Short answer: A palatal expander is an orthodontic device used to widen a narrow upper jaw from side to side. In childhood and adolescence, the bony seam in the middle of the palate has not yet fully fused, so the appliance slowly opens this line and expands the jaw skeletally. It is generally used for crossbite, crowded teeth and a narrow palate; suitability is determined by an orthodontic examination and X-rays.
In some children and teenagers, the upper jaw remains narrow compared with the lower jaw. This can lead to crowded teeth, a reverse bite of the back teeth or dark spaces at the sides when smiling. A palatal expander (jaw expansion appliance) is a treatment device used to correct this narrowing and is one of the most established methods in orthodontics. When used at the right age and for the right indication, it can widen not only the teeth but the upper jawbone itself.
Below we explain in plain language how the appliance works, at which ages it is most effective, its different types, the treatment process and the steps that follow.
What is a palatal expander?
A palatal expander is an orthodontic device placed in the palate that applies a controlled force to increase the transverse dimension of the upper jaw. In English-language sources, its most commonly used type is referred to as a rapid palatal expander.
The upper jaw consists of two halves joined by a bony seam (the midpalatal suture) running along the middle of the roof of the mouth. In childhood, this seam has not yet fully fused. As the screw in the middle of the appliance is turned at regular intervals, it slowly moves the two halves apart. Over time, new bone forms in the opened area and the jaw gains a wider structure.
The main situations in which the appliance is used are:
- Posterior crossbite: The upper back teeth biting inside the lower teeth
- Narrow, deep palate: The upper jaw looking narrow and V-shaped
- Crowded teeth: Not enough room for permanent teeth to erupt
- Class III tendency: In some cases, helping guide the upper jaw forward together with a face mask
At what age is it used?
The most suitable period for skeletal expansion is generally between ages 7-8 and mid-adolescence, because the palatal seam is still flexible during this time. Because the growth spurt begins earlier in girls, the suitable window also tends to close a little earlier.
Toward the end of adolescence the seam gradually fuses, and achieving skeletal expansion with a conventional appliance becomes more difficult. For this reason, different methods are considered in adults:
- Miniscrew-assisted expansion: Small screws are placed in the palate so that the force is transmitted directly to the bone. It is preferred in some cases in young adults.
- Surgically assisted expansion: Planned together with jaw surgery in adults whose seam has fully fused.
- Dental expansion: If the narrowing is mild, the arch can be widened by tipping the teeth outward. Clear aligners can be used for this type of movement.
Having a child assessed by an orthodontist for the first time at around age 7 is also an approach recommended by the American Association of Orthodontists. This examination allows the need for expansion to be noticed early. For more information on treatment options by age, see our article at what age can clear aligners be used.
What types of fixed and removable expanders are there?
Expansion appliances fall into two main groups, fixed and removable; the choice depends on the degree of narrowing and the patient's age.
Fixed expanders
Fixed appliances stay in the mouth by means of bands or caps usually bonded to the upper molars and are not removed by the patient.
- Hyrax type: Has a screw in the middle and metal arms, and is relatively easy to clean. It is the most widely used rapid expander.
- Haas type: Has acrylic parts that contact the palate; it distributes the force to both the teeth and the palatal tissue.
- Quad helix: Instead of a screw, it applies a slower, continuous force through spring-like wire loops. It may be preferred for mild narrowing and at younger ages.
Removable expanders
Removable plates are acrylic appliances that the patient can put in and take out. Thanks to the screw in the middle, they provide slow expansion, and their effect is mostly at the level of the teeth. Their success depends largely on consistent use; if they are not worn for most of the day, the expected effect does not occur.
What is the treatment process and how long does it take?
Expansion treatment usually proceeds in two phases, active expansion and stabilization; in most children the total duration is a few months.
- Impression and preparation: A digital scan or impression is taken and the appliance is custom-made.
- Placement: The appliance is bonded to the teeth. In the first days there may be a slight lisp and increased saliva; these usually pass quickly.
- Active expansion: The screw is turned with a special key as often as the orthodontist specifies. In most cases this phase lasts a few weeks. A brief feeling of pressure in the teeth and at the bridge of the nose when the screw is turned is normal.
- Gap between the front teeth: Once skeletal expansion begins, a temporary gap may form between the upper front teeth. This is an expected sign that the seam is opening and usually decreases on its own in the following weeks.
- Stabilization: Once the target width is reached, the screw is locked and the appliance is usually left in the mouth for a few more months so the new bone can mature.
During this process, it is important to avoid sticky and hard foods, brush carefully around the appliance and attend appointments regularly. Only the orthodontist decides how much and how often the screw is turned; families should not change these instructions on their own.
Are braces or clear aligners needed after expansion?
In most cases, yes; expansion solves the skeletal problem of the jaw, but a second phase of treatment is needed to align the teeth individually. The new space created during expansion is used to bring crowded teeth into line.
In this second phase, fixed braces or, in suitable cases, Invisalign clear aligners may be chosen. If most of the permanent teeth have erupted, alignment and bite correction can be planned with Invisalign. At younger ages, Invisalign First, developed specifically for the mixed dentition period, is one of the options considered for mild to moderate arch development needs.
If you are curious about the limits of the effect of clear aligners on jaw structure, our article do clear aligners correct jaw structure covers this topic in detail. In short, for pronounced skeletal narrowing, the approach of a palatal expander first and then alignment is used more often.
What happens if a narrow jaw goes unnoticed?
An untreated narrow upper jaw can, over time, disrupt chewing patterns and cause uneven tooth wear. In posterior crossbite, the lower jaw may shift to one side as it closes; in the long term this shift can contribute to a tendency toward facial asymmetry.
In addition, because the palate forms the floor of the nasal cavity, a narrow palate is seen together with a mouth-breathing habit in some children. The effect of expansion on breathing varies from person to person, and when necessary this is assessed together with an ear, nose and throat specialist. An early examination makes it easier to plan which intervention will be done and when.
Orthodontic assessment in Ankara
If you have noticed that your child's teeth bite in reverse, that there is crowding or that the palate looks narrow, clarifying the situation with an orthodontic examination is a good first step. At our clinic in Park Oran Ofis in Oran, Çankaya, after an intraoral examination and the necessary imaging, whether expansion is needed and the appropriate timing are discussed together with the family.
Frequently asked questions
Does a palatal expander hurt?
After the screw is turned, there may be a feeling of pressure in the teeth, palate and bridge of the nose lasting from a few minutes to a few hours. For most children this feeling is tolerable and decreases within days. If there is significant discomfort, the orthodontist should be informed.
Is the gap that opens between the front teeth permanent?
It is usually not permanent. This gap, which forms during skeletal expansion, shows that the seam has opened and tends to close largely on its own in the following weeks. Any remaining space is closed during alignment treatment in the second phase.
Can a palatal expander be used in adults?
A conventional appliance is usually not enough for skeletal expansion in adults because the palatal seam has fused. In this case, miniscrew-assisted or surgically assisted expansion options are considered. For mild narrowing, dental expansion may also be possible.
How long does the appliance stay in the mouth?
Active expansion usually lasts a few weeks; the appliance is then usually left in place for a few more months so the new bone can mature. The exact duration is determined by the orthodontist according to the degree of narrowing and age.
