School of Anthropology and Conservation, University of Kent
Friday All day, Plaza Level
Unlike modern human permanent teeth, all human deciduous teeth commence development in utero and birth is recorded at different times in the different tooth and cusp types. Birth can disrupt enamel growth, so it would seem likely that trends in incremental enamel development along the permanent tooth row may not be the same in deciduous teeth. Here, I reconstruct Retzius line periodicity, daily enamel secretion rates (DSRs), pre-natal and crown formation times for an archaeological sample of modern human deciduous mandibular (n=42) and maxillary (n=42) anterior teeth (canines, lateral and central incisors). Results are compared with previously published data for deciduous molars (Mahoney, 2011) to identify developmental trends along the deciduous tooth row.
Like human permanent teeth, Retzius line periodicity did not differ between deciduous teeth in one individual, though periodicity values of 5 days calculated for some individuals are low for modern humans. Unlike some permanent tooth types from extant hominoids, mean daily enamel secretion rates varied between teeth when equivalent enamel regions were compared along the dental row. Incisors had the fastest mean cuspal DSRs (mid and outer enamel range=3.74-5.63µm). Mandibular incisors also initiated enamel growth first, had the longest pre-natal formation time (mean=142-166 days) but the shortest crown formation time (mean=282-317 days), and based upon clinical studies are the first deciduous tooth type to erupt. Relatively rapid development in mandibular incisors in advance of early eruption may explain some of the variation in DSRs along the tooth row that cannot be explained by birth.