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Why do the enamel and dentine in rodent incisors wear at different rates?

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

Rodent incisors do not wear at different rates due to a biological process, but rather because they are composed of materials with inherently different physical properties.

The front of each constantly growing, rootless incisor is covered by a hard layer of enamel, while the back consists of softer dentine. Because dentine is significantly softer than enamel, it wears away more quickly during the animal's constant gnawing. This differential wear ensures that the teeth maintain a perpetually sharp, chisel-like edge, which is essential for the rodent's survival and feeding habits.12