Harmony · Side view · Lips
Lower Lip Burstone Line
The lower lip’s signed distance from a line running from nose base to soft-tissue chin.
What is measured
The calculation
Perpendicular lower-lip distance to the Burstone-line × photo scale
Side view / Measurement guide
Follow the measurement
Select a label to focus on its line. Select again to show all measurements.
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 relates the lower lip to the nose–chin framework. Reading it alongside the upper-lip distance helps distinguish the relationship of the two lips to the same reference.
- Negative in FaceIQ: the lip lies in front of the line.
- Positive in FaceIQ: the lip lies behind the line; zero means contact.
Where the idea comes from
Clinical reference
Burstone’s clinical work on lip posture used the nasal base and soft-tissue chin as a profile reference. Avoiding the nose tip changes which surrounding features influence the line. [1] [2]
A worked example
A lower lip 2 estimated mm behind the Burstone-line reads +2 mm. Moving it onto that unchanged line gives zero; 1 mm in front gives −1 mm.
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] Burstone · 1967
Lip posture and its significance in treatment planningHistorical clinical work on lip posture. Referencing the nasal base and chin provides another way to describe lip position.
[2] Buschang, Fretty & Campbell · 2011
Can commonly used profile planes be used to evaluate changes in lower lip position?Compared five lip reference lines, including Steiner’s S-line, in 79 orthodontic patients. Moving reference points can make a lip appear to move backward even when it moves forward.