Figure 1: Arches, tooth categories and numbering, and toothsurfaces. Representation of different locations in the mouth: eachtooth number is indicated. Teeth were grouped into eight toothcategories. Six tooth surfaces were studied: Mesiobuccal (MB),Buccal (B), Distobuccal (DB), Mesiolingual (ML), Lingual (L),Distolingual (DL). Tooth surfaces were also grouped into threeclasses: interproximal mesial surfaces (MB and ML), interproximaldistal surfaces (DB and DL) and mid-surfaces (B and L).