CMCS/PEGDA-based photoresponsive hydrogel with high efficiency for gingival retraction and rapid hemostasis.

Prosthodontics is a dental specialty with a long history of providing patients with prostheses to restore or replace damaged or missing teeth and dentition. Gingival retraction is a vital step after tooth preparation to obtain aesthetic and functional restorations. Gingival retraction materials have been used in clinics and are among the most prospective alternatives to gingival retraction cords. However, gingival bleeding, increased tension of the gingiva, and saliva flushing after tooth preparation might cause difficulties in gingival retraction. The previous materials generally have inadequate mechanical strength, poor hemostasis, and irritating effects. To achieve effective and rapid gingival retraction and hemostasis is a key clinical challenge. This article has described a novel photoresponsive hydrogel based on carboxymethyl chitosan/polyethylene glycol diacrylate (CMCS/PEGDA). CMCS/PEGDA hydrogel injected into the gingival sulcus can rapidly solidify and expand to push away the gingiva under blue light illumination. It possesses excellent rheological properties and mechanical strength, and shows great gingival retraction in the rabbit gingival sulcus. Additionally, CMCS/PEGDA hydrogel can promote clotting, which was verified in the rat tail amputation model. Compared with the control group, the blood loss of CP hydrogel decreased by 59.2%. The hemostatic mechanism of hydrogel is attributed to the concentration of coagulation factors, aggregation of red blood cells, and the activation of the coagulation pathway. The novel composite hydrogel developed in this study has distinguished biocompatibility, splendid mechanical properties, and wonderful hemostasis ability, demonstrating the potential for application in the field of gingival retraction.