Calcified Plaque From 1,000-Year-Old Teeth Preserves Medieval Bacteria Like ‘Microbial Pompeii’

It’s becoming clear that even medieval Europeans struggled to keep a nightly teeth-cleaning routine – and, like many of us, probably avoided an annual checkup like the plague. Researchers studying the teeth of 1,000-year-old German skeletons discovered bacteria and food particles entombed within calcified plaque. Using sophisticated methods of DNA sequencing, scientists were able to identify dietary records as well as the genomes of major periodontal pathogens, aka gum disease.

An international team of researchers says calcified dental plaque, known as calculus, is becoming increasingly important in analyzing ancient DNA. Unlike bone, which quickly loses much of its molecular material once it’s in the ground, calculus develops more slowly and enters the soil in a much more stable state, Futurity reports. This allows it to preserve biological material for a much longer time.

“Dental calculus is a window into the past and may well turn out to be one of the best-preserved records of human-associated microbes," Professor Christian von Mering, study author and group director at the SIB Swiss Institute of Bioinformatics, which performed the bioinformatics analysis, said in a statement.

The results of their study, published in the journal Nature Genetics, suggest that medieval Europeans suffered from many of the same bacterial gum diseases as we do today.

"One thing that is clear about the population we studied is that they didn't brush their teeth very often, if at all," Christina Warinner, an anthropologist at the University of Zurich in Switzerland and lead author of the study, told Live Science.

Warinner and her team were the first to use Raman spectroscopy, a means of studying the interaction between matter and radiated energy that is commonly used in chemistry, to study ancient dental plaque. They were able to look inside the ancient human oral microbiome (environment) and build a detailed image of people who lived more than 1,000 years ago.

“We knew that calculus preserved microscopic particles of food and other debris, but the level of preservation of biomolecules is remarkable,” study author Matthew Collins of the BioArCh research center in archaeology department at the University of York in England said in a statement. Collins likened the preserved plaque to “a microbiome entombed and preserved in a mineral matrix, a microbial Pompeii.”

This isn’t the first time ancient dental records have provided clues about the origin and spread of centuries-old bacteria. In January, scientists from the McMaster University in Canada analyzed teeth from two casualties of the Plague of Justinian, which killed as many as 25 million people worldwide during the 6th century AD, and were able establish links between that plague and other deadly pandemics in human history.