“She Can’t Close Her Lips and She Sleeps With Her Mouth Open” — What a Narrow Upper Jaw Really Looks Like
A real early-orthodontic case from our Gurgaon practice, explained for parents.
The short answer
When a child cannot close the lips comfortably, breathes through the mouth during sleep and has upper front teeth that stick out, the problem is usually not “crooked teeth” — it is a narrow, V-shaped upper jaw with too little width to hold the adult teeth. Widening the upper jaw with a palatal expander, while the growth suture in the roof of the mouth is still open (most often between about 7 and 12 years), creates that width, reduces the flare of the front teeth, widens the floor of the nose and can lower nasal airway resistance. Braces, if still needed, come afterwards — not before.
This case at a glance
- What the parent reported
- Lips that would not close comfortably at rest, upper front teeth that stick out, irregular and crowded teeth, and sleeping with the mouth open.
- Diagnosis
- A narrow, V-shaped upper jaw (maxillary transverse deficiency) with a high, constricted palate, at the mixed-dentition stage.
- Treatment plan
- Rapid maxillary expansion with a palatal expander, then about six months of retention, then re-evaluation for braces.
- Why timing matters
- The growth suture in the roof of the mouth is still open, most often between about 7 and 12 years of age.
- Where it stands
- Expansion has begun. Follow-up will be published on this page.
In this article
What did the parent notice first?
The parent did not arrive asking for braces. They arrived with four observations, and every one of them turned out to be a piece of the same picture:
- The child could not bring the lips together comfortably at rest.
- The upper front teeth were visibly protruding.
- The teeth looked irregular and crowded.
- The child slept with the mouth open.
Parents very often report these separately, as if they were four unrelated things. Clinically they usually are not. Lips that will not meet, protruding incisors and habitual mouth breathing tend to travel together, and the thing they have in common sits above the teeth — in the shape of the upper jaw itself.
What did we find on examination?
On clinical examination, the findings were consistent:
- A V-shaped (tapered) upper arch. A healthy upper arch is broad and U-shaped. This one narrowed towards the front into a V, with a high, constricted palate.
- Proclined, protruding upper incisors. With no width available sideways, the erupting front teeth were pushed forward instead of settling into line.
- A convex facial profile with incompetent lips — the lips do not meet without conscious muscular effort.
- Crowding and blocked-out teeth. The lateral incisors and canines had nowhere to go and were erupting out of the arch.
- Retained deciduous (milk) teeth still present alongside erupted permanent teeth — a mixed dentition, which is exactly the stage at which the upper jaw can still be influenced.
- A reported habit of open-mouth breathing during sleep.
Clinical photographs from this case, published with the patient’s face removed. Every mouth is different; these images illustrate one child’s presentation and are not a diagnosis of yours.
Why does an upper jaw end up narrow?
The upper jaw is not a fixed box. It is shaped, over years, by the forces that act on it from inside and outside.
When a child breathes through the nose with the lips sealed, the tongue rests up against the roof of the mouth. That resting tongue acts as scaffolding — it holds the palate broad from the inside against the constant inward pressure of the cheeks. When a child breathes through the mouth instead, the lips stay parted and the tongue drops low and forward to keep the airway open. The scaffolding is gone. The cheeks keep pressing inward, and over months and years the arch narrows into a V and the palate rises.
A narrower upper jaw also means a narrower floor of the nose, which can make nasal breathing feel harder, which reinforces the mouth breathing. That is why we treat this as a loop rather than a straight line.
An honest caveat
The direction of this relationship is not fully settled in the research literature, and it is not always the same child to child. Mouth breathing can be a cause of the narrow jaw, a consequence of it, or both at once. It can also be driven by something entirely outside the mouth — enlarged adenoids or tonsils, allergic rhinitis, or a deviated septum. This is why a child who mouth-breathes should be assessed by an ENT surgeon alongside the orthodontist. Widening the jaw does not clear a blocked nose.
What is the treatment plan for this child?
The plan agreed for this case has three steps, in this order: widen the upper jaw, hold the new width for about six months, then re-evaluate for braces.
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Phase 1 — Rapid maxillary expansion (the palatal expander)
Active turning: typically a few weeks
A fixed expander is cemented to the back teeth of the upper jaw, with a small screw sitting in the middle of the palate. The parent turns the screw a small, prescribed amount each day. Because the two halves of the upper jaw are still joined by an open growth suture at this age, the appliance separates them very gradually — a fraction of a millimetre a day — and the jaw widens along that suture.
In this case, expansion was chosen as the starting point because it addresses several of the parent’s complaints at their common source:
- It converts the V-shaped arch towards a U shape and increases the width of the maxillary base.
- It creates arch length, which relieves crowding and reduces the forward flare of the incisors — so the protrusion improves without any front teeth having been touched.
- It widens the nasal floor, which reduces nasal airway resistance and can make nasal breathing easier — supporting, though not by itself curing, the change from mouth to nose breathing.
The active turning phase is short. What takes time is what comes next.
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Phase 2 — Six months of retention
Approximately six months, appliance left in place
After the target width is reached, the appliance is not removed. It stays in place, passively, for approximately six months. During this period new bone fills in the gap that has opened along the suture and the new width becomes stable. Removing an expander early is the most common way expansion is lost — the jaw simply relapses towards where it came from.
