Papers by Keyword: Bioceramic

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Authors: Nelson H.A. Camargo, Priscila F. Franczak, Enori Gemelli, Bruna Ditzel da Costa, Aury Nunes de Moraes
Abstract: The calcium phosphate microporous bioceramics, and hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) biphasic compositions, in the granular form of microporous biomaterials, are research themes and present potential biomedical applications in rebuilding and repairing maxillofacial bone and tooth structure and in orthopedic applications. This is associated with microstructural characteristics of biocompatibility and bioactivity and osteoconductivity properties that these biomaterials offer when applied in vivo or in simulated environment. Another differential point of these biomaterials is the solubilization capacity that they present when applied in the biological environment. These compositions of calcium phosphates (hydroxyapatite matrix and/or β-tricalcium phosphate) allow for the gradual release of calcium and phosphate ions for the biological environment, which are absorbed and promote the formation of new bone tissue. These materials are also promising in applications in the field of traumatology as in the repair of traumatized bone tissue and drugs controlled release and bone structure treatments. The favorable results of these biomaterials as bone reconstruction matrix and drugs controlled release are associated with crystallographic characteristics, morphology, surface and solubility that these biomaterials present when in contact with body fluids. This work aimed to describe three types of calcium phosphate microporous granulated biomaterials. The biomaterials used were provided by the Biomaterials Group from Universidade do Estado de Santa Catarina - UDESC and are: hydroxyapatite, β-tricalcium phosphate and biphasic composition 60% hydroxyapatite/40% β-tricalcium phosphate. The Scanning Electron Microscopy technique (SEM) was used for carrying out the morphological characterization and microstructure studies of granulated biomaterials. The X-Ray Diffractometry (XRD) served for characterization of crystalline phases. Arthur Method was used for determining open porosity and hydrostatic density of biomaterials. The BET technique served to support determination of the surface area of microporous granulated biomaterials. The results are encouraging and show that these biomaterials present promising morphological characteristics and microporous microstructure as wettability and capillarity. These characteristics may contribute to biomaterial osteointegration by new tissue, bone formation and mineralization process.
Authors: Nobuyuki Kawashima, Peter G. Self, William M. Skinner, Roger St.C. Smart
Authors: Ren Long Xin, Yang Leng, Ji Yong Chen, Xiu Dong Yang
Abstract: Porous alpha- tricalcium phosphate (α-TCP) was implanted in rabbit and dog models to investigate its induction of calcium phosphate (Ca-P) formation. The morphology and structure of the formed Ca-Ps were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The results showed an animal-dependent behavior of in vivo Ca-P formation. There were flake-like octacalcium phosphate (OCP) precipitates in the rabbit but rod-like hydroxyapatite (HA) precipitates in the dog model. In addition, high-resolution TEM (HRTEM) image revealed that there was OCP structure in certain portions of the rod-like HA precipitates in the dog model. And the orientation relation of OCP/HA was deduced as OCP (010)//HA (0 10) and OCP (001)//HA (00 1) . This implied that the in vivo HA was formed via OCP precursor phase.
Authors: Kristine Salma, Zilgma Irbe, Dmitrijs Jakovlevs, Natalija Borodajenko, Liga Berzina-Cimdina
Abstract: In this work three different preparation techniques of biphasic calcium phosphate (BCP) bioceramics (consisting of both hydroxyapatite (HAp) and β-tricalcium phosphate (TCP)) are compared: sintering of synthetic calcium-deficient apatites (CDAs) (intimate mixture of HAp and TCP - SBCP), sintering of mechanical mixture of synthetic HAp and apatitic tricalcium phosphate (Ap-TCP) - MBCP and sintering of mechanical mixture of synthetic HAp and calcium metaphosphate glass (CMG) - GBCP. Two different HAp/TCP phase ratios were investigated: 20/80 and 60/40. Phase composition, microstructure, sintering properties and microporosity of obtained BCP bioceramics were investigated. The open porosity of prepared BCP bioceramics is strongly influenced by phase composition and preparation technique. BCP bioceramics SBCP and MBCP have homogeneous microstructure, whereas GBCP has inhomogeneous inclusions of dense TCP. High content of hydroxyapatite (HAp) phase in MBCP and SBCP correlates with high microporosity.
Authors: Sara Verusca de Oliveira, Marcus Vinícius Lia Fook, Elaine Patrícia Araújo, A.C.B.M. Fook, R.S.C. Lima, W.P.F. Barbosa
Abstract: In bioscience, there are several apatites constituteds by differents compositions. In the biological environment, apatites are found in bones and teeth of vertebrates with Ca/P ration from 2.0 to 0.5. It is not easy to determine the exact proportion of Ca2 + and PO43- in solution in the preparation of the process. In this study, apatites with Ca/P ration 1.0, 1.67 and 2.0 were prepared by direct reaction in an solution of H3PO4 in a suspension of Ca(OH)2, of same molarity, evalueting the crystallinity of CPP, Hap e TeCP with 1 mol/l, 3 mol/l and 5 mol/l. The samples characterized by X-ray diffraction (XRD) were compared with the standard of reference of the data base JCPDS. The composition of calcium phosphate for the differents molarity studied, resulted in a combination of phases with the exception of hydroxyapatite Ca/P ration 1.67 at concentrations 1 mol/l and 3 mol/l. But the diffractograms revealed that the increased molarity provided a decrease of some peaks of reflection of calcium phosphates with Ca/P ration 1.67. However, for the Ca/P ration 1.0 increasing the concentration, showed an increase of crystallinity of calcium phosphates. The FTIR confirmed the presence of phosphates in the spectrums around 1045 cm-1. The calcium phosphates obtained through direct reaction showed Ca/P ration is related with the technique employed, consolidating it in the preparation of these bioceramics.
Authors: Csaba Balázsi, E. Dolekcekic, Zsuzsanna Kövér, Ferenc Wéber, Stuart Hampshire, Péter Arató
Abstract: In this work partially and fully densified silicon nitride based composites have been prepared using carbon black and graphite additions. Alumina and yttria sintering additives were also added to silicon nitride starting powders. Sinter-HIP and pressure-less sintering (PLS) have been employed for composite processing. The effects of carbon nano- and micro-grains on the microstructure, bending strength and hardness have been investigated. Higher strengths could be achieved by HIP, whereas more homogeneous properties can be assured by PLS.
Authors: Kwang Mahn Kim, Sang Bae Lee, Se Ho Lee, Yong Keun Lee, Kyoung Nam Kim
Abstract: Cytotoxicity test was essential for the pre-clinical evaluation of bioceramics. Proliferation assays such as MTT, XTT and WST-1 were commonly used for measuring biocompatibility. WST-1 was more convenient than MTT because of its water-solubility and storage condition. The calcium phosphate glass and β-TCP have been used for bone substitute, and some magnetic ferrites have been used for hyperthermic treatment. L929, mouse fibroblast cell, was the representative cell-line for in vitro biocompatibility test. The extracts of test samples were prepared by ISO10993-12:2002. The biocompatibilities of the extracts were measured by MTT and WST-1 assay and their pH were measured with pH meter. The cellular survival rate of CPG was the lowest and the results of the WST-1 test showed results similar to those of the MTT test. Thus, proliferation assays using WST-1 may be conveniently and routinely applicable to pre-clinical evaluation of bioceramics.
Authors: Ecaterina Andronescu, Mihaela Năstase, C. Ghiţulica, Ella Ştefan
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