Sono-Catalytic Tooth Whitening and Oral Health Enhancement with Oxygen Vacancies-Enriched Mesoporous TiO₂ Nanospheres: A Nondestructive Approach for Daily Tooth Care

Tooth discoloration and the breeding of oral microorganisms pose threats to both one's aesthetic appearance and oral health. Clinical whitening agents based on H₂O₂ with high concentrations are effective in tooth whitening and bacterial elimination but may also cause enamel demineralization, gingival irritation, or cytotoxicity, necessitating professional supervision. Herein, leveraging sono-catalysis effects, a nondestructive and convenient tooth whitening strategy was developed, utilizing oxygen vacancies (OVs)-enriched mesoporous TiO₂ nanospheres. The introduction of OVs leads to TiO₂ bandgap narrowing, boosting the generation of reactive oxygen species (ROS) by TiO₂ under ultrasound treatment. Additionally, through the chemocatalysis effect, the ROS yield can be further augmented by employing OVs-enriched TiO₂ in conjunction with an extremely low concentration of H₂O₂ (1%) during ultrasound treatment. Hence, under ultrasound treatment simulating daily tooth brushing using an electronic toothbrush, the combination of OVs-enriched TiO₂ and 1% H₂O₂ proves to be effective in whitening teeth stained by tea, coffee, and mix juice. Furthermore, the combination of OVs-enriched TiO₂ and 1% H₂O₂ demonstrates potent bacterial-killing and biofilm-eradicating effects under ultrasound treatment within an extremely short duration (5 min). Additionally, given the mesoporous structure, curcumin, serving as an anti-inflammatory agent, can be efficiently loaded into OVs-enriched TiO₂ and then controllably released through ultrasound treatment. The curcumin-loaded TiO₂ facilitates the transition of macrophages to the anti-inflammatory M2 phenotype, potentially alleviating oral inflammation induced by bacterial infection without showing any biotoxicity. The OVs-enriched TiO₂ based sono-catalysis tooth whitening procedure provides the convenience of whitening teeth during daily brushing without requiring professional supervision.