(pic outlinks to raa.se)
"Caroline Arcini of Sweden's National Heritage Board analyzed 557 skeletons of men, women and children from between 800 and 1050 A.D. They discovered that 22 of the men bore deep, horizontal grooves across the upper front teeth. "'The marks are traces of deliberate dental modifications ... they are so well-made that most likely they were filed by a person of great skill,' Arcini wrote in the current issue of the American Journal of Physical Anthropology.
"Traces of teeth mutilation have been found in all parts of the world except Europe, with the practice reaching its peak from 700 to 1400 A.D., during the height of the Viking Age."
The speculation on why they did this is still all over the place... from marks indicating "pain resistance" (and therefore ferocity!) to marks of slavery (a sort of branding), according to the article.
Here's a closer look at what you're dealing with:
Ribbed for your, um, terror.