Fig. 2

Esthetic-related landmarks (a) Landmarks 1 and 2, the mesio-incisal angle of the maxillary central incisors on both sides; Landmark 3, the midpoint of the mesio-incisal angle ligature between the maxillary central incisors on both sides; Landmarks 4 and 5, the mesio-buccal cusp tip of the maxillary right and left first molars; Landmarks 6–11, the gingival edge apical top of the MAT on the labial side; Landmark 12–16, the top of the gingival papilla of the MAT; Landmark 23, the midpoint of the right maxillary central incisors at the gingival edge midpoint. b Landmarks 17–22, the top at the direction of the gingival edge of the MAT on the palate side