Computed tomography and the measurement of enamel thickness in extant hominoids: implications for its palaeontological application

Grine, Frederick E
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Bernard Price Institute for Palaeontological Research
Isolated permanent lower molars of Homo sapiens, Pan troglodytes and Gorilla gorilla were imaged by computed tomography (CT) using a 1,5 mm thick section through the mesial cusps. The teeth were examined dry and immersed in water. Measurements of enamel thickness were made on enlargements of hard copy images. Following CT examination, the crowns were sectioned in the same plane, and the cut faces with maximum dentine content were micrographed for measurement using a scanning electron microscope (SEM). Enamel thickness measurements from the CT images were noticeably exaggerated compared to the ideal (sectioned) values, and the CT values for dry specimen images were even larger than those for wet specimen images. These results indicate that CT cannot be employed to measure enamel thickness with any degree of reliability in modem specimens. There is no close correspondence between the SEM and CT values; therefore, the latter cannot even be used to predict the actual values. Thus, the application of CT in the measurement of enamel thickness in fossils is rather dubious.
CT scan, Hominoidea