Table 1.

Reference points and planes (modified from Fujiki et al. [14])

Landmark	Definition
ANS	Point at the tip of the anterior nasal spine
PNS	Point at the dorsal limit of the maxilla
Me	The most posterior point on the mandibular symphysis
I	Point at the edge of the maxillary incisor
C1	The most anterior point of the atlas
NF	Plane through ANS and PNS
SP	Plane passing the edge of the maxillary incisor and parallel to the palatal plane
AM	Boundary point between the maxillary central incisor and the palatal mucosa
E	Point nearest to the tongue base in the region of contact between tongue and palatal mucosa
MM	Point at which a line perpendicular to NF drawn through a point equidistant between ANS and PNS intersects the palatal mucosa
MT	Point at which a line perpendicular to NF drawn through a point equidistant between ANS and PNS intersects the dorsal tongue
MS	Point at which a line perpendicular to NF drawn through a point equidistant between ANS and PNS intersects SP
PM	Point at which the soft and hard palates intersect
PT	Point at which a line perpendicular to NF through point PM intersects the dorsal tongue
PS	Point at which a line perpendicular to NF through point PM intersects SP
D	Point at which a line through Me and C1 intersects the dorsal tongue
Ti	Tongue tip
SI	Point at which a line perpendicular to NF through PNS intersects SP