Comparison of different 3D-printed allogeneic bone and artificial polymer composite porous scaffold materials for repairing cranial bone defects in rats

• Low-temperature 3D-printed composites of PLGA or PCL with allogeneic bone powder (samples A and B) exhibited faster degradation, reduced inflammation, and enhanced new bone formation compared to high-temperature printed high-content PCL composite (sample C). • Sample B (PCL:bone=1:4) showed the earliest new bone formation at 8 weeks, while samples A and positive control showed new bone at 12 weeks; sample C showed no obvious new bone formation throughout the study. • All implanted materials degraded over time, with samples A and B degrading faster than the positive control, and sample C degrading slowest; inflammatory response decreased over time in all groups, most notably in sample A. • Expression of osteogenic markers (RUNX2 and type I collagen) increased over time in all groups, with significantly higher expression in positive control, sample A, and sample B groups compared to sample C at 12 and 26 weeks.