Teeth whitening, or dental bleaching, is a popular cosmetic procedure aimed at lightening teeth colour. Despite its widespread use, the impact of these treatments on the oral microbiome remains underexplored. What We Know: Most in-office teeth whitening treatments rely on hydrogen peroxide (HP) or its precursor, carbamide peroxide (CP). As products containing > 0.1% peroxide are typically restricted to dentist-prescribed use, over-the-counter alternatives have emerged, inclu