[The functional regulators (FR III, FR IV)].

The Frankel III appliance is used in Angle Class III, maxillary deficiency cases. The vestibular and buccal shilts changes the sagittal relationship of the jaws in Class III cases by developing the upper jaw sagittally, vertically and transversally. After 7 months of FR III treatment of an 11 year old Class III patient, the molar relationship and anterior crossbite were corrected. As the SNA angle increased, the -2 degrees ANB an le changed to 2 degrees. As there were no transversal and sagittal development in lower jaw, the upper jaw expanded transversally and sagittally. Also the FR IV appliance is used in the treatment of open-bite and bimaxillary protrusion cases.