Papers by Keyword: Bioglass

Abstract: Glasses based on the 3CaO.P2O5-SiO2-MgO system present high bioactivity aiming the use as bone restorations. On the other hand, the low mechanical properties reduce the importance of this glass aiming the use as restoration bulk specimens. In this work, glass-ceramics were obtained by devitrification of this glass using different temperatures. CaCO3, SiO2, MgO and Ca(H2PO4).H2O were used as starting-powders. Powder mixture was milled/homogenized and melted at 1600°C, for 2h and annealed at 700°C for 4h with cooling rate of 3°C/min. Glass specimens of 151550mm3 were characterized by DTA and XRD analysis. Specimens were heat-treated in different temperatures between 7000C and 1050°C, for 4 hours, obtaining glass-ceramics with different crystallized phase content. Hardness and fracture toughness were determined and correlated with crystalline phase content. The results indicated that crystallization-degree increase with the temperature, and the mechanical properties are improved: Hardness values present increases lower than 20% as function of the crystallization. Fracture toughness may increase 100% as function of temperature (crystallization degree).

Abstract: A number of combinations of biodegradable polymers and bioactive ceramics have been used for orthopaedic applications including in hard tissue regeneration. Ideally, composites aimed to be used in orthopaedic applications should combine adequate mechanical properties and bioactivity. Chitosan (CTS) has been widely used for biomedical applications, namely in tissue regeneration or drug delivery. In this sense, membranes of chitosan and chitosan with Bioglass® (BG) were prepared by solvent casting and characterised using Scanning Electron Microscopy. In vitro bioactivity tests were performed in the composite membranes, namely by monitoring their capability to induce the precipitation of apatite upon immersion in simulated body fluid (SBF). The results showed that the addition of BG promoted the deposition of an apatite-like layer. The deposition of apatite could influence the mechanical performance of the material. Therefore, in order to follow this biomineralization, the viscoelastic properties of these composite membranes (immersed in SBF) were evaluated. The change in the storage modulus (E’) and the loss factor (Tan δ) were measured as a function of immersion time using non-conventional dynamic mechanical analysis (DMA) tests, in which the samples were kept in wet conditions and at 37°C during the measurements. The mechanical properties of the chitosan membranes were improved by the addition of BG particles. An increase on the storage modulus was observed by the composite membranes while for the pure chitosan membranes the storage modulus was stable up to 7 days. Clear changes were detected in the composite membranes that contrasted with pure chitosan (CTS) membranes that exhibit stable viscoelastic properties up to 7 days. In addition, this work showed that sample characterization in the hydrated state can be useful to predict the mechanical performance of composites under meaningful physiological conditions.

Abstract: Papers reported that the pH value was rising slowly with the prolonging of soaking time when bioglass was studied into simulated body fluids, and it influenced the formation of apatite layer on the surface of bioglass obviously. An Intelligent Multi-parameter in vitro Simulated Evaluation （IMSE system） was used to study the bio-mineralization properties of 58S bioglass. The deposition of apatite formation on the surface of bioglass (BG) from dynamic r-SBF was studied systemically with IMSE system, which could control and stable such parameters as temperature, fluid rate, ion concentrations and pH value etc. precisely. Results showed that the rate of apatite formation was slowed down when pH value was stabled at about 7.35.

Abstract: The cementum, a mineralized tissue lining the tooth root surface, is required for development of a functional periodontal ligament. The presence of healthy cementum is considered to be an important criterion for predictable restoration of periodontal tissues lost as a consequence of disease. Despite the importance of cementum to general oral health, very little is known about the cells responsible for the formation of cementum, cementoblasts. The aim of this study was to examine the effect of the ionic products from the dissolution of bioactive glass with 60% of silica ( BG60S ) on the behavior of cementoblasts, osteoblasts and fibroblasts. The cell viability was tested by MTT assay based on mitochondria activity of the cell and Trypan Blue assay based on membrane cell viability. The membrane cell viability measured by Trypan Blue assay showed the beneficial effect on all the cell types tested. It was observed a higher proliferation in the presence of ionic products from dissolution of BG60S when compared to control. In the MTT assay we also observed increased cell viability on all the cell types, but proliferation of cementoblasts was higher (107%) than observed for the other cells (104%) compared to control. The results from this study suggest that Cementoblasts, osteoblasts and fibroblasts are important cells on events that control the development of mineralizing and not mineralizing tissues and the investigation of the comparative behavior of these cells can be a useful experimental model. The observed effect of the bioactive glass particles on cementoblasts shows that this material is an interesting alternative to be used in composite membranes for cementum tissue engineering.

