Additive Manufacturing of Material Scaffolds for Bone Regeneration: Toward Application in the Clinics

Additive manufacturing (AM) allows the fabrication of customized bone scaffolds in terms of shape, pore size, material type, and mechanical properties. Combined with the possibility to obtain a precise 3D image of the bone defects using computed tomography or magnetic resonance imaging, it is now possible to manufacture implants for patient‐specific bone regeneration. This paper reviews the state‐of‐the‐art of the different materials and AM techniques used for the fabrication of 3D‐printed scaffolds in the field of bone tissue engineering. Their advantages and drawbacks are highlighted. For materials, specific criteria, are extracted from a literature study: biomimetism to native bone, mechanical properties, biodegradability, ability to be imaged (implantation and follow‐up period), histological performances, and sterilization process. AM techniques can be classified in three major categories: extrusion‐based, powder‐based, and vat photopolymerization. Their price, ease of use, and space requirement are analyzed. Different combinations of materials/AM techniques appear to be the most relevant depending on the targeted clinical applications (implantation site, presence of mechanical constraints, temporary or permanent implant). Finally, some barriers impeding the translation to human clinics are identified, notably the sterilization process. Researchers are showing a growing interest in 3D‐printed scaffolds for bone regeneration. Herein, the various advantages and drawbacks of scaffolds materials are discussed. In parallel, the different additive manufacturing techniques used in bone tissue engineering are compared. The potential of combinations of materials and additive manufacturing techniques is evaluated in view of clinical translation.