SCIENCE MARVELLOUS SCHEMES : PRECIS

Regenerative dentistry : Scientists have used stem cells to regrow tooth enamel. The HUMAN body is a marvellous thing. But like anything built by evolution, it has plenty of flaws. Consider teeth.

Whereas sharks grow new teeth throughout their lives, adults humans get one set, which must last 60 years or more.

That is tricky. A combination of poverty, sugar-rich diets and poor hygiene means 2.5 billion people around the world suffer from tooth decay, in which acid produced by mouth-dwelling bacteria eats away at the hard enamel that coats the outside of a tooth.

That can open the door to painful infections, which cause further damage. Once decay has set in, all a dentist can do is fill the gap with an artificial plug - a filling.

But in a paper published in Cell, Hannele Ruohola-Baker, a stem-cell biologist at the University of Washington, and her colleagues offer a possible alternative.

Stem cells are those that have the capacity to turn themselves into any other type of cell in the body.

It may soon be possible, the researchers argue, to use those protean cells to regrow a tooth's enamel naturally.

STEM-cell-based therapies are not the only ones heading to clinical trials. Another class of treatments is known as biomimetic repair. This involves rebuilding the tooth crown using synthetic proteins, which are similar, but not quite identical, to human enamel.

Unlike stem-cell treatments, the proteins could be included in toothpaste, mouthwash and even cough drops. But synthetic formulations can be less durable than human enamel.

It will take time for either technology to arrive in the clinic. One question is just how durable the enamel made by stem-cell derived ameloblasts proves to be. Another is how best to deliver the stem cells to a patient's mouth.

But these findings are promising. As any dentist will tell you, prevention is better than cure. But a better cure would be welcome nonetheless.

The World Students Society thanks The Economist.