The secret behind the alligator’s toothy smile

A clump of dental stem cells gives alligators a steady supply of pearly whites.

Beneath each tooth in a gator’s megawatt smile, a small band of tissue houses stem cells that can kick-start dental growth, a new study finds. When an old tooth falls out, a slew of chemicals commands the cells to crank out new teeth, scientists led by Cheng-Ming Chuong of the University of Southern California report May 13 in the Proceedings of the National Academy of Sciences.

Using a combination of molecular techniques and X-ray imaging, researchers tracked down the chemicals and discovered that each tooth is actually a “family unit” embedded in the animals’ jaws. That unit consists of an old tooth, its budding replacement, and the band of dental tissue, the authors report. The reptiles rely on the band of dental tissue to pop out new teeth.

Unlike people, who replace their teeth only once, the American alligator, Alligator mississippiensis, replaces each of its 80 teeth about once a year. Because people also carry remnants of the stem cell-packed sheet, scientists may one day use the cells to replace missing human teeth, the researchers suggest.