Figure 2.

Reference and evaluation planes. (A): Reference plane #1 (RP-1) where the mesial contact point of the central incisors (a) and cusps of canines on both sides (b and c) are included; (B): Reference plane #2 (RP-2) perpendicular to the line connecting cusps of canines on both sides, and including the mesial contacting point of the central incisors; and (C): evaluation plane (EP) perpendicular to both RP-1 and RP-2, including the mesial contacting point of the central incisors, and including the central fossa of an artificial tooth of the first molar on the target mucosal area (d).