top of page

How do Maxillary Expanders work?

Palate expander

Maxillary or palatal expanders are one of the most commonly used tools in orthodontics.  Expanders play an important role in addressing skeletal and dental problems.  These appliances come in a variety of types and designs, and can have different effects depending on how they are used. 


Maxillary expanders have evolved significantly since they were first discovered over a century ago.  There have since been developments and modifications to designs of expanders, creating more ways to use them and more sophisticated appliances. Let’s explore types of palatal expanders and how they work.


How do expanders work?


Palatal expanders can have two effects: they can expand the teeth (dentoalveolar expansion) and/or expand the jaw (skeletal expansion).  These effects help create space for incoming or crowded teeth, correct crossbites, improve misaligned bites, and widen the upper jaw.  Expanders used to orthopedically widening the upper jaw can also widen the space inside the nasal cavity to help with breathing.  Effects of expanders depend on the type of appliance used, age of the patient, and the doctor’s protocol.


Traditional maxillary expanders are most predictable when children are growing.  This is because the upper jaw (maxilla) forms in two halves, with a split (suture) down the middle.  This split is open during childhood, and becomes increasingly fused along the midline as kids approach puberty.  Fusion or interdigitation of this suture makes widening the upper jaw difficult to achieve after puberty without additional accessories or surgical intervention.


Can expanders be used on the lower jaw?


Unlike the upper jaw, the lower jaw (mandible) is not split down the middle.  The mandible forms as one bone.  Without surgery, this makes orthopedic (jaw) expansion anatomically impossible.  However, expanders can still be used to move the teeth.  This allows for uprighting and dental expansion of the lower teeth, which can sometimes be necessary to fix a misaligned bite and create space for crowding. A commonly used lower teeth expander is the Schwartz appliance.


Common types of maxillary expanders


Upper jaw expanders come in a variety of designs, including the Rapid Palatal Expander (RPE or RME), Haas expander, bonded expander, W-arch, Quad-helix, and fan-type expanders.  Modern advances in technology have created the ability to design 3D printed expanders, which have the benefit of being smaller in size and not requiring separators (elastic bands) between teeth. 


Recent advances have also led to the development of Mini-screw Assisted Rapid Palatal Expanders (MARPE), which are anchored to the upper jaw bone.  These have shown success in treating more mature patients, after puberty, as an alternative to jaw surgery to widen the maxilla.


The type of maxillary expander chosen for you by your orthodontist will depend on the goals, age of the patient, and clinical preferences of the doctor.

How are expanders activated?

The way in which expanders are activated depends on the type of appliance. Many expanders, such as the RPE, Haas, and Schwartz, are all activated by using a special "key" to gently turn an expansion screw located in the middle of the appliance. Other types of expanders, such as the W-arch, are activated by the orthodontist and do not require turns.

What to expect with an expander


The first week with a maxillary expander is the breaking-in period and will be the most challenging.  We have found that patience, encouragement, and positive attitudes help patients quickly adapt.  


  • Pressure: During and immediately following the activation (turning) of the expander, some pressure may be felt on back teeth and in between front teeth.  It is also normal to experience pressure around the bridge of the nose and cheeks. 

  • Tooth tenderness: Some tooth tenderness is normal and can be relieved by taking over the counter pain reliever such as ibuprofen (Advil, Motrin) or Tylenol as instructed by your doctor and following all label instructions.

  • Speech and eating difficulties:  This is normal and usually resolve within a week.  Because the patient’s teeth don’t meet as they did prior to appliance placement, eating may be a challenge for a short time.   To help speech difficulties, have the patient talk and read out loud for the first week to help speech improve.

  • Changes in the bite: You will find that with each activation of the expander, the bite will continually change. It is helpful to eat softer foods for the first few meals.  Cold treats of smoothies or popsicles may relieve symptoms. 

  • Food accumulation: During meals, food may accumulate in the roof of the mouth and around parts of the expander.  It is best to try to dislodge the food by swishing a mouth full of your drink.  If this “swish and swallow” method does not work, try brushing around your expander gently with a soft toothbrush to dislodge the food. Some people have found a water pik or water flosser to be helpful. Avoid pulling or picking at the appliance. Also avoid sucking back the food from the appliance – this may cause the food particles to become lodged in the lungs.

  • Spacing between teeth: After about one week of activation, a space usually opens between the two upper front teeth.  This space is normal and an excellent indication that treatment is progressing.  This space will continue to increase with subsequent activations, and typically spontaneously close after all activations are complete. 


Maxillary expanders are a useful and effective orthodontic appliance. They offer solutions for correcting several skeletal and dental problems. To learn more about palate expanders, or if you think you or your child may benefit from this appliance, contact our office or book a free consultation online to meet with our orthodontist!


Commenting has been turned off.
bottom of page