Incisor display: the upper lip at rest
Quick facts
- Definition
- The amount, in millimeters, of the edge of the upper central incisors visible below the upper lip at rest.
- How to measure
- Lips relaxed and slightly apart, head in a natural position, from the edge of the upper lip to the edge of the tooth.
- Reference range
- Generally 1 to 4 mm in young adults, greater in women than in men.
- With age
- Tends to decrease, while the display of the lower incisors increases.
- Relevance in HOF
- Links upper lip planning to smile aesthetics and dentistry.
Incisor display is the amount, in millimeters, of the edge of the upper central incisors that shows below the upper lip when the mouth is at rest, with the lips relaxed and slightly apart. It is a smile aesthetics measurement that links dentistry to planning the lip: a long upper lip hides the teeth, and a short or very mobile lip shows more. In young adults, the reference is usually between 1 and 4 mm, generally greater in women.
How is it measured and what influences it?
The measurement is taken from the front, with the head in a natural position and the patient relaxed, after moistening the lips or saying a short word and letting the mouth rest. It is measured from the edge of the upper lip to the incisal edge of the central incisor.
| Factor | Effect on display |
|---|---|
| Upper lip length (base of the nose to the edge of the lip, the philtrum area) | A long lip hides the tooth; a short one shows more |
| Vertical height of the maxilla | A long maxilla tends to show more tooth and gum |
| Tooth length and wear | A worn or short tooth shows less |
| Lip tone and mobility | A very mobile lip changes the reading when speaking |
| Age | Upper display decreases and lower display increases |
Display at rest is different from display in the smile. In the smile, the reference becomes how much gum shows, a topic covered in botulinum toxin for a gummy smile.
Why does it matter in HOF?
- Lip filler: adding volume to the upper lip vermilion can slightly evert the border and change how much tooth shows. In a long, thin lip, reading the display helps understand why the patient complains of an "aged mouth" even without obvious volume loss.
- Proportion: display is read together with the lip proportion between upper and lower lip and with the length of the philtrum.
- Toxin near the mouth: an injection that weakens the lip elevators can change the smile and the display, as described in lip ptosis after toxin.
- Dentistry: crowns, veneers, wear and orthodontics change the tooth edge. Integrated planning is in dental treatment and filler.
How does it show up in the assessment?
- Frontal photo at rest, with the lips relaxed, and another in the smile.
- Measurement with a millimeter ruler or caliper, always using the same method.
- Examination of the teeth: wear, restorations and position.
- Philtrum length and position of the mouth corner.
Also called: dental display at rest, upper incisor display, incisal display.
Frequently asked questions
How much of the tooth should show with the mouth at rest?
There is no single number. Smile aesthetics references usually cite 1 to 4 mm of the upper incisors visible at rest in young adults, generally more in women. The amount decreases with age, and what matters is the balance with the lip, the smile and the face.
Why do the upper teeth show less with age?
Because the upper lip tends to get longer and thinner with aging, from loss of muscle tone, volume and bone support, and because teeth wear down. The result is less upper tooth and more lower tooth showing at rest.