Assessment of the accuracy of dental enamel thickness measurements using microfocal X‐ray computed tomography

Abstract

Tooth enamel thickness has long been an important character in studies of primate and especially hominin phylogeny, taxonomy, and adaptation. Current methods for accurately assessing enamel thickness involve the physical sectioning of teeth, because measurements of enamel thickness using some radiographic techniques are unreliable. However, because destructive methods limit sample sizes and access to important fossil specimens, it is desirable that they be replaced with nondestructive techniques. Although microfocal X-ray computed tomography (mCT) has been used recently in studies of enamel thickness, the accuracy of this technique has yet to be established. The present research compares physical sections to computer-generated mCT sections of teeth from a variety of primate and nonprimate, recent and fossil taxa to examine whether enamel thickness, tooth size, and diagenetic remineralization (fossilization) impact the ability of mCT to measure enamel thickness accurately. Results indicate that recent teeth of varying size and thickness are clearly and accurately depicted in mCT scans, with measurements from nearly identical planes in physical and mCT sections differing by 3-5%. A fossil papionin molar (ca. 2 Myr) was also accurately measured using mCT scans, although thinner enamel in much older therapsid (ca. 263-241 Myr) teeth could not be distinguished from dentine. mCT is thus an accurate technique for measuring enamel thickness in recent taxa, although heavily mineralized teeth pose an obstacle to the ability of mCT to distinguish dental tissues. Moreover, absolutely thin enamel (less than ϳ 0.10 mm) is difficult to resolve adequately in raw mCT images based on pixel values alone. Therefore, caution must be exercised in the application of mCT to the study of fossilized teeth. © 2006 Wiley-Liss, Inc.Key words: mCT; microfocal X-ray computed tomography; enamel thickness; measurement accuracy; diagenesis; dental enamel; dentine Tooth enamel thickness has long been considered to be of importance in the interpretation of human evolution because of its purported taxonomic and phylogenetic value

Orthodontic mechanotransduction and the role of the P2X7 receptor

“…Many studies have been published on the accuracy of µCT measurements the relationship of instrument settings to the rendering of tooth morphology and the results of bone morphometry (Kim, Paik & Lee, 2005;Kohler et al, 2005;Olejniczak & Grine, 2006;Thomsen et al, 2005;Waarsing, Day & Weinans, 2004;Yeni et al, 2005).…”

Observations of mineralised tissues of teeth in X-ray micro-computed tomography

“…The analysis of mineralised tissues is important -including tooth tissues. The extraordinary durability of the enamel allows determining by characteristics, inter alia, the age, suffered illnesses, eating habits, lifestyle, and makes comparing individual species among themselves possible [11,21]. In addition to the thickness of the enamel, X-ray micro-CT system can also generate the image of tooth structures accurately and reliably: the thickness and surface of the enamel, dentin and pulp chamber [11], and root canal system on different levels (Fig.…”

“…X-ray microtomography is applied to the qualitative and quantitative analysis if the test sample has a sufficiently large variation of absorption of X-ray radiation by its individual attenuation coefficient, and therefore for the highly mineralised tooth areas, reliable identification of different tissues using a micro-CT can be difficult. Moreover, the areas of very thin enamel (less than 100 microns) can be difficult to identify [21]. Computed X-ray microtomography facilitates performing a full morphometric analysis and thus provides a full set of quantitative data describing the tested structure [15].…”

State of the Art of Micro‐CT Applications in Dental Research

“…However, the low resolution and exaggerated effect of standard CT images makes the data grossly inaccurate. Application of Micro-CT systems has become an effective and nondestructive technique for the measurement of enamel thickness (Olejniczak and Grine, 2005;Olejniczak and Grine, 2006). It has been used to measure enamel thickness of a great variety of archaeological specimens Smith et al, 2009).…”