Why the obsession with dental plaque?
The technical name is dental calculus. It’s a partially mineralised accretion of bacterial gunk and food debris that builds up on teeth. At an average dental cleaning you may have 10-30 milligrams removed, but before modern dentistry as much as 600mg could build up on the teeth over a lifetime. It contains so many things – pollen, starch grains, animal muscle, bacteria, even a person’s DNA.
So it’s lucky ancient people didn’t floss?
Yes, for archaeologists. Calculus acts like a sink: it’s continually in contact with the mouth and the digestive and respiratory tracts. The plaque contains the remains of many bacterial species that inhabited the mouth and nasal passages, as well as immunological proteins associated with inflammation and infection. It’s like a time capsule. The amount of DNA is astounding. I’m finding 1,000 times more DNA by weight in fossilised calculus than in bone.
Story: Markus Becker, Spiegel | Photo: Spiegel