Table 1 Cephalometric landmarks and reference plane measurements
Landmark/Plane | Abbreviation | Definition |
|---|---|---|
Sella | S | The center of the pituitary fossa of the sphenoid bone. |
Nasion | N | The junction of the frontonasal suture at the most posterior point on the curve at the bridge of the nose. |
Porion | Po | The most superior point of the external auditory meatus. |
Orbitale | Or | The lowest point on the average of the right and left borders of the bony orbit. |
Posterior nasal spine | PNS | The tip of the posterior nasal spine. |
Anterior nasal spine | ANS | The tip of the anterior nasal spine. |
Point A | A | The most posterior point on the curve of the maxilla between the anterior nasal spine and superdentale. |
Upper incisor edge | UIE | The incisal edge point of the most prominent upper central incisor. |
Upper incisor apex | UIA | The incisal apex of the most prominent upper central incisor. |
Upper incisor resistance | UIR | The intersection point of the root axis and the upper border of the cervical third of the root. |
Point B | B | The most posterior point to a line from infradentale to pogonion on the anterior surface of the symphyseal outline of the mandible. |
Lower incisor edge | LIE | The incisal edge point of the most prominent lower central incisor. |
Lower incisor apex | LIA | The incisal apex of the most prominent lower central incisor. |
Lower incisor resistence | LIR | The intersection point of the root axis and the lower border of the cervical third of the root. |
Gonion | Go | The bisector of the angle between tangent through the posterior margin of the ascending ramus and tangent to the mandibular base at menton. |
Gnathion | Gn | The most anterior-inferior point on the contour of the bony chin symphysis. |
Sella-Nasion plane | SN | The plane through sella and nasion. |
Frankfort plane | FH | The plane through porion and orbitale. |
Palatal plane | PP | The plane through ANS and PNS. |
Mandibular plane | MP | The plane through gonion and menton. |
Horizontal reference plane | HRP | The plane parallel to FH plane passing through sella. |
Vertical reference plane | VRP | The plane was drawn as a perpendicular to HRP at sella. |