Enamel thickness variation in the deciduous dentition of extant large‐bodied hominoids

Abstract

Objectives: Enamel thickness features prominently in hominoid evolutionary studies. To date, however, studies of enamel thickness in humans, great apes, and their fossil relatives have focused on the permanent molar row. Comparatively little research effort has been devoted to tissue proportions within deciduous teeth. Here we attempt to fill this gap by documenting enamel thickness variation in the deciduous dentition of extant large-bodied hominoids. Materials and methods: We used microcomputed tomography to image dental tissues in 80 maxillary and 78 mandibular deciduous premolars of Homo sapiens, Pan troglodytes, Gorilla, and Pongo. Two-dimensional virtual sections were created from the image volumes to quantify average (AET) and relative (RET) enamel thickness, as well as its distribution across the crown. Results: Our results reveal no significant differences in enamel thickness among the great apes. Unlike the pattern present in permanent molars, Pongo does not stand out as having relatively thicker-enameled deciduous premolars than P. troglodytes and Gorilla. Humans, on the other hand, possess significantly thicker deciduous premolar enamel in comparison to great apes. Following expectations from masticatory biomechanics, we also find that the "functional" side (protocone, protoconid) of deciduous premolars generally possesses thicker enamel than the "nonfunctional" side. Discussion: Our study lends empirical support to anecdotal observations that patterns of AET and RET observed for permanent molars of large-bodied apes do not apply to deciduous premolars. By documenting enamel thickness variation in hominoid deciduous teeth, this study provides the comparative context to interpret rates and patterns of wear of deciduous teeth and their utility in life history reconstructions. K E Y W O R D S average enamel thickness, deciduous premolars, great apes, humans, relative enamel thickness 1 | INTRODUCTION Enamel thickness and its distribution across the tooth crown have long been recognized as an important source of taxonomic, phylogenetic, and functional information of extinct and extant primates

Evaluation of Dental Enamel Thickness in Maxillary Teeth of Alouatta guariba clamitans, Alouatta caraya, and Sapajus nigritus by Cone Beam Computed Tomography

“…One study observed that there is a difference in the pattern of tooth enamel distribution and thickness in deciduous molars of hominoids when compared to the pattern described for permanent molars. 28 Due to the scarcity of studies evaluating enamel in deciduous teeth, the authors have chosen to present the results of mean and standard deviation to serve as a parameter for future studies.…”

Measuring Dental Enamel Thickness: Morphological and Functional Relevance of Topographic Mapping

“…This can be achieved using digital techniques and 3D reconstructions. The aforementioned important features are used today in a variety of studies, in evolutionary research, taxonomical assessments, and morphological studies [21,25,26], representing, in some cases, methodological extensions of techniques proposed for studies on real teeth [27]. The combination of enamel thickness measurements with other techniques, e.g., geometric morphometrics, is also characteristic for current odontological studies [28].…”

Dental enamel

“…Variations in enamel thickness in the deciduous dentitions of hominoids (H. sapiens, Pan troglodytes, Gorilla and Pongo) have recently been explored. 5 The thickness of dental enamel may act as a proxy for the durability of a tooth and reflect dietary preferences and possibly the lifespan. The varying patterns of wear and of enamel thickness correlates with dietary preferences and can act as a proxy for different diets.…”