Two people can show exactly the same band of gum in a wide smile for completely different reasons. In one, the teeth and gums are normal and the upper lip simply lifts higher than average. In the other, gum shows even when the lips are relaxed, because of how the gum, teeth or upper jaw are proportioned. A photo of the big smile alone cannot tell them apart, which is why a careful gummy smile assessment always looks at the face at rest as well.
The resting view is the baseline
When your lips are relaxed and just touching, the muscles that raise the upper lip are switched off. Whatever shows in that position depends on fixed things: how long the upper lip is, how long the front teeth are, and where the gum line and the bone beneath it sit. Dentists call this the resting display. Many people show a little of their upper front teeth at rest and little or no gum.
The full smile then adds movement. The lip lifts, and how far it travels depends on the strength and activity of the smiling muscles. Comparing the resting view with a natural smile and a broad smile shows how much of the gum on display comes from structure and how much from lip movement. That comparison is the useful information, more than either view on its own.
Reading the pattern
"Excessive gingival display" is the clinical name for a gummy smile. It is not a diagnosis in itself, only a description of what is seen. The cause comes from the pattern across the different positions.
Little gum at rest, a lot in a full smile
This usually points to the lip. The resting position looks ordinary, the teeth are a normal length and the gum line sits where it should. When the person smiles broadly, a hypermobile upper lip rises further than most and uncovers gum that is hidden the rest of the time. A short upper lip can add to the effect.
Gum visible even at rest
When gum shows with the lips relaxed, the cause is more likely to be in the teeth, gums or jaw. One common reason is altered passive eruption, where the gum has not moved back to its usual adult position on the tooth after the teeth came through, so the teeth look short and square. Another is the vertical height of the upper jaw, where the whole upper jaw is taller than average. Sometimes the front teeth and their supporting bone have drifted downward over time. In these cases a broad smile adds a little more gum, but most of the picture is already there at rest.
A mixture
Many people have more than one factor. A slightly mobile lip combined with short-looking teeth is common, and that is one reason the assessment looks at several positions rather than one.
What a careful assessment includes
If you ask about your gum display at a consultation, expect your dentist to look at your face and smile in at least three states: lips relaxed and closed, a natural conversational smile, and a full broad smile. At Lumi Dental these views are captured in our clinical photography room, so they can be measured and compared accurately rather than judged from memory in the chair.
The dentist will also check:
- the health of the gums, since swollen or overgrown gums can make teeth look short
- the length and shape of the front teeth and where the gum line sits on each
- whether the gum lines on both sides are level
- how the upper lip moves and how long it is at rest
- the bite and the position of the front teeth, which can influence how much tooth and gum show
X-rays or a 3D scan are sometimes used to see where the bone sits in relation to the gum, which matters when altered passive eruption is suspected.
Why the cause decides the options
This article is about the assessment, not a treatment guide. The point to take away is that a lip-driven gummy smile and a structure-driven one are approached in different ways, because one involves how the lip moves and the other involves where the gum, teeth or bone sit. Treating the wrong cause tends to give a disappointing result.
Our other articles cover the options in more depth: gummy smile causes and treatment options, why gums show and how a gummy smile is treated, and the range of gummy smile treatments and what they involve. They are most useful once you know which pattern applies to you. Some cases, particularly those involving the jaw, may need assessment with a registered specialist.
Questions patients ask about gum display
How much gum is normal?
There is no single correct amount. Many people show a small amount of gum when they smile broadly and find it attractive. Whether a gummy smile is a concern is a personal judgement, and how much is noticeable also depends on lip shape, tooth proportions and facial features.
Does a gummy smile need treating?
No. As long as the gums are healthy, a gummy smile is an appearance concern, not a health problem. An assessment is about understanding why it happens so that you can make an informed choice, including the choice to leave it alone.
My teeth look short. Is that the same thing?
Sometimes. Short-looking teeth can be caused by gum covering more of the tooth than usual, by wear at the biting edges, or simply by the natural shape of the teeth. The assessment separates these, because each is managed differently.
Why do I look gummier in photos?
Photos often catch a broad, posed smile, which lifts the lip further than an everyday smile. Lighting and camera angle also change how much gum seems to show. Comparing standard clinical photos at rest and in different smiles gives a more reliable picture.
If you have wondered why your smile looks different in photos from how it feels day to day, Lumi Dental offers a free cosmetic consultation to look at your gum display and talk through what is causing it. Current offers are listed on our current deals page. This article is general information only and is not a substitute for an individual dental assessment.
