%0 journal article
%@ 0142-9612
%A Fierz, F.C.,Beckmann, F.,Huser, M.,Irsen, S.,Leukers, B.,Witte, F.,Degistirici, Oe.,Andronache, A.,Thie, M.,Mueller, B.

%D 2008
%J Biomaterials
%N 28
%P 3799-3806 
%R doi:10.1016/j.biomaterials.2008.06.012
%T The morphology of anisotropic 3D-printed hydroxyapatite scaffolds
%U https://doi.org/10.1016/j.biomaterials.2008.06.012
28 
%X Three-dimensional (3D) scaffolds with tailored pores ranging from the nanometer to millimeter scale can support the reconstruction of centimeter-sized osseous defects. Three-dimensional-printing processes permit the voxel-wise fabrication of scaffolds. The present study rests upon 3D-printing with nano-porous hydroxyapatite granulates. The cylindrical design refers to a hollow bone with higher density at the periphery. The millimeter-wide central channel follows the symmetry axis and connects the perpendicularly arranged micro-pores. Synchrotron radiation-based micro computed tomography has served for the non-destructive characterization of the scaffolds. The 3D data treatment is essential, since, for example, the two-dimensional distance maps overestimate the mean distances to the material by 33–50% with respect to the 3D analysis. The scaffolds contain 70% micrometer-wide pores that are interconnected. Using virtual spheres, which might be related to the cells migrating along the pores, the central channel remains accessible through the micro-pores for spheres with a diameter of up to (350 ± 35) μm. Registering the tomograms with their 3D-printing matrices has yielded the almost isotropic shrinking of (27 ± 2)% owing to the sintering process. This registration also allows comparing the design and tomographic data in a quantitative manner to extract the quality of the fabricated scaffolds. Histological analysis of the scaffolds seeded with osteogenic-stimulated progenitor cells has confirmed the suitability of the 3D-printed scaffolds for potential clinical applications.