Originally published 2021-07-15.
Can tooth enamel grow back? On its own, no. But in 2018 a team at the University of Washington showed that a lab-made peptide, modelled on a protein that builds enamel in the first place, could coax a fresh mineral layer onto damaged teeth. The work was done on extracted teeth in the laboratory, not in patients, and no product based on it has reached dentists' offices. It is a promising idea for very early decay, not the end of fillings.
What the University of Washington team found
The research group, led by materials scientist Mehmet Sarikaya with dentistry researcher Sami Dogan, doctoral student Deniz Yucesoy, research scientist H. Fong and orthodontics chair Greg Huang, published its results in the journal ACS Biomaterials Science & Engineering. The university announced the study on 12 April 2018, and ScienceAlert covered it a few days later.
The team designed short peptides, chains of amino acids too small to count as full proteins, based on amelogenin. On teeth with artificially created early lesions, the peptide helped build a new mineralised layer that bonded to the enamel underneath. According to the university, each application laid down roughly 10 to 50 micrometres of new mineral. Lesions treated with fluoride for comparison did not develop a comparably thick, enamel-like layer, ScienceAlert reported.
The story resurfaced widely in July 2021 when ScienceAlert republished its article, which is why many readers met it as fresh news three years after the paper appeared.
Why enamel cannot repair itself
Enamel is the hardest substance in the human body. It is about 96 percent mineral, mostly a crystalline calcium phosphate called hydroxyapatite, and it can be up to about 2.5 millimetres thick on the chewing surfaces of molars.
It is built before a tooth erupts by cells called ameloblasts. These cells secrete proteins, including amelogenins, that act as scaffolding while minerals crystallise into tightly packed rods. Once the tooth is fully formed the scaffolding proteins are largely removed, and when the tooth comes through the gum the ameloblasts are gone. Unlike bone, enamel has no living cells to patch it. Lost enamel stays lost.
What the mouth can do is remineralise: saliva carries calcium and phosphate that can redeposit into the surface of a tooth when conditions are right. Fluoride helps that process and leaves a surface that resists acid somewhat better. But natural remineralisation only works on very early, shallow damage, and it does not rebuild the organised structure of original enamel.
How cavities start
Decay is a chemistry problem. Bacteria in dental plaque feed on sugars and other fermentable carbohydrates and release acid as a by-product. When the pH at the tooth surface drops to around 5.5, enamel minerals begin to dissolve. Dogan put the mechanism in plain terms in the university's announcement: the acid produced by those bacteria will demineralise the enamel.
Every snack or sugary drink starts a new acid attack, and saliva needs time to neutralise it. That is why dentists stress how often you eat sugar, not just how much. If the attacks outpace repair, a chalky white spot forms. Left alone, the weakened area can collapse into a hole that reaches the softer dentine underneath, and then the nerve. At that point a filling, root canal treatment or extraction becomes necessary.
How the peptide approach works
The idea behind the Washington work is biomimicry: instead of filling a hole with a foreign material, help the tooth do what amelogenin once did. Yucesoy explained that the peptides attach to the tooth surface and then recruit calcium and phosphate ions from their surroundings, guiding them into an ordered mineral layer.
The researchers pictured several delivery forms, including toothpaste, gels, rinses and composite materials, sold over the counter or used by dentists. Sarikaya was upbeat about the approach, calling peptide-guided remineralisation "a healthy alternative to current dental health care."
The project was funded by the Washington State Life Sciences Discovery Fund and a fund within the university's Department of Restorative Dentistry.
What the study did not show
Headlines claiming that cavities could end "forever" went well beyond the evidence. A few limits are worth keeping in mind:
- Lab only. The tests used teeth and artificial lesions outside the body. A real mouth has saliva flow, eating, brushing and constant bacterial activity, and ScienceAlert noted it was still unknown whether the peptide would work as well there.
- Early damage only. The treatment targets shallow, early lesions in enamel. A cavity that has already reached the dentine would still need a filling, ScienceAlert reported.
- Time on the tooth. Any remineralising agent needs contact time to work, and keeping a gel in place long enough in everyday life is a practical hurdle.
- No approval yet. Treatments for teeth need clinical trials and regulatory approval before they can be marketed with health claims. The 2018 announcement described the technology as still in development and reported no human trial results.
None of this makes the research unimportant. Rebuilding enamel-like mineral rather than drilling it away is a long-standing goal in dentistry, and peptide-guided repair is one of several lines of work pursuing it.
Common myths about enamel repair
"Some toothpastes regrow enamel"
Products marketed as enamel "repair" can help strengthen weakened surfaces, mostly through fluoride or added calcium and phosphate. They do not regrow lost enamel or close a real cavity.
"A white spot is already a cavity"
Not necessarily. A chalky white spot is often early demineralisation that can still harden again with good habits and fluoride. That stage is exactly where future peptide treatments would be most useful.
"If it doesn't hurt, it's fine"
Decay is often painless until it is deep. Regular check-ups catch problems while they are small.
Protecting your enamel today
While researchers work on regeneration, the proven basics still do most of the work:
- Brush twice a day with a fluoride toothpaste and clean between your teeth.
- Keep sugary snacks and drinks to mealtimes rather than sipping or grazing all day.
- Drink water after acidic foods and drinks, and wait a little before brushing after them.
- See a dentist regularly, and talk to a dentist or doctor about any sensitivity, pain or spots you notice.
The peptide research points to a future in which early decay could be reversed with something as simple as a gel. For now, it remains a laboratory result worth following, and prevention is still the most reliable way to keep your own enamel.
Sources: University of Washington News, 12 April 2018: Peptide-based biogenic dental product may cure cavities; ScienceAlert, 16 April 2018; ScienceAlert, republished July 2021; Wikipedia: Tooth enamel.
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