History of Orthodontics - Dento-facial Orthopaedics originated in Europe - Edward Angle introduced Fixed Orthodontics to the United States - Norman William Kingsley demonstrated jumping the bite with an anterior bite plate - Hotz developed the Vorbissplate, a modification of Kingsley's plate - Wilhelm Roux studied the effects of functional forces on Orthodontics in 1883

Development of Functional Appliances - Pierre Robin developed the Monobloc in 1902, one of the first functional appliances - Viggo Andersen developed the widely accepted Activator appliance in 1908 - Emil Herbst introduced the Herbst Appliance in 1905, later revived by Hans Pancherz in the 1970s - Wilhem Balters modified Andersen's Activator and created the Bionator Appliance - Harold Kesling developed the Positioner Appliance in 1944 for the finishing stage of treatment

Passive Components of Removable Appliances - Labial bow provides retention for incisor teeth, usually with U-Loops at the end - Adams clasps are used for retention, typically fabricated in the molar areas - C clasps are used on canines - Southend Clasp is used on anteriors - Ball-ended clasp is primarily used with the Twin Block system in the lower anteriors

Active Components of Removable Appliances - Springs provide light forces to move teeth orthodontically - Palatal Finger Springs move teeth buccally or lingually - Buccal Canine Retractor brings a buccally placed canine more lingual - Z-Spring moves one or two teeth labially - T-Spring moves teeth labially

Springs and Wires in Removable Appliances - Springs made of 0.5mm thick stainless steel wire move one tooth - Thicker wire (0.6 or 0.7mm) is used to move more teeth or larger/multi-rooted teeth - Coffin Spring is used for expansion and can replace a screw in an expansion device - Active Labial Bows, such as Mills Bow or Roberts retractor, move teeth labially - Screws and elastics are also considered active components in removable functional appliances