School of Anthropology and Conservation, University of Kent
Friday All day, Park Concourse
Studies have shown that enamel thickness generally increases along the human permanent tooth row from incisors to distal molars. Some attribute this trend between molars to a functional purpose, related to bite force during chewing. Others propose a morphological explanation, arguing that the relatively increased molar enamel thickness can be explained by a reduction in the distal molar crown size, which is facilitated by a reduced proportion of dentin. Here I assess average enamel thickness (AET) and dentin proportions along the entire human deciduous mandibular (n=91) and maxillary (n=95) tooth rows (incisors, canines, molars) in an archaeological sample of human children. Thin sections were prepared using standard histological methods. Sections were examined under a microscope (Olympus BX51), digital images were produced (Olympus DP25), captured, and analyzed (Olympus Cell D). Results were evaluated against functional and morphological interpretations of enamel thickness derived from permanent teeth.
Mean AET (and RET) increased from deciduous incisors to distal molars. Distal molars had the smallest proportion of dentin. These trends are similar to reported values for permanent teeth. However, changes in crown size do not explain the trends in deciduous teeth, in the way that has been proposed for permanent molars. For example, the deciduous distal molar is larger not smaller than the first molar. In contrast, there is some support for a relationship between bite force and enamel thickness in childrens teeth. The greater deciduous molar AET, compared to incisors, corresponded to recently reported differences in bite forces between these tooth types.
Maxillary molar sections were funded by the Royal Society.