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Phase 3 — Re-evaluation for braces
After retention is complete
After retention, the child is re-examined. By then the arch is wider, the crowding is reduced, more permanent teeth have erupted and the picture has changed. Braces are planned from that new position — and are often shorter and simpler than they would have been, because the foundation was corrected before the teeth were aligned on top of it. In some children, the braces phase is significantly smaller than the parent expected at the first visit.
The sequencing principle, in one line
Width first, alignment second. Straightening teeth inside a jaw that is too narrow to hold them is building on a foundation that has not been fixed.
What can palatal expansion do, and what can’t it do?
Palatal expansion reliably widens the upper jaw while the growth suture is open, but on its own it does not cure mouth breathing caused by the nose, straighten teeth, or promise a particular change in facial appearance.
What it reliably does
- Widens the upper jaw at the skeletal level while the mid-palatal suture is open
- Creates arch space and reduces crowding and incisor flare
- Widens the nasal floor and reduces nasal airway resistance
- Corrects a posterior crossbite where one is present
- Often makes later orthodontic treatment shorter and less complex
What it does not do on its own
- Cure mouth breathing caused by enlarged adenoids, tonsils or allergic rhinitis
- Straighten teeth — that is what the later phase is for
- Guarantee any specific change in facial appearance
- Replace an ENT assessment or a sleep evaluation where one is indicated
- Work equally well after the suture fuses in the mid-teens, when surgical assistance may be required
Which signs are worth getting checked in any child?
Any of the following is worth an orthodontic check, ideally by around age seven:
- Lips that do not meet at rest, or a child who is always slightly open-mouthed
- Sleeping with the mouth open, snoring, restless sleep, or waking unrefreshed
- Upper front teeth that visibly protrude, or that have been chipped in a fall
- Adult teeth erupting out of line, or a second row of teeth behind the first
- Milk teeth still firmly in place well past the age at which their neighbours were lost
- Upper back teeth biting inside the lower ones on one or both sides
- A jaw that shifts to one side when the child closes
None of these is an emergency. All of them are easier and cheaper to correct at eight than at eighteen. To learn more about our services, see kids dentist in Gurgaon and orthodontic treatments in Gurgaon.
Common questions from parents
At what age should a child first see an orthodontist?
By around age seven. At that age the first permanent molars and incisors have usually come through, which is enough for a specialist to see how the jaws are developing. Most children who are screened at seven need nothing at all — but the ones who do need something are found while their growth can still be used, rather than worked against.
Is a palatal expander painful?
It is not usually described as painful. Children commonly report pressure across the palate and under the nose for a few minutes after each turn, and some tenderness in the first two or three days. Speech and swallowing feel odd for roughly a week and then normalise. Most children adapt faster than their parents expect.
How long will my child wear it?
The active widening usually takes a few weeks. The appliance then stays in passively for about six months while new bone fills the suture and the width becomes stable. Taking it out early is the main reason expansion relapses.
Will the expander stop my child’s mouth breathing?
It removes one of the obstacles by widening the nasal floor and lowering nasal airway resistance, and many children breathe through the nose more easily afterwards. It does not clear a nose blocked by enlarged adenoids, large tonsils or allergy — those need an ENT assessment and their own treatment. Expansion works best as part of that combined picture, not as a substitute for it.
A gap appeared between my child’s front teeth after we started turning. Is that a problem?
No — it is the expected sign that the appliance is working. The gap shows the two halves of the upper jaw have separated at the suture, which is the point of the treatment. It closes on its own, usually within a few weeks, as the fibres between the teeth draw them back together.
Why does my child still have baby teeth when the adult teeth are already through?
Usually because there is not enough room in the arch, so the adult tooth erupts alongside or behind the milk tooth instead of pushing it out. Retained milk teeth next to erupted permanent ones are a useful early warning that arch width should be assessed, rather than something to simply wait out.
Can we skip this and just do braces later?
Sometimes, yes — not every child needs early treatment. But if the underlying problem is skeletal width, braces alone can only move teeth within the jaw that exists. Once the mid-palatal suture fuses, usually in the mid-teens, widening the jaw becomes far harder and may need surgical assistance. Where a narrow jaw is diagnosed in the mixed dentition, the window is genuinely time-limited.
Will my child’s face change?
Expansion acts on the upper jaw, so some change in the mid-face and in lip posture is possible, and lips that previously could not meet often close more easily as the incisors come back into line. What we do not do is promise a specific facial outcome. Growth varies between children, and any orthodontist who guarantees a particular face is guessing.
What happens if we do nothing?
Crowding usually does not resolve on its own. Protruding upper incisors carry a measurably higher risk of trauma in falls and sport. Habitual mouth breathing is associated with more gum inflammation, more decay and disturbed sleep. And the skeletal correction that is straightforward at nine may need surgery at nineteen.
Where are we with this case?
This child has begun rapid maxillary expansion, with six months of retention planned and a re-evaluation for braces after that. We will publish the follow-up on this page as the case progresses, so that parents can see the actual sequence rather than a promise.
Last updated:
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Medically reviewed by Dr. Sidharth Bhatia, Orthodontist, Dr. Bhatia’s Dental Clinic. This article describes one patient’s presentation and treatment plan and is published for general education. It is not a diagnosis and not a substitute for an in-person examination. Clinical photographs are published with consent and with all identifying features removed. Individual results vary.