Impact of residual carbon after DLP and SPS-Sintering on compressive strength and in-VITRO bioactivity of calcium phosphate scaffolds

Digital Light Processing was used to fabricate bioactive ceramic scaffolds for bone regeneration using β-tricalcium phosphate (β-TCP) powder as a starting material. The 3D structures were de-binded in vacuum and divided in two batches: Carbon Containing samples and Carbon Free samples (obtained by firing at 750 °C in air after de-binding). All samples were then sintered in pressure-less SPS either at 1200 °C or 1500 °C, resulting in two different polymorphs (β and α -TCP). The influence of the de-binding method, the in-situ formation of a carbonaceous phase and different phase composition of resulting scaffolds was evaluated in terms of mechanical performance and in vitro bioactivity and solubility in simulated body fluid (SBF). All scaffolds exhibited compressive strengths within the range of cancellous bone and bone-like apatite precipitates were visible on their surface after 21 days of immersion in SBF, with the exception of carbon-free samples sintered at 1200 °C.