Overview
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.
Description
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.
Eligibility
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.
