Nasolabial Angle
Pronunciation: nay-zo-LAY-bee-al
The angle formed at the junction of the columella of the nose and the upper lip, used to assess soft-tissue harmony in profile analyses.
Full Definition
The nasolabial angle is a soft-tissue cephalometric measurement defined as the angle between a line tangent to the columella base and a line tangent to the upper lip. It typically measures between 90° and 110° in a well-balanced profile. An acute nasolabial angle may suggest a protrusive upper lip or a downturned nasal tip, while an obtuse angle may indicate lip retrusion. The measurement is used in treatment planning for orthognathic surgery, rhinoplasty, and orthodontics. Editors must distinguish it from the nasal tip angle and should ensure the reference lines used to construct the angle are described in methods sections.
Usage
Usage note: Hyphenate as 'nasolabial' (one word, no hyphen). Distinguish from 'mentolabial angle', which is measured at the lower lip–chin junction.
In Context
- "A nasolabial angle of 88° confirmed upper lip protrusion as a component of the patient's profile imbalance." — Orthognathic surgery treatment planning record
- "The paper reports the nasolabial angle but does not define the reference lines; clarification is needed." — Peer-review editorial comment