Smile line: high, medium, and low
Quick facts
- Definition
- Position of the upper lip relative to the teeth and gums during a smile.
- Classification
- High (shows gum), medium (shows teeth and papillae), and low (does not show all the teeth).
- How to assess
- With the spontaneous smile, in person and in a photo or short video, not only the posed smile.
- Relevance in orofacial harmonization (HOF)
- Guides lips, toxin for gummy smiles, and the expectation of tooth display.
The smile line describes how far the upper lip rises when a person smiles. It is classified as high, medium, or low, depending on how much tooth and gum is visible. It is an individual trait, related to lip length, the height of the lower third, and the activity of the elevator muscles.
What are the three classifications?
| Classification | What is seen in the smile |
|---|---|
| High | Full front teeth and a band of gum above them |
| Medium | Front teeth and the gum between the teeth (papillae) |
| Low | Part of the front teeth, with the lip covering the upper portion |
This classification is descriptive. There is no right or wrong line: each pattern suits a face, and the focus of the assessment is the patient's comfort and the harmony of the whole.
Why does it matter in orofacial harmonization (HOF)?
A high smile line makes any change in the upper lip more evident, because the lip rises and the area is exposed. With a low line, the opposite holds: the upper lip shows little and the lower lip takes center stage.
This affects decisions such as:
- the volume of the upper lip relative to the lower (the lip proportion changes with the smile);
- the design of the Cupid's bow and the philtrum, which move when smiling;
- the approach to a gummy smile, in which botulinum toxin may be considered to reduce the action of the levator labii superioris muscle, when the cause is muscular;
- the reading of incisor display at rest and when smiling.
How to assess it in practice
The posed smile is deceptive. The best reading comes from the spontaneous smile, a relaxed conversation, or a short video. Also observe the symmetry of the smile and the position of the intercommissural line at rest and in motion.
In Harmy
The Lips point of the marking simulates lip filler seen from the front, with the face at rest in the photo. Smile dynamics are not simulated. For this reason, it is worth agreeing with the patient that the projection is illustrative and that the smile in motion is assessed in person.
Also called: smile height, gingival display.
Frequently asked questions
What is a gummy smile?
It is a smile in which a wide band of gum shows above the teeth, characteristic of a high smile line. Causes can be dental, skeletal, or muscular, and the approach depends on assessment.