Gummy Smile: What Causes It and What the Options Are

When you smile, your upper lip rises and uncovers some combination of tooth and gum. The proportion between those two is what people are reacting to when they say a smile looks gummy. Nothing is wrong with the gum; it is simply that more of it is on show relative to the teeth than the viewer expected.

Dental and orthodontic texts tend to use a working convention of somewhere around two to three millimetres of gum visible on a full smile before they start describing the display as excessive. It is worth being precise about what that number is and is not. It is a convention for writing up cases consistently, drawn from studies asking laypeople and clinicians to rate smile images. It is not a diagnostic threshold, it does not appear on any scan, and crossing it does not mean anything is wrong with you. Plenty of people show considerably more and have never once thought about it.

There is also a strong population pattern worth knowing before you compare yourself to anyone: on average, women show more gingival display than men, and gum display tends to decrease across a lifetime as the upper lip lengthens and loses some tone. A smile that shows gum at twenty often shows less at forty-five without anyone doing anything. If you are comparing your smile against photos of people much older than you, or of a different sex, you are not comparing like with like.

The upper lip is lifted by a small group of muscles — principally levator labii superioris, its alaeque nasi portion, and zygomaticus minor and major. In some people that group is simply more mobile, pulling the lip higher than average from rest to full smile. Clinicians call this a hypermobile upper lip, and it is one of the most common single causes of a gummy smile in people whose teeth and jaw are entirely unremarkable.

A short upper lip is a related but different thing. Here the lip does not travel unusually far; it just starts higher because there is less of it. Lip length is measured from the base of the nose to the lower border of the upper lip, and someone with a naturally short lip may already be showing tooth at rest, before smiling enters the picture at all. Lip mobility and lip length can occur together or entirely separately, and they respond to different approaches, which is exactly why the distinction is not academic.

This category is also the reason the same person's gum display varies so much photo to photo. A polite, posed, camera-ready smile uses these muscles far less than a real one. If you have ever noticed you look gummy in candid photos and not in posed ones, that is not the camera — it is the difference between a social smile and a genuine one recruiting the full elevator group.

Why genuine smiles show more gum

A spontaneous, felt smile is structurally different from a posed one. It pulls the corners of the mouth harder and it activates orbicularis oculi around the eyes, producing the crinkle that psychologists use to distinguish a Duchenne smile from a social one. That harder pull travels through the same muscles that lift the lip, so the most genuine smiles in your camera roll are often the gummiest ones. Our smile genuineness read at /analyze looks at exactly that eye activation — whether the smile reaches the eyes — which is a useful thing to know if you are about to conclude that your best, most genuine photographs are your worst ones.

Teeth erupt through the gum in stages, and the gum margin is supposed to migrate up the crown to its final position during that process. When it does not finish migrating, the crowns stay partly covered. The teeth themselves are a normal size, but the visible portion is short and square, and the gum occupies space that would otherwise be tooth. Clinicians call this altered passive eruption, and it is one of the more commonly missed causes because from the outside it looks like too much gum rather than too little visible tooth.

There is a useful self-observation here, though it is observation and not diagnosis: look at the proportions of your upper front teeth in a straight-on photograph. Central incisors that appear noticeably wider than they are tall, with a squat, blocky outline, point in a different direction than teeth with normal proportions sitting under a lip that travels a long way. A dentist can distinguish the two properly, because it depends on where the bone crest sits under the gum, which nothing visible from outside will tell you.

A second version of this is over-eruption of the upper front teeth, where the teeth have drifted further down than the ones beside them and carried their gum margins with them. This often travels with a deep bite and with wear on the biting edges, and it is one of the cases where the appearance question and a functional question overlap.

The version that is actually a health question

Gum tissue can also be genuinely enlarged rather than just well-positioned. Long-standing plaque and inflammation can thicken it. So can several categories of long-term medication — certain anticonvulsants, some calcium channel blockers used for blood pressure, and some immunosuppressants are all recognised for this effect. If your gum display changed noticeably as an adult rather than being lifelong, or if the tissue is red, puffy or bleeds when you brush, that is a different conversation entirely and belongs with a dentist and, where medication is involved, the doctor who prescribed it. Cosmetic framing is the wrong frame for that case.

The third cause is skeletal. If the upper jaw is longer vertically than average, the entire dental structure it carries sits lower in the face, and the lip has further to travel before it clears the gum line. Clinicians refer to this as vertical maxillary excess, and it is usually the one that comes with other proportional signs: a longer lower third of the face, sometimes visible tooth at rest without smiling, sometimes lips that do not meet comfortably when the face is relaxed.

This category matters disproportionately because it is the one where the gum display is a symptom of the facial proportion rather than the thing itself. Addressing the gum line without addressing the underlying vertical relationship, in a case where the vertical relationship is the driver, is treating the readout instead of the cause. It is also the category that requires proper imaging to establish — cephalometric radiographs, not photographs — because the position of bone is not something any surface measurement can infer.

In practice, most real cases are mixed. A moderately mobile lip plus slightly short crowns plus an unremarkable jaw produces the same visible result as one strong single cause, and the mix is what determines which options are even relevant. This is the whole reason a proper assessment exists and the reason a stranger cannot look at your photograph and tell you what you have. If you are interested in the broader question of how facial proportion is measured and where the limits of surface measurement sit, our face rating breakdown covers what geometry from a photograph can and cannot establish.

Being direct about this, because the honest version is more useful than the flattering one. RealSmile measures 17 facial-geometry metrics from 68 facial landmarks. Several of those landmarks trace the outer border of the lips and the inner border of the mouth opening, which means the geometry we can genuinely produce includes mouth width, lip proportions, the relationship of the mouth to the rest of the face, and how large the mouth aperture is when a smile is held. Those are real measurements from real landmark positions.

