Lower Lip Burstone Line in FaceIQ Labs Harmony Analysis: What It Measures

Key facts

• The Lower Lip Burstone Line is measured in side view and belongs to FaceIQ Labs' Harmony pillar.
• The calculation is the perpendicular lower-lip distance to the Burstone line multiplied by the photo scale.
• The Burstone line runs from the nose base (subnasale) to the soft-tissue chin.
• In FaceIQ Labs, negative means the lip lies in front of the line, positive means it lies behind the line, and zero means contact.
• A negative value is not automatically a poor result.
• Millimeter values are estimates: FaceIQ Labs scales photos using an assumed 190 mm hairline-to-chin height.
• The concept traces to Burstone's 1967 clinical work on lip posture.
• FaceIQ Labs states its score weights and reference ranges are model settings, and the cited papers do not collectively validate the scoring system.
• Harmony is weighted roughly 60% from the front photo and 40% from the side photo, and side photos are standardized to the Frankfort horizontal plane during landmarking.

What does the Lower Lip Burstone Line measure?

The Lower Lip Burstone Line is a side-view Harmony measurement in FaceIQ Labs. It is the lower lip's signed perpendicular distance from a line running from the nose base (subnasale) to the soft-tissue chin, multiplied by the photo scale. In FaceIQ Labs guides, nasion means the nasal root, subnasale the nose base, and pogonion the most forward chin point.

What do positive, negative and zero values mean?

• Negative: in FaceIQ Labs, the lower lip lies in front of the nose-base-to-soft-tissue-chin line.
• Positive: the lower lip lies behind the line.
• Zero: the lip is in contact with the line.
• A negative value is not automatically a poor result; the sign describes position relative to a reference line.
• The sign convention describes FaceIQ Labs' result.

Why does FaceIQ Labs include the Lower Lip Burstone Line?

FaceIQ Labs includes the Lower Lip Burstone Line to relate the lower lip to the nose–chin framework of the face in side view. Reading it alongside the upper-lip distance helps distinguish how the two lips relate to the same reference. Using the nasal base reduces nose-tip influence, but the value still depends on chin and nose-base position.

Where does the Burstone line come from?

The Burstone line comes from Burstone's clinical work on lip posture, which used the nasal base and soft-tissue chin as a profile reference. FaceIQ Labs' guide cites Burstone's 1967 paper. Avoiding the nose tip changes which surrounding features influence the line.

How does a worked example of the Lower Lip Burstone Line read?

In FaceIQ Labs' worked example for the Lower Lip Burstone Line, a lower lip estimated 2 mm behind the line reads +2 mm. Moving it onto that unchanged line gives zero, and a lip 1 mm in front reads −1 mm. These values explain the calculation; they are not a target range or measurements of the schematic.

How accurate are the millimeter values for this measurement?

The millimeter values FaceIQ Labs reports for the Lower Lip Burstone Line are estimates, not calibrated physical measurements. FaceIQ Labs scales each photo using an assumed 190 mm hairline-to-chin height, so the values are approximate.

Does published research validate FaceIQ Labs' scoring for this measurement?

No. FaceIQ Labs states that its score weights and reference ranges are model settings, and the papers cited in the Lower Lip Burstone Line guide do not collectively validate the scoring system. The two sources explain the history or related evidence behind lip-position measurement.

Which research does the Lower Lip Burstone Line guide cite?

• Burstone, 1967: 'Lip posture and its significance in treatment planning'. Historical clinical work on lip posture; referencing the nasal base and chin gives another way to describe lip position.
• 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.

Where does this measurement fit in FaceIQ Labs' Harmony scoring?

FaceIQ Labs' Harmony pillar measures 70+ facial ratios and angles compared with ideal ranges adjusted for gender and ethnicity. The Lower Lip Burstone Line is a side-view guide within Harmony. Harmony is weighted roughly 60% from the front photo and 40% from the side photo, and side photos are standardized to the Frankfort horizontal plane during landmarking.

Which related side-view lip measurements does FaceIQ Labs offer?

• Upper Lip Burstone Line
• Lower Lip S-Line Position
• Upper Lip S-Line Position
• Lower Lip E-Line Position
• Upper Lip E-Line Position
• Holdaway H Line
• Mentolabial Angle

Frequently asked questions

Is a negative Lower Lip Burstone Line value bad?

No. FaceIQ Labs states that a negative value, meaning the lower lip lies in front of the nose-base-to-chin line, is not automatically a poor result. It describes position relative to a reference line.

Why does the Burstone line use the nose base instead of the nose tip?

Burstone's clinical work used the nasal base and soft-tissue chin as a profile reference. Avoiding the nose tip changes which surrounding features influence the line, though the value still depends on chin and nose-base position.

Are the millimeter values exact physical measurements?

No. FaceIQ Labs scales photos using an assumed 190 mm hairline-to-chin height, so the millimeter values are estimates rather than calibrated physical measurements.

Does published research validate FaceIQ Labs' scoring for this measurement?

FaceIQ Labs says the cited papers, Burstone (1967) and Buschang, Fretty and Campbell (2011), explain history or related evidence but do not collectively validate its score weights and reference ranges, which are model settings.

How is the Burstone line related to the S-line and E-line measurements?

FaceIQ Labs offers Burstone line, S-line and E-line positions as separate guides. The 2011 study it cites compared five lip reference lines, including Steiner's S-line, and found that moving reference points can make a lip appear to move backward even when it moves forward.