An antibacterial chitosan-based hydrogel as a potential degradable bio-scaffold for alveolar ridge preservation

Post-extraction, preventing the absorption of alveolar ridge to retain the supporting construction for implanted teeth is still a challenge. Herein, we developed modified chitosan (CS)-based hydrogel using N-hydroxysuccinimide-terminated 4-arm poly (ethylene glycol) (4-arm-PEG-NHS) as the crosslinking agent, after introducing it to the polyhexamethyleneguanidine hydrochloride (PHMB) solution, CS/PEG/PHMB hydrogel with the enhanced antibacterial properties was obtained. The CS/PEG hydrogel and CS/PEG/PHMB hydrogel prepared here showed excellent mechanical strength and their compressive strength could reach 440 kPa and 450 kPa, respectively. The composite hydrogel was designed to be directional porous, low cytotoxic, pH-sensitive, and degradable. The weight of the hydrogel was reduced by ∼30% after 28 days of incubation, and it swelled significantly in the acidic condition while it did not swell in the neutral and weakly alkaline environments, indicating an excellent biodegradability in the inflammation site. In vitro antibacterial experiments showed that the bacteriostatic rate of the CS/PEG/PHMB hydrogel against S. aureus was above 90%, which could effectively inhibit the spread of the bacteria and inflammation in the alveolar ridge. Additionally, the hybrid hydrogels demonstrated good biocompatibility with the NIH 3T3 fibroblast cells. Overall, the CS/PEG/PHMB hydrogel is a promising biological scaffold for maintaining the alveolar ridge and subsequently improving the success rate of the dental implant.