Professor Nigel Pitts, from the university's Dental Institute, said:
"The way we treat teeth today is not ideal. When we repair a tooth by putting in a filling, that tooth enters a cycle of drilling and re-filling as, ultimately, each 'repair' fails.
"Not only is our device kinder to the patient and better for their teeth, but it's expected to be at least as cost-effective as current dental treatments.
"Along with fighting tooth decay, our device can also be used to whiten teeth."
A Scottish firm, Reminova Ltd, is now trying to find private investment to develop the technique.
Tooth decay could soon be treated with a painless "remineralisation" technique developed in London, that means damaged enamel repairs itself, dentists said today.
The technique, which spells the end of drilling, could be available in three years.
The new treatment, developed at King's College London, is called Electrically Accelerated and Enhanced Remineralisation and is expected to cost around the same as fillings.
It speeds up the natural movement of calcium and phosphate minerals into the damaged tooth, which then repairs itself.
Decay is normally removed by drilling, followed by a filling with a material such as amalgam or composite resin.
The new process prepares the damaged area of enamel, then uses a tiny electric current to push minerals into the repair site so the enamel can repair itself.