Functionalization Strategies of 3D-Printed Materials for Bone Repair: From Structural Scaffolds to Regenerative Regulation

Bone defects remain a prevalent challenge in oral and maxillofacial surgery, orthopedics, and implantology. Critical-sized defects may not heal spontaneously, while conventional grafts are limited by donor availability, biosafety concerns, and inadequate patient-specific fit. Three-dimensional (3D) printing enables personalized scaffolds with tunable geometry and porosity. This review summarizes functionalized 3D-printed bone repair materials, including material selection, fabrication methods, and core design requirements. It examines strategies that combine osteogenic growth factors, bioactive ions, antimicrobial agents, and immunomodulatory components to promote vascularized osteogenesis, control infection, and regulate the local immune microenvironment. The technology supports structural customization and incorporation of multiple biological functions, extending scaffolds beyond passive defect filling. However, unresolved issues include controlled bioactive release, coordination of mechanical performance with degradation and regeneration, inconsistent evaluation standards, manufacturing reproducibility, and clinical translation. Emerging directions include artificial intelligence-assisted design, multimaterial printing, and microenvironment-responsive scaffolds. This review provides a framework for optimizing functionalized 3D-printed scaffolds and evaluating their translational potential in bone repair.