Bioactive glass products used in clinical applications are fairly simple in form, being mostly plates or crushed glass. Novwl applications require a versatile palette of products ranging from fibres and porous bodies to composites or moulded implants with special product dimensions. However, the low silica and the high lime content of bioactive glasses make them sensitive to the forming process used within the viscosity range ~108-103 dPas. Bioactive glasses show two distinct responses depending on the primary phase formed on crystallisation. Glasses which form sodium calcium silicate crystals possess low glass stability, and crystallise around 100C above the glass transition. Glasses, which form wollastonite crystals, crystallise above 800C, thus allowing for example viscous flow sintering of crushed glass to produce porous implants.
