Biomechanics in the Enamel of Mammalian Teeth

Abstract

The formation of mammalian enamel is strictly determined genetically but yields important functional adaptations on the levels of gross morphology and micro-structure. Differentiation of enamel thickness is frequently found in hypsodont teeth of smaller and medium-sized mammals. It is mainly due to the position on the leading or trailing edge. In the enamel microstructure, the Schmelzmuster, defined as a specific combination of different enamel types, again shows a close relationship to the leading or trailing edge especially in small mammals. The various enamel types, defined by prism orientation, have different functional meanings. Some, like Hunter-Schreger bands, reinforce enamel to resist tensile forces and possess crack-stopping properties as well. In hypsodont molars of larger mammals, specific stresses occur near the enamel-dentine junction. The characteristic modified radial enamel found in this region is regarded as a special adaptation to these stresses. Modified radial enamel evolved convergently in several lineages. Because enamel types are mainly functionally determined, the taxonomical value of enamel structures is largely restricted to the level of Schmelzmuster.