1Human Evolution, Max Planck Insitute for Evolutionary Anthropology, 2Department for Paleontology and Quaterny Paleontology, Senckenberg Research Institute,
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During mastication, forces are applied to the dentition and mandible according to the properties of the food particles. Mandibular and dental morphology is related to diet or more specifically, to different mechanical loads applied during mastication. For example, species with a “hard” diet show a more robust (broad) mandibular corpus than species feeding on a “soft” diet who exhibit a taller and more gracile corpus. Recent studies have linked crown size and mandibular morphology to chewing function. Root dimensions, however, are of particular interest since the periodontal ligament attaches the root to the alveolar bone and acts as a shock absorber. Therefore, more ligaments would be found on a larger root surface area which could tolerate higher occlusal forces.
We test the hypothesis of a positive correlation between molar root dimensions and mandibular robusticity and expect to find large root surface areas together with a high robusticity index (broad mandible). Using µCT data from more than adult chimpanzees (Pan troglodytes verus), we quantify root length, root surface area, root volume and cervical area in the molars. The robusticity index is measured at coronal cross sections of each tooth.
Root dimensions and cross sectional shape vary along the molar tooth row within an individual. We find overall high levels of variability within our single species sample and findings point to a complex functional and/or spatial relationship between root dimensions and mandibular size.