The study aiming at evaluation of the Skeletal and Dento-alveolar expansion in adult patents using Two Mini-screws Supported Hyrax compared with untreated control group.

Methodology:

• Basic orthodontic record will be taken.
• impression with bands on upper first molars will be taken.
• Two eyelets will be soldered to the body of the hyrax appliance (size 10, Dentaurum, Germany).
• CBCT will be taken while patient wearing 1 mm thickness vacuum on the lower arch to dis-occlude both arches.
• Delivery, check the retention and fitness of the appliance.
• Cementation of the appliance using band cement(compomer).
• Using 3M contra-angle driver, the screws (Tomas screw size 10, Dentaurum, Germany) will be loaded and inserted.
• Activation of the appliance by opening it two turns immediately, followed by two turns everyday till cross bite correction or appearance of midline diastema.
• Closure of the device, and leave the appliance in-situ for five months as a retention.
• Post-expansion CBCT will be taken and continue fixed orthodontic treatment. Outcome: skeletal and dento-alveolar expansion will be evaluated

Inclusion Criteria:

• Unilateral or bilateral Dental posterior cross-bite
• Skeletal Maxillary constriction
• Male and female patients.
• Chronological age (18-30 years).
• Mid-palatal suture maturation (Grade C,D ) according to F Angileri classification
• Good oral hygiene.
• No craniofacial anomalies or syndromes

Exclusion Criteria:

• Scissor-bite
• Orthodontically-treated
• functional cross bite due to premature occlusal contact
• patients with a syndrome
• cleft patients