Papers by Keyword: Bioactive Glass

Abstract: Hydroxyapatite (HA) was widely used as coating on metals and alloys to enhance the interconnection between metal implants and bone. To improve the bonding strength and bioactivity, in this work, bioactive glass (G) was added and HA-G composite coating was prepared on Ti-6Al-4V at low temperature. The scanning electronic microscope (SEM) graphs showed that the surface of the coating was composed with needle-like crystals, and the X-ray diffractometer (XRD) and Fourier transform infra-red spectrometry (FTIR) results proved that the crystals was carbonate hydroxyapatite (CHA), no other crystal phase was detected. The SEM micrographs of the cross section showed that the coating was porous and bonded closely with the surface of the alloy. The energy diffraction spectra (EDS) result show that a Si-Ti-Al-V-O layer was formed at the interface and enhance the interconnection between the coating and alloy. The bonding strength of the coating was 34.8±6.8MPa, which was much higher than that of the pure HA coating on Ti-6Al-4V prepared by plasma spraying method. The HA-G composite coating on Ti-6Al-4V showed high bonding strength, porous structure, and bone like CHA composition, which has good potential to be used as bone substitutes.

Abstract: We observed the cytotoxicity of human bone marrow stromal cells(hBMSCs) by microparticles of bioactive glass with four particle groups(same chemical composition-45S5 but produced by two different manufacturer and two different size groups). In vivo test using rat calvaria were also carried out. The apoptosis rates of all small particle groups(10-20 ㎛) were increased than large(500-700 ㎛ or 200-900 ㎛) particle groups in any culture time and any amount of particles with statistical significance. In vivo study we observed pathologic signs such as macrophages and foreign-body giant cells in rat calvaria by micro-particles of bioglass. Small(10- 20 ㎛) sized particles induced foreign body reaction and bone resorption. There was proliferation of macrophages and cells in large number. But in large particle groups, only fibroblasts were surrounding the particles. The micro-particles of bioglass induced apoptosis of hBMSC and foreign body reaction in calvaria of rat, therefore micro-particles of bioglass may cause osteolysis if used in replacement arthroplasty.

Abstract: fabricated by pressureless sintering process. The effect of BG on the sintering ability and mechanical strength of the ceramics, and the adhesion and proliferation of osteoblasts were investigated. The results showed that the optimum amount of BG was 20wt.% and the samples sintered at 1100oC for 5h revealed a bending strength of 172 MPa, which was approximately 2-times higher than that of the pure CaSiO3 ceramics. The cell experiments showed that BG reinforced CaSiO3 ceramics supported osteoblast adhesion and possessed higher proliferation than that of the pure CaSiO3 ceramics, which indicated excellent biocompatibility. Our results suggested that BG reinforced CaSiO3 ceramics could be potential candidates as bioactive bone implant materials.

Abstract: Factors controlling the antibacterial ability of three bioactive glasses were studied by comparing the changes in the SBF during immersion of the glasses with their response to four microorganisms. After immersion of 100 mg/ml fine powder (<45μm) of the glasses in the SBF for 1, 2, 4, 8, 16, 27 and 48 hours, the immersion solutions were filtered and the pH in the bulk solution was measured. Ionic concentrations of Na, K, Ca, Mg, P and Si ions in the immersion solutions were determined by ICP-OES. The antibacterial activity of the glasses showed good correlation with the changes of the pH values in the SBF solutions. No correlation was found between the ionic concentration and the antibacterial ability of the three glasses against the four tested microorganisms. The results suggest that, the antimicrobial effect of the glass powder against the microorganisms tested is mostly dependent on the increase of the pH in the solution to values detrimental for the bacteria growth.

Abstract: Implants with long lasting bioactivity and mechanical sustainability would be of interest in several novel clinical applications. By processing bioactive glass fibers and biodegradable polymers into 3D structures, bone formation ability of glasses and flexibility of polymers can be combined. In order to achieve desired physiological response, reactivity of bioactive glass fibers must be specified. Bundles of fibers within the range of bioactivity were soaked in the simulated body fluid at stationary conditions for several time intervals after which the cross-sectional surfaces of the fibers were studied with SEM-EDXA. The reaction layers and precipitations formed on the fiber surfaces suggest that the fibers react according to three mechanisms depending on the glass composition. Fibers with a high in vitro bioactivity showed the formation of distinct and thick silica –rich and calcium phosphate –rich layers already at one day’s immersion. Fibers of medium bioactivity did not show any clear silica –rich layer but a formation of calcium phosphate precipitations or layers at one day’s immersion. Slow glasses showed sporadic calcium phosphate precipitation only after the longest immersion times. The results indicate that the medium and slow glasses are interesting alternatives for applications where a long term mechanical durability suggested by their slow reactivity in combination with their osteoconductive tendency is desired.

Abstract: Surface topography plays an important role in determining the functional performance of engineering materials as well as cell-material interactions. In this work is investigated the surface topography of an apatite layer that was developed on Bioglass® (PerioGlas® Synthetic Bone Graft Particulate, US Biomaterials)-modified dental ceramics, used in fixed prosthetic restorations, after immersion in a Simulated Body Fluid (SBF). The visualization of the surface morphology and structure and the gradual formation of the apatitic layer were followed by CLSM, as well as by ESEM and EDS. Topography profiles on specimens’ surface revealed high surface roughness and a fluctuation of RMS values in relation to immersion time in SBF, due to the continuing process of apatite precipitation.

Abstract: The objective of this work is to evaluate the cytotoxicity, acute and chronic inflammatory response and mutagenicity of a high porosity bioactive glass (BG60S), produced by sol-gel method. The BG60S analyzed by direct contact and elution tests showed cytotoxic levels compatible with international standards (ISO 10,993-5). The BG60S extract reduced by ≈50% the cellular viability of L929, CHO and CPis cells measured by the MTT assay. The diluted extract (1:3) restored the cellular viability. We did not find edema induction in the rat paw test, nor cell migration to peritoneum, as measured by the inflammatory acute response. A BG60S implant did not induce chronic inflammation measured by hemoglobin levels (blood vessels formation), as well as the presence of macrophages and neutrophils (NAG and MPO activities, respectively). The BG60S extract was unable to induce colony reversion of Salmonella thyphimurium (with or without S9), thus precluding its mutagenic activity.

Abstract: Bioactive glass scaffolds have been developed with interconnected macropore networks, with pore diameters in excess of 500µm and apertures in excess of 100µm, by foaming sol-gel derived bioactive glasses. Bioactive glasses bond to bone by forming a hydroxycarbonate apatite (HCA) layer on their surface on contact with body fluid, which is similar to the composition of the apatite in bone. The aim of this work was to investigate the how changing the atomic structure of the glass affects HCA layer formation. Scaffolds were synthesised at 3 sintering temperatures and were characterised using 29Si and proton MAS-NMR, from which the silica network connectivity and Si-OH groups were quantified. The rate of HCA layer formation decreased as the number of Si-OH groups decreased, confirming the role of Si-OH groups in HCA layer formation.

Abstract: Various works have been done to produce a cellular form of bioactive ceramics for a scaffold. However, the most of these cellular implants have low compressive strength. In this study, therefore, glass-infiltrated cellular alumina with compressive strength of 7.3MPa was first prepared. Bioactive glass was then coated on the cellular alumina. When the specimen was reacted in simulate body fluid, hydroxyapatite developed on the bioactive glass coat in 18 hours.