The oral health of 21 medieval settlers from Denmark is revealed in an analysis of dental plaque published in Nature Communications this week. The study suggests that specific profiles of proteins can distinguish healthy individuals from those more vulnerable to oral diseases. These differences are not observable using traditional methods, and the authors argue this illustrates the value of their approach in understanding historical oral health.

Dental plaque preserves a wide variety of molecules, some of which are human while others originate from bacteria or food. This molecular composition differs in health and disease, and it has been suggested to be as unique as a fingerprint.

Jesper Olsen, Enrico Cappellini and colleagues used a method called metaproteomics to identify and quantify human, bacterial and dietary proteins in the dental plaque of 21 individuals dating from around 1100-1450 CE retrieved from the archaeological excavation of the cemetery of Tjaerby, Denmark. They compared these samples to those from seven healthy present-day participants. The authors' analysis reveals one group of medieval samples that is mainly defined by pathogenic bacteria and a second group showing greater similarities to the healthy oral flora of living individuals. The protein profiles also indicate general differences between ancient and modern plaque, which might mirror changes in lifestyle and hygiene.

The findings suggest that metaproteomics has the potential to enable more detailed reconstructions of human health in archaeological populations, the authors conclude.