Frankel's Functional Regulator is used in patients with Class 3 malocclusion. In this appliance the lip pads are used in the maxillary arch to allow the maxilla to grow. The mandibular arch does not have pads in the anterior to allow the soft tissue forces to act on the mandible.
Doctor Fränkel's appliances correct some abnormal functions (improper deglutition, buccal respiration, improper tongue position, weak lip seal) while enabling harmonious development of muscles and maxillaries. These appliances exert their forces on the vestibules, on which two vestibular screens part the buccal and labial muscles of the dentition (from 0.5 to 3mm). Pressure exerted on the maxillaries by the cheeks and lips is thereby eliminated. By this very fact, the tongue provides natural expansion of the dental arches. Indeed, these appliances first transmit their force into the development of the bone base, while above, the dental arches resume their proper positions on their own. In general, expansion gained with a Fränkel is maintained. In comparison with other orthopaedic appliances, risks of relapse are low.