Fig 4. Comparison of dental wear facet patterns between the pre-industrial and industrial groups.

Above: Comparison of lower second molar dental wear facet patterns between the medieval and early post-medieval Periods and the industrial Period. Wear facets are marked as follows: buccal phase I facets are blue, lingual phase I facets are red, phase II facets are green and tip crushing areas are orange. Note large phase II wear facets in the industrial period relative to buccal phase I wear. In the earlier periods, lingual phase I wear facets and buccal phase I facets occupy a larger proportion of the overall wear facet area. Below: Ternary plot showing the relationship between period and relative wear facet area of the lower second molar (composed of buccal phase I (BPI), lingual phase I (LPI) and phase II (PII) facet areas). The industrial group is displayed as dark grey circles and the medieval and early post-medieval group as light grey circles. The centre value for each period is represented as a larger filled shape surrounded by 95% confidence regions. The industrial group is represented by a large black circle and the medieval group a white circle.