The functional appliances include Activators, Frankels, Bionators, Orthopedic Correctors, Twin Block™ and Herbst® designs. The doctor can choose from various removable and fixed appliance designs. All functional appliance designs address Skeletal Class II problems by advancing the mandible forward to a corrected Class I position.

Once “three-point” contact has been achieved a fixed or removable incline bite plane is used to support Class II correction. The Stage II appliance is used until the bicuspids have erupted into occlusion and the posterior open bite has been closed.