XMaS teeth studies establish our ancestors’ journeys

Scientists have teamed up with archaeologists to use X-rays to perform the world’s most detailed analysis of tooth structure and composition. The findings will make it possible to re-interpret archaeological records of ancient human migrations and may one day help scientists regrow teeth lost due to disease or ageing.

A team led by Dr Maisoon Al-Jawad from Queen Mary’s University of London visited the XMaS X-ray diffraction beamline, housed at the European Synchrotron Radiation Facility in Grenoble.

They used an X-ray diffraction technique whereby specially designed vacuum tube slits developed at XMaS focused an X-ray beam 20 microns across on teeth samples. By collecting the scattered beams of light after they interact with the teeth, they were able to build up two-dimensional diffraction images at 20 microns spatial resolution over the entire crown.

“We know that enamel grows in a complex mechanism involving interactions between proteins and minerals, but we wanted to shed light on the processes behind its development,” Dr Al-Jawad told Laboratory News.

Al-Jawad and colleagues placed three teeth from three children who died at different ages and therefore represented different stages in enamel development (provided by archaeologists). The most mature teeth came from a nine year old child from Northamptonshire, who lived in Anglo-Saxon England. The others were from children aged 1.5 and 2.5 years who died in the early 19^th century in East London.

Enamel composition is affected by diet, and archaeologists are able to study the ratio of elements such as strontium and lead present in teeth to find markers of the geology of the soils where the plants the person ate were grown. Studies that date back to the Neanderthal times are based on a widely accepted theory that tooth enamel grows uniformly outwards creating incremental growth, in much the same way as tree rings are used to estimate age.

Al-Jawad and her team discovered that the oldest teeth demonstrated an increased complexity in how mineralisation is distributed and a more diverse orientation of these crystals. However, they also found that mineralisation does not occur across the whole tooth surface. Instead, it is focused initially at the interface with the underlying dentine and inside the cusps (the tips of your teeth). It then spreads into the bulk of the enamel as you get older.

“I hope that these findings will benefit the study of the past, but also have applications for regenerative dentistry of the future. Archaeologists want to find out how our teeth developed, but current models are too simplistic. Only by looking at teeth at different stages of development (which is not possible in a clinical setting) can we establish this.” Al-Jawad told Laboratory News.

Trials are currently taking place in mice to grow bioengineered artificial teeth, and other studies are looking at ways to grow a new tooth in the lab made from an individual’s own cells. The findings will help these teams tailor their therapies.

“What we have shown for the first time at XMaS is the conventional understanding of how teeth mature is too simplified. We’re eventually hoping to create a truly accurate four-dimensional model of enable growth that will useful for both archaeologists and trainee dentists,” Al-Jawad added.

The UK government has awarded XMaS £6 million funding to enable the facility to continue delivering world class science.