Botulinum Toxin for a Gummy Smile: How to Assess
A gummy smile is the exposure of gum above what the patient finds pleasing when smiling. The concern is aesthetic, but the diagnosis is anatomical and functional: the gum may show because the lip rises too much, because the lip is short, because the maxilla grew more vertically or because the teeth look short. Botulinum toxin only acts on the first of these causes.
That is why the most important step is not the injection but the assessment. This guide is a review: it gives no doses, points or technique, which are the qualified professional's decision, in line with the product's package insert and the rules of their professional council.
What defines a gummy smile?
There is no single number that turns gum exposure into a problem. The literature often uses as a reference an exposure above about 3 to 4 mm in the spontaneous smile, but perception varies with sex, age, tooth proportions and, above all, with how much it bothers the patient.
A few facts help put this in context:
- Gum exposure tends to decrease with age, because the upper lip loses tone and descends.
- A posed smile usually shows less gum than a spontaneous one. Assess both.
- A small amount of gum exposure is, to many observers, a sign of a youthful smile.
What causes a gummy smile?
| Cause | How to recognize it | Where toxin fits | Usual treatment of the cause |
|---|---|---|---|
| Upper lip hypermobility | Lip of normal length at rest, but rises a lot when smiling | It is the main indication | Toxin, or lip repositioning surgery in selected cases |
| Short upper lip | Short lip already at rest, with more tooth exposure than usual | Limited effect | Individual assessment; sometimes a combination of approaches |
| Vertical maxillary excess | Lengthened lower third, gum exposure at rest, lips that do not close without effort | Small or no effect on the cause | Orthodontics and orthognathic surgery, with specialist assessment |
| Altered passive eruption | Short clinical crowns, gum covering part of the enamel | Does not treat the cause | Periodontal surgery (crown lengthening) |
| Gingival enlargement | Thick or enlarged gum, sometimes from inflammation or medication | Does not treat the cause | Periodontal treatment |
| Dentoalveolar extrusion | Front teeth more "descended" relative to the back teeth | Does not treat the cause | Orthodontics |
Many patients have combined causes. In those cases, toxin can be part of the plan, but not the whole solution. When the cause is bony, dental or periodontal, the path is referral for specialist assessment.
Which muscles take part in lifting the lip?
Lifting the upper lip in a smile depends on a set of muscles working together. The ones most cited in gummy smile are:
- Levator labii superioris, which lifts the central and lateral portion of the lip.
- Levator labii superioris alaeque nasi, which lifts the lip and flares the nostril, with an important role in anterior gum exposure.
- Zygomaticus minor and major, which lift and pull outward the corner and lateral portion of the lip.
- Depressor septi nasi, which in some patients takes part in shortening the lip when smiling.
On the opposite side, the orbicularis oris gives the lip its tone. The result of the smile is the balance among these groups, and so muscle treatment must consider the whole smile, not just the gum.
What are the types of muscular gummy smile?
To guide planning, gummy smile of muscular origin is usually described by the area where the gum shows:
| Type | Where the gum shows | Muscles most involved, in general |
|---|---|---|
| Anterior | In the area of the incisors and canines | Levator labii superioris alaeque nasi |
| Posterior | In the area of the premolars and molars | Zygomatics and levator labii superioris |
| Mixed | Anterior and posterior | Combination of the groups above |
| Asymmetric | More on one side than the other | Unequal activity between the sides |
This reading helps in understanding each patient's smile. The choice of muscles, points and doses is an individual clinical decision, based on the anatomy observed.
How to assess a gummy smile at the visit?
An organized assessment avoids most errors:
- Lip at rest. Observe the length of the upper lip, the exposure of the incisors and lip seal.
- Spontaneous and posed smile. Ask the patient to laugh at something, not just "smile for the photo." Record both.
- Amount and location of exposure. Anterior, posterior, mixed or asymmetric.
- Teeth and gum. Width-to-height proportion of the crowns, gum contour and periodontal health. Short crowns call for periodontal assessment.
- Facial proportion. A lengthened lower third and gum exposure at rest suggest a skeletal component. See facial assessment by thirds.
- Symmetry. Record the smile's facial asymmetry before any intervention.
- Lip. Volume, vermilion and philtrum affect how the smile reads; assessment of the thin lip is in thin lip: how to assess.
What are the risks of toxin for a gummy smile?
The area is small, the muscles are close together and the result is judged in motion, which makes unwanted effects very noticeable:
- Excessive drop of the upper lip, with the lip covering the teeth more than desired.
- Asymmetric smile, from unequal response between the sides.
- Stiff or artificial smile, when lifting is limited too much.
- Apparent lengthening of the lip and a change in the look of the philtrum.
- Altered speech or fine movements, usually mild and temporary.
- Effect on neighboring muscles, changing the mouth corner or the dynamics of the nasolabial fold.
These effects are usually temporary, but the patient lives with them for weeks. A conservative approach, with a follow-up visit to assess, tends to be the safest.
What is the expected timeline?
| Moment | What usually happens |
|---|---|
| First days | Little visible change |
| Up to about two weeks | The effect sets in; less gum shows when smiling |
| Follow-up | Assess symmetry and naturalness of the smile, with photos and video |
| A few months | The effect fades and the gum exposure gradually returns |
Timeframes vary with the product and the patient. See how long toxin takes to work and how long toxin lasts. Post-injection instructions are in care after botox.
How to explain it to the patient?
If the cause is different, say so clearly and refer. A patient who understands why toxin is not the best option for them trusts the professional more. Document the assessment and use an informed consent that mentions possible effects on the smile; a template is at consent form for botulinum toxin.
And in Harmy?
Checklist before toxin for a gummy smile
- Gum exposure measured in the spontaneous and posed smile.
- Cause identified: muscular, short lip, skeletal, dental or periodontal.
- Referral made when the cause is not muscular.
- Type recorded: anterior, posterior, mixed or asymmetric.
- Photos and video of the smile with standardized framing.
- Indication checked against the registered product's package insert.
- Patient informed about lip drop, asymmetry and a stiff smile.
- Follow-up scheduled to assess symmetry and naturalness.
Frequently asked questions
Does botox fix a gummy smile?
It can soften it when the main cause is excessive lifting of the upper lip when smiling. When the gum exposure comes from the jawbone, from short clinical crowns or from excess gum tissue, toxin has a limited effect or none. Diagnosing the cause comes first.
How long does botox last for a gummy smile?
The effect is temporary and usually lasts a few months, as in other areas treated with toxin, varying with the product, the dose and the patient. To maintain it, the injection has to be repeated after a new assessment.
Can botox for a gummy smile make the smile look strange?
It can. If the effect is greater than needed or reaches neighboring muscles, the upper lip may drop too much, the smile may become asymmetrical or look stiff. The effect is usually temporary, but it bothers the patient a lot.
What causes a gummy smile?
The most described causes are an upper lip that rises too much when smiling, a short upper lip, excessive vertical growth of the maxilla, teeth with short clinical crowns from altered passive eruption, and excess gum tissue. Often there is more than one cause at the same time.
Harmy images are illustrative simulations generated by AI from the patient's photo to support the conversation between practitioner and patient. They are not a promise of results. Indication, technique, product and volume are solely the decision of the licensed practitioner. This content is for information only and does not replace a clinical assessment.