GM bug to tackle tooth decay

By BBC News Online's Caroline Ryan in Boston

Scientists believe they have found a way to stop tooth decay using a genetically modified mouthwash.

US researchers have developed the spray and it is hoped clinical trials will begin in both the UK and US by the end of this year.

Details of the research were presented to the American Association for the Advancement of Science annual meeting in Boston.

The GM mouthwash would be squirted in the mouth in a one-off five-minute treatment, costing less than £100. It is claimed the treatment would remain effective for a considerable time.

Our approach has the potential...of eliminating most tooth decay

Professor Jeffrey Hillman

Tooth decay is caused not by sugar but by a bacterium which lives in the mouth and turns the sugar into lactic acid. It is this acid which affects the teeth.

Professor Jeffrey Hillman, of the University of Florida has genetically altered the bacterium called Streptococcus mutans into a form which does not produce lactic acid and therefore does not cause tooth decay.

Experiments on animals have shown the GM bacterium took the place of the bad bacterium once it was in the mouth.

The GM bacterium did not cause tooth decay even when rats were fed a high-sugar diet, and it even appeared sugar helped the bacterium to colonise the surface of the teeth.

Professor Hillman told the BBC: "Our approach has the potential, if it works the way we anticipate that it will, of eliminating most tooth decay."

'Genetically stable'

He said the altered bacterium appeared genetically stable and safe for humans.

"I've spent 25 years working on this project, and I would not even begin to imagine distributing it if I couldn't be completely confident it was safe for use by the general public," he said.

When details of the GM spray were first published, Dennis Mangan, chair of the Infectious Diseases and Immunity Branch at the National Institute of Dental and Craniofacial Research, which funded Professor Hillman's research, said: "It takes us one step closer to the day when everyone will be free from dental caries throughout their lifetime."

But he warned that toothbrushes were not redundant just yet. "Good dental hygiene will always be necessary because of plaque build up."