Abstract
This paper demonstrates the utility of coextrusion-based 3D plotting of ceramic pastes (CoEx-3DP) as a new type of additive manufacturing (AM) technique, which can produce porous calcium phosphate (CaP) ceramic scaffolds comprised of hollow CaP filaments. In this technique, green filaments with a controlled core/shell structure can be produced by coextruding an initial feedrod, comprised of the carbon black (CB) core and CaP shell, through a fine nozzle in an acetone bath and then deposited in a controlled manner according to predetermined paths. In addition, channels in CaP filaments can be created through the removal of the CB cores during heat-treatment. Produced CaP scaffolds had two different types of pores with well-defined geometries: three-dimensionally interconnected pores (~360 × 230 μm2 in sizes) and channels (>100 μm in diameter) in hollow CaP filaments. The porous scaffolds showed high compressive strengths of ~12.3 ± 2.2 MPa at a high porosity of ~73 vol % when compressed parallel to the direction of the hollow CaP filaments. In addition, the mechanical properties of porous CaP scaffolds could be tailored by adjusting their porosity, for example, compressive strengths of 4.8 ± 1.1 MPa at a porosity of ~82 vol %. The porous CaP scaffold showed good biocompatibility, which was assessed by in vitro cell tests, where several the cells adhered to and spread actively with the outer and inner surfaces of the hollow CaP filaments.
Highlights
Calcium phosphate (CaP) ceramics are one of the most promising biomaterials for reconstruction of bone defects in dental, maxillofacial, and orthopedic applications, since they can have excellent biocompatibility and bioactivity owing to their chemical compositions similar to inorganic phase of natural bones [1,2]
Produced calcium phosphate (CaP) scaffolds showed a periodic arrangement of straight hollow filaments at an orientation of 0°/90°, as well as three-dimensionally interconnected pore networks (~360 × 230 m2 in sizes)
The fracture behavior and mechanical properties of the porous filaments through solvent extraction in acetone allowed for the 3D deposition of filaments with good shape tolerance
Summary
Calcium phosphate (CaP) ceramics are one of the most promising biomaterials for reconstruction of bone defects in dental, maxillofacial, and orthopedic applications, since they can have excellent biocompatibility and bioactivity owing to their chemical compositions similar to inorganic phase of natural bones [1,2]. These materials in the form of paste have been extensively used as the bone cements in orthopedic surgery, which can be molded or injected into bone defects and implants sites, followed by in situ setting and hardening [3]. The bone regeneration ability and mechanical functions of CaP scaffolds strongly depend on their porous structure, such as porosity, pore size, and pore interconnectivity, as well as pore configuration [6,7].
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