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The periodicity of enamel laminations in human deciduous molars

Barnard, Petrina, McFarlane, Gina, Deter, Chris, Loch, Carolina, Mahoney, Patrick (2025) The periodicity of enamel laminations in human deciduous molars. Archives of Oral Biology, 171 . Article Number 106164. ISSN 0003-9969. (doi:10.1016/j.archoralbio.2024.106164) (KAR id:108155)

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https://doi.org/10.1016/j.archoralbio.2024.106164

Abstract

Objective: Enamel laminations are closely spaced incremental lines that run parallel to striae of Retzius or the developing enamel surface. Here, the timing of enamel laminations is calculated for naturally exfoliated deciduous molars (n=111) from three modern-day populations (Aotearoa New Zealand, Britain and Canada).

Design: Teeth were sectioned using standard histological methods and examined using a high-powered microscope. Mean daily secretion rates (DSR) were calculated for the outer enamel of each molar in cuspal, lateral and cervical enamel regions. These DSRs were used to determine the periodicity of enamel growth across laminations in each region. Lamination periodicity was compared between populations and sexes, and within molars to assess the relationship between lamination periodicity and the angle between laminations and the outer surface.

Results: Laminations were present in 57% of all molars (n=63 out of n=111). Their presence did not vary between populations or by sex. A mean two-day periodicity was observed in cuspal and lateral outer enamel sampling regions. A mean one-day periodicity was observed in the cervical outer enamel. The angle of laminations relative to the outermost surface of the enamel was significantly related to the presence of laminations.

Conclusions: A two-day periodicity for laminations indicates that this incremental marking is not a reliable proxy for a circadian 24-hour rhythm in human deciduous molars. The orientation of laminations was similar to Retzius lines but differed to the orientation of cross-striations.

Item Type: Article
DOI/Identification number: 10.1016/j.archoralbio.2024.106164
Subjects: G Geography. Anthropology. Recreation
Q Science > QD Chemistry
Divisions: Divisions > Division of Natural Sciences > Chemistry and Forensics
Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Funders: University of Kent (https://ror.org/00xkeyj56)
Depositing User: Patrick Mahoney
Date Deposited: 13 Dec 2024 14:29 UTC
Last Modified: 22 Jan 2025 16:40 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/108155 (The current URI for this page, for reference purposes)

University of Kent Author Information

Barnard, Petrina.

Creator's ORCID:
CReDIT Contributor Roles:

McFarlane, Gina.

Creator's ORCID: https://orcid.org/0000-0002-7441-2281
CReDIT Contributor Roles:

Deter, Chris.

Creator's ORCID:
CReDIT Contributor Roles:

Mahoney, Patrick.

Creator's ORCID: https://orcid.org/0000-0002-2715-3096
CReDIT Contributor Roles:
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