The application prospects of 4D printing tissue engineering materials in oral bone regeneration

Scientists have developed smart shape memory materials that can adapt their structure or function to external stimuli. The demand for dynamic oral bone tissue repair is driven by continuous changes in bone and surrounding tissues during the repair process, such as tooth growth, movement, and reconstruction of oral soft tissues, as well as skeletal differences of alveolar and craniofacial bones. These changes challenge the mechanical stability of bone implants and the precision of printing. Consequently, 4D printing technology introduces "time", allowing pre-programmed changes in material shape or functionality which enables scaffolds to intelligently respond to complex oral environments, achieving dynamic repair of bone and surrounding tissues. Despite its theoretical benefits in oral bone tissue engineering, the study and use of 4D printing technology is still in its infancy. This review explores the most recent advances in 4D- printing in dentistry, discussing skeletal structure, etiology of bone defects, and bone repair mechanisms. It also provides an overview of the materials, cells, and growth factors used in 4D-printing bone tissue engineering. Thus, by reviewing existing studies, this review provides valuable insights for the future development of 4D printing technology in oral bone tissue engineering.