Harmony · Side view · Jaw
Gonial Angle
The angle between the ascending jaw-side direction and the lower mandibular border.
What is measured
The calculation
Angle between ear-notch–upper-gonion and chin-bottom–lower-gonion directions
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 the turn at the jaw corner in profile. It is different from jaw width, chin projection and the sharpness of the overlying soft tissue.
- Lower: a more closed turn between the constructed jaw directions.
- Higher: a more open turn between them.
Where the idea comes from
Clinical reference
The gonial angle comes from anatomical and cephalometric jaw analysis. FaceIQ approximates the border directions with external photo landmarks; that is not a radiographic bone measurement. [1]
A worked example
Two constructed jaw borders meeting at 120° form a more closed angle than borders meeting at 135°.
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.