Indications:

• Skeletal Class III due to maxillary retrusion in growing patients (ages 7–12).

• Anterior crossbite with deficient midface projection.

• Maxillary transverse constriction + need for protraction.

• Hyperdivergent or vertical growers → bonded design gives vertical control.

Contraindications:

• Skeletal Class III due to mandibular prognathism.

• Non-growing adolescents/adults (unless combined with MARPE/SARME + facemask).

• Poor oral hygiene, deep caries, or weak enamel (risk of decalcification under bonded acrylic).

• Patients with limited nasal airway who cannot tolerate bonded acrylic splints.

Corrects:

• Forward displacement of maxilla (skeletal protraction).

• Transverse maxillary deficiency (via expansion screw).

• Corrects anterior crossbite.

• Improves soft-tissue profile (enhanced midfacial support).

• Bonded version also provides posterior bite block effect → controls vertical dimension & limits eruption.

Design:

• Acrylic splints bonded over occlusal surfaces of posterior teeth (from molar to premolar/deciduous molars).

• Midline Hyrax-type jackscrew for expansion (0.25 mm/turn, 1–2 turns/day).

• Rigid wire framework embedded in acrylic for strength.

• Hooks/arms placed in canine/premolar region → attachment for facemask elastics (350–450 g/side).

• Provides rigid unit → distributes orthopedic forces to multiple teeth + palatal vault.

Philosophy:

• “Disarticulate and displace” principle:

  • Rapid expansion opens midpalatal&circummaxillary sutures.

  • Facilitates anterior protraction of the maxilla with facemask elastics.

• Bonded splint → acts as a vertical control appliance (bite block) → useful in hyperdivergent Class III.

• Continuous orthopedic forces transmit through acrylic coverage → more skeletal and less dental tipping compared to banded version.

Modifications:

• Bonded Hyrax with bite opening (thicker posterior acrylic → anterior open bite correction).

• Semi-rapid or slow expansion protocol for more controlled movement.

• Hybrid bone-anchored protraction splint (MARPE bonded design) for older patients.

• Bonded splint with facemask + Class III elastics for combined anchorage.

Advantages:

·         Combines maxillary expansion and protraction in a single appliance.

·         Bonded design – full occlusal coverage minimizes tipping of teeth and vertical opening.

·         Enhanced skeletal effects – effective in early Class III with maxillary deficiency.

·         Improves smile aesthetics by expanding and advancing the maxilla.

·         Minimizes patient discomfort compared to banded or removable alternatives.

·         Reduces relapse risk – bonded coverage maintains expansion during retention.

Facilitates facemask therapy – intraoral hooks or attachments for elastics.