A New Highly Bioactive Composite for Bone Tissue Repair

In the last few years several attempts have been made to combine hydroxyapatite (HA) with bioactive glasses of different composition, with the aim to obtain composite materials with improved bioactivity or mechanical properties for hard tissue surgery applications. However, high-temperature treatments are usually required in order to sinter HA-based composites, causing the bioactive glass to crystallize into a glassceramic, with possible negative effects on its bioactivity. Recently, a new glass composition, named BioK and inspired by the 45S5 Bioglass (R), has been formulated by substituting the sodium oxide with the potassium oxide. The potassium oxide is expected to reduce the tendency to crystallize of the parent glass. In this work, for the first time the BioK is applied to realize HA-based composites. The novel samples can be sintered at a relative low temperature (750 degrees C) compared with the widely studied HA/45S5 Bioglass (R) composites. The new glass formulation and the relatively low sintering temperature of the BioK-based composites greatly help to preserve the amorphous nature of the glass. According to in vitro tests, this has excellent effects in terms of bioactivity. Moreover Vickers microindentation measurements show that the BioK-containing composites preserve their local mechanical properties during immersion in body fluids.