Papers by Keyword: Hydroxylapatite

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Authors: Atsushi Nakahira, K. Shiba, S. Yamaguchi, K. Kijima
Authors: Masataka Ohgaki, Kimihiro Yamashita
Authors: Lars Raue, Helmut Klein
Abstract: Dental enamel is the most highly mineralised and hardest biological tissue in human body [1]. Dental enamel is made of hydroxylapatite (HAP) - Ca5(PO4)3(OH), which is hexagonal (6/m). The lattice parameters are a = b = 0.9418 nm und c = 0.6875 nm [1]. Although HAP is a very hard mineral, it can be dissolved easily in a process which is known as enamel demineralization by lactic acid produced by bacteria. Also the direct consumption of acid (e.g. citric, lactic or phosphoric acid in soft drinks) can harm the dental enamel in a similar way. These processes can damage the dental enamel. It will be dissolved completely and a cavity occurs. The cavity must then be cleaned and filled. It exists a lot of dental fillings, like gold, amalgam, ceramics or polymeric materials. After filling other dangers can occur: The mechanical properties of the materials used to fill cavities can differ strongly from the ones of the dental enamel itself. In the worst case, the filling of a tooth can damage the enamel of the opposite tooth by chewing if the interaction of enamel and filling is not equivalent, so that the harder fillings can abrade the softer enamel of the healthy tooth at the opposite side. This could be avoided if the anisotropic mechanical properties of dental enamel would be known in detail, hence then another filling could be searched or fabricated as an equivalent opponent for the dental enamel with equal properties. To find such a material, one has to characterise the properties of dental enamel first in detail for the different types of teeth (incisor, canine, premolar and molar). This is here exemplary done for a human incisor tooth by texture analysis with the program MAUD from 2D synchrotron transmission images [2,3,4].
Authors: Xiao Peng Zhu, Tian Yun Ning, Xiao Hua Xu, Wei Liu, Quan Li Li
Abstract: Minocycline, a semi-synthetic tetracycline antibiotic, was incorporated into gelatin- hydroxyapatite (HA) composite by using a biomimetic co-precipitation method, Firstly, a certain amount of acidic solution of hydroxyapatite was added into gelatin solution dropwise. After that, different amounts of minocycline (0mg, 50mg, 100mg, 200mg, 300mg) solution was added into the reaction system respectively , and obtain the hydroxyapatite - gelatin- minocycline composite. The results showed that the amount of the minocycline impacted the structure of the composite, and minocycline affects HA crystal growth by maybe bonding to 300 face. The approach described here may provide a basis for the preparation of an antibacterial biomaterial for bone regeneration.
Authors: Arda Aba, Celaletdin Ergun
Abstract: It has been reported in the biocompatibility researches performed in-vivo and in-vitro that the electric signals produced by piezoelectric implants may induce accelerated healing of the injured tissue after implantation. Barium titanate (BaTiO3; BTO), as a well known piezoelectric ceramic, is a suitable candidate to be used in these kind of biomedical researches about the effect of the electrical polarity and piezoelectricity on tissues. The excellent biocompatibility and faster bone adaptation characteristics of hydroxylapatite (HA) have been well documented in the literature. Therefore, HA / BTO composites may be a suitable bioceramic material introducing both the piezo effect and biocompatibility at the same time. However, the main point to process such composites should be to keep HA and BTO phases as stable as possible not to loose the biocompatibility of HA and the piezoelectricity of BTO ceramics. In this research HA / BTO, piezo-composites were prepared with powder mixing method in various mixing ratios and sintered at the temperatures between 500 and 1300 oC. Sintering was carried out under different atmospheres to evaluate the effect of atmosphere on the phase stability of composites. Then composites are characterized with XRD, DTA, density measurements and d33 piezoelectricty coefficient measurements.
Authors: Hong Ru Lin, Yu Jen Yeh, Chun-Jung Kuo, C.Y. Yang
Authors: Fu Hua Wen, Feng Wang, Ying Gai, Mei Ting Wang, Qi Hui Lai
Abstract: Mesoporous hydroxylapatite was prepared by Liquid phase precipitation method, using Polystyrene microspheres as template. Polystyrene microspheres mixed uniformly with the prepared hydroxylapatite slurry, then the mixture dryed and sintered at reasonable temperature, mesoporous hydroxylpatite ceramics were obtained. The phase constituent was analyzed by X-ray diffraction (XRD) and the microstructure was observed under scanning electron microscopy (SEM). The results showed that the prepared mesoporous hydroxylapatite ceramics were of high purity and their pores were evenly distributed, with big pore 0.8-1.0 um and small pore 30-80nm in diameter.
Authors: Ying Gai, Feng Wang, Jian Xing Shen, Lan Lan Yang
Abstract: Polystyrene (PS) microspheres were prepared by dispersion polymerization method and using PS microspheres as pore former porous hydroxylapatite (HA) was prepared by Liquid phase precipitation method. The phase constituent was analyzed by X-ray diffraction(XRD) and by Fourier transform infrared(FTIR) and the microstructure was observed under scanning electron microscopy (SEM), field emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The results showed that the prepared porous HA was of high purity and their pores were evenly distributed, with pore about 200nm in diameter. PS microspheres were probably the most economic and environmental pore-forming materials.
Authors: Egbert Brandau, Thorsten Brandau
Abstract: Clinical applications of Calcium phosphate compounds are done in most cases with powders of Calcium-tri-phosphate and/or Hydroxylapatite to enhance the surgery of orthopaedic repair. The application of microspheres of these compounds has big advantages to faster surgery and higher strength of the bone structure. The special processes to produce microspheres of narrow size distribution and high sphericity out Calcium-tri-phosphate and Hydroxylapatite are described. Properties and composition of these microspheres as calcined and as sintered are given.
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