3D robocasting magnesium-doped wollastonite/TCP bioceramic scaffolds with improved bone regeneration capacity in critical sized calvarial defects

Using artificial biomaterials in bone regenerative medicine for highly efficient osteoconduction into the bone defect to decrease the bone healing time is still a challenge. In this research, magnesium (Mg)-doped wollastonite (similar to 10% Mg was substituted for calcium (Ca) in beta-CaSiO3) (CSi-Mg10) bioceramic scaffolds with ultrahigh mechanical strength were fabricated using ceramic ink writing three dimensional (3D) printing. To evaluate the potential of other additives on the new bone regeneration efficiency, beta-tricalcium phosphate (beta-TCP) was introduced to the CSi-Mg10 ceramic ink at a concentration of 15% and the biphasic bioceramic scaffolds (CSi-Mg10/TCP15) were also fabricated using 3D printing. The mechanical characterization indicated that introduction of beta-TCP led to nearly 50% mechanical decay, although the effect of the two heating schedules (one- and two-step sintering) on the compressive and flexural strengths of the scaffolds was significantly different. The bone regeneration results in critical sized calvarial defect of rabbits showed that the CSi-Mg10/TCP15 scaffolds displayed a markedly higher osteogenic capability than those on the CSi-Mg10 and beta-TCP scaffolds after eight weeks, and reached similar to 35% new bone tissue regeneration at 12 weeks postoperatively. These findings demonstrate that the CSi-Mg10/TCP15 bioceramic scaffolds can be well suited for stimulating in situ bone regeneration and for use in tissue engineering applications.