Injectable Dual Network Hydrogel Containing Mg²⁺-Gallate-Based MOF and Bone Growth Polypeptide for Extraction Socket Site Preservation

Tooth extraction often leads to significant alveolar bone resorption, posing a major clinical challenge that compromises subsequent prosthodontic rehabilitation. This impaired bone regenerative capacity is primarily attributed to excessive reactive oxygen species (ROS), insufficient angiogenesis, and inadequate osteoinductive stimulation within the socket, collectively delaying the healing process. To address this, we developed an injectable dual-network hydrogel system loaded with metal-organic framework (MOF) and osteogenic growth peptide (OGP) to promote the tooth extraction socket healing. The double-network hydrogel, composed of gelatin methacryloyl (GelMA) and oxidized dextran (ODex), forms a dynamic network through the Schiff base reaction between the amino groups of GelMA and the aldehyde groups of ODex, enabling injectability and adaptation to the irregular shape of the socket, while the second covalent network, formed by photo-cross-linking, enhances its mechanical properties. Besides, MOF decomposes to release magnesium ion (Mg²⁺) and gallic acid (GA) to eliminate excess ROS and promote endothelial cell differentiation, facilitating angiogenesis, while OGP is an efficient osteoinductive agent. In vitro studies demonstrate that the composite hydrogel system efficiently exerts antioxidant properties to eliminate ROS, promotes angiogenesis, and enhances osteogenesis. Moreover, in vivo trials show that the composite hydrogel facilitates angiogenesis and bone formation in the tooth extraction socket, ultimately promoting the bone repair process.