Teeth that grow back again for alligators could, in the view of researchers, reveal a way for humans to grow a third set of teeth after their adult teeth decay.

The teeth of reptiles and mammals are not that different, except that alligators have teeth that replace themselves. It might one day be possible to stimulate the growth of new teeth in people, according to the research team of Dr. Cheng-Ming Chuong at the University of Southern California in Los Angeles.

At the moment, he cautions, such a vision remains scarcely more than an idea.

When humans lose their baby teeth to be replaced by permanent ones, they lose their capability for renewing teeth. Reptiles such as snakes, geckos and alligators retain this capability. In fact, alligators regularly lose their teeth, and each year, about one tooth in 10 is replaced by a new one.

In the course of an alligator’s life, each of the 80 individual teeth can be regenerated up to 50 times, the researchers reported in the science journal PNAS.

Dr. Chuong and his colleagues undertook a more precise study of the teeth of alligator embryos and of young alligators.

They say that in reptiles, each tooth is comprised of three components - a functional tooth, a replacement tooth, and a special tissue layer or dental lamina. In humans, too, the baby teeth and permanent teeth emerge from the dental lamina.

When an alligator loses one of its teeth, the replacement unit moves forward: the reserve tooth develops into a fully-grown one, the lamina becomes the next reserve tooth and a tissue layer splits away to form what will become the next dental lamina.

In addition, the researchers discovered a kind of socket area at the end of the dental lamina. They believe that this serves as a collection point for stem cells. They also identified the molecules which play an important role in regulating the tooth regeneration process of reptiles.

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