Novel bioactive glass coating for dental implant
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With an increasingly ageing population the requirement for titanium implants will grow. A major challenge is to speed up the rate and strength of osseo-integration. Bioactive glass coated titanium is postulated to improve bone-bonding ability of titanium. However, bioactive glasses have a higher thermal expansion coefficient (TEC) than titanium and are more prone to crystallization during coating process. Therefore, the aim was to develop a bioactive glass coating that matches the TEC of titanium does not crystallize during coating process and forms surface apatite in vivo and in vitro. To achieve these qualities certain compounds (MgO, CaF2 and MgF2 and fluorapatite (FA) crystals) were substituted or added to the glass composition. The glasses were prepared using melt-derived route. The ground glasses were sieved to obtain less than 45 μm diameter glass particles and this powder characterised using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Glass rods were cast to measure TEC, glass transition temperature (Tg) and softening temperature (Ts) using Dilatometry. Glass structure was investigated by measuring glass density and oxygen density. The apatite-forming ability of the glass powder was assessed in both Tris-buffer and simulated body fluid (SBF). Filtrates were analysed by inductively coupled plasma spectroscopy (ICP). Titanium disks were coated with bioactive glass/composites using the enamelling technique. Coated samples were characterised by (XRD, FTIR) and scanning electron microscopy (SEM-EDS). Bioactivity of coating samples was studied after 1 month immersion in Tris-buffer solution or SBF. Biocompatibility assays of glass coatings were assessed using UMR106 osteoblast-like cells and a fibroblast cell line. The results generated some interesting findings – firstly it is possible to produce glasses with comparable TEC of titanium and wide sintering windows. Although most preparations were more bioactive compared with those of Saiz and Tomsia–not all preparations were bioactive. Some coatings were biocompatible with fibroblasts, but not osteoblast-like cells. Whilst some glasses might not be suitable for a coating, they may have use as structural scaffolds for skeletal reconstruction.
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