Facial convexity
 Lateral cephalometric radiograph (Commons). Facial convexity is a profile angle on a tracing, not a rating-app score.
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| Field | Anatomy |
|---|---|
| Also known as | facial convexity angle, G–Sn–Pog, angle of facial convexity
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| Related | Chin; Riedel's line; Ricketts E-line; Pogonion; Midface |
Facial convexity is how the side profile bends from the forehead through the base of the nose to the chin. The usual soft-tissue construction is the angle G–Sn–Pog (or G–Sn–Pg′): glabella, subnasale, and soft-tissue pogonion, with the vertex at subnasale.[1][2] A straighter run through those three points sits nearer 180°. Looksmaxxing reads a more convex profile (chin behind the midface) as a weak lower third, and a concave profile as a strong chin or a recessed midface.
Two conventions collide in forum talk. Some papers report the internal angle at subnasale (often ~165–175° in orthognathic Class I talk). Others report the supplement — how far the profile departs from a straight line (Legan and Burstone’s facial-convexity figure near 12° ± 4° in a Caucasian surgical sample).[2] The same face can be “12° convex” and “168° G–Sn–Pog.” State which construction you mean.
Godt and colleagues compared several photographic convexity angles against skeletal Class from Wits appraisal. Variants through nasion or glabella to Sn/Pog separated Class II from Class III cleanly; Class I versus Class II was harder, and method error sat around a degree.[1] A phone screenshot is not a cephalogram.
Method
What moves the angle is bone and fat, not a filter.
- Chin — sliding genioplasty or an implant advances Pog′ and flattens a convex profile. See Riedel's line.
- Midface — bimaxillary osteotomy, MARPE, or a paranasal implant changes Sn relative to the chin.
- Fat and posture — submental fat and a forward head fake convexity on camera. Body fat and chin tuck are the free levers.
- Ceph — a lateral film in natural head position is the clinical tool.[3]
This wiki's view
Convexity is a useful profile word if you name the landmarks. It is not a PSL score. Do not treat a 165° screenshot as a surgical indication.