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NCT Number: NCT07301918

Leaf Expander Versus Hyrax Expander in Mixed Dentition Patients With Posterior Crossbite.

Design: Two-arm parallel randomized clinical trial in mixed dentition (6-12 years).

Arms: (1) 9 mm, 900 g leaf expander; (2) 9 mm Hyrax expander. Follow-up: From appliance insertion → completion of intended expansion → 6-month retention.

Primary outcome: Pain perception during the first 7 days post-insertion (daily patient-reported scale).

Secondary outcomes: Skeletal and dental changes on CBCT.

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Key information

Conditions

Posterior Crossbite Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Craniofacial Abnormalities Jaw Abnormalities Jaw Diseases Mandibular Diseases Maxilla; Hypoplasia Maxillofacial Abnormalities Musculoskeletal Abnormalities Musculoskeletal Diseases Retrognathia Stomatognathic Diseases Stomatognathic System Abnormalities

Age range

6 year–12 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Cairo University

Cairo, Egypt

Location status: Recruiting

Location contact

Noura Saleh, Masters in Orthodontics

CONTACT

[email protected]

122476422

About this study

Participants receive a banded maxillary expansion appliance cemented to maxillary first permanent molars, assigned to:

Leaf expander arm: Nickel-titanium leaf-spring expander, 9 mm screw, delivering force of ~900 g.

Hyrax expander arm: Conventional tooth-borne jackscrew expander, 9 mm screw. Standard activation: two turns per week.

Retention: Both appliances kept passively in situ for 6 months of retention following achievement of planned expansion.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male and female patients
  • Mixed dentition stage
  • Unilateral or bilateral posterior crossbite.
  • Patients in prepubertal stage with cervical vertebral maturation stage 1-3.
  • Fully erupted maxillary and mandibular permanent first molars.
  • Skeletal class I or II.

Exclusion criteria

  • Previous orthodontic treatment.
  • Missing teeth.
  • Inadequate oral hygiene.
  • Patients with bad oral habits.
  • Patients with medical conditions.
  • Patients with cleft lip and palate.

Treatment and study plan

The Leaf expander

Device

The Leaf expander incorporates Nickel Titanium springs that will not require the patients' home activation

Hyrax expander

Device

Hyrax expander incorporates a screw that requires the patients' home activation

Primary outcomes

  1. Pain perception

    Time frame: first week after appliance insertion

    Pain perception during the first week after insertion using Wong-Becker faces scale with minimum value of zero and maximum value of ten, ten score represents the worst pain percieved.

Secondary outcomes

  1. skeletal expansion

    Time frame: 6 months post expansion

    skeletal expansion using Cone Beam Computed Tomography skeletal expansion: linear distances of the midpalatal suture opening measured in mm between the pre- and post-axial cuts of the CBCT

  2. dental tipping

    Time frame: 6 months post-expansion

    Angular measurement of upper first molars angulation measured in degrees between pre- and post-coronal cuts of the CBCT

  3. digital models parameters

    Time frame: six months post-expansion

    Intermolar width, intercanine width

Sponsors and collaborators

Lead sponsor

Cairo University

Other

Registry information

Official study title

Evaluation of the Effects of the Leaf Expander Versus Hyrax Expander in Mixed Dentition Patients With Posterior Crossbite: A Randomized Clinical Trial.

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Dec 24, 2025
Registry last updated
Jun 4, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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