A Moment Of Tooth

Yes, but does the end of tooth loss mean the end of tooth-loss dreams?

"To the extent that many dreams about losing teeth do seem to be inspired by seeing elderly people lacking teeth and incorporating that as a metaphor for mortality or aging or infirmity of later life, I think that proportion of the dreams would be expected to disappear," says Deirdre Barrett of Harvard, editor of "The New Science of Dreaming."

Welt is not so sure. "Obviously, people dream about being naked or partially clothed in public places -- or about having to take an exam unprepared -- without having these experiences," he says.

And for all we know, the rarer tooth loss becomes, the more nightmarish it will be.

Rise Again

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 -- say ahhhhh. So are adult stem cells, found abundantly in both wisdom and baby teeth -- no embryos required, 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. "The whole tooth -- we've got a long way to go," says Shi.

But his 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."