Facial Convexity Angle: Glabella, Nasion and Measurement

The facial convexity angle describes the bend of a side profile. A common soft tissue construction joins glabella on the lower forehead, subnasale beneath the nose and pogonion at the most forward chin point, with the angle measured at subnasale. A construction starting at nasion uses a different upper landmark. Check both the landmarks and angle convention: an internal angle of 170° and its 10° supplement can describe the same traced profile.

On a true side profile, mark glabella, subnasale and the most forward visible chin point. Draw glabella-to-subnasale and subnasale-to-pogonion, then measure the internal angle at subnasale.

State whether the report uses that internal angle or the deviation from a straight line, calculated as 180 degrees minus the internal angle. Also record the direction of the bend when distinguishing convex and concave profiles.

Some constructions use soft tissue nasion in place of glabella, while others include the nasal tip. These measure different outlines. Do not compare them as if they were the same angle.

In 386 orthodontic patients aged 9–25, soft tissue convexity was associated with skeletal measures including ANB and Wits appraisal. An association in that sample does not make the surface angle a substitute for skeletal assessment (PMID 33809695).

Chin position, midfacial contour and the selected forehead landmark all contribute. Inspect each point before assuming the lower jaw is the cause of a convex profile.

A retrospective study of 180 adult orthodontic patients used profile silhouettes rated by orthodontists and laypeople. Several lower-face measurements had nonlinear relationships with ratings, and the relevant variables differed between the two evaluator groups (PMID 40120461).

The study examined selected post-treatment profiles. It cannot give an individual an attractiveness score from one convexity angle, or establish that making the profile straighter will improve every face.

An orthodontic study of 75 Class II patients measured lip and profile changes across extraction and non-extraction groups. Its results concern treatment in that setting and do not predict a response from the starting angle alone (PMID 35461792).

A surface angle can also change when the landmark placement or soft tissue contour changes. Distinguish a measured difference from a claim about its anatomical cause.

Include the forehead, nasal base and chin, with the lips resting naturally. Avoid deliberately projecting the jaw or pursing the lips to alter the profile.

Use the same side orientation and camera distance. Repeat the capture and tracing, then report the range across attempts. A near-straight profile is especially sensitive to which angle convention is used.

Shastra estimates surface geometry. Check its landmarks and angle convention before comparing its output with a cephalometric paper.

Compare chin height, nasomental angle and E-line lip position rather than asking one combined angle to explain the whole profile.

The useful result is a labelled construction with a consistent convention. A profile can be described geometrically without assigning a diagnosis or a universal beauty target.

Return to the measurement directory for the individual nose, lip and chin measurements.