Rapid palatal expanders (RPE), also known as rapid maxillary expanders (RME) or palatal suture appliances (PSA), are fixed appliances designed for rapid and efficient palatal expansion. Unlike appliances that gradually move teeth, RPEs work by separating the median palatal suture. After initial insertion and activation, the screw is activated by the patient’s family, typically 1-2 times daily. The suture breaks within a few days, allowing the two maxillary halves to separate with minimal resistance. Once expansion is complete the appliance remains in place until new bone fills the gap.

A key advantage of RPEs is the rapid application of force. This causes the suture to break and release pressure before significant tooth movement within the alveolar ridge or tissue damage occurs.

RPEs commonly feature a four-arm, 12mm screw. Various other screws are available, including different expansion mechanisms and range sizes. Also two-arm mini screws or mechanisms to prevent back-up. All expanders include a deluxe activation key. Auxiliary options like face mask hooks, tubes, springs to simultaneously align anterior teeth and habit cribs can be added.

Types of Rapid Palatal Expanders

Hyrax RPE (Hygienic RPE):

This all-metal, highly efficient and hygienic appliance commonly used for upper arch expansion. It typically features bands on the first molars with lingual bars extending to the first bicuspids. It can also be fabricated in a four band version or with rests for greater stability.
This design allows for even force distribution and excellent stability. The Hyrax can be customized with auxiliary components such as face mask hooks, tubes, or habit cribs to enhance functionality and support comprehensive treatment planning.

Lower Hyrax RPE:

Designed specifically for mandibular expansion, the Lower Hyrax utilizes a compact two-arm screw capable of up to 12mm of expansion. Lingual extensions can be formed toward the cuspids or sweep springs added to help round out the lower arch as expansion progresses.
This appliance is ideal for correcting posterior crossbites or improving arch symmetry in growing patients. Its low-profile design ensures maximum comfort while maintaining optimal mechanical efficiency.

Bonded RPE:

Similar to the Hyrax, but with acrylic pads covering the posterior teeth for attachment. This design facilitates disclusion and bite opening, proving particularly useful in correcting crossbites. Optional features include debonding loops, hooks, and tubes, as well as variable thicknesses for the acrylic pads.

Haas RPE:

The Haas Rapid Palatal Expander (RPE) achieves expansion by exerting pressure on both teeth and palatal tissues, promoting more extensive skeletal growth. Constructed with molar bands and a lingual bar reaching the bicuspids, the Haas RPE can also be configured with four bands or enhanced stability using occlusal rests.

This device is particularly advantageous when significant transverse development is needed or when extra palatal coverage is desired for better retention and force delivery.

However, the Haas RPE presents a less hygienic option compared to the Hyrax expander.

Screw Options

Hyrax & Bonded Screw Varieties:

• GOLD: Premium screw with four arms, minimal body, 12mm expansion, and gold-plated spindle. The gold spindle aids identification and prevents back-up.
• Snap-Lock: Hexagonal keyhole and flat spring steel prevent back-up. The seating design also provides tactile feedback during activation.
• Mini: Smallest screw (two arms, one guide pin, 12mm expansion) for lower expanders or patients with small palates/gag reflex. Can be used for all expanders for patient comfort.
• Memory: 10mm expansion using NiTi spring coils for continuous, gentle force.
• Fan: 9mm expansion focusing on the anterior, ideal for cleft palate cases.
• VECS: 10mm or 14mm expansion using a gear system for variable expansion per activation.
• Superscrew: Open-end wrench operated, offering 17mm expansion and high stability.

Haas Type Screw Options:

• Transverse: Embeddable skeleton screw in various sizes, up to 11mm expansion.
• Memory: Embeddable expansion using NiTi coils for gentle, continuous force.
• Fan: 8mm expansion focusing on the anterior.