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Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Arts (MA)

Department

Anthropology

Supervisor

Shelley R. Saunders

Language

English

Abstract

This study presents data on the extent of the sexual dimorphism observed in tissue measurements of the deciduous tooth crowns for a heterogeneous modem human sample. A series of linear and area measurements were taken from crowns sectioned in a buccolingual plane. The buccal enamel and perpendicular buccal enamel, situated towards the incisal surface, are significantly thicker in female deciduous upper canines than male upper canines (p = 0.002 and p = 0.001 , respectively). Furthermore, there is a distinct trend for the female enamel to be thicker than male enamel in the lower first incisor, and upper second incisor, and more so in the buccal enamel rather than lingual enamel. No differences in dentine-pulp thickness were observed between the sexes. Area measurements did not exhibit significant levels of sexual dimorphism, although the enamel cap area relative to both the total crown area and cervical diameter tend to be larger in the female lower canines, while the male lower canine dentine-pulp area relative to total crown area tends to be larger.

These results support conclusions of previous research that a sexually dimorphic distribution of enamel exists within the tooth crown, and that dimorphism centers on the canine. Unlike the plethora of permanent crown data which demonstrate that dentine is the main contributor to crown dimorphism- for the deciduous anterior crowns, this preliminary data suggests otherwise. The present study hypothesizes that tissue . dimorphism of the deciduous anterior crowns anses during amelogenesis rather than during the mitotic phase of crown development. Sexual dimorphism, therefore, is suggested to be a result of the interplay between differential ameloblast secretion rates, extension rates and geometric factors affecting the deposition of enamel, rather than the result of mitotic embryonic tissue growth proposed for the permanent crowns.

This study provides an important preliminary step towards understanding the mechanisms which dictate deciduous crown tissue dimorphic characteristics. Furthermore, it offers evidence which suggests that deciduous canine buccal enamel is sufficiently dimorphic to provide a basis for sub adult sex determination of modern humans.

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