Scientists have developed a synthetic tooth enamel that they suggest could end the need for small fillings.
Scientists are looking for ways to eradicate the need for the drill
The paste is made of modified hydroxyapatite, which is chemically similar to the natural tooth enamel.
Writing in Nature, researchers from the FAP Dental Institute in Tokyo said the paste removed the need for drilling.
Currently, repairing small areas of tooth decay can be difficult as it means part of the healthy tooth must be removed to make the filling stick.
The Japanese researchers are among a number of teams across the world investigating ways of repairing dental caries which do not require drilling, and therefore damage to the healthy tooth.
The team tested the paste on a lower premolar tooth which showed the early signs of tooth decay.
When they examined the filling, it was found the synthetic enamel had merged with the natural enamel.
In addition to repairing the cavity, the paste prevents more developing by making the tooth stronger.
They compared the modified hydroxyapatite paste with another alternative treatment for filling, acidic phosphate fluoride solution, which also does not require the removal of healthy tooth enamel.
However, it was found the fluoride solution left a gap with the natural enamel.
Writing in Nature, the team led by Kazue Yamagishi, said: "We have shown that our synthetic material can reconstruct enamel without prior excavation, in a process that not only repairs early caries lesions but can also help to prevent their re-occurrence by strengthening the natural enamel."
However, the researchers said it was important that the paste did not come into contact with the gums because it could cause inflammation.
Professor Liz Kay, Scientific Adviser to the British Dental Association, said: "The BDA is supportive of scientific enquiry into new methods of dealing with the problem of tooth decay.
"However, it has long been known that very early decay can be repaired by the application of fluoride, and by maintaining an alkaline or neutral pH in the mouth.
"Whilst this article is interesting, it does not seem to describe a new 'cure' for this condition.
"Ensuring that teeth are in an acid-free environment and brushing twice a day with a fluoride toothpaste is a simple, clinically proven method of combating early tooth decay."