What is it?
The upper jaw is made of two halves joined along a line that runs down the middle of the palate. During the growing years this join is flexible and the jaw can widen sideways. When that widening is not enough, the upper dental arch stays narrow compared with the lower one; in orthodontics this is called a transverse deficiency.
The most common result is a crossbite: the upper back teeth, which would be expected to close outside the lower ones, fall inside them instead. When the narrowness leads to a one-sided bite, the jaw can shift to one side as it closes. The palate looks high and narrow; crowding from a lack of space, and tooth marks along the side of the tongue, may be present.
The floor of the upper jaw is also the floor of the nasal cavity. A narrow upper jaw can therefore be seen alongside pictures in which breathing through the nose is difficult. The relationship does not run in one direction only; breathing through the mouth for a long time can also affect how the jaw develops. The effect of widening on breathing varies from person to person, and widening on its own is not regarded as a treatment for breathing.
Signs
You will not necessarily have all of these at once.
Why does it happen?
- 01
Inheritance and the pattern of growth
The size of the jaws runs in families. The width of the upper jaw falling behind the lower one can appear without any habit being involved.
- 02
Long-standing mouth breathing
When the tongue does not rest against the palate, the upper jaw is not supported from the inside and the pressure coming from the cheeks comes to the fore. When this pattern lasts for years, the arch can narrow.
- 03
Sucking habits that carry on too long
Thumb sucking and dummy use that continue beyond the baby teeth years can affect the shape of the palate. How marked the effect is depends on how long the habit lasts and how often it happens each day.
- 04
Losing baby teeth early
When the back baby teeth are lost before their time, the neighbouring teeth drift into the gap. The arch shortens and the space set aside for the adult teeth is reduced.
How does it progress?
- Baby and mixed dentition
When widening is easiest
The join in the palate is still flexible. Rapid maxillary expansion can widen the jaw at skeletal level; the widening is completed within a few weeks, and a period of holding it in place follows.
- Teenage years
The years when the window starts to close
The join begins to knit together. Widening happens more through tipping of the teeth and the skeletal effect decreases. Screw-supported methods can come up in this period.
- Young adult
The time of appliances anchored to bone
Expanders supported by mini-screws placed in the bone of the palate can be an option. The result varies with age, with the structure of the bone and with how far the join has closed; the same response is not expected in every patient.
- Adult
Surgically assisted widening
Once the join has closed completely, widening is prepared with a procedure carried out by oral and maxillofacial surgery and then continued orthodontically. The decision is made by the orthodontist and the surgeon together.
How is it treated?
The assessment is made with an examination, impressions or a scan of the mouth, photographs and X-rays. Three-dimensional imaging is requested where needed; this separates whether the narrowness comes only from the tipping of the teeth or from the base of the jaw. If the crossbite goes together with the jaw shifting to one side, that is recorded too, because it changes the treatment plan.
The most common procedure during the growing years is rapid maxillary expansion. A fixed appliance is used that is anchored to the back teeth and has a screw in the middle; the screw is turned on the schedule set by the orthodontist and the upper jaw is widened step by step. In the first few days a feeling of pressure, a temporary gap between the front teeth and a short-lived change in speech are regarded as normal. Once the widening is complete, the appliance is left in place for a while; if this holding period is skipped, relapse is expected.
In adults the join has closed, so the same appliance may not be able to produce skeletal widening. In that case expanders supported by screws anchored in the bone of the palate, or surgically assisted widening prepared by oral and maxillofacial surgery, are considered. Which route suits you is decided by looking at your age, the structure of the bone and the bite as a whole.
- The jaw shifting to one side as the mouth opens and closes, and this becoming more marked over time
- Severe pain, swelling of the gum, or a screw that will not turn while an expansion appliance is in place
- Pauses in your child's breathing during sleep, or snoring that carries on every night
How is it prevented?
- Have your child's first orthodontic assessment at around seven years of age; narrowness is easy to notice at this age.
- If there is mouth breathing, look into the cause; the jaws do not develop comfortably while the nose is not clear.
- Do not let thumb sucking and dummy use carry on beyond the baby teeth years.
- If a baby tooth is lost early, ask your dentist whether a space maintainer is needed.
Frequently asked questions
- Is widening the palate painful?
- In the first few days a feeling of pressure in the palate and at the bridge of the nose is normal; a short-lived tightness can be felt at the moments the screw is turned. That feeling usually settles within a few minutes. Severe, continuous pain is not expected, and if it happens the appliance needs to be checked.
- Is the gap that opens between my front teeth permanent?
- A gap appearing between the upper front teeth during rapid expansion is an expected finding, and it shows that the widening is happening at skeletal level. This gap usually closes on its own in the weeks after the expansion has stopped. Where it does not close, it is dealt with as part of the treatment plan.
- Will widening cure snoring or sleep apnoea?
- No such result can be promised in advance. In some children an improvement in breathing symptoms has been reported as the nasal airway widens, but the effect varies from person to person. If there are pauses in breathing during sleep, the diagnosis is made with a sleep study and the treatment decision is made together with the doctor who deals with sleep.
This content is for general information and does not replace an in-person examination. Symptoms overlap between conditions, and a diagnosis can only be made clinically.