The document provides an overview of the evolution of functional appliances in orthodontics. It discusses early pioneers like Pierre Robin who developed the monobloc appliance in 1902 to treat malocclusions. Viggo Andresen is credited with developing the first true functional appliance called the activator in 1908, inspired by earlier works. The activator aimed to correct malocclusions by modifying muscle function rather than just tooth movement. The document traces the development of different functional appliances and controversies between the European and American approaches to orthodontics, with Europeans focusing more on removable appliances and functional treatment while Americans emphasized fixed appliances.