Palatal Expander (Hyrax Appliance) in Ukraine

The upper jaw is not a single solid bone. It consists of two halves joined by the midpalatal suture, a strip of connective tissue running along the palate from the front teeth backwards. In children and teenagers this suture is still pliable, so the two halves of the jaw can be moved apart mechanically, and the space between them later fills with new bone.

This is the basis of the method. A fixed appliance is attached to the first permanent molars, sometimes with additional anchorage on the premolars: metal bands are joined by rigid arms to an orthodontic screw in the centre of the palate. Each turn of the screw puts pressure on the bones, and the suture gradually opens. The Hyrax appliance has no plastic parts and sits clear of the roof of the mouth, which makes it easier to keep clean.

The appliance is most often fitted for a crossbite in the side areas, when the upper teeth close inside the lower ones on one or both sides. Another common reason is a narrow upper jaw with too little room for the permanent teeth: expansion widens the arch so the erupting teeth have enough space. The method is also used to help an impacted canine erupt, to prepare for face mask treatment in Class III cases, and in patients with a cleft palate, where a separate protocol applies.

In some situations expansion is not done or is postponed. A single tooth in crossbite is usually corrected by simpler means rather than with an appliance for the whole jaw. Active caries, gum inflammation and poor hygiene need treating first, as plaque builds up more easily under the bands than on exposed enamel. Sound anchor teeth are also essential: loose or badly decayed molars cannot provide anchorage. Adults are a different case: in most of them the suture has already fused, and the same appliance will tip the teeth outwards without moving the bones apart.

MediUkraine is a treatment search and coordination service, not a clinic. We choose the dental centre and a doctor with the right specialism, arrange the appointment dates and support your family throughout, including if you are travelling from another city or country. The diagnosis, type of appliance and scope of treatment are decided by the orthodontist after an in-person examination.

The Hyrax appliance consists of four elements: an orthodontic screw in the centre of the palate, rigid arms, metal bands on the anchor teeth and the cement that holds it all in place. The bands are attached to the first permanent molars, and if needed, extra anchorage is added on the premolars or baby molars. The screw has four holes for the key: each quarter turn moves its halves apart by about 0.2 mm. The appliance is entirely metal and sits clear of the roof of the mouth, so food debris rinses away easily; that is why it has become the standard choice at most clinics.

The Haas appliance is built on the same principle but has two acrylic pads that rest against the palate on either side of the screw. The load is shared between the teeth and the palatal tissues, and some orthodontists choose this design when there are few anchor teeth or they are small. The trade-off is care: food gets trapped under the acrylic and the tissue under the pads can become irritated and red, so the area has to be flushed with a water flosser after every meal. Studies show no fundamental difference in how many millimetres of expansion the two designs achieve, so the choice usually depends on the clinical situation and the orthodontist's approach.

The activation schedule is set individually by the orthodontist and must not be changed on your own. The classic rapid expansion protocol is one to two quarter turns a day, that is 0.2–0.4 mm, usually in the morning and evening. The active phase lasts 2–4 weeks, during which the arch widens by 6–8 mm, and the signal to stop is not the number of turns but what the orthodontist sees clinically: the palatal cusps of the upper molars should reach roughly the cheek-side cusps of the lower ones. The slow protocol, one quarter turn every two to three days, stretches the process over two to three months and is chosen when gentler forces on the teeth and tissues are preferred.

A gap between the front teeth is an expected stage, not a complication. It appears in the second or third week of the active phase and shows that the suture has genuinely opened, rather than the teeth simply tipping. The gap can be noticeable, up to a few millimetres, and it is what worries children and parents most. After the turns stop, the gap (diastema) mostly closes on its own over a few weeks or months: the fibres connecting the teeth pull them back together. If a gap remains at the end of retention, it is closed at the next stage of treatment, with braces or a plate.

Retention is half the result. Once the turns are finished, the screw is locked so it cannot unwind, and the appliance stays in the mouth for another 3–6 months while the space in the suture fills with new bone. Removing the appliance as soon as the target width is reached sharply increases the risk of relapse: the bone has not yet formed, and the two halves of the jaw move back towards their original position. After removal, a removable plate or a fixed arch is sometimes fitted to hold the width until the next phase of treatment.

