Optimized biological tools: ultrastructure of rodent and bat teeth compared to human teeth

Abstract

Enamel, the outer layer of the teeth of vertebrates, is the hardest tissue in their body. In general, enamel is highly mineralized and has a special ultrastructure that directs the mechanical properties of teeth and thereby their biological functions. However, there are differences between the enamel ultrastructures of different species. The authors compare the teeth of the Eurasian beaver Castor fiber, the African mole rat Fukomys kafuensis and the common pipistrelle bat Pipistrellus pipistrellus by high-resolution analytical methods, including scanning electron microscopy, quantitative wavelength-dispersive X-ray spectroscopy and X-ray powder diffraction. The enamel of all animals consists of long, thin and differently oriented calcium phosphate crystallites (length > 1 µm; thickness about 50 nm). On the outer surface of the beaver tooth, a thin layer of brown iron oxide was found. The diameter of the dentin tubuli was between 1 and 3 µm for all species – that is, comparable to that for human teeth.