Tooth grooves, occlusal striations, dental calculus, and evidence for fiber processing in an Italian...

We conducted a systematic macroscopic and microscopic examination of occlusal and para-occlusal wear in a large dental sample (n = 3,014) from 217 individuals dated to the Early Bronze age site of Gricignano d'Aversa, Italy. We used macroscopic and microscopic techniques to document nondietary occlusal and para-occlusal wear and to analyze calculus inclusions in some of the teeth. In combining an analysis of the wear with the calculus inclusions we linked the specific wear to the likely fiber that was involved in producing it.

Teeth and their high resolution epoxy casts were analyzed through SEM and reflected light microscopes. Nineteen individuals (fifteen with activity induced dental modifications and four as a control sample) were examined for the presence of calculus inclusions.

Activity induced dental modifications (AIDMs), notches, grooves and micro-striations, were found in the 62.2% of the adult females, in 21.2% of the adults of unknown sex and in a single male. We found the full spectrum of dental manipulations from very minor nonocclusal wear in some young individuals to severe attrition at the other extreme. The width of the striations and grooves, mostly on the upper incisors, suggests a craft activity involving fibers and thread production and manipulation. From the dental calculus of two females with grooves and striations, we extracted three fragments of fibers, identified as hemp (Cannabis, sp.). Previously from Gricignano woven hemp fibers were found on both surfaces of a metal blade associated with a male burial.

This study found the co-occurrence of tooth AIDMs and the actual fibers preserved in the dental calculus. As more work is done analyzing dental calculus in a variety of humans, it is apparent that this biological material holds rich resources documenting non-dietary habits.