Table 1 Definition of landmarks

UL6

Mesiobuccal cusp of maxillary left first molar

UL2I

Midpoint of the incisal edge of maxillary left lateral incisor

UL2C

Midpoint of the cervical palatal margin of maxillary left lateral incisor

UL1I

Midpoint of the incisal edge of maxillary left central incisor

UL1C

Midpoint of the cervical palatal margin of maxillary left central incisor

UR1I

Midpoint of the incisal edge of maxillary right central incisor

UR1C

Midpoint of the palatal cervical margin of maxillary right central incisor

UR2I

Midpoint of the incisal edge of maxillary right lateral incisor

UR2C

Midpoint of the cervical palatal margin of maxillary right lateral incisor

UR6

Mesiobuccal cusp of maxillary right first molar

UL2D

Distal surface of maxillary left lateral incisor

UR2D

Distal surface of maxillary right lateral incisor

UL3M

Mesial surface of maxillary left canine

UR3M

Mesial surface of maxillary right canine