Scaffolds from ceramics such as tricalcium phosphate, hydroxyapatite or blends thereof are excellent candidates for artificial bone replacement materials as they resemble the chemical composition of the inorganic portion of native bone and, consequently exhibit very good biocompatibility and can even be resorbed and remodeled into bone tissue upon implantation. However, scaffold structures providing defined and open porosity in the order of magnitude of native bone are challenging to produce.
Using additive manufacturing (AM) of ceramics it became possible to manufacture very complex scaffolds of adjustable pore geometry and size in highly reproducible manner. One promising approach among the ceramic AM technologies is vat photopolymerization. Lithography-based ceramic manufacturing (LCM) belongs to this group of AM technologies. LCM is a slurry-based AM technique that relies on the selective curing of photosensitive ceramic suspensions and subsequent debinding and sintering to obtain pure ceramic 3D objects. Using LCM scaffolds with defined pore sizes were produced from TCP and HA and the resulting parts were characterized concerning their density, homogeneity, and precision. The pore and strut sizes were measured by light and scanning electron microscopy as well as computer tomography. Using this data, nominal-actual comparisons were performed and the reproducibility of pore geometry could be determined. Besides structural characteristics, the mechanical properties of these objects were evaluated with respect to the degree of porosity and the used lattice types. The achieved high resolution and reproducibility show that the proposed approach is a suitable technique to produce biomimetic scaffolds of bioresorbable ceramics. It could be shown that highly porous scaffolds could be produced with a minimum feature resolution down to around 80 µm for struts and 150 µm pores as well as with a low standard deviation of well below 2% even for small features.
In addition, biological testing was performed and the obtained results underline the good suitability for the usage of such structures as scaffolds in non-load bearing applications.