Immunology in Osseointegration After Implantation

Bone tissue is renowned for its regenerative capabilities, yet handling extensive defects and complex fractures presents considerable medical challenges. Osteoimmunology, studying the complex mechanism of the mutual influence within the range of immunity and skeletal systems, has highlighted the indispensable function of immune reactions in the process of bone integration. This procedure, primarily immune-driven, fosters new bone formation around implants instead of relying solely on osteogenic mechanisms. Traditionally, implant research has emphasized bone bonding and osteoinduction, often overlooking the significant influence of immune interactions. Implants pose risks including donor site morbidity, decreased bioactivity, and pathogen transmission risks. To mitigate these, implant surfaces are modified through altering local factors such as electrical fields and applying physical treatments to change roughness, hydrophilicity, and nanotopography. These modifications aim to regulate immune reactions at the surface of the bone implant, improving osseointegration and the repair of bone. This review examines the types of immune cells in osseointegration, especially the pivotal function that macrophages serve in the regeneration of bone tissue, and investigates key implant features-morphology, wettability, cytokine interaction, and metal ion and bioactive molecule adsorption-that impact immune responses. These insights underscore the immune system's importance in bone repair and advance osteoimmunology as essential for developing strategies to control bone immune responses, enhancing implant integration and bone regeneration.