Wear plus arecoline traces = betel nut.

In CPL-R2a, the wear was so extreme that it had reached the root in some areas.

The diagram of inferred nut positions based on the dental wear pattern, published in the paper, shows where the nuts were held: pressed against the rear molars, creating the grinding groove as the nut was moved slightly while being held in place for extended periods.

The pain this would have caused — once the pulp was exposed in the most severely damaged teeth — would have been constant and severe.