Rodents’ striking orange teeth not down to iron-rich enamel as thought

Iron-enriched enamel gives rodents’ teeth strength, but not the characteristic orange colour, as was previously believed. Researchers propose adopting the name ‘Fe-rich enamel’ for the material currently known as pigmented enamel, to reflect the discovery.

Rodents, such as beavers, squirrels, coypus and rats, have extremely strong teeth that grow continuously throughout their lives. The front of their teeth are covered by a hard enamel surface, angled to stay sharp as they gnaw, and strikingly yellow to orange in colour. Rodent enamel is composed of around 96% hydroxyapatite crystals by weight, but is known to contain iron that contributed to the durability of rodent teeth.