Fast Cross-Linked Hydrogel as a Green Light-Activated Photocatalyst for Localized Biofilm Disruption and Brush-Free Tooth Whitening

Biofilm-driven caries and tooth discoloration are two major problems in oral health care. The current methods have the disadvantages of insufficient biofilm targeting and irreversible enamel damage. Herein, an injectable sodium alginate hydrogel membrane doped with bismuth oxychloride (Bi₁₂O₁₇Cl₂) and cubic cuprous oxide (Cu₂O) nanoparticles was designed to simultaneously achieve local tooth whitening and biofilm removal through a photodynamic dental therapy process. This fast cross-linked hydrogel could form a biofilm removal coating on the target tooth surface precisely. Afterward, reactive oxygen species was effectively released on demand under green light, which could not only eradicate the biofilm but also whiten the tooth non-destructively in a facile manner without significant damage to both the enamel and biological cells. After the usage, the removal of this hydrogel can also enhance the effect of biofilm destruction and caries prevention.