Harmony · Side view · Jaw
Mandibular Plane Angle
The inclination of the lower jaw border relative to horizontal in the oriented photo.
What is measured
The calculation
Acute angle of the constructed jaw-border line against image horizontal
Side view / Measurement guide
Follow the measurement
Dots mark the landmarks. Lines show how the measurement is taken.
In these guides, nasion means the nasal root, subnasale the nose base, and pogonion the most forward chin point. Frankfort refers to the direction from the ear-opening landmark to the lower orbital landmark.
Why it matters
This describes how steeply the lower jaw border runs toward the chin. It separates lower-border inclination from the local turn measured by the gonial angle.
- Lower: a lower jaw border closer to horizontal.
- Higher: a steeper lower jaw border.
Where the idea comes from
FaceIQ adaptation
Mandibular-plane angles belong to cephalometric analysis. FaceIQ uses an image-horizontal reference after photo orientation, rather than recalculating a bony plane from an X-ray. [1]
A worked example
A jaw border 20° from horizontal gives 20°. Rotating an uncorrected image by 5° can change the apparent inclination.
Example values explain the calculation. They are not a target range and are not measurements of the schematic above.
Research & further reading
The sources below explain the history or related evidence. FaceIQ’s score weights and reference ranges are model settings; these papers do not collectively validate the scoring system.
[1] Holdaway · 1984
A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part IIExplains how lip, chin and skeletal relationships must be considered together, with a range of profiles compatible with balance.