Gummy smile: the cause decides the treatment

What exactly is a gummy smile

Some gum showing above the upper front teeth when you smile is natural for many people. Under a definition often used in studies, a ‘gummy smile’ means more than 2 mm of gum showing above the upper front teeth at your widest smile. Even so, millimetres alone do not settle it: some people are not bothered by a clearly visible gum line, while others are unhappy with far less. What matters most is where the look comes from, because the treatment depends on it.

Possible causes

More than one cause can be present at the same time. These are the ones discussed most often:

• Teeth covered by too much gum: the teeth are a normal length, but as they came through, the gum did not move back as far as it should have. The teeth look short and square.
• A short or very mobile upper lip: if the lip rises higher than usual when you smile, or is naturally short, more gum shows, even though the teeth and gums may be healthy.
• Too much vertical growth of the upper jaw: the gum then shows across the whole smile and over a wide area.
• Tooth wear and tooth position: worn front teeth can keep moving down over time and bring the gum with them; front teeth that tip inwards or have come down too far can give a similar look.
• Gum enlargement: inflammation, some medicines or a fixed brace that is hard to clean can make the gum swell and spread over the teeth.

How the cause is identified

The decision is not made from a single photo. Your dentist looks at how much tooth shows when your lips are at rest, how far your lip rises when you smile, how long your teeth are and how their width relates to their length. Where the enamel ends under the gum and where the bone begins are checked with a fine measuring instrument and, if needed, an X-ray: having only too much gum and having bone that sits too close to the tooth call for different treatment. If the jaw is suspected, facial measurements and orthodontic records are also needed.

If the teeth are covered by gum

When the gum covers too much of the tooth, the aim is to bring the gum margin closer to where the enamel ends. If the bone is far enough from the tooth, removing the excess gum may be enough. If the bone sits very close to where the enamel ends, removing gum alone may not work, because the gum tends to grow back towards its old position; the edge of the bone is then reshaped as well. This is called crown lengthening. The gum margin takes time to settle, so any planned crowns or veneers are usually made after healing.

If the lip is the cause

When the teeth and gums are of normal proportions but the lip rises too far, treatment targets the lip movement. Botulinum toxin injected into the muscles that lift the lip reduces this movement temporarily. According to one meta-analysis, the effect lasts at least 12 weeks and returns close to the starting point within about 24 weeks; it worked especially well for gummy smiles of up to 4 mm. Keeping the effect means repeating the injections.

In lip repositioning surgery, a strip of tissue is removed from the inside of the upper lip to limit how far the lip can rise. In a meta-analysis, the improvement was clear in the first months but faded over time, with about 25% relapse reported at 12 months. If the lip is naturally short, what can be done on the teeth and gums may be limited.

If the jaw or tooth position is the cause

If the upper jaw has grown too far vertically or the front teeth have come down too far, the problem lies not in the gum but in the position of the teeth and bone. In milder cases, orthodontic treatment, often supported by small screws placed in the bone, can move the front teeth upwards. In marked jaw-related cases, jaw surgery is discussed alongside orthodontics; a systematic review reports that surgical results hold up well over time, especially where the upper jaw has grown too far vertically, while orthodontics works well in milder cases. For worn teeth, orthodontics, crown lengthening and crowns that restore tooth length may be planned together.

A mock-up: seeing it before you decide

Your dentist records your smile in photos and video and designs the new tooth length and gum line digitally or on a model. The design is then transferred onto your teeth in a temporary material; this is called a mock-up. It lets you see how longer teeth look with your own lips, when you talk and smile, before anything irreversible is done. The same design can also become a guide showing how much gum to remove during crown lengthening. A mock-up only shows the change to the teeth, though; it does not remove the part played by the lip or the jaw.

This content is for general information only and does not replace an examination.