Abstract: The objective of this study was to physico/chemically characterize a commercially available and a newly developed Bioglass and also to evaluate their degradation properties. Materials and Method: Two bioresorbable glasses were utilized, a bioglass synthesized at Chemical Engineering College (University of São Paulo, Lorena, São Paulo) (BG1), and the other bioglass utilized was Biogran (BG2) (3i Implant Innovations, Brazil). Particles size distribution histograms were developed for both materials, and then they were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) before and after immersion in simulated body fluid (SBF) for 30, 60, and 90 days. Results: The particle size distribution showed that the mean particle diameters at 10%, 50%, and 90% of the total volume were 17.65, 66.18, and 114.71 µm for BG1, and 354.54, 437.5, 525.00 µm for BG2. SEM images of BG1 showed that the as-received material had a rough surface and as the time of degradation elapsed, this surface became smooth. The images of BG2 showed that the as-received material also had a rough surface, and after immersion in SBF, the material’s crystalline content/morphology could be observed. The X-ray diffraction recorded that BG1 showed a silica peak, not seen at BG2. FTIR revealed that both bioglasses were of similar composition, except for the CO3-carbonate minor peak, present at the BG2 sample. Conclusions: 1. The particle size distribution showed a polydispersed pattern for both materials. 2. The material suffered degradation, and the decomposition increased as a function of immersion in SBF. 3. Both bioglasses had similar composition.

Abstract: Mineralization experiments on glasses of the Si-Ca-P-Mg system were carried out for 7 days in carbonated simulated inorganic plasma (CSIP) buffered with CO2/HCO3 -. This method enables physiological buffering of the solution within the 7.3–7.4 pH interval by maintaining a HCO3 - concentration between 24 and 27 mmol.L-1, which is the normal concentration range in blood plasma. XRD, SEM/EDS and FTIR were used to characterise the glass surfaces. All glasses exhibited an apatite-like deposit whose Ca/P ratio was dependent on glass composition.

Abstract: By mimicking the microstructure of human cortical bone, a variety of bioactive particle reinforced polymer composites have been developed for hard tissue repair. Apart from biological assessments, these composites must be fully evaluated in terms of their mechanical performance before they can be used in patients. The bioactive particles in these composites are normally hard (relative to matrix materials) and brittle bioceramics such as hydroxyapatite (HA), tricalcium phosphate (TCP), Bioglass, etc. The matrices can be either “biostable” polymers such as high density polyethylene (HDPE) and polysulfone (PSU) or biodegradable polymers such as polyhydroxybutyrate (PHB) and poly(L-lactide) (PLLA). These polymers on their own possess different mechanical properties and display different deformation behaviours. With the incorporation of various amounts of particulate HA, TCP or Bioglass, the bone analogue polymeric composites exhibit a spectrum of deformation and fracture characteristics. In our systematic studies of HA/HDPE, Bioglass/HDPE, HA/PSU, HA/PHB, TCP/PHB and a few other bone analogues biomaterials over the past fifteen years, mechanical tests were conducted under a variety of loading conditions (tension, compression, bending, torsion, etc.). Comparisons of deformation and fracture behaviours of these composites were made and presented. The insights that have been gained are important for developing other bioactive ceramic-polymer composites.

Abstract: The aim of the study was the synthesis and characterization of bioactive osteoinductive glasses, in the SiO2 – CaO – P2O5 system. In order to maintain the bioactive character of bioglasses, for SiO2 contents higher than 60%, the sol – gel method was used for preparation. On the obtained powders, thermal, grain size and X - ray diffraction analysis were performed. The X - ray diffraction emphasized the formation of phosphate phases, whose proportion decreases as the silica content is increased. Later, the powders were thermally treated at temperatures between 1000 and 14000C, the phase composition evolution being monitored through XRD analysis. On the powder suspensions in physiological serum, the evolution of pH was investigated, in order to establish the chemical stability. The behavior of the obtained powders in physiological medium was studied, by immersing samples in simulated body fluid and excerpted after different periods of time.

Abstract: In order to form the firm active fixation with the adjacent bone, a new kind of bioactive composite hydrogel was prepared as calcic layer of cartilage with polyvinyl alcohol (PVA) and bioglass (BG). The biomineralization properties of the PVA/BG biocomposite hydrogel were studied through Fourier transformed infrared spectroscopy, XRD and SEM with EDX. Results showed that hydroxylcarbonateapatite was formed on the surface of the PVA/BG biocomposite hydrogel after the biocomposite hydrogel soaked into SBF solution. The composite possesses good mineralization properties and could form good firm active fixation with the adjacent bone.

Abstract: Bioglass (BG) particles were treated by 3-aminopropyltriethoxysilane (APTES) in order to improve the interface compatibility with polymer materials. The surface structures of modified BG were characterized through Fourier transformed infrared spectroscopy with attenuated total reflectance accessory, thermogravimetric analysis, differential scanning calorimetry analysis and X-ray photoelectron spectroscopy. The results showed that APTES was successfully grafted on the surface of BG. The biomineralization properties of APTES modified bioglass were also studied through FTIR, XRD and SEM. Results showed that hydroxylcarbonateapatite (HCA) was formed on the surface of modified BG after soaked into SBF solution. It was shown that the APTES modified BG could possess good mineralization properties and could be intended as a composition of scaffolds for bone tissue engineering applications.