SiO2 film-coated surfaces. Cell morphology study showed that the cells attached, spread and grew well on the three kinds of film-coated surfaces. It can be concluded that the three kinds of film coatings can bioactivate the surfaces of Ti samples effectively. Overall, Ti sample with HA film-coated surface exhibited the best bioactivity.
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