Sinterability of binder-jetted scaffolds of bioactive glasses with different crystallization tendencies

The sinterability of scaffolds, 3D-printed by binder jetting, and their uniaxially pressed compact counterparts made from the bioactive glasses BG 13–93 and BG F3 was investigated with heating microscopy, DTA, optical and electron microscopy, and XRD. As the 3D-printed specimens had lower initial relative densities, more shrinkage and more time to reach full densification were needed. In the case of the slow-crystallizing BG 13–93, this delay did not provoke crystallization-induced sinter retardation. For the more readily crystallizing BG F3, however, a final relative density > 95% was reached only for the particle size fraction <32 µm. For this particle size fraction, the BG 13–93 scaffolds reached bending strengths quite similar to those measured on bulk glass samples, whereas BG F3 scaffolds reached about 30% less. In vitro cell viability tests on (<32 µm)-scaffolds proved their cytocompatibility with pre-osteoblasts on both BGs.