Masked stereolithography of hydroxyapatite bioceramic scaffolds through an integrative approach: From powder tailoring to evaluation of 3D printed parts properties

Abstract

In this paper, the tailoring of hydroxyapatite powders properties for the preparation of highly hydroxyapatite-loaded photocurable organic slurries was discussed. A methodical study was conducted to investigate suspensions properties and processability to find the most outstanding formulation for the production of hydroxyapatite scaffolds by stereolithography-based additive manufacturing technique. A debinding-sintering process was designed to avoid the formation of cracks during the pyrolysis of the resin and sintering of the ceramic part. A total porosity of 35 vol. % was observed for the scaffolds with an interconnected macroporosity, which could facilitate the flow transport of nutrients necessary to maintain living cells. A compression strength of 4.9±0.3 MPa was obtained for the specimens printed diagonally (45º to the printing stage surface). A slow degradation rate was shown for the printed parts mainly due to the high degree of crystallinity and the intrinsic stability of the hydroxyapatite phase. Our findings indicate that the tailoring of hydroxyapatite powders is needed for better processability as filler in photocurable suspensions. Moreover, it was demonstrated the feasibility of printing hydroxyapatite parts showing promising results for their application in surgery in the case of minor or non-load bearing implants requiring slow resorption properties.