A team of dental physical scientists have been using x-ray
diffraction to study the development of children's teeth in order
to track migration patterns of our ancestors.
The team has been using the festively-named XMaS facility (X-ray
Magnetic Scattering) at the European
Synchrotron Radiation Facility in Grenoble to perform detailed
analysis of tooth structure and composition. The work will make it
possible to re-interpret archaeological records of ancient human
migrations and may also help scientists to regrow human teeth lost
due to disease or age.
The composition of enamel -- the hard outer-coating on teeth --
is affected by diet. Archaeologists are able to study the ratio of
elements such as strontium and lead present to find markers of the
geology in the soils where the plants the person ate were grown.
These variations can show a change in eating habits brought on by a
migration when the person was a child, when their enamel was still
These studies have been used to map human migrations right back
to Neanderthal times. They are based on the widely accepted theory
that tooth enamel grows uniformly outwards, creating incremental
growth lines a bit like tree rings. However, this theory has never
been put to the test, and results of the XMaS studies have shown
that in reality, tooth enamel is much more complex.
In order to do this, a team led by dental physical scientists
Maisoon Al-Jawad from Queen Mary, University of London used an
x-ray diffraction technique using specially designed vacuum tube
slits to focus an x-ray beam 20 microns across the teeth samples.
By collecting the scattering beams of light after they interacted
with the teeth, they built up two dimensional images at 20 micron
spatial resolution over the whole tooth. Al-Jawad studied teeth
from three children who died at different ages and therefore at
different stages of enamel development, including a nine-year-old
child who lived in Anglo-Saxon England and a 1.5-year-old and a
2.5-year-old who died in the early 19th century in London.
The team discovered that as children get older and enamel
develops, you see an increased complexity in how mineralization is
distributed. Furthermore, growth in crystal size is not uniform
across the whole tooth; mineralization is focused initially at the
interface with the underlying dentine layer and the tips of your
teeth. It then spreads into the rest of the enamel as you get
In addition to helping track ancient populations, the new
understanding will help in regenerative dentistry. Enamel is not
able to repair itself in the way that bone and dentine does. A
number of trials are looking to grow bioengineered artificial teeth
using a person's stem cells.
Dr Al-Jawad said: "The research is the first step towards a
truly accurate four dimensional model of enamel growth that will
allow scientists to more accurately interpret the movements and
feeding habits of ancient people. What we have shown for the first
time at XMaS is the conventional understanding of how teeth mature;
akin to the tree ring analogy is too simplified. With a complete
and accurate model we can start to re-interpret the archaeological
record and improve our understanding of how our ancestors moved
around the world as well as providing important information to
underpin future dental treatment."
The XMaS facility recently received funding of £6 million from
BIS and EPSRC to
continue working on material science studies such as this. The
facility has also been used to study magneto-electric materials
that could be used to make more efficient data storage and for
exploring new methods of reducing corrosion of cultural heritage
The results of the research will be published in European Cells &