Dentists, as it turns out, may have one more reason than the rest of us to be wary of alligators. The toothy reptiles may one day put those who install implants, bridges and dentures out of their jobs.
Alligators continually make new teeth to replace the ones they lose. A single gator can make 2,000 to 3,000 teeth in a lifetime -- and scientists say they have figured out how the animals do it.
How the research was done
In a new study published in the journal Proceedings of the National Academy of Sciences, researchers reported that pockets of stem cells at the base of each tooth allow alligators to renew their teeth.
Using a variety of methods - including studying cells under a microscope, 3-D imaging and experimentation inside and outside the body - researchers at the University of Southern California and other institutions found a thin layer of slow-growing stem cells that seemed to be responsible for replacing the reptiles' lost chompers.
The cells sit in a layer of tissue called the dental lamina. Humans also have dental lamina tissue, but it goes dormant in young children soon after they finish making their first and only set of replacement teeth.
By learning more about how the lamina stays active in alligators, scientists hope they may one day be able to reawaken the process in humans.
"This paper does a really nice job of clearly classifying what's happening and drawing parallels and differences with mammals and fish and mice and crocodiles and pigs and humans," said Pamela Yelick, a professor of oral pathology at Tufts University in Boston.
A 'back-up' set?
"In the future, could there be a dental visit when you're a young child to induce another set of teeth to form from your adult teeth so you could have a backup set in case something happens?" asked Yelick, who studies tooth regeneration in zebra fish, but was not involved in the current research.
Other scientists think they're close to identifying some of the key growth factors that may spur dental stem cells into action.
"We can inject things into the jaws of the gecko and we can follow the way teeth are replaced using dental wax bites," said Joy Richman, a professor of oral health sciences at the University of British Columbia, in Vancouver.
Richman said geckos are somewhat easier to study than alligators because they make new teeth every five weeks or so, instead of every year, as gators do.
She said the process of manipulating tooth regeneration needs to be carefully studied in many different kinds of animals before it should be tried in humans, however, since the same stem cells that make teeth can also make oral cancers if they are overstimulated.
"What we'd like to be able to do is basically get people to make new teeth on demand, but using a person's own cells to do it," said Richman, who was not involved in the alligator study.
To learn how to keep teeth healthy, head to the American Dental Association.