Short answer: A rapid palatal expander (RPE) is a fixed orthodontic device placed against the palate with a screw in the middle. As the screw is turned according to the schedule given by the orthodontist, the bony suture in the palate separates during the growth years and the upper jaw widens. The active phase usually lasts a few weeks; the device then stays in the mouth for months so the bone can consolidate. Suitability is determined by an orthodontic examination.
An upper jaw that is narrow relative to the lower jaw is one of the most common structural mismatches in growing children. Rapid palatal expansion (RPE) uses a fixed orthodontic appliance that widens the upper jaw by separating the bony suture in the middle of the palate in a controlled way. It is also popularly known as a jaw expansion screw or Hyrax appliance. In this article we explain in plain language what the device is, how the screw is turned, what the gap that opens between the front teeth means and what is possible in adults.
What is a rapid palatal expander?
A rapid palatal expander is a fixed device placed against the palate to increase the width of the upper jaw, with a small screw in the middle. During the growth years, the upper jaw consists of two halves joined in the middle by a suture (a line where bones meet). When the screw is turned at regular intervals, these two halves move slightly apart, and new bone tissue gradually fills the space between them.
In a Hyrax-type device, metal bands are cemented to the side teeth (usually the first molars and, if necessary, the premolars), the screw sits in the middle of the palate and there is no acrylic in the device, which makes cleaning easier. There are also models with acrylic sections. Which type is suitable is decided according to the mouth structure, the number of teeth and the orthodontist's plan. You can find general types of appliances on our orthodontic appliances page, and the basic logic of jaw expansion in our article on palatal expansion appliances.
When is it used?
Rapid palatal expansion is usually planned when the upper jaw is narrow and this is reflected in the teeth or the bite. The following findings on examination and the necessary imaging can be reasons for expansion:
- Crossbite in the back teeth: The upper molars sitting inside the lower molars.
- Marked crowding and a lack of room for the teeth due to a narrow upper jaw.
- A marked difference between the widths of the lower and upper jaws.
- A narrow palate together with mouth breathing in some children; in this case orthodontists and ear, nose and throat specialists assess the child together.
If the cause of a crossbite is truly a bony narrowness of the upper jaw, aligning the teeth alone is not enough; the width must be corrected first. In milder crossbites of dental origin, different approaches may be considered. We have covered how this issue is approached with clear aligners separately on the page clear aligners and crossbite.
The decision is usually based not only on an intraoral examination but also on imaging such as panoramic and cephalometric X-rays. These help in understanding the position of developing teeth, how the jawbones relate to each other and whether expansion is really necessary. Not every palate that looks narrow needs expansion; in some children monitoring alone may be enough.
How is the appliance fitted, and what are the first days like?
Before the device is fitted, impressions of the teeth are taken or a digital scan is made; then the bands are tried on the appropriate molars and fixed with a special cement. The fitting is usually completed in a single appointment, and the child and family are shown in practice how to turn the screw, in which direction and at what time of day.
In the first two or three days, the metal part sitting against the palate may bother the tongue, and appetite may temporarily decrease. Soft, easy-to-chew foods make this period easier. During the active phase, check-up appointments are usually every few weeks; at these sessions the orthodontist assesses whether the width is sufficient and decides when to stop turning the screw.
How and how often is the screw turned?
The screw is usually turned by a parent according to a set schedule, using a special key the orthodontist demonstrates at the first session. Each turn opens the screw by a small fraction of a millimeter; most programs recommend one or two turns a day, but the frequency depends on the orthodontist's plan, the child's age and the mouth structure.
In most cases the active phase of expansion lasts two to four weeks. During this time, you should not deviate from the schedule the orthodontist has prescribed, skip turns or do several at once. With the first turns, there may be a feeling of pressure and brief tension in the palate, around the nose and in the teeth; this feeling usually eases within a few minutes to a few days. If there is severe or increasing discomfort, you should contact the clinic. Tying a string to the end of the key so it does not fall is a practical precaution orthodontists often recommend. Turning the screw at the same time every day, for example in the evening after brushing, reduces the chance of forgetting; keeping a calendar or chart also helps.
Why does a gap open between the front teeth?
A gap opening between the two upper front teeth is an expected sign that the expansion is working. As the palatal suture separates, the front teeth also move apart in the middle; that is why the gap is noticeable in most children within a few days.
The gap is not a mistake in the treatment and, although it often surprises families, it is not a cause for concern. After the expansion stops, the gap closes on its own in most cases thanks to the fibers in the gums and the pressure of the lips and cheeks; gaps that do not close are closed with braces or aligners in the next orthodontic phase. It is not right to try to close the gap at home or pull it together with a band.
How long does the appliance stay in the mouth?
A rapid palatal expander is kept in the mouth for a while after active expansion ends, and in most cases it may stay in for six months to a year in total. The reason is that the newly formed bone tissue needs time to harden; if the device is removed early, some of the width can be lost again.
Things to keep in mind during this time:
- Sticky and hard foods (caramel, chewing gum, hard nuts) are risky for the device; they can loosen the bands.
- Using an interdental brush or a water flosser along with a toothbrush reduces food buildup around the palate and the bands.
- In the first days there may be a slight change in speech and increased saliva; in most children the tongue adapts within a few days to two weeks.
- If a band loosens or there is pain or a sore around the screw, contact the clinic without waiting for your appointment.
After the device is removed, the tooth alignment phase begins. At this stage, depending on the orthodontist's plan, fixed braces or, in suitable cases, orthodontics with Invisalign may be considered.
Can the upper jaw be expanded in adults?
In adults, classic rapid expansion is usually not enough, because the palatal suture ossifies with age and the force of the device is directed at the teeth and their surroundings instead of the bone. For this reason, expansion is most predictable during childhood and adolescence, while growth is still ongoing; the exact age limit varies from person to person, and many orthodontists prefer to plan the procedure before adolescence is complete.
Options in adults include surgically assisted expansion, mini-screw-supported methods in some cases, and plans aimed at dental expansion; their suitability can only be determined by examination and imaging. Clear aligner treatment can contribute to limited expansion of the dental arch, but it does not change the structure of the jawbone; for details, see the page can clear aligners correct jaw structure. In younger children, the Invisalign First approach may be discussed to support alignment and arch development; with marked skeletal narrowness, however, a fixed expander is often needed.
Examination for palatal expansion in Ankara
If you notice a crossbite, a narrow upper jaw or marked crowding in your child, you can start the process with an examination by an orthodontist at our clinic in Park Oran, Çankaya. After the examination and imaging, whether a device is needed, how long treatment will take and fee information are shared in writing. You can make an appointment through our Contact page.
Frequently asked questions
Does a palatal expander hurt?
In the first days there may be a feeling of pressure and tension in the palate, around the nose and in the teeth. In most children this feeling eases quickly. If the discomfort is severe or increasing, you should see the orthodontist.
At what age is a palatal expander fitted?
Childhood and early adolescence, while growth is ongoing, are usually preferred, because the palatal suture opens more easily during this period. The exact age is determined by an orthodontic examination according to the child's development.
What happens if I forget to turn the screw?
If one or more turns are missed, the expansion is delayed, but you should not make extra turns on your own to catch up. The right approach is to let the clinic know and ask the orthodontist how to continue the schedule.
Does the appliance affect speech and eating?
In the first few days there may be a slight change in speech and increased saliva. The tongue usually adapts quickly. Sticky and hard foods should be avoided.
Is the expansion permanent?
Leaving the device in the mouth for a while after active expansion helps the new bone consolidate. When this process is followed, the results are maintained in most cases; even so, the subsequent orthodontic phase and follow-up visits are important.
