Fixed palatal suture appliances commonly known as RPE, RME (rapid palatal/maxillary expander) or PSA’s (palatal suture appliance) are designed for fast and efficient expansion. While most expansion appliances are designed to slowly move teeth these appliances work by breaking the median suture. After insertion and initial activation, the screw can be activated by the patients’ family from 1-2 times daily. Within a few days the suture is broken & then the two halves of the maxilla can be separated to the desired position with little resistance. The appliance remains in position until the bone has had a chance to fill the gap between the two halves of the maxilla.
A major benefit of this method of expansion is with quick application of force the suture breaks & the pressure is released before the teeth have time to move within the alveolar ridge or any tissue is damaged beyond recovery.
Maxillary expanders are typically fabricated with a four arm 12 mm screw. Other expansion screws are available upon request including various sizes and 2 arm mini screws with or without positive ratcheting mechanisms to prevent unwanted back-up. All expanders come with a deluxe activation key. Auxiliary options such as face mask hooks, tubes & habit cribs can also be added to these appliances.
This all metal appliance also known as a hygienic RPE is typically fabricated with bands on the first molars and lingual bars extending to the first bicuspid. May also be fabricated in a four-band version or with bondable rests as shown here.
Lower Hyrax RPE
The 2-arm hyrax screw which also provides 12mm expansion is used for lower expanders, lingual extension arms can also be formed toward the cuspids or sweep springs could be added lingual to the anterior teeth to assist in rounding out the arch as the RPE opens.
Similar to the Hyrax with the exception of how it attaches to the teeth. Used when it is desirable to disclude the upper or open the bite. Fabricated with an acrylic pad of minimal thickness over the posteriors. Debonding loops, hooks, & tubes are optional as well as varying the thickness of the acrylic pad to open the bite
The Haas acts on both the tissue & tooth. Typically fabricated with bands on first molar & lingual bar extending to first bicuspid. May also be fabricated in four-band version or further stabilized by adding occlusal rests.
Hyrax & Bonded Screw Varieties
GOLD: The best screw I’ve ever used and our standard screw, made in Germany by Forestadent. Features 4 strong arms, minimal skeleton body, 12mm of expansion & gold plated threaded spindle. The gold spindle performs 2 very important features that differentiate this screw from its competition. Gold spindle makes for easy identification by patients’ family member who is activating the screw & the softer than steel gold metal deforms slightly as the screw is activated making this virtually impervious to the screw backing up under the pressure of expansion.
Snap – Lock: features a hexagonal keyhole barrel & flat spring steel back so that the flat areas mechanically hold the spindle in place to prevent unwanted back-up. The positive seating design can also be felt by the patient during activation due to tension on the device. The flat steel back also prevents key from extending through the screw & poking patient in roof of mouth
Mini: this is the smallest bodied screw with only 2 arms & one guide pin. Still delivers 12mm expansion. This is the screw we use in our lower hyrax expanders but can be also be used in upper hyrax or bonded RPE’s for patients with small, narrow palates, strong gag reflex or are otherwise bothered by traditional sized hyrax screw. Some practices choose to use this screw on all expanders due to its superior comfort.
Memory: 10mm expansion using NiTi spring coils inside the closed body housing. As the spindle is activated it compresses coils which deliver a more comfortable painless “continuous light force” instead of the direct force of traditional screws
Fan: Expands mostly anterior with minimal posterior involvement using a fan shaped 9mm screw. Excellent for use in cases of cleft palate.
VECS: 10mm or 14mm expansion. The VECS screw operates completely differently in that it uses a hex key that rotates in the keyhole & turns a gear that opens the body of the screw this changes the dimensions of the screw body & can allow for completely variable expansion with each activation
Superscrew: Utilizes an open end wrench to turn body, very stable & strong screw that offers an incredible 17mm of expansion.
Haas type screw options
Transverse: the embeddable skeleton screw comes in several sizes with expansion up to 11mm
Memory: embeddable expansion using NiTi spring coils inside the closed body housing. As the spindle is activated it compresses coils which deliver a more comfortable painless “light continuous force” instead of the direct force of traditional screws
Fan: Expands mostly anterior with minimal posterior involvement using a fan shaped 8mm screw.