Department of Anthropology, McMaster University
April 17, 2020 , Platinum Ballroom
The presence of the neonatal line (NL) in enamel has long been used in histological investigations of the perinatal period and growth and development. Dentine precedes enamel formation and we reviewed previously published literature to establish that a NL is present in the first permanent molars (M1s) and all primary teeth of live births. Incremental dentine formation was plotted for the complete dentition and a new method for locating the NL, which is not always clearly visible in dentine, was devised. A measurement is taken from the NL in the enamel to the dentino-enamel junction (DEJ), and an equal distance was measured from the DEJ into the dentine to establish the baseline for in utero formation in teeth with a NL. This information was then used to investigate the mother infant dyad using Interglobular dentine (IGD) as evidence for vitamin D deficiency in Canadian sample of M1s from living (n=9, Ontario) and archaeological individuals (n=9, 18th century Quebec). Four individuals had IGD, one modern and three archaeological. Two archaeological individuals, both from Quebec City, had prenatal IGD. The densely built environment of the growing city and social ideals on clothing for women, resulted in deficiency in pregnant females. We investigated IGD, but these techniques could also be used in investigation of stable isotopes. The neonatal line accurately demarcates tooth formation from the prenatal versus postnatal period, allowing detailed investigations of in utero health and providing a window into the experiences of women in past communities and potentially public health debates.
This research was undertaken, in part, thanks to funding from the Canada Research Chairs program. Canada Research Chair 231563, SSHRC