Abstract
he essential requirement for an artificial material to show bone-bonding ability (bioactivity) is the formation of a bonelike apatite layer on its surface in the living body. An acellular simulated body fluid (SBF) with ion concentrations nearly equal to those in human blood plasma was shown to reproduce in vivo bonelike apatite formation on bioactive materials. Recently, new bone-repairing materials with bioactivity and mechanical properties analogous to those of natural bone have been strongly desired to be developed. Therefore, inorganic-organic composites are considered to be suitable for this purpose. It has been reported that titanium oxide with an anatase structure (TiO2) shows high bioactivity, and that ultra-high molecular weight polyethylene (PE) shows good biocompatibility. In the present study, bioactive PE/TiO2 composites were prepared by hot press. The composites were prepared from the powder mixtures of PE (90 vol%) and TiO2 (10 vol%) obtained by three different mixing processes, 1) an agate mortar mixing, 2) ball milling and 3) Theta-composer mixing. Their bioactivity and the effects of the mixing on the mechanical properties of the composites were investigated. The Theta-composer can prepare the composite particles of PE covered uniformly with the TiO2 powders without any agglomerations of TiO2. After hot press, the composites prepared from Theta-composer powder mixture gave the most uniform distribution of the TiO2 powder in the PE matrix. All of these composites formed the apatite layer on their surfaces after soaked in SBF. The composite prepared from Theta-composer powder mixture showed the highest bending strength. These composites show high extensibility. These composites are considered to be useful as bone-repairing materials.
