Table 1 Cephalometric landmarks and reference lines
Measurement | Description |
|---|---|
S = sella | Midpoint of the sella turica |
N = nasion | Most anterior point on the frontonasal suture in the middle |
Or = orbitale | Most inferior and anterior point on the orbital margin |
Po = porion | Upper- and outer-most point on the external auditory |
ANS = anterior nasal spine | Tip of the bony anterior nasal spine in the middle |
PNS = posterior nasal spine | Tip of the posterior nasal spine in the midline |
A = subspinale | Deepest point on the curved profile of the maxilla between the anterior nasal spine and alveolar crest |
B = supramentale | Deepest point on the curved profile of the mandible between the chin and alveolar crest |
Go = gonion | Most posterior and inferior point on the angle of mandible |
Gn = gnathion | Most anterior and inferior point on the bony chin |
Pg = pogonion | Most anterior point on the bony chin |
Me = menton | Most inferior point of the mandibular symphysis in the midline |
U1 | Tip of the crown of the most anterior maxillary central incisor |
U6 | Mesial cusp tip of the maxillary first molar |
FH⊥N | A perpendicular line passing through the nasion to the Or-Po plane |
U1/ANS–PNS | Axial inclination of the maxillary incisors to the ANS-PNS plane |
U1/SN | Axial inclination of the maxillary incisors to the SN plane |
Pn = pronasale | Most prominent anterior part of the nose tip |
Cm | Most anterior point on the base of the nose (columella) |
Sn = subnasale | Junction between the lower border of the nose and beginning of the upper lip in the mid-sagittal plane |
Ss | Deepest point on the curved profile of the upper lip between Sn and Ss |
Ls = labrale superius | Maximum convexity of the vermillion border most prominent in the mid-sagittal plane |
Li = labrale inferius | Most prominent point on the vermillion border in the mid-sagittal plane |
Si | Deepest point on the curved profile between Li and Pg’ |
Pg’ = pogonion | Soft tissue pogonion, the most prominent or anterior point on the soft tissue chin |
Nasolabial angle | An angle formed between the upper lip and base of the nose (columella) |
E line | A line drawn from tip of the nose to soft tissue pogonion |
CFH | The horizontal reference line, the x-axis, a line drawn with an angle of 7 degrees to the SN line at the sella point |
VRL | The vertical reference line, the y-axis, a perpendicular line passing through the sella to the x-axis |