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3D printing has been applied in the fabrication of Ti‐6Al‐4V implants due to its high processing efficiency and flexibility. However, the biological inertness of 3D‐printed Ti‐6Al‐4V implant surface limits its further clinical application. This paper aims to improve the biocompatibility of 3D‐printed Ti‐6Al‐4V implants through multi‐scale composite structure and bioactive coating. The samples are prepared by selective laser melting (SLM). The multi‐scale composite structure is constructed by acid etching and anodic oxidation, and then the bioactive coating is added by hydrothermal treatment. The results indicate that acid etching removes the residuals on the surface and builds micron‐/sub‐micron structures. Anodic oxidation superimposes TiO2 nanotube arrays with a diameter of ≈80 nm, forming the multi‐scale composite structure. The polydopamine‐magnesium ion coating is added by hydrothermal treatment on the basis of retaining the multi‐scale composite structure. After modification, the surface wettability and corrosion resistance are improved, and the roughness is slightly reduced. Regarding the biocompatibility of the modified 3D‐printed Ti‐6Al‐4V implant, its admirable osteogenic induction performance is verified on osteoblasts (MC3T3‐E1). Also, the addition of magnesium ions achieves better antibacterial properties. The results provide new target points for the surface modification of 3D‐printed Ti‐6Al‐4V implant to attain better clinical performance.

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Titanium and its alloys have been widely used in bone tissue defect treatment owing to their excellent comprehensive properties. However, because of the biological inertness of the surface, it is difficult to achieve satisfactory osseointegration with the surrounding bone tissue when implanted into the body. Meanwhile, an inflammatory response is inevitable, which leads to implantation failure. Therefore, solving these two problems has become a new research hotspot. In current studies, various surface modification methods were proposed to meet the clinical needs. Yet, these methods have not been classified as a system to guide the follow-up research. These methods are demanded to be summarized, analyzed, and compared. In this manuscript, the effect of physical signal regulation (multi-scale composite structure) and chemical signal regulation (bioactive substance) generated by surface modification in promoting osteogenesis and reducing inflammatory responses was generalized and discussed. Finally, from the perspective of material preparation and biocompatibility experiments, the development trend of surface modification in promoting titanium implant surface osteogenesis and anti-inflammatory research was proposed.

Multi‐Scale Composite Structures In article number 2200598, Zhenbing Ji, Yi Wan, Chao Liu, and co‐workers prepare a 3D‐printed Ti‐6Al‐4V implant with osteogenic induction and antibacterial properties. Multi‐scale composite structures and bioactive coatings constructed on the implant surface by acid etching, anodic oxidation, and hydrothermal treatment show excellent ability to improve the rate of bone integration and antibacterial effect compared with the unmodified implant surface.