Gonial angle
what a photo can give, and how we take it.
Two things a photo can see: jaw taper, the soft-tissue angle from the jaw angle to the chin, levelled to your pupils, and jaw definition, the shadow step across the jaw line. Both come from your ¾ views. Jaw:cheek width comes from the front. Each carries an error bar and a grade.
Also searched as jaw angle, ideal gonial angle, gonial angle measurement and mandibular angle.
What we report
Two things a photo can see: jaw taper, the soft-tissue angle from the jaw angle to the chin, levelled to your pupils, and jaw definition, the shadow step across the jaw line. Both come from your ¾ views. Jaw:cheek width comes from the front. Each carries an error bar and a grade.
Why not the clinical number itself
Gonion is a landmark on the mandibular BONE. In a photograph it is hidden under the masseter muscle and subcutaneous fat. What a photo-based tool measures instead is the angle of the soft-tissue silhouette: the muscle-plus-fat envelope, not the jaw underneath it. That outline also swings by tens of degrees with a few degrees of head yaw. Gonial angle is a lateral-cephalogram or CBCT measurement (adult norms ≈118–128°), and it cannot be recovered from a selfie.
Sources
- Lim et al. 2022 — bigonial breadth from 2D photogrammetry off by 9.3 mm vs calipers despite ICC 0.91 — doi.org/10.3389/fpubh.2021.813058
Ratios of near-coplanar frontal distances, angles relative to the interpupillary line, and skin appearance. Each comes with an error bar, and each is placed against a population you choose. Start an analysis or read the methodology.
The others people ask for
Same question, different measurement: what the clinical version needs, and what a photograph can give instead.
What is measured instead
How every bone-level measurement is taken here · methodology · glossary · all 35 insight pages