Papers by Keyword: Bioceramic

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Authors: J.P. Gittings, I.G. Turner, A.W. Miles
Abstract: Calcium phosphate (CaP) ceramics possessing an interconnecting porosity network in the appropriate size range for vascularisation offer the possibility of providing a structural matrix for replacement of diseased or damaged bone. Such bioceramics must possess sufficient mechanical strength to avoid failure whilst offering a bioactive surface for bone regeneration. The objective of the current study was to produce a hydroxyapatite/tricalcium phosphate (HA/TCP) bioceramic that imitated the orientated trabecular structure found in cancellous bone. The structure-property relationship of these bioceramics was then analysed. It was hypothesised that the mechanical properties would be linked to the shape of the pore structure due to the orientation of the open porous scaffolds (OPS) produced. OPS bioceramics possessed an interconnected macroporosity network of 40-70% by volume with bending strengths of 0.30MPa ± 0.01MPa and apparent densities of 0.35g/cm3 ± 0.05g/cm3. Typically, pore sizes in the range of 150-300µm were produced. The fabrication of CaP OPS resulted in a wide range of macroporosity in the correct size range for osseointegration to occur. Elongating the pore structure did not affect the total porosity of the bioceramics. Strengths were low due to microcrack formation on sintering and not due to the shape of the pores present in the scaffold as initially hypothesised.
Authors: Chan Wai Chan, K.H.K. Wong, K.M. Lee, Ling Qin, H.Y. Yeung, H.B. Fan, Yun Yu Hu, Jack C.Y. Cheng
Abstract: Basic fibroblast growth factor (bFGF) has been shown to maintain the osteogenicity of bone marrow derived mesenchymal stem cell (MSCs) in vitro. This study was to investigate whether bFGF with osteogenic supplements could enhance bone formation of posterior spinal fusion. Rabbit bone marrow derived mesenchymal stem cells were selected by adherence on plastic culture-ware. The MSCs were exposed to dexamethasone with (bFGF group, n=6) or without bFGF (OS group, n=6). Treated cells of two groups were seeded on β-tricalcium phosphate ceramics for one day and then implanted onto L5 and L6 transverse processes of the same animal in posterior spinal fusion without decortication. The ceramics acted as control (n=6). Three fluorochromes were injected sequentially as tetracycline at week 2, xylenol orange at week 4 and calcein at week 6. The spinal segments were harvested at week 7. The bone mineral content (BMC) and volume of transverse processes was measured by peripheral quantitative computed tomography. The specimens were underwent undecalcified histology. The mineralization process was examined by fluorescent microscopy. The BMC of transverse processes in OS group was 16% greater than bFGF and control group significantly. The volume of transverse process in OS and bFGF group was significantly greater than control group by 54% and 46% respectively. The volume of transverse processes in OS group was 6% greater than bFGF group though not statistically significant. In histology, newly formed bone grew from two processes towards each other resulting in a relatively short gap distance in OS and bFGF group while less regenerated bone was observed in the control group. At the mineralization front, calcein which was injected into animal at week 6, was predominately labeled in bFGF group. In OS group, both xylenol orange (at week 4) and calcein labeled were found. In conclusion, mesenchymal stem cells pre-exposed to bFGF were not found to give additional enhancement effect on bone formation in the posterior spinal fusion model.
Authors: S. Bandyopadhyay-Ghosh, Ian M. Reaney, A. Johnson, I.M. Brook, K. Hurrell-Gillingham, P.V. Hatton
Abstract: Novel fluorcanasite based glass-ceramics were produced by controlled two stage heattreatment of as-cast glasses. Castability of parent glasses was determined using a graduated spiral cast piece. Fluorcanasite glasses were also cast to form complex shapes using the lost wax casting technique. Gypsum and phosphate bonded investments were used to investigate their effect on the casting process, cast surface crystallinity and biocompatibility. The stoichiometric composition had the greatest castability but the other two modified compositions also had good castability. X-ray diffraction showed similar bulk crystallisation for each glass irrespective of the investment material. However, some differences in surface crystallisation in the presence of different investment materials were detected. Discs cast using gypsum bonded investment showed greater in vitro biocompatibility than equivalent discs cast using phosphate bonded investment under the conditions used. Gypsum and phosphate bonded investments could both be successfully used for the lost wax casting of these novel fluorcanasite glasses.
