How do rodents’ continuously growing incisors stay sharp?

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black-tailed prairie dog — rodent Black-tailed prairie dog (*Cynomys ludovicianus*).

Rodents possess rootless incisors that grow continuously throughout their lives. These teeth remain sharp due to a specialized structural design: the front of each incisor is covered in a hard layer of enamel, while the back consists of softer dentine.123

As the rodent gnaws, the softer dentine wears away more quickly than the harder enamel. This differential wear pattern ensures that the teeth are constantly honed into sharp, chisel-like edges.2