A comparison of enamel daily sections rates in deciduous molars from modern-day children living in Aotearoa New Zealand, Britain, Canada, France, and Sweden
Résumé
The daily enamel secretion rate (DSR) of ameloblasts can be reconstructed from incremental markings retained in teeth. Within palaeoanthropology, bioarchaeology, and forensic contexts, DSRs are used to establish the pace of dental development, the timing of birth and weaning, and age-at-death in juveniles. Yet compared to permanent teeth, little is known about DSRs of modern-day children including whether rates vary between populations. Here we report DSRs of naturally exfoliated deciduous molars (n = 345) from five populations (Aotearoa New Zealand, Britain, Canada, France, and Sweden). Each tooth deciduous molar was thin sectioned and examined using a high-powered Olympus BX51 microscope and DP25 digital microscope camera. Mean DSRs were recorded for the inner, mid, and outer regions of cuspal and lateral enamel, excluding the first and last formed 100μm of enamel. Mean DSRs did not vary significantly between populations, or by sex. Cuspal enamel grew slightly faster than lateral enamel (mean difference 0.16 μm per day p < 0.001). The trajectory of DSRs from inner to outer enamel showed a minor increase that was significant in lateral enamel only (p = 0.003). The DSRs of deciduous molars from modern children are remarkably consistent when compared among populations. Furthermore, while growth rates are faster in cuspal than lateral enamel, DSRs only show a minor increase in pace from inner to outer regions. The trajectory described for deciduous enamel of modern-day children differs to that of permanent molar enamel, which typically displays a steep increase in matrix deposition from inner to outer enamel.