Traces of beeswax filling inside a tooth in a prehistoric human jawbone have given scientists a rare glimpse of early dentistry.

Team leaders Federico Bernardini and Claudio Tuniz, of the Abdus Salam International Centre for Theoretical Physics in Italy, worked with researchers at Sincrotrone Trieste and other centers in Italy and Australia to analyze the 6,500-year-old "human mandible".

They write about their findings in a paper published online in the open access journal PLoS ONE on 19 September.

The tooth is part of a human jawbone found in Slovenia near Trieste. The researchers note that evidence of prehistoric dentistry is sparse, so they hope the find will help them better understand early dental practices.

The tooth is a left canine, whose crown bears the traces of filling with beeswax.

The researchers used a range of tools to examine the tooth, including "synchrotron radiation computed micro-tomography (micro-CT), Accelerator Mass Spectrometry (AMS) radiocarbon dating, Infrared (IR) Spectroscopy and Scanning Electron Microscopy (SEM)".

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The results showed the tooth was worn, exposing an area of dentin, and also bore a vertical crack in the enamel and dentin layers, the upper part of which was filled with beeswax.

The team suggests the filling was probably applied around the time of the individual's death, but can't be sure whether it was shortly before or even shortly after.

"If the filling was done when the person was still alive, the intervention was likely aimed to relieve tooth sensitivity derived from either exposed dentine and/or the pain resulting from chewing on a cracked tooth," they write.

If it was applied before death, then it is the earliest known direct evidence of a dental filling being applied for therapeutic, pain-relieving reasons.

In a press statement, Tuniz speculates that the severe wear of the tooth is probably due to the fact people of that era used their teeth for lots of other things, not just eating, for instance Neolithic women used their teeth to cut or hold thread when weaving.

Bernardini says this is possibly the "most ancient evidence of pre-historic dentistry in Europe and the earliest known direct example of therapeutic-palliative dental filling so far".

The study is part of the ICTP/Elettra EXACT Project (Elemental X-ray Analysis and computed Tomography) funded by Friuli Venezia Giulia of Italy.

Written by Catharine Paddock PhD