In short. How a muscle-relaxing injectable softens a gummy smile by relaxing overactive lip-lifting muscles, which smile types respond, and when dental or surgical causes need a different answer.
Key points
- Assessment photographs the smile at rest and at full animation, measures gum display, and identifies which elevator muscles dominate.
- Treatment uses very conservative doses at a small number of points, because the goal is a few millimeters of lip lowering — not a weakened smile.
- Review at two to three weeks measures the actual change and refines if needed.
A gummy smile — where a generous band of gum shows above the upper teeth when smiling — has several possible causes, and only one of them responds to injections. When the cause is overactive muscles that lift the upper lip too high, small doses of botulinum toxin can lower the smile line by a few millimeters, keeping the smile natural while covering more of the gum. Getting the cause right is the whole art of this treatment.
Why gums show: four different causes
Gum display can come from hyperactive lip-elevating muscles, a short or very mobile upper lip, excessive upper-jaw height, or altered tooth eruption that leaves more gum over the teeth. These causes often coexist, and each has a different correct treatment — from injections to lip repositioning, orthodontic or gum surgery, or jaw surgery. Assessment distinguishes them before any treatment is discussed, because injecting the wrong cause wastes time and money.
How botulinum toxin helps the muscular type
In the muscular pattern, the muscles that elevate the upper lip pull it unusually high in a full smile. Small, precisely placed doses of botulinum toxin reduce that elevation, so the lip sits a few millimeters lower at maximum smile. The resting lip position and normal speech are unchanged when dosing is conservative. Effects develop over days and typically last three to five months.
Who it suits — and who needs another path
Good candidates show several millimeters of gum mainly when smiling broadly, with a normal-length upper lip at rest and healthy teeth and gums. People whose gum display comes from jaw structure or tooth eruption will see little benefit from muscle relaxation; they deserve referral for dental or surgical opinion instead. A combined dental and medical assessment is often the most honest first step.
Treatment planning
Small doses, measured in millimeters
Assessment photographs the smile at rest and at full animation, measures gum display, and identifies which elevator muscles dominate. Treatment uses very conservative doses at a small number of points, because the goal is a few millimeters of lip lowering — not a weakened smile. Review at two to three weeks measures the actual change and refines if needed. Over-correction is harder to live with than under-correction, so the ladder climbs slowly.
Timeline and recovery
There is no downtime beyond avoiding rubbing the area for the day. Change appears over three to seven days and settles by two weeks. Results are temporary — typically three to five months — and maintenance sessions sustain the effect for those who like it.
Side effects and safety
Brief tenderness or bruising is common. The specific risks of this area are an asymmetric smile, a feeling of stiffness when smiling widely, or slight lengthening of the upper lip’s appearance if the lip drops more than intended — all temporary, and all minimized by conservative dosing and precise placement. Because the area sits close to muscles involved in speech and expression, experience matters.
Combination and follow-up
For mixed causes, toxin can be combined with dental treatments such as gum contouring, or with lip filler when a thin lip contributes. Follow-up reviews photograph the smile under the same conditions each time so the plan responds to measured change, not impression.
Arrange a medical review if
- Your smile becomes noticeably asymmetric or your speech feels altered after treatment — early review guides management while the effect resolves.
- Gum display is accompanied by gum inflammation, bleeding, or tooth mobility — dental health comes before cosmetic treatment.
- You are pregnant, breastfeeding, or have a neuromuscular condition — treatment should be deferred or avoided.
Frequently asked questions
Will injections help if my gums show because of jaw shape?
No. Gum display has several causes, and only the muscular pattern responds to injections. Where the cause is excessive upper-jaw height or altered tooth eruption, a dental or surgical opinion is the honest path, and injections will not help.
How much can the smile line be lowered?
The goal is a few millimetres, not a transformed smile. Small conservative doses at a few points reduce how high the upper lip lifts. Over-correction is harder to live with than under-correction, so treatment climbs the ladder slowly.
How long does gummy smile treatment last?
Change appears over three to seven days and settles by two weeks, and results are temporary, typically lasting three to five months. Maintenance sessions sustain the effect for people who like it. No downtime is needed beyond avoiding rubbing the area for a day.
Risks & Limitations
- Vascular occlusion — a time-critical emergency in which filler blocks a blood vessel. It can cause skin loss and, rarely, blindness.
- Nodules, lumps or granuloma formation, which may need treatment or dissolution.
- Infection at the injection site.
- Asymmetry or over-correction; over-treatment is harder to correct than under-treatment.
- Migration of filler away from the intended area.
- Temporary brow or eyelid droop after botulinum toxin, which resolves as the effect wears off.
- Bruising and swelling. All injectable results are temporary and maintenance is required.
When to Seek Care
- Severe pain out of proportion to the procedure, or skin turning white, grey, mottled or dusky — this is a vascular emergency; seek care immediately.
- Any change in vision — seek emergency care immediately.
- Fever, spreading redness, warmth or pus at an injection site.
- A hard, painful lump that is growing.
- Drooping eyelid, difficulty swallowing, or difficulty breathing after botulinum toxin.
References & Further Reading
- American Academy of Dermatology (AAD) — injectable safety information
- American Society of Plastic Surgeons (ASPS) — injectable guidance
- U.S. Food and Drug Administration (FDA) — approved filler and neurotoxin products
- National Medical Products Administration (NMPA, China) — approved product status
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.