There is no scientific evidence regarding which is the ideal force in Orthodontics, but it seems that the light and intermittent forces are the best because they avoid the collapse of the periodontal vessels. In the orthopaedic treatment of the Class II division 1 malocclusions we try to combine these forces at the same time using thermal wires, miodynamic functional appliances and miniscrews. The purpose of this lecture is to explain our biomechanics and to show you different severe Class II division 1 cases. We have made changes in the design of the functional appliances to adapt them to simultaneous use with fixed appliances. Another characteristic of the SWLF technique is the FSC ( Friction Selection Control) , the control of the orthodontic tooth movement tooth-by-tooth by means to select the proper bracket and type of ligature according to the biomechanic needs. This type of biomechanic philosophy reduces the length of the orthodontic-orthopaedic treatment and increases the patient´s compliance.