What counts as a gummy smile
There is no disease called gummy smile. The working definition used in dental and aesthetic literature is excessive gingival display: more than about three to four millimetres of gum visible above the upper front teeth during a full, spontaneous smile. Below that threshold, some gum show is normal, common, and in many faces rather charming.
Whether it needs treating at all is a personal judgement, not a clinical one. What is clinical is the diagnosis, because the same appearance can be produced by entirely different anatomy, and the treatments do not overlap. A patient treated for the wrong cause spends money, takes risk, and keeps the smile they disliked.
The four causes, and why diagnosis comes first
| Cause | What is happening | First-line treatment |
|---|---|---|
| Hyperactive lip elevators | The muscles lifting the upper lip, chiefly levator labii superioris alaeque nasi and its neighbours, pull too strongly on smiling | Botulinum toxin |
| Vertical maxillary excess | The upper jaw itself is vertically long, carrying teeth and gums downwards | Orthodontics, orthognathic surgery in marked cases |
| Short or hypermobile upper lip | The lip is anatomically short, or travels an unusually long way on smiling | Toxin, lip filler, or lip repositioning surgery |
| Altered passive eruption | Gum tissue never fully receded from the crowns, so teeth look short and gums look tall | Periodontal crown lengthening |
Most real patients are mixtures. A careful assessor measures gum show at rest and on smiling, measures lip length and lip travel, looks at tooth proportions, and examines the jaw skeletally. Ten minutes of measurement changes the whole treatment conversation, and its absence is the most reliable sign you are in the wrong chair.
Toxin treats one cause of a gummy smile out of four. The consultation that skips diagnosis is selling you the syringe on the desk, not the treatment you need.
How botulinum toxin treatment works
Where the cause is muscular, small doses of botulinum toxin are injected into the lip elevator complex, most commonly at a point either side of the nostril where several elevator muscles converge. The toxin temporarily reduces the force of lip elevation, so the lip rises less on smiling and covers more of the gum.
The word small matters. This is among the lowest-dose treatments in facial aesthetics, typically in the low single units per side, precisely because the target muscles also shape normal speech and expression. Overdosing flattens the smile, lengthens the upper lip at rest, and can affect pronunciation of certain sounds for the duration of the effect. A conservative first dose with review at two weeks, topping up only if needed, is the defensible protocol.
Botulinum toxin is a prescription-only medicine in the UK. It must be prescribed after a consultation with a qualified prescriber, a requirement explained in our guide to what is actually regulated in UK aesthetics, and prescribers can be verified through the GMC or NMC registers. Practices across west London, including several in Chiswick, treat gummy smile routinely, and the treatment's popularity there reflects how quick and low-commitment it is when the diagnosis is right.
Dosing, results and duration
Effect begins within three to five days, settles fully by two weeks, and lasts roughly three to four months, in line with cosmetic toxin generally. The first two weeks can feel strange: patients describe the lip as heavy or slow, and spontaneous smiles look unfamiliar in the mirror before the brain adjusts. That adjustment is normal and worth warning patients about, because it is the period in which most regret and reassurance-seeking happens.
Photographic review at two weeks is good practice. If gum show remains excessive, a unit or two more per side can be added. If the smile looks restricted, nothing can be done except wait, which is exactly why the conservative first dose matters.
Repeated treatment does not cure the underlying muscle pattern. Some patients report the effect softening their smile habit over years of treatment, but the evidence for permanent change is anecdotal, and the working assumption should be maintenance three to four times a year for as long as the result is wanted.
Alternatives beyond toxin
- Lip filler. Where the upper lip is thin or short, adding structure can increase its coverage of the gums on smiling. It also carries its own risks, including migration over time, covered in our piece on how and why lip filler migrates.
- Orthodontics. Where teeth are over-erupted or the bite contributes, alignment can reduce gingival display over months to years. Slow, but it treats cause rather than appearance.
- Crown lengthening. A periodontal procedure reshaping the gum margin where altered passive eruption makes teeth look short. Definitive for that specific cause.
- Lip repositioning surgery. A soft-tissue procedure limiting how far the lip can rise. Longer-lasting than toxin, with surgical recovery and some relapse rate.
When surgery is the answer
Vertical maxillary excess is the cause toxin cannot reach. If the upper jaw is skeletally long, the gums sit low because the whole dental arch sits low, and weakening the lip merely drapes a curtain over a structural problem, incompletely and temporarily. Marked cases show gum on gentle smiling and sometimes at rest, often with a longer lower facial third.
The definitive treatment is orthognathic surgery, in which the maxilla is repositioned upwards, planned jointly by orthodontist and maxillofacial surgeon. It is a significant undertaking with months of preparation, and it is emphatically not an aesthetic clinic procedure. The appropriate route is referral through a dentist to an NHS or private maxillofacial service. Guidance on commissioned orthognathic care is published through NICE and NHS England, and a reputable injector should recognise the skeletal pattern and refer rather than treat.
The test of a good clinic is whether it will say so. A patient with obvious maxillary excess who is offered toxin without that conversation has been sold the wrong treatment.
Because the margin between a corrected smile and a heavy upper lip is measured in single units, injector experience matters more than the treatment sounds. West London practices working at this level, including Dr Harry Clinic in Chiswick, assess lip elevation dynamically rather than at rest, which is what separates a good result from a flat one.
Cost and choosing where to be treated
Because doses are small, gummy smile toxin is one of the cheaper injectable treatments: observed UK pricing in 2026 runs from roughly £100 to £250 per session, sometimes bundled with other toxin areas. Lip repositioning surgery is typically in the £1,500 to £3,500 range privately, crown lengthening from a few hundred pounds per tooth, and orthognathic surgery runs to five figures privately. Our 2026 price survey gives the wider context.
Given how cheap the toxin option is, the temptation to skip diagnosis is strong on both sides of the desk. Resist it. Ask the practitioner which of the four causes you have, how they measured it, and what they would do if toxin underdelivers. The quality of those answers is worth more than any before-and-after photograph.
