Cephalometric analysis is used by the orthodontists to evaluate the dento-skeletal relationships, detect malocclusion and predict jaw growth. In order to have measurable variables we need to detect the cephalometric points and draw the
cephalometric lines and angles. By measuring these landmarks we will be able to compare it with the norm and diagnose the pathological condition.
The appropriate x-ray for an orthodontic assessment is called lateral cephalogram. It is a lateral projection of the skull where skull base, maxilla and mandible are visible along with the soft tissue profile.
Pogonion (Pg or Pog) is a cephalometric point located at the most forward projected point in the middle of the anterior surface of the chin. Its soft tissue analogue (soft tissue Pogonion) is usually marked as Pg' or Pog'. This craniometrial landmark is quite easy to locate since there is no superposition of bone structures or soft tissues in the anterior part of the mandible.
Gnathion is below the Pogonion and the B-point is just above it. Therefore Pog is situated between Gn and B-point.
Cephalometric measurements than include the Pogonion point are:
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Ar-Pg (mm) - The distance between Articulare and Pogonion
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Pg-NB (mm) - The distance between Pogonion and Nasion-B point
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H Angle (º) - The angle between Nasion-B point and soft tissue pogonion - upper lip
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N-A-Pg (º) - The angle between Nasion - A point and A point - Pogonion
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E line-labialis superior (mm) - The distance between upper lip and E-Line (Soft tissue pogonion - Nose tip)
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E line-labialis inferior (mm) - The distance between lower lip and E-Line (Soft tissue pogonion - Nose tip)