Three-dimensional reconstruction of enamel thickness and volume in humans and hominoids

Enamel thickness is an important diagnostic characteristic in Hominoidea. However, the sample size is extremely small, relying upon mostly fractured specimens and a few sectioned specimens, providing an estimate of enamel thickness only. What is needed to fully understand the significance of enamel thickness is a non-destructive technique that is able to obtain the thickness, density, and volume of the dental hard tissues of large samples, thereby providing an accurate means of relating thickness, area, volume, and the pattern of distribution of both enamel and dentin. Investigators have attempted to circumvent this problem by developing a variety of indexes. However, we are still left with subjective descriptions, such as 'thin', 'thick', 'intermediate thick', and 'hyperthick'. The purpose of this investigation was therefore to demonstrate the ability of high-resolution X-ray computed microtomography (HRXCT), as a non-destructive method, to produce, accurately and reliably, contiguous slices revealing the thickness and area of enamel, dentin, and pulp chamber. Using imaging software, three-dimensional reconstructions were produced, which provided volume data for enamel and dentin. Three-dimensional reconstruction of HRXCT images provide, for the first time, the capability of accurately quantifying enamel and dentin thickness, distribution and volume, thereby eliminating the necessity of destructive thin-sectional analysis.