Abstract
AbstractThis work deals with the additive manufacturing and characterization of hydroxyapatite scaffolds mimicking the trabecular architecture of cancellous bone. A novel approach was proposed relying on stereolithographic technology, which builds foam‐like ceramic scaffolds by using three‐dimensional (3D) micro‐tomographic reconstructions of polymeric sponges as virtual templates for the manufacturing process. The layer‐by‐layer fabrication process involves the selective polymerization of a photocurable resin in which hydroxyapatite particles are homogeneously dispersed. Irradiation is performed by a dynamic mask that projects blue light onto the slurry. After sintering, highly‐porous hydroxyapatite scaffolds (total porosity ~0.80, pore size 100‐800 µm) replicating the 3D open‐cell architecture of the polymeric template as well as spongy bone were obtained. Intrinsic permeability of scaffolds was determined by measuring laminar airflow alternating pressure wave drops and was found to be within 0.75‐1.74 × 10−9 m2, which is comparable to the range of human cancellous bone. Compressive tests were also carried out in order to determine the strength (~1.60 MPa), elastic modulus (~513 MPa) and Weibull modulus (m = 2.2) of the scaffolds. Overall, the fabrication strategy used to print hydroxyapatite scaffolds (tomographic imaging combined with digital mirror device [DMD]‐based stereolithography) shows great promise for the development of porous bioceramics with bone‐like architecture and mass transport properties.
Highlights
Bone tissue is able to self-regenerate, but, in the presence of large defects due to trauma, tumor removal or congenital diseases, surgical insertion of a bone graft is needed to promote a faster and effective tissue healing
Trabecular-like hydroxyapatite scaffolds for bone repair were obtained by digital light processing (DLP) technology using a computer-aided design (CAD) file created from micro-C T of a polyurethane sponge
The as-printed samples initially exhibited a gray-white appearance and changed colour to light blue after sintering (Figure 3D). This is a normal chromatic effect in sintered hydroxyapatite, which was observed in some commercial products: negligible traces of manganese can change the hydroxyapatite color to blue after sintering at high temperature in oxidizing atmosphere as a result of the oxidation of manganese ions within the crystalline lattice of hydroxyapatite.[36]
Summary
Bone tissue is able to self-regenerate, but, in the presence of large defects due to trauma, tumor removal or congenital diseases, surgical insertion of a bone graft is needed to promote a faster and effective tissue healing. Like most additive manufacturing techniques applied to bone scaffolds, DLP-based stereolithography aims at layer- wise reproducing a virtual model which typically derives from (i) computer-b uilt geometries based on repetitive geometrical elements such as unit cells (eg, grid-like structures) that, are unable to properly replicate the trabecular architecture of cancellous bone, or (ii) medical reconstructions of patient's bone, which may be more difficult to acquire and/or use as input files (problems of compatibility between medical file type and printing apparatus) Another issue with the latter approach is the large file size that comes with precise approximations of naturally occurring stochastic cellular/tissue designs. Polymeric sponges are highly suitable templates for scaffolding since they have been used for many years in the production of bone- like glass and ceramic scaffolds by the conventional sponge replica method due to their similarity with the trabecular architecture of cancellous bone.[15]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
