The research, published in Science Advances, involved applying a gel to human teeth which had been removed, damaged with acid and kept in a solution which recreates the human mouth environment. The gel contained both calcium and phosphate which is used to create real enamel.

Using the gel, the teeth formed new enamel with the same microscopic structure as real enamel within 48 hours. The new layer of enamel was only three micrometres thick - which is around 400 times thinner than real enamel - but the researchers suggest that it could be repeatedly applied to build up a thicker layer.

Previous research has also tried to regrow enamel with limited success. Enamel is the most visible part of your teeth, coating the outer layer of each tooth. It is the hardest and most mineralised tissue in the body and has a very complicated structure which makes it difficult to recreate.

It plays a key role in preventing la carie dentaire, protecting the deeper layers of the teeth from acid and plaque, but can become damaged itself without good hygiène bucco-dentaire. Unlike other tissues in the body, enamel will not regenerate once it has been destroyed because it contains no living cells.

"The regeneration of tooth enamel, the hardest biological tissue, remains a considerable challenge because its complicated and well-aligned apatite structure has not been duplicated artificially," said the researchers from Zhejiang University in China.

The researchers are currently testing the new gel in mice and plan to test in people once they can be sure that the chemicals are safe and can withstand the real environment of the mouth, including eating and drinking. The gel could reduce the need for fillings for tooth cavities, which aren't permanent and can become loose as they aren't made from the same material as the teeth.

This study was published in Science Advances.