Application of injectable hydrogels in the treatment of periodontitis.

Periodontitis is a chronic inflammatory disease driven by dental plaque biofilms and characterized by chronic inflammation, oxidative stress, and progressive alveolar bone destruction. Although conventional therapies can control infection, their clinical efficacy is often limited by insufficient local drug retention, short release duration, and limited regenerative capacity. Injectable hydrogels have emerged as promising local delivery systems because of their biocompatibility, injectability, and controllable release behavior, allowing minimally invasive administration into irregular periodontal defects. Beyond prolonged local drug delivery, injectable hydrogels can also modulate inflammation and promote periodontal tissue regeneration through combined antibacterial, antioxidative, and immunoregulatory effects. This review summarizes recent advances in injectable hydrogels for periodontitis treatment, with emphasis on material classification, multifunctional therapeutic strategies, and stimuli-responsive systems triggered by pH, reactive oxygen species, and temperature changes. Remaining challenges related to mechanical stability, functional integration, and clinical translation are also highlighted.