While traditional dentistry relies on drilling and filling, researchers are working on easier, non-invasive ways to stop cavities before they get worse. Applied directly to the surface of teeth, it can stop small cavities from progressing and even prevent new ones from forming. Inspired by silver diamine fluoride, he developed a new single-step treatment: zinc tetramine difluoride. Southern Dental Industries, an Australian company that produces restorative dental materials, purchased the license for Walters’s zinc technology. If their work succeeds, dentistry could move beyond silver—and finally offer patients a clear, painless way to protect their smiles.