title: Calcium phosphate scaffolds mimicking the gradient architecture of native long bones.
abstract: The synthesis of beta-tricalcium phosphate (β-TCP) scaffolds offering both the macroporous inner structure required for proper in vivo degradation and a non-macroporous outer structure for the enhancement of mechanical properties continues to be a challenge. The hypothesis of this study was to realize biomimetic β-TCP scaffolds with a macroporous inner structure and a compact outer structure using a lost wax casting technique. The porosity, macropore size, interconnectivity of the inner porous structure, and diameter of the outer compact structure were adjusted to specific values using a three-dimensional wax printer to manufacture the wax molds for the casting process. After the slip casting, the wax was pyrolyzed and the specimens were sintered. The resulting graded β-TCP scaffolds (porous + compact) were characterized and compared with β-TCP scaffolds with overall apparent macropores (only porous) and samples without macropores (only compact). The porosity and the compressive strength of the only compact, porous + compact, and only porous β-TCP samples were 31.4 ± 0.4 vol %, 55.6 ± 0.9 vol %, and 66.9 ± 0.4 vol % and 192 ± 7 MPa, 36 ± 2 MPa, and 9 ± 1 MPa, respectively. The macropore size was 500 µm and the micropore size was up to 10 µm, both featuring a completely open porous structure. From these results, we conclude that the lost wax casting technique offers an excellent method for the fabrication of β-TCP scaffolds with an inner macroporous structure and compact outer structure which mimics the cancellous and cortical structure of natural bone.
authors.affiliation: Dental Materials and Biomaterials Research, RWTH Aachen University Hospital, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Lindner
authors.forename: Christian
authors.initials: C
authors.lastname: Bergmann
authors.forename: Rainer
authors.initials: R
authors.lastname: Telle
authors.forename: Horst
authors.initials: H
authors.lastname: Fischer
mesh_terms: D001842:Bone and Bones / Q000187:drug effects*; D002130:Calcium Phosphates / Q000494:pharmacology*; D019245:Compressive Strength / Q000187:drug effects; D017076:Computer-Aided Design; D010316:Particle Size; D016062:Porosity; D054457:Tissue Scaffolds / Q000737:chemistry*; D014057:Tomography, X-Ray Computed
chemical_list: D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate
keywords: bioceramics; biomimetic; calcium phosphate; functionally graded material; pore size