Bone regeneration in 3D printing bioactive ceramic scaffolds withimproved tissue/material interface pore architecture in thin-wallbone defect

摘要

Three-dimensional (3D) printing bioactive ceramics have demonstrated alternative approaches tobone tissue repair, but an optimized materials system for improving the recruitment of host osteogeniccells into the bone defect and enhancing targeted repair of the thin-wall craniomaxillofacial defectsremains elusive. Herein we systematically evaluated the role of side-wall pore architecture in thedirect-ink-writing bioceramic scaffolds on mechanical properties and osteogenic capacity in rabbitcalvarial defects. The pure calcium silicate (CSi) and dilute Mg-doped CSi (CSi–Mg6)scaffolds withdifferent layer thickness and macropore sizes were prepared by varying the layer deposition modefrom single-layer printing (SLP)to double-layer printing (DLP) and then by undergoing one-, or twostep sintering. It was found that the dilute Mg doping and/or two-step sintering schedule wasespecially beneficial for improving the compressive strength (～25–104 MPa) and flexural strength(～6–18 MPa) of the Ca-silicate scaffolds. The histological analysis for the calvarial bone specimensin vivo revealed that the SLP scaffolds had a high osteoconduction at the early stage (4 weeks) but theDLP scaffolds displayed a higher osteogenic capacity for a long time stage (8–12 weeks). Although theDLP CSi scaffolds displayed somewhat higher osteogenic capacity at 8 and 12 weeks, the DLP CSi–Mg6 scaffolds with excellent fracture resistance also showed appreciable new bone tissue ingrowth.These findings demonstrate that the side-wall pore architecture in 3D printed bioceramic scaffolds isrequired to optimize for bone repair in calvarial bone defects, and especially the Mg dopingwollastontie is promising for 3D printing thin-wall porous scaffolds for craniomaxillofacial bonedefect treatment.