Palatal expander

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A palatal expander.

A palatal expander, also known as a rapid palatal expander, rapid maxillary expansion appliance, palate expander, orthodontic expander, Haas, or Hyrax, is used to widen the upper jaw (maxilla) so that the bottom and upper teeth will fit together better.[1][2] This is a common orthodontic procedure. Although the use of an expander is most common in children it can be and has successfully been used in adults, although the effects of expansion are slightly more uncomfortable. Also, depending on the amount of correction and age of the patient, it may result in surgical separation of the maxilla. Use of a palatal expander is most often followed by braces to straighten out all the teeth now that room has been created.

Indications for a Palatal Expander[edit]

Some most notable indications for the need of a palatal expander include:[3]

  1. Posterior cross bite
  2. Crowding of the teeth
  3. Most cases of malocclusion
  4. Rhinologic and respiratory ailments
  5. Cleft lip
  6. Cleft palate

The Palatal Expansion Process[edit]

Rapid Palatal Expansion[edit]

The expansion process usually results in a large gap between the patient's 2 top front teeth, although this does not always happen. This gap is closed naturally and the teeth may overlap which leads to braces being needed. Sometimes with expanders, patients have to turn the expansion screw themselves to tighten up the expander. For expansion that is not managed by the patient and on the lower jaw, a bionator may be a more suitable alternative.

The expander works by turning a key inside the center of the expander. The turn of this key will push the arms of the expander by roughly 1-2 millimeters a week. Often, orthodontists direct their patients to turn 2 times a week for a period of 2 to 3 weeks before their next visit to determine the next step in the overall procedure.

Although it may vary from person to person, most usually feel slight pressure on their teeth. As the patient turns the expansion screw using the key, a space develops between the front two teeth. Some may develop a large space while others do not develop a space at all. It usually takes a week or two for one to adjust to eating and speaking after first receiving the rapid palatal expander.

When the palatal expander is first removed, patients usually report that their mouth feels extremely big and spacious. After the patient's expander is removed they also have a large gap in their mouths.

A palatal expander usually remain in the patient's mouth for about 9 weeks, but this time may vary between patients.[4] After extraction of the palatal expander, the patient enters a six month retention period in which the palate attempts to fix back to the position it was originally. To prevent this radical movement, a retainer is given to the patient to keep the teeth in proper alignment.[5]

Surgically Assisted Rapid Palatal Expansion[edit]

Once a patient reaches maturity (puberty) the palate halves fuse together into a single palate tissue. If the patient suffers a type of malocclusion, a palatal expander would need to be applied. However, with the matured palate, the palatal expander would need to be surgically inserted onto the mid-palatal suture. Typically, the patient would be under the care of an oral-maxiofacial surgeon and the surgical procedure would commence.[6][7]

The mid-palatal suture is first cut open into two parts. The center of the midpalatal suture is then inserted into the open slit. Once fully inserted, the mid-palatal suture of the patient is then closed by the surgeon. The orthodontist will then finish the procedure by connecting the palatal expanders band rings to the patients maxillary molars.[6][7]

Effects on the Palatal Expander[edit]

The four main factors that effect the palatal expanders work on the patient include:

  1. Age of the patient
  2. Duration of Treatment
  3. Applied Force
  4. Rate of Expansion

Effects of a Palatal Expander[edit]

Patients who have expanders may experience extra saliva and lisps[8] (pronouncing the letter s, t, and r blends become very difficult). Patients may experience pain and headaches while wearing palatal expanders and when the screw is turned. They may also feel a sore on their tongue from contact with the expander's metal bars.[8]


  1. ^ Haas, A.J. (1965). "treatment of maxillary deficiency by opening the mid palatal suture". Angle Orthod. 35. pp. 200–217. 
  2. ^ Angle, E.H. (1860). "Treatment of irregularity of the permanent or adult teeth". Dent. Cosmos. 1. pp. 540–544. 
  3. ^ Baccetti, T. (2001). "Treatment Timing for Rapid Maxillary Expansion" (PDF). American Journal of Orthodontics. 
  4. ^ Umasankar, K.; Umasankar, Nagalakshmi (2001). "Palatal Expanders in the Correction of Bilateral Posterior Crossbite - Which one, When & How?". J Ind Orthod Soc 34. pp. 107–113. Retrieved 2015-02-17. 
  5. ^ Haas, A.J. (1970). "Palatal Expansion just the beginning of dentofacial orthopedic". American Journal of Orthodonitcs. 
  6. ^ a b Rienbatcher, K.E. (2013). "Surgically Assisted Rapid Maxillary Expansion: Feasibility of nor releasing the nasal septum". JOMS. 
  7. ^ a b Babacan, H. (2006). "Rapid Maxillary Expansion and Surgically Assisted Rapid Maxillary Expansion Effects on Nasal Volume". Angel Orthod. 
  8. ^ a b Stevens, Kyle; Bressmann, Tim; Gong, Siew-Ging; Tompson, Bryan D. (2011). "Impact of a rapid palatal expander on speech articulation". Am J Orthod Dentofacial Orthop 140 (2). pp. 67–75. doi:10.1016/j.ajodo.2011.02.017. Retrieved 2015-02-17.