Researchers have discovered what is believed to be the oldest ever dental filling.
A left canine crown from a 6500-year-old human mandible found in Slovenia appears to have a filling made from beeswax, Italian researchers have found.
Their findings have been published in the online journal PLoS One.
The fossilised jawbone, which is believed to have belonged to a 24 to 30-year-old, was found early last century, and has been filed away in a museum in nearby Trieste, Italy ever since.
"The jawbone remained in the museum for 101 years without anybody noticing anything strange," Claudio Tuniz, from the International Centre for Theoretical Physics in Trieste, told New Scientist.
However when Tuniz and his colleague Federico Bernardini used the specimen to test new X-ray imaging equipment they discovered unusual material attached to a canine.
Scans found the material, which infrared spectroscopy identified as beeswax, filled a large crack and a cavity in the tooth. Radiocarbon dating of the wax and the tooth found both to be around 6500 years old.
The researchers believe the beeswax was applied around the time of the individual's death, but cannot confirm whether it was shortly before or after.
If it is before, they say it was it was likely the beeswax was used to reduce pain and sensitivity from the vertical crack in the enamel and dentin layers of the tooth.
Tuniz said the severe wear of the tooth "is probably also due to its use in non-alimentary activities, possibly such as weaving, generally performed by Neolithic females".
It is possible the wax was applied after death, perhaps as part of a funeral ritual, and the tooth cracked when it dried out in the cave it was found. However the researchers believe this to be unlikely to the way the wax is placed in the crack.
The discovery is not the earliest example of prehistoric dentistry; In 2001 researchers discovered drill holes in 11 human molars in a graveyard in Pakistan, believed to be 7500 to 9000 years old.
Researchers said the latest discovery may help provide insight into early dental practices.
"This finding is perhaps the most ancient evidence of pre-historic dentistry in Europe and the earliest known direct example of therapeutic-palliative dental filling so far," Bernardini said.