A randomized clinical trial is set out to compare the effectiveness of two types of functional appliances in the correction of a Class II malocclusion. (Class II malocclusions are where upper front teeth bite significantly further forward in relation to lower front teeth).

It is a multicenter randomized clinical trial with two arms parallel group. The patients will be randomly divided into two groups, group one: Myobrace appliance will be used while, and group two Twin-block appliances will be used. Cephalometric x-ray will be taken before starting the treatment (T1) and at the end of treatment (T2) at 9 months. The effectiveness of the two appliances will be assessed and measured comparing the difference in the cephalometric X-ray before and after treatment.

Inclusion Criteria:

1. Growing children who need myofunctional appliance.
2. Cl II div. 1 malocclusion.
3. No previous orthodontic or orthopaedic treatments.

Exclusion Criteria:

1. Patients with systemic involvement.
2. Congenital malformations such as cleft lip and palate.
3. Facial deformities.
4. Finger sucking habit will be excluded

Blinding to treatment allocation is possible only for the outcomes assessor because the clinicians could know the intervention. All the trial documents will be labeled with the study ID number, which be used for participant identification and data collection without unmasking the allocation group.