What the landmark model does not have is any point on the gum line, and no points on individual teeth. It sees the boundary of the mouth opening and it does not see what is inside it. So the tool can tell you how much of your face the mouth aperture occupies during a smile, but it cannot separate gum from tooth within that aperture. That is precisely the measurement a gummy smile question needs, and it is the one we do not have. Anyone claiming to give you a millimetre figure for gingival display from an ordinary uncalibrated photograph is doing something the input does not support — a photo has no absolute scale unless something of known size is in the frame.

The list of things we cannot assess at all is worth stating plainly: tooth alignment, cavities, gum health, bite relationships, bone position, or anything else that is clinical. We are a geometry tool, not a dental examination, and no amount of image processing turns one into the other. What we can do at /analyze is read smile genuineness — whether the muscles around the eyes are engaged, the Duchenne signal — which is a genuinely different question and one photographs can support.

One more caveat that applies to any photo-based measurement, ours included. Face measurements from a single photograph carry real variance from lighting, camera distance, lens focal length and head angle. The same face photographed twice under different conditions does not produce identical numbers. Treat any single reading as one sample, and if you want a stable picture of anything, take several photographs under consistent conditions rather than trusting one.

This section describes what exists and what each approach is aimed at. It is not a recommendation, and nothing here should be read as advice about your case, which depends on findings only an examination produces. Every option below has candidacy criteria, trade-offs and outcomes that vary between people, and those conversations belong with a qualified clinician.

Aimed at the gum and crown

Gingival contouring and crown lengthening reshape the gum margin to expose more of the existing crown, sometimes with adjustment of the underlying bone crest where the bone is what limits the position. These are aimed squarely at the altered passive eruption category — cases where the tooth is a normal size but partly covered. They are surgical procedures with a healing period, and the amount of change available is constrained by where the bone sits, which is why the assessment precedes the plan rather than following it.

Aimed at tooth position

Orthodontic intrusion moves over-erupted front teeth up into the bone, taking their gum margins with them. Modern approaches often use temporary anchorage devices — small screws placed in the bone to give the appliance something fixed to push against. This addresses the over-eruption version specifically and takes the timescale you would expect of orthodontics, measured in months to a couple of years rather than in appointments.

Aimed at the lip

Botulinum toxin injected into the lip elevator muscles reduces how far the lip travels. It is temporary by nature and wears off over a period of months, which cuts both ways: it is one of the few genuinely reversible options, and it is also a recurring commitment rather than a one-time change. Lip repositioning surgery takes a more permanent approach, removing a strip of tissue from inside the upper lip so that the lip has less range to elevate. Both target the hypermobile-lip category and neither does anything for crown length or jaw position.

Aimed at the skeleton

Where the underlying cause is a vertical jaw relationship, orthognathic surgery repositions the upper jaw itself. This is the largest intervention on the list by a wide margin — general anaesthetic, an orthodontic phase before and after, a substantial recovery — and it is reserved for skeletal cases established through proper imaging. It exists on this list for completeness, so that you recognise the category if a clinician raises it, not as something to weigh casually.

Doing nothing

This is a real option and it deserves to be on the list rather than mentioned as an afterthought. A gummy smile in the absence of gum disease is not a health problem, it is mechanically a by-product of genuine smiling, and gum display naturally decreases with age. If the only thing bothering you is how a particular photograph looked, the intervention you are considering may be considerably larger than the problem. That is a judgement only you can make, but it should be made with the option properly on the table.

If you do take this to a dentist or orthodontist, the quality of the conversation depends heavily on what you ask. The following questions are aimed at establishing whether the assessment has actually been done before the options are discussed, which is the most common place these conversations go wrong.

Which of the causes is driving mine, and how did you determine that? Is my crown length short, is my lip travelling a long way, or is it the jaw relationship — and what specifically told you? Is any part of this a health issue rather than an appearance one, particularly the condition of the gum tissue itself? What happens if I do nothing, over five years and over twenty?

Then, for whatever option is proposed: is it reversible, and if not, what exactly is permanent about it? How long does the result last and what maintains it? What is the realistic range of outcomes, including the disappointing end of that range? What is the recovery like in practical terms — days off, eating, speaking, visible healing? And how many of this specific procedure do you do, because volume matters for anything technique-sensitive.

A useful thing to bring with you is photographs: your face at rest, a posed smile, and a genuine one caught candidly. The range between them is informative in a way that a single clinic photograph taken while you are self-conscious is not, and the range is what you actually live with day to day.

A gummy smile sits in an awkward place. It is not a disease, so the medical frame does not fit well, but the interventions are genuinely clinical, so the cosmetic frame underplays what is involved. The honest position is that this is a proportion question with clinical consequences, and it deserves to be treated more carefully than a haircut and less anxiously than an illness.

It is also worth noticing where this question usually starts. Most people do not notice their gum display in the mirror. They notice it in a photograph, usually one taken from below, usually one they did not know was being taken, and usually while genuinely enjoying themselves. Camera angle changes apparent proportion substantially, and a lens close to the face exaggerates whatever is nearest it. Before concluding anything about your smile from an image, it is worth checking that the image is telling you about your face rather than about the photograph.

If the wider goal is looking better in general rather than this specific feature, the ordinary things are still the ones that move the needle furthest for the least intervention: sleep, skin condition, grooming, and how you handle a camera. Our guide to building a skincare routine covers the lowest-cost end of that spectrum, and unlike anything in this article it requires no clinician and no commitment.