Age and the maturity of the suture determine whether the method will work. Expansion is most predictable in the mixed dentition, roughly from 7 to 11 years, and usually remains possible in adolescence. After that the suture gradually ossifies, at a different pace in each person: in some girls it has already fused soon after the age of 14, while in some young men it remains pliable even at 18. So before treating a teenager or young adult, the orthodontist relies not on their age on paper but on a CBCT cross-section showing the stage of suture maturation.

In adults with a fused suture, a banded appliance mainly tips the teeth outwards: the crowns move apart but the bones do not, and the cost can be gum recession and pain. For adults there are two solutions. An expander anchored on mini-screws placed in the bone of the palate transmits force directly to the bone rather than through the teeth, and in young adults it often opens the suture without surgery. In surgically assisted expansion, a maxillofacial surgeon makes cuts in the bone where resistance is greatest, after which the appliance works in the usual way. Both options are planned jointly by the orthodontist and the surgeon, and both require separate diagnostics with CBCT.

Nasal breathing comes up with almost every other family. Expanding the upper jaw also widens the floor of the nasal cavity, and measurements show that resistance in the nasal passages decreases after treatment while the volume of the cavity increases. At the same time, the appliance does not treat allergic rhinitis, enlarged adenoids or a deviated nasal septum: if these are the reason a child does not breathe through the nose, expansion alone will not be enough. In children with obstructive sleep apnoea and a narrow jaw, expansion is part of comprehensive treatment and in some patients reduces the number of apnoea episodes, but it does not replace an examination by an ear, nose and throat (ENT) specialist and polysomnography. The right order is to find the cause of the breathing problem first, and only then decide what role orthodontics should play.

Other expansion appliances solve other problems. A removable plate with a screw mainly moves the teeth and suits a slight lack of space, the quad-helix is a wire spring for slow expansion in the mixed dentition, and aligners give limited dentoalveolar expansion in adults. None of these opens the midpalatal suture the way a banded screw appliance does, so with marked skeletal narrowing they are not considered an equivalent substitute.

Expansion is almost never a complete treatment in itself. It is the first phase, which creates space in the arch, and in the second phase the teeth are aligned with braces, aligners or removable appliances, usually after all the baby teeth have been replaced. Between the phases there may be a pause of several months or years, during which the child is examined every six months. The orthodontist should explain this at the outset: removing the appliance is not the end of treatment but the move to the next stage.

The first days after fitting are the hardest, and it is worth warning the child about this in advance. The appliance feels like a foreign body, there is more saliva, 's' and 'sh' sounds change, and your child will need to eat slowly and in small bites. Getting used to it usually takes 3–5 days, and speech recovers within one to two weeks, faster if the child talks more and reads aloud.

Each activation causes brief but noticeable pressure in the palate, under the nose and between the eyes. It lasts a few minutes and passes on its own. If the pressure turns into sharp pain or lasts for hours, make the next turn only after speaking to the orthodontist: pain is a warning sign here, and regularly taking painkillers to mask it is not advisable.

In the second or third week a gap appears between the upper incisors. This is expected, not a breakage: it confirms that the suture is opening. Explain this to your child in advance and show them photos of similar cases; otherwise the gap can feel like a ruined smile, at an age when appearance already matters.

Check-up visits during the active phase are scheduled every 1–2 weeks. The orthodontist checks how far the teeth have moved apart, whether a band has come loose and whether the soft tissues are irritated, and decides when to stop the turns. The active phase usually ends after 2–4 weeks, and the target width includes a small margin, because some of the expansion is lost over time.

Then the retention period begins, when almost nothing seems to be happening. The appliance stays in the mouth for another 3–6 months, visits become less frequent, and meanwhile bone fills the space in the suture. This is the stage families most often want to cut short, yet it is exactly what determines whether the arch width is maintained. Removing the appliance takes a few minutes and needs no anaesthesia; afterwards the enamel under the bands is polished and its condition assessed.

The result also has to be judged at the right time. Arch width is measured straight after removal, the bone in the suture is assessed on a follow-up X-ray, and the effect on breathing is assessed by an ENT specialist no earlier than a few months later. The bite changes as the face grows, so the child is followed up until growth is complete, and the second phase is planned around the bite as it develops. Timelines and progress vary from child to child, so only an orthodontist can predict the result for an individual child after an examination.