Which of the following is a myofunctional appliance?: (A) Catalan's appliance, (B) Hawley's appliance, (C) Expansion screw, (D) Derichsweiler appliance.
Answer is A. Catalans or lower anterior inclined plane appliance is used to treat cross bites. The inclined plane has a 450 angulation, which forces the maxillary teeth in cross bite to a more labial position. It is teeth supported functional appliance. Expansion screw and Derichsweiler are expansion appliances.