A moldable weak-acid–responsive I₂/TCP/PBST composite hydrogel for use in inflammatory extraction socket preservation and bone augmentation

Teeth extracted because of periodontitis or severe apical periodontitis are frequently accompanied by severe infection and multi-wall alveolar bone defects, which compromise socket preservation and subsequent implant restoration. Here, we developed a moldable, weakly acidic pH-responsive I₂/TCP/PBST composite hydrogel to address the inability of current materials to simultaneously provide infection control, defect adaptation, and bone regeneration. The hydrogel is based on a PBST scaffold, incorporates iodine nanosheets (I₂-NS) for broad-spectrum antibacterial activity, and contains submicron porous tricalcium phosphate (TCPS) to promote osteogenesis. The resulting composite showed favorable biocompatibility and biodegradability, together with suitable mechanical properties, stable tissue adhesiveness, and good in situ moldability, enabling adaptation to extraction sockets with different defect geometries. In vivo, the I₂/TCP/PBST hydrogel effectively suppressed local inflammation and promoted new bone formation under infected conditions. These findings identify I₂/TCP/PBST as a promising biomaterial platform for the simultaneous management and repair of complex infected extraction sockets.