Sr-, Ca-Doped BaTiO ₃ with Synergistic Piezoelectric Catalysis and Microbial Balance Effects Enables Tooth Whitening for Home Oral Health

White teeth provide an aesthetic foundation for smiling with confidence. However, teeth were easily stained in daily life by drinking tea, coffee, wine, or smoking, which leads to a growing demand for teeth whitening. Traditional peroxide-based dental whitening agents effectively remove external stains but pose safety risks due to their strong oxidizing action, including enamel demineralization, soft tissue irritation, and potentially causing microbial imbalance. Additionally, their application requires specialized equipment and professional oversight, limiting accessibility for nonexperts. Herein, a nondestructive, convenient teeth whitening strategy based on Ba_0.9Sr_0.05Ca_0.05TiO₃ (BSCT) accompanied by piezoelectric catalysis, biomimetic remineralization, and microbial community regulation has been reported. BSCT can generate •O₂^- and •OH in situ under mechanical vibration, resulting in degradation of organic dyes and inhibition of cariogenic bacterial activity. Besides, the Ca²⁺ and Sr²⁺ ions released from BSCT form localized ion-enriched zones on enamel and dentin surfaces, promoting remineralization of minerals. Mechanistically, we reveal that the piezoelectric polarization field enhances antibacterial efficacy by disrupting the bacterial membrane potential and structural integrity, weakening the proton motive force (PMF), and subsequently inhibiting F₀F₁-ATP synthase activity to block ATP synthesis. Notably, this study presents an innovative discovery that BSCT selectively inhibits dominant pathogenic bacteria while promoting the restoration of beneficial microbial communities, thereby facilitating the reconstruction of oral ecological homeostasis. By overcoming the limitations of traditional teeth whitening technologies, this strategy provides a safe, home-applicable alternative for whitening, mineral repair, caries prevention, and long-term maintenance of oral health.