Salvianolic acid B functionalized injectable GelMA hydrogel for pulpitis in a vital pulp therapy: a dual anti-inflammatory property and enhanced reparative dentinogenesis activity material

BACKGROUND: Vital pulp therapy (VPT) is recognized as a minimally invasive alternative to root canal treatment for teeth with initial and mild to moderate pulpitis. However, effective inflammation control remains a key challenge, as existing pulp capping materials exhibit limited anti-inflammatory efficacy. This study aimed to develop an injectable, photocurable pulp capping material with dual anti-inflammatory and pro-odontogenic functions to improve VPT outcomes for inflamed pulp. METHODS: The Sal B/GelMA composite hydrogel was synthesized and characterized for physicochemical properties, drug release profile, and biodegradation. Its cytocompatibility was assessed using CCK-8 assay, live/dead staining, and cytoskeletal (F-actin) observation. The migration of human dental pulp stem cells (hDPSCs) was evaluated via a wound healing assay. In vitro, hDPSCs were cultured with lipopolysaccharide (LPS) to mimic an inflammatory environment. The anti-inflammatory effect of Sal B/GelMA hydrogel was evaluated by measuring the mRNA levels of IL-1β, IL-6, and TNF-ɑ. Odontogenic differentiation was assessed by alkaline phosphatase (ALP) activity, alizarin red S staining, and the expression of Runx2, OCN, DMP1, and DSPP. A rat pulpitis model was established for in vivo evaluation. The hydrogel’s ability to alleviate inflammation and stimulate reparative dentin formation was evaluated using micro-CT, hematoxylin and eosin (H&E) staining, Masson’s trichrome staining, and immunohistochemistry. RESULTS: The hydrogel exhibited a porous microstructure, excellent cytocompatibility, biodegradability, and sustained Sal B release kinetics. In LPS-induced hDPSCs, it significantly suppressed pro-inflammatory cytokine expression while concurrently enhancing odontogenic differentiation, as evidenced by upregulated gene expression, increased ALP activity, and enhanced mineralization. In vivo, the Sal B/GelMA hydrogel exhibited favorable biocompatibility with no signs of obvious tissue necrosis at the implantation site. Moreover, it effectively reduced early inflammatory infiltration and induced substantial reparative dentin formation with superior structural homogeneity compared to iRoot BP Plus. CONCLUSIONS: The Sal B/GelMA hydrogel possesses dual anti-inflammatory and pro-odontogenic functionalities, suggesting its potential as a promising bioactive pulp capping material to enhance inflamed pulp repair and improve VPT outcomes.