Photodynamic therapy based on bismuth oxyiodide nanoparticles for nondestructive tooth whitening

Achieving a desired whitening effect through short treatments without using peroxide and without compromising the integrity of tooth enamel remains a challenge in teeth whitening. Here, we developed a highly safe and efficient photodynamic therapy (PDT) strategy based on visible light-activated bismuth oxyiodide nanoparticles for nondestructive tooth whitening. The Bi₇O₉I₃ nanoparticles (NPs) exhibited efficient photocatalytic activity owing to their narrow band gap, effectively harnessing the broad spectrum of visible light to generate ample electrons and holes. Meanwhile, the presence of oxygen vacancies, low oxidation state Bi³⁺ and the high specific surface area endow Bi₇O₉I₃ NPs with effective electron-hole separation ability and potent redox potentials. Empowered by these characteristics, Bi₇O₉I₃ NPs effectively catalyzed O₂ into radicals (O₂^•-), facilitating the degradation of dental surface pigment molecules for tooth whitening. Concurrently, they eradicated oral bacteria and bacterial biofilms adhering to tooth surfaces, thereby having a positive effect on the effectiveness of tooth whitening. This PDT strategy with Bi₇O₉I₃ NPs shows broad application prospects in tooth whitening.