The first thing people notice when they meet you is your smile. To be more confident when giving wide-mouthed, eye-crinkling smiles, people want healthy, pearly white teeth. But toothpastes only remove surface stains, and whitening treatments can harm enamel, leading to cavities and discoloration. Now, researchers report a new hydrogel treatment that breaks apart cavity-forming biofilms and whitens teeth without damaging them.