Authors: Girts Salms, Vladislavs Ananjevs, Vladimirs Kasyanovs, Andrejs Skagers, Ilze Salma, Janis Vetra, Vita Zalite, Liga Stipniece, Sandris Petronis
Abstract: Investigation of biomechanical properties of the rabbit bone tissue from a corner of the lower jaw was done. Experimental osteoporosis was induced by ovariectomy and following injections of methylprednisolone. The defects in the greater trochanter region was created and filled with granules of a hydroxyapatite and tricalcium phosphate (HAP/TCP 30/70) or HAP/TCP 30/70 together with 5% strontium ranelate. After 3 month animals were euthanased, squared samples have been cut out from a corner of the lower jaw and tested on a bend. Results of research show, that the corner of a lower jaw in rabbit becomes more rigid after filling of defects in the greater trochanter region with granules of a hydroxyapatite and tricalcium phosphate (HAP/TCP 30/70) or granules together with strontium ranelate. The ultimate strain for the bone tissue in the 2nd and 3rd group is less, than for control group. Thus, local uses calcium – phosphatic bioceramic material around the greater trochanter region improves biomechanical parameters of a bone tissue in the lower jaw of animals.
Authors: Jun Hyuk Seo, Hyun Seung Ryu, K.S. Park, Kug Sun Hong, Hwan Kim, Jae Hyup Lee, D.H. Lee, Bong-Soon Chang, C.K. Lee
Authors: Waléria Silva de Medeiros, Luiz Carlos Pereira, Robson Pacheco Pereira, Marize Varella de Oliveira
Abstract: Synthetic Hydroxyapatite (HA) has been used as coating in order to enhance biocompatibility of titanium implants. Osseointegration at the implant-bone interface can be positively affected by the presence of HA coating and other biocompatible calcium phosphates (CaP) deposited on titanium implants, due to the high biocompatibility of these bioceramics. The biomimetic process is based on the nucleation and growth of a bioceramic film onto a substrate immersed in a body fluid solution (SBF) and it can be applied to deposit CaP coatings onto metallic substrates. The present work presents results on the characterization by SEM of CaP coating deposited on porous titanium samples by a biomimetic process.
Authors: Kazuki Ishiwata, Kazumasa Tawara, Junichi Matsushita
Abstract: The material study on bioactivitying artificial bone is lacking results for improve the quality of life (QOL) for individuals to fulfill their happy life in the society, which requires artificial bone to be replaced with neonatal bone by absorbing, regenerating the bone, which is not possible. Hydroxyapatite Ca10(PO4)6(OH)2, (HAp) has excellent biomaterial for biomedical and dental applications because of its superior properties. However, HAp had poor mechanical properties such as low hardness and fracture toughness. In this study, HAp containing titanium and titanium hydride (TiH2) sintered bodies were studied in order to investigate the possibility of its advanced biomaterials application. The nano particle size starting powders were milled by using mortar and muddler equipment. The sintered bodies were prepared by pressureless sintering at argon-hydrogen gas atmosphere. The samples were evaluated for bioactive performance by using simulated body fluid (SBF) solution for. The HAp-Ti, the HAp-TiH2 composite material is attractive as a bioceramics compared with HAp ceramics.
Authors: Li Gou, Shun Qiao Cheng, Jun Guo Ran, Bao Hui Su
Abstract: The porous structure of calcium phosphate ceramics is one of the essential conditions resulting in bone formation. The porous structure of biphasic HA/β-TCP ceramics was improved by adding microporous porosifer and the porous characteristics such as porosity, pore size and pore size distribution were determined by the mercury intrusion porosimetry, the cell culture in vitro and the animal experiment. By means of SEM and fluorescence decoration, cells were observed firstly attaching the edge of macropores of specimens and the wall of the macropores with micropores when co-cultured with HA/β-TCP ceramics. The specimens were also implanted in dorsal muscles of healthy dogs for 1.5and 3 months. More bone formation in the specimen with microporous porosifer was found by histological observation after taking out. It suggested that the micropores in the walls of macropores of bioceramics had important effect upon their osteoinduction.
Authors: Hakan Engqvist, Tobias Jarmar, Fredrik Svahn, Leif Hermansson, Peter Thomsen
Abstract: A key feature in the understanding of the mechanisms of integration of implant materials is a deepened in-sight of the elemental and molecular composition of the interface zone between the implant and tissue. To analyze the interface at the ultrastructural level, transmission electron microscopy (TEM) is needed. However, techniques to fabricate thin foils for TEM are difficult and time consuming. By using focused ion beam microscopy (FIB) for site-specific preparation of TEM-samples, intact interfaces between bioceramics and calcified tissue can be prepared. The site-specific accuracy of the technique is about 1 mm. By using a dual-beam FIB, which is a combined scanning electron and focused ion beam microscope, the sample can be imaged with both electrons and ions (generating both secondary electrons and ions). Results from interface studies between Ca-aluminate based orthopaedic cement, dental materials, HA-coated Ti-implants and bone are presented. The interfaces were imaged in scanning-TEM and bright field mode, the crystal structures were determined using electron diffraction and elemental composition analyzed with energy dispersive spectroscopy. The technique fulfils a demand to correlate the surface properties of bioceramic implants with the structure and composition of preserved interfaces with tissues.
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