ORCID
https://orcid.org/0000-0002-9869-181X
Date of Award
9-14-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Teeth must fracture foods while avoiding being fractured themselves. This dissertation consists of three studies aimed at assessing adaptations of molars that may confer biomechanical strength against certain types of diet. The first study evaluates dome biomechanical models used to describe tooth strength. The second study tested the hypothesis that australopith molars, which have enlarged molars and thick enamel, are mechanically strong and well adapted to withstand high bite forces. The third study tested biomechanical predictions derived from experiments performed on a dome model that examined how tooth strength changes at progressive stages of wear under loading regimes representing different types of diet. Finite element analysis (FEA) was used for all studies. Finite element models (FEM) were built from microCT scans of a human M3, orangutan M2, gorilla M2, chimpanzee M2, two A. africanus M2s, and two P. robustus M2s. The FEAs included three loading regimes simulating contact between 1) a hard object and a single cusp tip, 2) a hard object and all major cusp tips, and 3) a soft object and the entire occlusal basin. The results of the first study showed that geometrically simple biomechanical models are valuable tools for understanding tooth function but do not fully capture aspects of biomechanical performance in actual teeth whose complex geometries may reflect adaptations for strength. For our second study we observed that australopith teeth are generally as strong or stronger than extant ape teeth during bites on hard objects but can be surprisingly weak when biting with high force on compliant objects. The results of our third study found that all teeth became more susceptible to fracture as wear increased for loading regimes that mimic biting on a hard object. When biting on a soft or compliant object, however, either no change in the risk of fracture was observed or in some cases the teeth became less susceptible to fracture.
Language
English (en)
Chair and Committee
David Strait
Recommended Citation
Sender, Rachel, "The Biomechanics of Tooth Strength in australopiths" (2023). Arts & Sciences Electronic Theses and Dissertations. 3172.
https://openscholarship.wustl.edu/art_sci_etds/3172