A gel that can help decayed teeth re-grow in just weeks, which could in turn mean an end to fillings, has been developed by French researchers.
The gel works by prompting cells in teeth to start multiplying.
They then form healthy new tooth tissue that gradually replaces what has been lost to decay.
Researchers said in lab studies it took just four weeks to restore teeth back to their original healthy state.
The gel contains melanocyte-stimulating hormone, or MSH.
Experts believe new tooth cells would be stronger and a permanent solution.
The French team mixed MSH with a chemical called poly-L-glutamic acid.
The mixture was then turned into a gel and rubbed on to cells, called dental pulp fibroblasts, taken from extracted human teeth.
The researchers found the gel triggered the growth of new cells and also helped with adhesion - the process by which new dental cells 'lock' together.
In a separate experiment, scientists applied the gel to the teeth of mice with dental cavities. In just one month, the cavities had disappeared.
The gel is still undergoing testing but could be available for use within three to five years.
Damien Walmsley of the British Dental Association said the gel could be an interesting new development, but stressed it is unlikely to be able to repair teeth that have been extensively damaged by decay.
"There are a lot of exciting developments in this field, of which this is one. It looks promising, but we will have to wait for the results to come back from clinical trials and its use will be restricted to treating small areas of dental decay," the Daily Mail quoted him as saying.
Scientists have also developed a 'tongue' gel as part of a new approach to tackling bad breath and preventing tooth decay.
The findings were published in the American Chemical Society journal ACS Nano.