It is characterized by muscle component, which is fundamental. He attributed to the imbalance between muscle forces that are the cause of malocclusions and impeding bone growth .
The Frankel built their devices so they are vestibular , work by neutralizing muscle forces . The language has freedom of movement and is remodeling the oral cavity. Frankel four types are described :
– Type 1: for malocclusion class 1 and class 2 Division 1
– Type 2: For Class 2 malocclusion and Division 2
-Type 3: for progeny TYPE 4: to open bites