Table 1 Definitions of the reference landmarks, lines and planes used in this study
Identification | Abbreviation | Definition |
|---|---|---|
Anatomical landmark | ||
Nasion | N | Anterior- and superior-most point of the frontonasal suture |
Sella | S | Sella turcica, which refers to the central area of the hypophyseal fossa located in the middle cranial fossa |
Orbital | Or | Right and left inferior-most points on the margin of the orbit |
Porion | Po | Right and left highest midpoint on the roof of the external auditory meatus |
Articulare | Ar | Right and left points that can be identified where the posterior margin of the ramus intersects with the lower boundary of the cranial base |
Gonion | Go | Right and left points of the bisecting angle between the ramus line and the body of the mandible line |
Menton | Me | Lowest most inferior point of the symphysis |
Subspinale | A | Deepest point of the premaxilla contour |
Supramental | B | Deepest point on the anterior mandible contour |
Anterior nasal spine | ANS | Most anterior point of the maxilla’s anterior nasal spine |
Posterior nasal spine | PNS | Point found at the medial end of the posterior border of the palatine bone horizontal plate |
U1 incisal edge | U1i | Upper incisor’s incisal edge |
U1 apex | U1a | Upper incisor’s root apex |
L1 incisal edge | L1i | Lower incisor’s incisal edge |
L1 apex | L1a | Lower incisor’s root apex |
Pronasale | Pn | Most protruding nasal tip point |
Labrale superior | Ls | Anterior-most point of the upper lip |
Labrale inferior | Li | Anterior-most point on the lower lip |
Soft tissue pogonion | Pog` | Most protruding point of the chin soft tissue contour |
Reference lines and planes | ||
Sella nasion plane | S-N | Line extending from the midpoint of the sella turcica to the nasion point |
Palatal plane | PP | Line connecting the anterior and posterior nasal spines |
Frankfort horizontal plane | FHP | Horizontal plane that passes through the bilateral orbital and porion points |
Mandibular plane | MP | Plane connecting the bilateral gonion and menton |
Nasion subspinale line | N-A | Line extending from the nasion to the subspinale point |
Anterior facial height | AFH | Line extending from the nasion to the menton point |
Posterior facial height | PFH | Line extending from the sella turcica to the midpoint between the two gonions |
Bisected occlusal plane | BOP | Plane formed by the lines bisecting the incisal tips, upper and lower anterior teeth and bilateral upper and lower first molar occlusal surfaces |
Functional occlusal plane | FOP | Plane constructed by the points bisecting the bilateral occlusal midpoints of the first permanent molars and the midpoints bisecting the intercuspation of the bilateral first premolars |
Long axis of the upper or lower incisor | UIx, LIx | Line that extends from the incisor edge to the incisor apex |
Aesthetic plane | E-P | Line between the nasal tip’s highest point and the most protruding point of the soft tissue contour of the chin |