EGCG-Loaded Zinc Ion-Cross-Linked Injectable Sodium Alginate Hydrogel for Extraction Socket Healing

Postextraction wound healing under inflammatory conditions remains a crucial clinical challenge due to persistent oxidative stress and compromised bone regeneration. To address this critical issue, injectable hydrogel dressings offer a promising strategy for inflammatory wound healing after tooth extraction. Herein, we developed an epigallocatechin gallate (EGCG)-loaded sodium alginate/zinc ion (SA/Zn²⁺) composite hydrogel (designated SZE) through ionic cross-linking and multiple physical bonding interactions. The SZE hydrogel with high cytocompatibility could effectively scavenge intracellular ROS, protect mitochondria, inhibit the expression of inflammatory factors, and modulate macrophage polarization, as well as enhance the osteogenic differentiative potential of bone marrow mesenchymal stem cells. Meanwhile, the SZE hydrogel demonstrated good bactericidal effects against Staphylococcus aureus and Escherichia coli. Based on in vivo rat extraction socket models with/without S. aureus infection, SZE accelerated socket healing by eliminating infection, alleviating oxidative stress, inhibiting excessive inflammation, and promoting bone regeneration and effectively augmented infected socket healing. Overall, our research indicates that the developed SZE hydrogel offers a promising strategy for achieving accelerated and ideal healing of extraction sockets, especially under bacteria-infected inflammatory conditions.