History and Development of the Frankel Appliance - Developed by Rolf Fränkel in Germany in the 1950s - Fränkel used the activator functional appliance with mixed results - Believed in correcting functional deviations of muscles along with dentition for stable treatment outcomes - Developed functional regulator appliances to train and reprogram the musculature around the mouth - Published around 70 articles emphasizing the importance of his appliance in expanding dental arches

Fränkel's Philosophy and Principles - Mirrored Melvin Moss's philosophy - Functional performance of oral capsule muscles influences functional spaces - Atmospheric pressure also influences functional spaces - Perioral muscles have a restraining effect on dental arches - Appliance insertion expands the capsule and allows new muscle adaptation

Types of Frankel Appliances - Frankel Appliance I (FR 1): Used for Class 1 and Class 2 Division 1 malocclusion - Frankel Appliance II (FR II): Primarily used for Class 2 Division 1 and 2 malocclusion - Frankel Appliance III (FR III): Used for Class 3 malocclusion - Frankel Appliance IV (FR IV): Used for open bite and bimaxillary protrusion cases - Frankel Appliance V (FR V): Used with headgear in patients with high mandibular plane angle and vertical maxillary excess

Modifications of the Frankel Appliance - Otton (1992): Capped Frankel Appliance - Owen (1985): Modified functional regulator for Vertical Maxillary Excess - Chate (1986): Changed angulation of Cross Wires - Kingston: Modified buccal shields - Haynes (1986): Modified appliance with continuous buccolabial shield palatal acrylic support

References and Research on the Frankel Appliance - De Almeida, Marcio Rodrigues; Henriques, José Fernando Castanha; Ursi, Weber (2002-05-01). Comparative study of the Fränkel (FR-2) and bionator appliances in the treatment of Class II malocclusion. - Bionator/Orthopedic Corrector - DynaFlex. - Rudzki-Janson, I.; Noachtar, R. (1998-03-01). Functional appliance therapy with the Bionator. - Perillo, Letizia; Cannavale, Rosangela; Ferro, Fabrizia; Franchi, Lorenzo; Masucci, Caterina; Chiodini, Paolo; Baccetti, Tiziano (2011-02-01). Meta-analysis of skeletal mandibular changes during Frankel appliance treatment. - Rodrigues de Almeida, Marcio; Castanha Henriques, José Fernando; Rodrigues de Almeida, Renato; Ursi, Weber (2002-10-01). Treatment effects produced by Fränkel appliance in patients with class II, division 1 malocclusion.