The African silvery mole rat continuously replaces its cheek teeth, with new teeth displacing old ones in an escalator-like fashion, researchers in France have found.1

Paleontologist Mr H. Gomes Rodrigues and colleagues used a form of X-ray CT scanning to create 3D renderings and virtual slices of the teeth of 55 silvery mole rats. They discovered that the rodents' teeth undergo continuous replacement, similar to most non-mammalian vertebrates. The mole rat's teeth are also replaced horizontally, unlike the vertical replacement found in humans and most mammals. The authors suggest that this may help silvery mole rats preserve their teeth when they dig into hard, abrasive soil to build extended burrows and find food.

When the researchers compared the mole rats with the four other mammalian species known to continuously replace their teeth, they found a set of common traits: a forward movement of new teeth from the rear to the front of the jaw, the continued eruption of teeth after the age of sexual maturity, and the growth of extra teeth. The authors suggest these traits are essential prerequisites for the development of continuous dental replacement.

These dental traits are partially present in humans but absent in mice, suggesting that mole rats are more appropriate than mice for studying the genetic mechanisms behind dental regeneration in humans, according to Gomes Rodrigues and colleagues.