Shaping by microstereolithography and sintering of macro–micro-porous silicon substituted hydroxyapatite

Additive manufacturing of silicon substituted hydroxyapatite (SiHA) ceramics with controlled macro–micro-porous architecture by microstereolithography and sintering is reported. Due to the role of silicon in bone calcification, the incorporation of silicate in hydroxyapatite has become of interest for applications in bone tissue engineering. But, the shaping and the sintering of SiHA remain few studied. For the shaping process, the formulation of a photopolymerizable suspension and microstereolithography parameters were optimized. Adjustment of the sintering parameters allowed the production of ceramics with controlled open microporosity in a wide range of variation, while preserving phase pure SiHA. A dimensioning model that takes into account the overcure due to light scattering during photopolymerization and the shrinkages during sintering was established. Using this method, macropores of various cross-sections, within the size range of interest for bone ingrowth, were shaped demonstrating the efficiency of microstereolithography for the direct manufacturing of bioceramic scaffolds with accurate architecture.