Patients with class II malocclusion and retrognathic mandibles will be treated using functional appliances and asses the remodeling that is expected to occur in the temporomandibular joint (TMJ) using cone-beam computed tomography (CBCT) images and we will register mandibular movements using electronic axiograph ( a specific apparatus used to record jaw movements in three dimensions).

There are three groups :

1. Activator Group
2. Twin block Group
3. Control Group with no treatment.

Patients will be allocated to the three groups randomly.

Data will be collected using three different approaches:

• CBCT images before treatment and 12 months after treatment
• Axiograph registrations before treatment and 12 months after treatment

The main purposes of this project are:

1. to evaluate the remodeling effects that would take place in the bone structures of the temporomandibular joint (TMJ) during functional treatment.
2. to evaluate the possible change that may occur in mandibular movements following functional treatment.
3. to evaluate the possible change in the spatial relationship between centric occlusion (CO) and centric relation (CR) following functional treatment

Inclusion Criteria:

Class II malocclusion Skeletal class II with retruded mandibles. Old between 10-13 years Healthy TMJ Horizontal or normal growth pattern

Exclusion Criteria:

Patients who have been treated previously Patients with syndromes or congenital deformities Signs or symptoms of temporomandibular disorders.