In 1908, Viggo Andersen developed the Activator appliance. This was the first functional appliance to be widely accepted, especially in Europe. This appliance became the “Norwegian” system of treatment in Orthodontics in early 1900s.
Viggo Andersen first used this appliance on his daughter’s mandibular teeth in the summer of 1908. He took the mechanical braces off from his daughter, and he had her wear the “Biofunctional Retainer” throughout the summer in the mandibular arch. The maxillary arch received Hawley retainer. After a while, Viggo realized that her daughter’s occlusion remained the same. He then started using his retainer in his own private practice on his patients, and he saw similar results. Viggo, who was born in Denmark, moved to Norway in the 1920s. There he met Karl Haupl with whom Viggo devised the name “Activator” to describe his appliance. Haupl and Andersen worked closely together and published many textbooks pertaining to the Activator Appliance. The name Activator was first used in their first edition of textbook in the 1920s. Haupl believed that “Shaking of Bone Hypothesis” by Wilhelm Roux was the functional concept that described how the appliance would work. Their way of working with this appliance was named as the “Norgwegian System”. The original activator was tooth-borne, passive appliance which was indicated to be loose-fitting.