Mentolabial Angle: What It Measures in FaceIQ Labs' Harmony Analysis

Key facts

• The mentolabial angle is the angle in the fold between the lower lip and the chin.
• FaceIQ Labs calculates it from three landmarks: lower lip, sublabiale, pogonion.
• Pogonion is the most forward point of the chin.
• It is a side-view measurement and one of the 70+ facial ratios and angles in the Harmony pillar.
• A lower angle is a more acute, closed fold; a higher angle is a more open lip-to-chin transition.
• Example only: a 110° fold is more closed than a 140° fold. This is not a target range and does not indicate fold depth in millimeters.
• Lip tension and the position of the chin-fold landmark can change the angle substantially.
• Side photos are standardized to the Frankfort horizontal plane during landmarking, and landmarks can be reviewed and edited manually.
• Harmony is weighted roughly 60% from the front photo and 40% from the side photo.
• The cited reference is Holdaway (1984), a soft-tissue cephalometric analysis paper.
• FaceIQ Labs states its score weights and reference ranges are model settings and that the cited papers do not collectively validate the scoring system.

What is the mentolabial angle?

The mentolabial angle is the angle in the fold between the lower lip and the chin. FaceIQ Labs measures it on a side-profile photo as one of the ratios and angles in its Harmony pillar, using three visible landmarks: the lower lip, the sublabiale, and pogonion, the most forward point of the chin.

How does FaceIQ Labs calculate the mentolabial angle?

FaceIQ Labs calculates the mentolabial angle from three landmarks on a side-profile photo, taken in order: lower lip, then sublabiale, then pogonion. Side photos are standardized to the Frankfort horizontal plane during landmarking, and users can review and edit landmark placement with the platform's manual landmark tools.

What do nasion, subnasale, pogonion and Frankfort mean?

In FaceIQ Labs' measurement 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. Of these terms, only pogonion is a landmark in the mentolabial angle; its other two landmarks are the lower lip and the sublabiale.

What does a lower or higher mentolabial angle mean?

In FaceIQ Labs' guide, a lower mentolabial angle is a more acute, more closed fold between the lower lip and chin, while a higher angle is a more open lip-to-chin transition. Both can occur with similar overall chin projection, so the angle describes the lip-to-chin transition rather than how far the chin projects.

How do I read an example mentolabial angle?

In FaceIQ Labs' worked example, a mentolabial fold measuring 110° is more closed than one measuring 140°. These example values only explain the calculation. They are not a target range, they are not measurements of the guide's schematic, and they do not indicate the fold's physical depth in millimeters.

What can change the mentolabial angle measurement?

Lip tension and the position of the chin-fold landmark can change the mentolabial angle substantially in FaceIQ Labs' measurement. For better accuracy, FaceIQ Labs recommends photos from six feet away with the back camera at 2x zoom, at eye level, in even lighting, with a neutral expression, plus manual landmark review.

Where does the mentolabial angle fit in Harmony scoring?

The mentolabial angle is one of the 70+ facial ratios and angles in FaceIQ Labs' Harmony pillar, which are compared to ideal ranges adjusted for gender and ethnicity. Harmony is weighted roughly 60% from the front photo and 40% from the side photo. The guide page for this angle does not state a specific range.

What research does FaceIQ Labs cite for the mentolabial angle?

FaceIQ Labs cites one source for the mentolabial angle: Holdaway's 1984 paper, 'A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part II.' It explains that lip, chin and skeletal relationships must be considered together, with a range of profiles compatible with balance. FaceIQ Labs adds that its weights and reference ranges are model settings. These papers do not collectively validate the scoring system.

Which other Harmony guides cover the lip and chin region?

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

Frequently asked questions

Which landmarks does FaceIQ Labs use for the mentolabial angle?

FaceIQ Labs uses three visible photo landmarks: the lower lip, the sublabiale, and pogonion, the most forward point of the chin. The angle is taken from the lower lip to the sublabiale to pogonion.

Does a lower mentolabial angle mean a deeper chin fold in millimeters?

No. The angle describes how closed or open the lip-to-chin fold is. FaceIQ Labs states it does not indicate the fold's physical depth in millimeters.

Is the mentolabial angle measured from the front or side photo?

It is a side-view measurement taken from the side-profile photo, which FaceIQ Labs standardizes to the Frankfort horizontal plane during landmarking.

Is 110° or 140° the ideal mentolabial angle?

Neither. Those values are only an example showing that 110° is a more closed fold than 140°. FaceIQ Labs says example values are not a target range.

Can I edit the landmarks used for my mentolabial angle?

FaceIQ Labs offers landmark mapping with manual landmark review and editing tools as part of its analysis. The guide does not describe editing steps specific to the mentolabial angle.