title: The morphology of anisotropic 3D-printed hydroxyapatite scaffolds.
abstract: 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)mum. 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.
authors.affiliation: Biomaterials Science Center, University of Basel, 4031 Basel, Switzerland.
authors.forename: Fabienne C
authors.initials: FC
authors.lastname: Fierz
authors.forename: Felix
authors.initials: F
authors.lastname: Beckmann
authors.forename: Marius
authors.initials: M
authors.lastname: Huser
authors.forename: Stephan H
authors.initials: SH
authors.lastname: Irsen
authors.forename: Barbara
authors.initials: B
authors.lastname: Leukers
authors.forename: Frank
authors.initials: F
authors.lastname: Witte
authors.forename: Ozer
authors.initials: O
authors.lastname: Degistirici
authors.forename: Adrian
authors.initials: A
authors.lastname: Andronache
authors.forename: Michael
authors.initials: M
authors.lastname: Thie
authors.forename: Bert
authors.initials: B
authors.lastname: Müller
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism; D017886:Durapatite / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008422:Materials Testing; D008954:Models, Biological; D016062:Porosity; D011327:Printing / Q000379:methods*; D013234:Stem Cells / Q000166:cytology / Q000502:physiology; D013499:Surface Properties; D023822:Tissue Engineering / Q000379:methods; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite