Injectable living hydrogel as engineered biotherapeutic to promote tooth-extraction wound healing and alveolar bone regeneration

Effective wound healing and functional bone regeneration following tooth extraction remain clinical challenges, underscoring the significant need for multifunctional strategies that address the complex, multistage and translational demands of socket management. Herein, an injectable live biotherapeutic hydrogel was fabricated by integrating probiotic <i>Lactobacillus rhamnosus</i> GG (LGG) and calcium phosphate nanoparticles (CP NPs) into a photopolymerizable poly (ethylene glycol) (PEG) matrix. Upon in situ injection and activation with dental blue light, the hydrogel rapidly forms a conformal, protective and bioactive scaffold to the extraction socket. Therapeutically, LGG probiotics remodel the wound microenvironment through antibacterial and immunomodulatory bioactivities to promote early-stage healing. Simultaneously, LGG can facilitate the release of calcium and phosphate ions from CP NPs, which synergizes with microbe-assisted biomineralization to promote osteogenic differentiation and bone regeneration. In vitro and in vivo validations confirmed that this probiotic-mineral biotherapeutic hydrogel concurrently integrates infection control, immune regulation, and osteoinduction within a single clinically deployable platform, representing not only a transformative strategy for post-extraction socket management but also a paradigm for the development of living biomaterials in dynamic tissue engineering applications.