Doctoral Dissertation Research: Microstructure and Mechanical Properties of Primate Tooth Enamel

This doctoral dissertation study will explore an important aspect of teeth and their role in dietary ecology, by testing the ability of tooth enamel to resist fracture and wear from forces applied during chewing. Tooth enamel from different primate species will be imaged and mechanically tested using methods from materials science engineering to better understand the relationship between the internal structure of teeth and their performance. The results of this study will illustrate the mechanisms that allow teeth to chew tough and hard foods, which may inform research to develop stronger replacements for worn and broken teeth, as well as research to better reconstruct the diet of extinct humans and animals. The study will support graduate student training and the development of undergraduate laboratory coursework that emphasizes the use of concepts from dental biology and anthropology in engineering applications.

This study will address how the form of enamel contributes to its function in resisting tooth failure. At micro- and nanometer scales, enamel is formed out of many small crystals that are bundled together in complex patterns. These patterns are thought to help teeth resist wear by aligning crystals in a direction where they are strongest in response to abrasion. Additionally, a highly complex pattern of interwoven crystals is believed to help prevent cracks from moving through enamel and leading to a chipped or cracked tooth. This study combines ion beam microscopy to image micro- and nanometer structures of enamel in fine detail, and indentation methods from material science engineering to determine how enamel structures respond when forces are applied. To understand how these structures function in human teeth, the variation in their properties will be compared with those of other closely related species. For this reason, the analytical sample includes teeth from humans and a range of non-human primates including chimpanzees and baboons. Ultimately, this study will strengthen the inferences that can be made when determining diet from fossils in our evolutionary past, and help to illustrate how and why teeth break.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.