Researchers at King's College London have found that keratin, a protein found in hair, skin, and wool, can repair and protect tooth enamel, outperforming fluoride in laboratory tests. The findings were published in Advanced Healthcare Materials. Because enamel does not regenerate naturally once lost, any material that can rebuild it represents a meaningful shift in how early-stage decay and erosion might be managed. In the study, keratin extracted from wool was applied to tooth surfaces and exposed to saliva minerals. The protein organised into a crystal-like structure that attracted calcium and phosphate ions, forming a durable, enamel-like layer that blocked nerve channels linked to sensitivity. The research team envisions two delivery formats: a daily-use toothpaste and a professional gel applied in-clinic, similar to nail varnish. First author Sara Gamea, a PhD researcher at King's College London, noted that keratin is sustainably sourced from biological waste and does not rely on the plastic resins commonly used in restorative dentistry, which she described as toxic and less durable. The team estimates keratin-based products could reach the public within two to three years, pending further development and industry partnerships. Funding came from the Wellcome Trust Seed Award, the Academy of Medical Sciences, and the National Institute of Health Research.