Table 1 Definitions of cephalometric reference points, lines, and planes
Name | Symbol | Definition |
|---|---|---|
Sella | S | The center of the hypophysial fossa (sella turcica) |
Nasion | N | The most anterior point of the fronto-nasal suture |
Orbitale | Or | Lowest point on the inferior margin of the orbit |
Porion | Po | Uppermost point of bony external auditory canal |
Anterior nasal spine | ANS | The anterior tip of the sharp bony process of the maxilla in the midsagittal plane |
Posterior nasal spine | PNS | The most posterior aspect of the palatine bone in the midsagittal plane |
Subspinale | A | The deepest point in the midline concavity of the anterior maxilla between the ANS and the alveolar crest (prosthion) |
Supramentale | B | The deepest point in the midline concavity of the anterior mandible between the alveolar crest (infradentale) and pogonion |
Pogonion | Pg | The most prominent point on the chin |
Gnathion | Gn | The most anterior inferior point of the bony chin |
Menton | Me | The most inferior point on the mandibular symphysis |
Gonion | Go | Most posterior inferior point on angle of mandible, located by bisecting the angle formed by the ramal and mandibular planes |
Articulare | Ar | Intersection of posterior border of ramus and inferior border of occipital bone |
Condylion | Co | Most posterior superior point on mandibular condyle |
Pterygomaxillary fissure | Ptm | The intersection of the anterior and posterior walls of the pterygomaxillary fissure inferiorly |
Maxillary incisor tip | Is | The incisal tip point of the most prominent maxillary central incisor |
Mandibular incisor tip | Ii | The incisal tip point of the most prominent mandibular central incisor |
Infradentale | Id | The most anterosuperior point on the labial crest of the mandibular alveolar process |
Molar superius mesial cusp | Ms | The mesio-buccal cusp tip of the maxillary first permanent molar |
Soft tissue subspinale | A’ | The point of greatest concavity in the midline of the upper lip between subnasale and labrale superius |
Labrale superius | Ls | The most anterior point on the convexity of the upper lip |
Labrale inferius | Li | The most anterior point on the convexity of the lower lip |
Soft tissue submentale | B’ | The point of greatest concavity in the midline of the lip between labrale inferius and soft tissue pogonion |
Soft tissue pogonion | Pg’ | The most prominent or anterior point on the soft tissue chin in the midsagittal plane |
Horizontal reference plane | HR | A line established by rotating 7° clockwise from sella-nasion plane |
Vertical reference plane | VR | A vertical line passing through sella and perpendicular to the HR plane |
Sella-Nasion line | SN | Reference line joining sella and nasion points |
Frankfort Horizontal | FH | Reference line joining porion and orbitale points |
Nasion perpendicular | Na Perp | Nasion perpendicular line to FH plane |
Occlusal plane | OP | Plane drawn through the region of overlapping cusps of first premolars and first molars |
Palatal plane (Maxillary horizontal reference line) | PP (x − Mx) | Reference line joining anterior nasal spine and posterior nasal spine |
Mandibular plane | MP | Reference line joining menton and gonion |
Mandibular horizontal reference line | x − Md | Reference line joining gnathion and gonion |
Maxillary vertical reference line | y − Mx | A vertical line passing through the PNS and perpendicular to x − Mx |
Mandibular vertical reference line | y − Md | A vertical line passing through the gonion, perpendicular to the x − Md |