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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
30
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
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