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April 6, 2009

Compositional dependence of bioactivity of glasses in the system Na//2O- K//2O-MgO-CaO-B//2O//3-P//2O//5-SiO//2

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The bioactivity, i.e., bone-bonding ability, of 26 glasses in the system Na//2O-K//2O-MgO-CaO-B//2O//3-P//2O//5-SiO//2 was studied in vivo. This investigation of bioactivity was performed to establish the compositional dependence of bioactivity, and enabled a model to be developed that describes the relation between reactions in vivo and glass composition. Reactions in vivo were investigated by inserting glass implants into rabbit tibia for 8 weeks. The glasses and the surrounding tissue were examined using scanning electron microscopy (SEM), light microscopy, and energy-dispersive X-ray analysis (EDXA). For most of the glasses containing less than 59 mol % SiO//2, SEM and EDXA showed two distinct layers at the glass surface after implantation, one silica-rich and another containing calcium phosphate. The build-up of these layers in vivo was taken as a sign of bioactivity. The in vivo experiments showed that glasses in the investigated system are bioactive when they contain 14-30 mol % alkali oxides, 14-30 mol % alkaline earth oxides, and less than 59 mol % SiO//2. Glasses containing potassium and magnesium bonded to bone in a similar way as bioactive glasses developed so far. (Author abstract) 30 Refs.

Brink, Maria Turunen, Tia Happonen, Risto-Pekka Yli-Urpo, Antti

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