The process of evaluating dental and skeletal relationships usually in lateral view by the use of measurements taken directly from the head or from cephalometric radiographs and tracings. Tracings can be made on which specific landmark lines and points are marked. The commonly used cephalometric points and lines include the Frankfort plane, maxillary plane, mandibular plane, and the upper, lower, and total face height.Important cephalometric angles are the SNB, SNA, ANB, upper incisor to mandibular plane (UiMx), upper incisor to lower incisor (UiLi), and the lower incisor to mandibular plane (LiMd).
Cephalometric norms for Caucasians (Eastman Standard) have been defined.The key features which can be identified are the relative size and position of the mandible and maxilla, and the steepness of the angle between the jaws and the angles of the upper and lower incisors to each other and to the skeletal base. Cephalometric radiographs can be taken at different stages of growth development and tracings of these superimposed on each other to show growth change. If no orthodontic treatment has been carried out then these changes will be due solely to growth.
Cephalometric angles (MMPA and SNB)
Cephalometric angle (ANB)
Commonly used cephalometric points and reference lines
Reference points and lines
A point (A)
The point of deepest concavity on the anterior surface of the maxilla.
Anterior nasal spine (ANS)
The tip of the anterior process of the maxilla at the lower border of the nasal aperture.
B Point (B)
The point of deepest concavity of the anterior surface of the mandibular symphysis.
The most anterior-inferior point on the chin.
The most posterior inferior point on the angle of the mandible.
The lowest point on the mandibular symphysis.
The point at which the frontal and nasal bones of the skull meet. It is a soft tissue landmark at the deepest point of the depression at the base of the nose in the midline and a hard tissue landmark at the most anterior point of the fronto-nasal suture.
The lowest anterior point on the lower margin of the orbit.
The most anterior point on the mandibular symphysis (chin) in the midline.
The uppermost outermost point on the bony external auditory meatus.
Posterior nasal spine (PNS)
The tip of the projection from the posterior border of the horizontal plate of the palatine bones.
The midpoint of the sella turcica.
A line connecting the midpoint of the sella turcica with the nasion. It represents the cranial base.
The line joining the porion and the orbitale.
The line joining the gonion and the menton.
The line joining the anterior nasal spine with the posterior nasal spine.
Functional occlusal plane
A line drawn between the cusp tips of the permanent molars and premolars (or primary molars in a mixed dentition).
Cephalometric norms for Caucasians (Eastman Standard)
81° ± 3°