The 89th Annual Meeting of the American Association of Physical Anthropologists (2020)

Developmental defects of deciduous teeth can be linear too: an analysis of enamel hypoplasia in juvenile great apes


1UMR 5199 PACEA, Université de Bordeaux, 2Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, 3Department of Biology, Universität Hildesheim, 4UMR 5060 IRAMAT – CRP2A, Université Bordeaux Montaigne, 5Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent

April 18, 2020 , Platinum Ballroom Add to calendar

Linear hypoplastic defects of enamel are horizontal grooves on the tooth surface, representing disruptions to enamel secretion in response to disturbances during development. Compared to permanent teeth, much less is known about hypoplastic defects in deciduous teeth. Localized hypoplasia of the primary canine (LHPC) has been described in hominoids, appearing as roughly circular depressions on the labial surface. LHPC has been linked with compromised somatic development and crypt fenestration and/or localized trauma to developing teeth. We report enamel hypoplasia prevalence in a collection of juvenile wild-captured great apes (Gorilla gorilla, Pan troglodytes, Pongo spp.). LHPC prevalence is higher than previously reported: 11 of 12 observable individuals have LHPC on the lower deciduous canines, and 7/12 have LHPC on the upper deciduous canines. LHPC presence, but not morphology, matches across antimeres. Previous studies suggested that linear defects do not occur in deciduous teeth of hominoids, but 4/12 individuals have linear hypoplasia on their upper and/or lower deciduous canines. Linear defects, with or without pits, also occur on the deciduous incisors (5/10 individuals). One individual has localized defects resembling LHPC on the central incisors. Confocal imaging shows exposed Tomes’ pit processes in the floors of both defect types, signaling that matrix secretion ceased abruptly. Linear deciduous defects are shallower than those in permanent teeth from the same taxa, which might make the former harder to reliably identify ‘by eye’. Ongoing surface characterization will allow these features to be compared between populations and better understood in terms of formation processes.

This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 798117.

Slides/Poster (pdf)