Dental Health Imaging, Jobs, Education & Resources

In a stunning development, a global group of researchers led by USC pathology Professor Cheng-Ming Chuong, M.D., Ph.D., have discovered extraordinary cellular and molecular mechanisms behind tooth restoration in American alligators. Their study, called "Specialized stem cell niche enables repetitive renewal of alligator teeth," is featured in Proceedings of the National Academy of Sciences, the official journal of the United States National Academy of Sciences.

"Humans naturally only have two sets of teeth: baby teeth and adult teeth. Ultimately, we want to identify stem cells that can be used as a resource to stimulate tooth renewal in adult humans who have lost teeth. But, to do that, we must first understand how they renew in other animals and why they stop in people,” said Chuong.

While most vertebrates possess the ability to replace teeth throughout their entire lifespan, human teeth can naturally be restored only once; regardless of the residual substance of a band of epithelial tissue called the dental lamina, which is a key player in tooth development. Due to an alligator’s well-structured teeth and similarity between mammalian teeth, and capability of perennial tooth renewal, the researchers deduced alligators teeth may serve as representations for mammalian tooth rejuvenation.

"Alligator teeth are implanted in sockets of the dental bone, like human teeth,” said assistant professor of pathology at the Keck School of Medicine and first author of the study Ping Wu, Ph.D. "They have 80 teeth, each of which can be replaced up to 50 times over their lifetime, making them the ideal model for comparison to human teeth.”

By use of microscopic imaging methods, the researchers determined that each alligator tooth is made up of three components: a functional tooth, a replacement tooth, and the dental lamina. The three components mark the tooth in different developmental stages. In addition, the tooth components are composed in a manner that allows a seamless alteration from expulsion of the functional tooth, to the maturity and replacement of the new tooth. Therefore, researchers believe that the alligator dental laminae hold stem cells from which new teeth are generated.

"Stem cells divide more slowly than other cells," said co-author and associate professor of pathology at the Keck School of Medicine, Randall B. Widelitz, Ph.D. "The cells in the alligator's dental lamina behaved like we would expect stem cells to behave. In the future, we hope to isolate those cells from the dental lamina to see whether we can use them to regenerate teeth in the lab."

Researchers also plan to learn what molecular networks are activated and used to repair and renew teeth and seek to apply the same principles to regenerative medicine in the near future.