Researchers from Northwestern University have discovered something remarkable about beaver teeth, probably the toughest chompers in the animal kingdom.

Despite a lifetime of gnawing on massive tree trunks, the semi-aquatic rodents' teeth are immune to tooth decay. The question is why?

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Researchers found out that tiny iron-rich nanowires interwoven throughout the enamel core of those outsized incisors make beaver teeth almost super tough. The enamel is one of the tissues that make up the teeth of humans and many animals, including beavers.

Enamel is meant to be resistant to acids but when too much acid in a person's food "dissolves" the enamel, making the teeth more sensitive and at risk of developing cavities.

All enamel is consists of rods or nanowires stacked and woven together. These spaghetti-like structures are mainly composed of hydroxylapatite, a type of calcium apatite.

Encasing these rods or wires is a layer rich in iron and magnesium. It's this lamination of minerals that help protect teeth from acid damage.

Researchers found that the ionic make-up of this lamination is the key as to why beaver teeth are so strong.

They looked into enamel of three animals, including rabbits and beavers, and analyzed the enamel's amorphous structure using atom probe tomography. This technique provided high-res imagery of the enamel's inner atomic and ionic composition.

"A beaver's teeth are chemically different from our teeth, not structurally different," said lead study author Derk Joester, a researcher at Northwestern University.

The findings may be helpful in gaining a better understanding of oral health, especially how tooth decay develops.

The study appears in the Frontiers in Psychology journal.

Tagsbeaver, enamel, tooth decay, oral health, beaver's teeth, human tooth decay