Dentures’ future in fast decay

WASHINGTON – As long as there are hockey players, there will be niche markets for false teeth. But the real news about the future of dentures is that there isn’t much of one. Toothlessness has declined 60 percent in the United States since 1960. Baby boomers will be the first generation in human history typically to go to their graves with most of their teeth.

And now comes tooth regeneration: growing teeth in adults, on demand, to replace missing ones. Soon.

It turns out that wisdom teeth are prolific sources of the kind of adult stem cells needed to grow new teeth for you. From scratch. In your adult life, as you need them. In the near future, according to the National Institutes of Health.

For thousands of years, losing teeth has been a routine part of human aging. That’s over. “We’re there, right now,” says Pamela Robey, chief of the Craniofacial and Skeletal Diseases Branch at the National Institute of Dental and Craniofacial Research, part of the NIH. “A lot of people will go and never lose a tooth. With good health care and proper habits, there’s no reason to lose a tooth.”

The way of Washington’s

Although it came with controversy, the introduction of cavity-preventing fluoride into drinking water and toothpaste is viewed as one of the 10 greatest public health accomplishments of the 20th century, right up there with vaccinations, according to the Centers for Disease Control and Prevention.

Leslie Seldin has some perspective on this. He graduated from dental school in 1966 and was the editor of “The Future of Dentistry,” a report published in 2001 by the American Dental Association.

“When I was growing up” – in the ’50s – “reaching the teen years you’d develop enormous amounts of decay,” he says. It wasn’t until the ’60s, when most baby boomers were growing up, that fluoridation really started having a major impact. By the ’90s, “if new patients came in that were young people, under 30, you really were surprised if you saw significant” cavities.

Fundamentally intact teeth, plus the increased attention paid to gum disease that can loosen them, have brought about a transformation.

“When I started out in dentistry, in my practice it wasn’t uncommon for people losing their teeth – you took out all their teeth and made a denture. You were working on a denture at all times,” says Seldin. “Now, five new dentures a year, that’s a lot. We go out of our way to avoid them.”

So what’s the future of dentures?

“Hopefully, they will become a relic,” says Mary MacDougall, director of the Institute of Oral Health Research at the University of Alabama. “Like Washington’s false teeth.”

‘Give me a root’

Regenerating a whole tooth is no less complicated than rebuilding a whole heart, says Songtao Shi, of the University of Southern California, who heads a team working on creating such a tooth.

Not only do you have to create smart tissue (nerves), strong tissue (ligaments) and soft tissue (pulp), you’ve got to build enamel – by far the hardest structural element in the body. And you have to have openings for blood vessels and nerves. And you have to make the whole thing stick together. And you have to anchor it in bone. And then you have to make the entire arrangement last a lifetime in the juicy stew of bacteria that is your mouth.

It’s a nuisance, but researchers are closing in on it. In fact, they think the tooth will probably be the first complex organ to be completely regenerated from stem cells. In part this is because teeth are easily accessible. So are adult stem cells, found abundantly in both wisdom and baby teeth, and your immune system won’t reject your own cells.

Nobody is predicting when the first whole tooth will be grown in a human, although five to 10 years is a common guess.

But Shi’s team is pursuing what he believes is a practical and immediate result: growing important parts of teeth that he thinks people will want to use right away. They’re working on creating a living root from scratch. “I think it will take a year,” Shi says. “Depends on how lucky we are, and how good we are.”

“How to make a root is real important,” says Robey. “Dentists say, ‘Give me a root and I can put a crown on it.’ ”

In addition, “we’re really, really close to treating periodontal disease with regeneration,” Shi says. Groups in Japan and Taiwan and at the University of Michigan are using stem cells to create hard and soft tissue in humans, he says. The idea is to take a tooth about to fall out and reconnect it firmly.

When you ask Shi how close we are to growing full teeth on demand, he laughs. But his crew has already created a living root using stem cells in a pig. “We did it. It works. We’re happy. We still have some questions to answer, but we’re working on it.”

He expects tooth regeneration “to be pretty common in the future.”