An interventional study of The Leaf expander and Hyrax expander in Posterior Crossbite and Maxilla; Hypoplasia, sponsored by Cairo University. Recruiting at 1 site in Egypt. Open to participants aged 6 Years to 12 Years. Per ClinicalTrials.gov, last updated 2026-06-04.
Sponsored by Cairo University · Not applicable, Interventional, and Other
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.
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.
62 studies on the registry are indexed under Retrognathia; 15 are open to participants now.
This study's planned enrollment of 30 is below the median of 34 across 52 interventional studies indexed under Retrognathia.
Browse Retrognathia studies →Cairo University is the lead sponsor of 4,941 studies on the registry; 1,458 are open to participants now.
Of its 37 completed or terminated interventional studies of FDA-regulated products, 5 (14%) have results posted.
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Exclusion Criteria:
9mm leaf expander delievering 900 gm force will be supported on the upper first permanent molars with the appliance arm extending to the canines
Device: The Leaf expander
9mm Hyrax expander will be supported on the upper first permanent molars with the appliance arm extending to the canines
Device: Hyrax expander
The Leaf expander incorporates Nickel Titanium springs that will not require the patients' home activation
Hyrax expander incorporates a screw that requires the patients' home activation
Pain perception
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.
Time frame: first week after appliance insertion
skeletal 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
Time frame: 6 months post expansion
dental tipping
Angular measurement of upper first molars angulation measured in degrees between pre- and post-coronal cuts of the CBCT
Time frame: 6 months post-expansion
digital models parameters
Intermolar width, intercanine width
Time frame: six months post-expansion
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
No contact was published for this record. The registry link below has the sponsor’s details.
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