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Timelines in Teeth: investigating the timing and pattern of enamel maturation in developing human teeth
A research project of the Department of Archaeology.
Isotope analysis of human teeth is an extremely useful method through which archaeologists can learn about what ancient individuals ate and how they moved around the landscape. As techniques evolve permitting smaller and smaller samples to be measured, we need to establish if, by reducing the sample size, we are also reducing the period of time represented by the sample we measure. Dentine mineralization is completed in a very short period of time but enamel takes longer and has a far more complex pattern of maturation which is difficult to investigate in living children. What is the best strategy to obtain time-bound isotopic information from human enamel?
Archaeological collections include many juveniles who died while their teeth were forming. The arrested development of these teeth represents a “snapshot” of the maturation process and a unique opportunity to examine density changes associated with the normal formation of a tooth. Developing teeth from archaeological and modern collections, such as the Stack Collection curated by the Hunterian Museum, have been subjected to state-of-the-art micro-CT scanning and synchrotron XRD analysis. Micro-CT scanning has been undertaken at the Microscope and Imaging Facility, University of Aberdeen using a SkyScan-1072 high-resolution desk-top micro-CT system and in Belgium at the SkyScan facility using a larger SkyScan-1073 system to accommodate whole jaws with developing teeth. An example of the images produced can be seen at http://www.youtube.com/watch?v=eJrk41fny6k. RAMAN spectroscopy and electron microprobe have been used to establish that these density changes are due to normal development rather than diagenetic alteration.
The project is currently validating identified potential “time-lines” of mineralization in fully developed teeth containing known isotopic changes by high-resolution sampling using a New Wave Micromill to establish the best sampling strategies and pathways for unknown samples.
This is the largest study to date using micro-CT of developing human teeth. The results will provide fundamental evidence to inform future isotope aiming to extract seasonal information on mobility, climate and diet from archaeological and fossil human enamel, and studies of tooth morphogenesis and enamel biomineralization. Understanding the pattern and timing of human enamel mineralization is essential if we are to extract time-series information from human tooth crowns, and to interpret this data rigorously.
The research project is headed by Dr Janet Montgomery and Dr. Julia Beaumont, BDS, (University of Bradford) in collaboration with Dr Maisoon al-Jawad and Dr Lisa Simmons (Dental Institute, Queen Mary, University of London), Kevin Mackenzie (University of Aberdeen), Phil Salmon (Skyscan, Belgium), Roger Shore and Steven Brookes (Leeds Dental Institute), Niels Lynnerup (University of Copenhagen), Dr Edward Faber (University of Nottingham), Professor Howell Edwards (University of Bradford) and Dr. Geoff Nowell (University of Durham). The samples are by kind permission of BARC, University of Bradford and the Hunterian Museum, Royal College of Surgeons, London.
This project was funded by: a NERC standard grant 2008-2012 (PI Dr. Janet Montgomery); ESRF grant “2D texture mapping to study the biomineralisation of dental enamel” (PI Dr. Maisoon al-Jawad); and a Wellcome Trust VIP Award “Mapping the spatial and temporal progression of enamel biomineralization using synchrotron x-ray diffraction” (PI Dr. Maisoon al-Jawad). Dr Simmons presentation of this project won the GSK-Mineralised Tissue Group (MINTIG) Prize at the BSODR conference, Sheffield, 2011.
- Beaumont, J., Gledhill, A., Lee-Thorp, J. & Montgomery, J. (2013). Childhood diet: a closer examination of the evidence from dental tissues using stable isotope analysis of incremental human dentine. Archaeometry 55(2): 277-295.
- Simmons, Lisa M., Montgomery, Janet, Beaumont, Julia, Davis, Graham R. & Al-Jawad, Maisoon (2013). Mapping the spatial and temporal progression of human dental enamel biomineralization using synchrotron X-ray diffraction. Archives of Oral Biology 58(11): 1726-1734.
- Montgomery, Janet, Beaumont, Julia, Mackenzie, Kevin, Gledhill, Andrew, Shore, Roger, Brookes, Steven, Salmon, Phil & Lynnerup, Niels (2012). Timelines in teeth: using micro-CT scans of partially mineralized human teeth to develop a new isotope sampling strategy. American Journal of Physical Anthropology 147(Supplement 54): 216-216.