Want to Chew Through a Tree? The Secret to Beavers’ Tough Teeth

When was the last time you saw a beaver brushing his teeth. Flossing? Hard to come across at your neighborhood beaver pond. And they never go to the dentist.

OK, then how can a beaver keep his or her teeth strong and healthy enough to chew through the trunk of a 20-inch tree? One word — iron.

A recent study on tooth enamel by Northwestern University delved into the true composition of tooth enamel. The goal was to understand why some teeth, like those of beavers and other rodents that aren’t exactly eating a soft diet, could be so strong. The study found that iron in a beaver’s teeth make them much more protected against decay than the enamel of the teeth of humans. So, don’t go out and chew on the elm in your backyard.

What is the difference in their enamel and ours? Beavers have “pigmented” enamel, the reason their teeth are brown. The ingredient that makes them brown is iron. It is built into the chemical structure of their teeth. This pigmented enamel is both harder and more resistant to acid than regular enamel, including enamel treated with fluoride. And to think, beavers don’t have to sit in the chair and bite down on grape-flavored fluoride trays for two minutes.

The Northwestern team broke down the complex structure of beaver tooth enamel. The study notes that layers of well-ordered hydroxylapatite “nanowires” are the core structure of enamel, in both humans and beavers. The difference is what’s surrounding these nanowires. In human enamel small amounts of magnesium can be found there, but in beavers and other prolific chewers it’s iron.

The lead of the study was Derk Joester, associate professor of materials science and engineering at Northwestern. “A beaver’s teeth are chemically different from our teeth, not structurally different,” Joester said. “Biology has shown us a way to improve on our enamel.”

In the experiments on rabbit, mouse, rat, and beaver enamel, Joester and his team subjected teeth to acid and took images before and after exposure. Through atom-probe tomography they mapped the enamel’s structure atom by atom. That’s where they found the iron, the Kevlar of the tooth enamel. They were particularly interested in the beaver’s incisors, since trees are no match for their strength.

Although us humans probably don’t want to have the dark orange/brown teeth of beavers anytime soon, this info about iron could be helpful. After all, worldwide 60 to 90% of children and nearly 100% of adults have or have had cavities, according to the World Health Organization. In the U.S. $111 billion is spent on dental services yearly, with a large part of that going to cavity and decay problems.

Until the day we all have iron in our enamel, however, a visit to Dr. Egger’s for your twice-yearly cleaning and exam will have to do the trick. Call us for your next appointment, 989-773-3560.