The Function of Nonprismatic Enamel in Mammals: Dental Structure, Oral Physiology and Dietary Niche

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9507488 Dumont The organization of enamel in mammalian teeth can vary between simple parallel arrangement of crystallite (nonprismatic enamel) to complicated non-parallel arrangements (prismatic enamel). Prismatic enamel increases the strength of the tooth, but we know relatively little about the function of non-prismatic enamel. In humans, non- prismatic enamel is more resistant to erosive destruction by dietary acids and sugar by-products than is underlying prismatic enamel. This research examines tooth structure, diet diversity, and salivary chemistry in an array of mammal species. It will test the hypothesis that exaggerated superficial layers of nonprismatic tooth are adaptations that permit dietary emphases on acidic or sugary food sources. For each species, food hardness, sugar content and acidity of natural diets are measured, together with salivary pH and buffering capacity. The proportion of nonprismatic enamel in molar teeth is measured using scanning electron microscopy. Mammals with high proportions of nonprismatic enamel are predicted to consume foods that are more sugary, acidic, and softer than those eaten by species that exhibit relatively little nonprismatic enamel. Salivary pH and buffering capacity are predicted to be relatively lower among species that exhibit large proportions of nonprismatic enamel. This study will provide evidence of the interactions between tooth enamel morphology, oral physiology and feeding behavior that limit the diversity of foods that mammals select. It will lead to better understanding of the relationships between anatomy, physiology and behavior that influence the ways in which animals share food plant resources. It will provide insight into the diets of extinct or poorly known species. The results of this study may also yield insights into the role of human nonprismatic e namel in resisting dental erosion and the initiation of tooth decay.