Patients with skeletal class II malocclusion who have a retracted lower jaw will be treated in this study. The efficacy of clear Plates in the treatment of Skeletal Class II Malocclusion will be assessed. The skeletal, dental and soft tissues changes resulted by this intervention will be studied and compared with the results of Traditional treatment with fixed appliances.

There are two group:

1. a group of patients in which participants will be undergo to Modified Twin-Block Appliance with Clear Plates.
2. a group of patients in which participants will be undergo to the traditional Twin-Block Appliance.

phase Intervention/treatment Condition or disease

Not applicable Other:

Modified Twin-Block Appliance with Clear Plates.

Other:

Traditional Twin-Block Appliance. Skeletal class II Malocclusion

Inclusion Criteria:

• - Patients with mixed dentition at age 10.5-13 years.
• The patient has Skeletal class II malocclusion caused by mandibular retraction ANB > 5, 8 mm >O.J> 5 mm, SNB<78, angle (NSAr) ≥ ° 125 and normal placement of the upper jaw.
• The patient is willing to accept treatment with a removable device.
• No previous orthodontic treatment
• the growth model is within the normal or horizontal maxillary opening angle of 30 >MM or angle of 400 > Björk
• patients do not have an upper alveolar dental protrusion.

Exclusion Criteria:

• -Patients with periodontal disease.
• patients with a neuromuscular disorder.
• patients of class I or III of malocclusion.
• Patients with temporomandibular joint disorder.
• Patients with Skeletal open bite.
• Patients with poor oral and gingival health
• the presence of a unilateral or bilateral posterior crossbite.
• patients who have upper jaw stenosis and need to be prepared by expansion before functional treatment.
• any patient who does not meet one or more of the Inclusion criteria will be removed from the study.