Removable Functional Appliances in the Treatment of Class II Malocclusion

Whilst the genesis and evolution of functional appliances was primarily a European phenomenon, the first description of what could be considered a functional appliance was in 1880 by Norman Kingsley, a dentist based in New York. This consisted of a vulcanite bite plate ligated to the teeth in the upper arch with an inclined anterior bite plane that postured the mandible forward to correct ‘excessively retreating lower jaws.’ This principle of forward posturing of the mandible underlies the basic treatment modality of all subsequent systems and appliances irrespective of the philosophies of growth that underlie them. The appliances largely only vary in how this posturing is achieved. Here we focus on the Twin Block, a remarkably effective and adaptable removable functional appliance.