IAN SAMPLE
11/03/2009 11:32:24 PM
The days of whining drills and shrieking patients that can make a trip
to the dentist an experience to dread may be numbered. Scientists
claim they may have found a way to regrow rotting teeth.
Researchers studying tooth development have singled out a gene that
controls the growth of enamel, the hard outer layer of teeth, which
cannot grow back naturally once it is damaged by tooth decay.
The discovery sheds fresh light on the way teeth form and could pave
the way for dental treatments that heal decayed teeth by regenerating
a layer of enamel, making traditional drilling and filling obsolete.
Scientists at Oregon State University found the gene after noticing
that mice born without it grew teeth with no enamel covering.
Tooth enamel is the hardest tissue in the body and begins to form when
humans are still embryos. Specialised cells called ameloblasts in the
tooth bud make enamel by releasing calcium phosphate minerals into a
protein “scaffold” that shapes them into tightly packed rods of
enamel.
When our teeth are fully formed, they erupt from the gums and the
enamel-forming cells die, making it impossible for our teeth to grow
new enamel later.
For most animals this is not a problem, but in humans the large amount
of sugar and starch in our diet is turned into acid by bacteria living
on our teeth, which slowly dissolve the enamel to make a hole in the
tooth. If untreated, cavities can cause life-threatening infections in
the body.
In the latest research, published in Proceedings Of The National
Academy Of Sciences, a team led by Chrissa Kioussi and Mark Leid bred
mice that lacked a gene known as Ctip2. They found that the gene was
crucial for the enamel-producing cells to form and work properly.
By understanding the genetics of tooth development, Ms Kioussi said it
might be possible to repair damaged enamel and even produce new teeth
in the laboratory.
Some groups have already succeeded in growing the soft tissues inside
teeth, but they do not have the hard enamel covering needed to
withstand chewing and biting.
“Enamel is one of the hardest coatings found in nature. It evolved to
give carnivores the tough and long-lasting teeth they needed to
survive,” she said. “A lot of work would still be needed to bring this
to human applications, but it should work. It could be really cool; a
whole new approach to dental health.”
If scientists can perfect a way of regrowing teeth and replacing the
drill in the dentist’s surgery, it could have important knock-on
effects for patients.
In 2005 a survey by researchers at the University of Toronto found
that 5 per cent of patients were extremely anxious about visiting the
dentist, and half were so afraid that they either cancelled their
appointment or failed to show up. By missing appointments, patients
risk turning a fairly minor dental problem into a serious risk to
their health.
Last year a poll by the Irish Dental Association found that parents
passed on their fear of dentists to their children by telling them
they were being brave or had nothing to fear from a visit.
Despite rates of dental cavities falling for the past 30 years, almost
half of children and adolescents and more than 55 per cent of adults
in Britain are still affected by holes in their teeth.
Paul Sharpe, an expert on tooth development at the Dental Institute at
King’s College London, said: “If you could find some way of growing
ameloblasts that make enamel, you could find a way to repair teeth.
“Any gene like this is worth understanding. The more we learn about
it, the more we can use the information to make biological models of
tooth repair.”
Professor Sharpe’s own work focuses on using stem cells to regenerate
teeth, but he said the introduction of the Human Tissue Act had made
it difficult to obtain teeth from patients on which to do the work.
“We’ve probably lost a year because we’ve not been able to get hold of
the right cells, and often these are from wisdom teeth that people are
choosing to have removed,” the professor said.
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