About the research
This project has arisen out of my unusual career pathway: practising as dentist and orthodontist for 30 years and studying temporal isotope profiles in archaeological teeth for my research led me to combine both in a novel approach which allows me to work with specialists in both clinical and anthropological disciplines.
What do we know already?
Primary dentine in a human tooth is laid down in a regular incremental manner and does not remodel (Dean and Scandrett 1985). Like incrementally-growing tissues such as hair and fingernails, it records carbon and nitrogen isotope ratios (δ15N and δ13C) of the body at the time of formation (Müldner et al 2011). From modern studies of nutritional distress (e.g. Neuberger et al. 2013) we know that dietary and physiological changes are recorded in incrementally-growing tissues through changes in the δ15N and δ13C. In other words, δ15N and δ13C profiles in tissues such as teeth can be used to explore temporal resolution of diet and physiology retrospectively. We also know that the first 0.5mm of dentine in deciduous teeth is formed before birth and retains the isotope ratios of that period of life (AlQahtani et al 2010, Montgomery and Beaumont unpublished).
What was found
I used my technique to analyse teeth of children buried during the Kilkenny Workhouse Famine in Ireland (Beaumont et al 2013a, 2015). I found a marked difference in nitrogen levels in between those children who died early and those children who survived from Neolithic (Montgomery et al., 2013; Armit et al., 2015), Iron Age and 19th-Century Britain and Ireland (Beaumont et al., 2015). The earliest-forming dentine (which corresponds to the in utero stage) was much higher and wider-ranging than predicted from adult diets.
A small number of modern teeth have also been analysed. 16 teeth extracted as part of dental treatment at the Medical School, Khartoum, Sudan, were collected with medical histories and analysed. After NRES approval (REC reference number 14/EE/1038) 8 teeth were collected from participants of the Born in Bradford cohort study and analysed with reference to pseudonymised medical data. High nitrogen correlated to low birth weight in both studies.
Why is this important?
The Barker hypothesis states that nutrition and growth before birth (i.e. quality of life in the womb) alter the development of the foetus and therefore, are predictors of health later in life (Barker 2009) and can also affect future generations (Champagne et al., 2013). Therefore, techniques for retrospectively assessing antenatal quality of life could identify those children at higher risk of health difficulties later in life.
The potential for this as a marker for in utero malnutrition was discussed in my most recent article in the AJPA (Beaumont et al., 2015) and publicity which centered on an article in the Guardian Newspaper.
If enrichment of the δ15N in dentine could be attributed to higher individual stress levels, this could be of benefit in the assessment of the health of children during the period of growth of the teeth. Identifying children at the age of 6-7 (when the first deciduous teeth exfoliate) at risk of obesity, diabetes and heart disease using a non-invasive method could allow resources to focus preventative measures for these individuals. In a population, it could also help to promote measures to improve maternal nutrition during pregnancy. Analysis of teeth in forensic cases of nutritional neglect would be a further application.