Fillings could be consigned to history after scientists found that a drug given to Alzheimer's patients can help teeth regrow and repair cavities.
Researchers at King's College London found that the drug Tideglusib stimulates the stem cells contained in teeth so that they generate new dentine, the material under the enamel.
Teeth can already regrow dentine if the pulp inside the tooth becomes exposed by trauma or infection, but it can only naturally make a very thin layer and not fill deep cavities of tooth decay.
Tideglusib switches off the enzyme called GSK-3 which prevents dentine from carrying on forming.
Scientists showed it is possible to soak a small biodegradable sponge with the drug and insert it into a cavity, where it repairs the damage within six weeks.
The sponges melt away over time, leaving only the repaired tooth.
"The simplicity of our approach makes it ideal as a clinical dental product for the natural treatment of large cavities, by providing both pulp protection and restoring dentine," said Prof Paul Sharpe, the study's lead author, of the Dental Institute, at King's College London.
"Using a drug that has already been tested in clinical trials for Alzheimer's disease provides a real opportunity to get this dental treatment quickly into clinics."
Currently, dentists use man-made fillings to treat cavities but these fail to disintegrate, meaning the mineral level of the tooth is never completely restored.
The new technique could reduce the need for fillings, which are prone to infection.
The study was published in the journal Scientific Reports.