Production and evaluation of porous titanium scaffolds with 3-dimensional periodic macrochannels coated with microporous TiO2 layer

This study examined the utility of a combination of the thermoplastic green machining (TGM) and micro-arc oxidation (MAO) for the production of porous Ti scaffolds with 3-dimensional (3-D) periodic macrochannels coated with a microporous TiO2 layer, which would provide high mechanical properties and excellent biocompatibility simultaneously. The TGM technique allowed for the creation of tightly controlled 3-D periodic macrochannels with a diameter of similar to 828-837 mu m by machining a thermoplastic compound consisting of 70 vol% titanium hydride (TiH2) powder and 30 vol% thermoplastic binders, followed by heat-treatment in a vacuum. The overall porosity and mechanical properties of the porous Ti scaffolds were controlled by creating various periodic arrays of 6 x 6, 7 x 7, or 8 x 8 macrochannels in each face of a cube. The compressive strength and modulus was decreased from 358 +/- 7 to 100 +/- 8 MPa and from 5.2 +/- 0.66 to 3.5 +/- 0.32 GPa, respectively, with increasing porosity from 48 vol% to 64 vol%. The biocompatibility and bioactivity, which was assessed by in vitro cellular assays, were improved remarkably by creating a microporous TiO2 coating layer using the MAO treatment. (C) 2012 Elsevier B.V. All rights reserved.