According to New Scientist VIKING warriors may have filed deep grooves into their teeth to indicate class or military rank.
From the article:
Caroline Arcini of Sweden's National Heritage Board analysed 557 skeletons from four major Viking-age Swedish cemeteries and discovered that around 10 per cent of men, but none of the women, bore horizontal grooves across the upper front teeth.
The marks, which were cut deep into the enamel, are often found in pairs or triplets and appear precisely made. They might have marked certain men as members of a group of tradesmen or warriors, or signified their ability to withstand pain, says Arcini...
Most of the men bearing the grooves were young, but in the absence of any distinctive injuries or artefacts buried with the skeletons, the exact reason for the marks remains a mystery.
This is the first known case of tooth filing in Europe, but it was common practice in the Americas between AD 800 and 1050. Since the skeletons date from around the same time, this raises the possibility that the Vikings picked up the practice during their travels. Arcini hopes future finds will reveal where the practice arose and how it spread.
The research has been published in the AJPA...