Book contents
- Frontmatter
- Contents
- Acknowledgements
- 1 Why development and why teeth?
- 2 Development schedule, body size and brain size
- 3 How teeth grow in living primates
- 4 Microscopic markers of growth in dental tissues
- 5 Building dental development sequences
- 6 Human evolution, pace of development and life history
- 7 Dental markers of disease and malnutrition
- 8 Health, stress and evolution: case studies in bioarchaeology and palaeoanthropology
- 9 Conclusions
- Appendix A Tables
- Appendix B Technical information
- References
- Index
4 - Microscopic markers of growth in dental tissues
Published online by Cambridge University Press: 05 June 2014
- Frontmatter
- Contents
- Acknowledgements
- 1 Why development and why teeth?
- 2 Development schedule, body size and brain size
- 3 How teeth grow in living primates
- 4 Microscopic markers of growth in dental tissues
- 5 Building dental development sequences
- 6 Human evolution, pace of development and life history
- 7 Dental markers of disease and malnutrition
- 8 Health, stress and evolution: case studies in bioarchaeology and palaeoanthropology
- 9 Conclusions
- Appendix A Tables
- Appendix B Technical information
- References
- Index
Summary
This chapter uses the example of human teeth because specimens are more readily obtainable, but the histological details are similar in chimpanzees, gorillas and orangutans.
The tooth surface
Take a permanent tooth from a human in your hand and examine it in good light. The crown is coated in white shiny enamel which overlies the yellow or brown of the root, often stained darker in fossils or archaeological specimens. Enamel, however, retains its glossy lustre in the great majority of ancient teeth. It is difficult to focus on the surface, which has a glass-like, translucent quality. Enamel is not actually a glass, but is very finely crystalline and contains microscopic discontinuities that scatter light back to the observer. Just below the surface, the light passes through without being much affected, but the deeper it penetrates, the more discontinuities it encounters and the more light is scattered, rendering the tissue bright white. To see features on the surface of the crown, it is necessary to tilt the tooth from side to side to make out the details amongst the bright reflections. In an unworn molar or premolar, the cusps form smooth mounds, separated in the occlusal surface by deep, narrow fissures. Incisors bear a row of small cusplets called mamelons, but these wear rapidly to make a smooth edge. The crown side bulges out below the cusps, then tapers gradually towards the root, which it meets at the cervix of the tooth. The boundary line with the root is the cervical margin of the crown. It is also the point at which the enamel of the crown meets the cement which coats the root surface, and so it may be called the cement-enamel junction (CEJ). In incisors and canines, the single root may bulge out a little below the crown before tapering down to the point of the apex. The multiple roots of molars branch out below the root trunk at the point known as a furcation and each root has its own apex.
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- Tooth Development in Human Evolution and Bioarchaeology , pp. 70 - 111Publisher: Cambridge University PressPrint publication year: 2014
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