Lasers vary in type, but one major brand, Waterlase, works by heating water molecules in the tooth, which then expand and dislodge decayed tooth structure, according to manufacturer Biolase Inc.

WSJ: To Cut Tooth Decay: A Laser vs. a Drill

The physical anthropologist who carried out the examinations, Professor Andrea Cucina said the work could have been done to treat tooth decay, and suggested some plant or other material, which would have since decayed, could have been inserted into the hole.

BBC: Prehistoric dentistry evidence found