The Bionator and the Orthopedic Corrector, are removable ortho appliances designed to correct Class 2 cases. The Bionator, a monoblock appliance, usually incorporates a midline adjustment screw set lingual to the lower incisors. Both the Bionator and the Corrector can be constructed to open, close or maintain the bite. Since these appliances work to retrain the muscles of mastication, they are very helpful in preventing relapse. With the exception of eating and brushing, these appliances are worn at all times.