The document discusses the history and development of the Edgewise appliance, which was Edward Angle's greatest contribution to orthodontics. It describes how Angle developed the appliance over time, starting with the pin and tube appliance and ribbon arch appliance, and culminating in the edgewise appliance in the 1920s. The edgewise appliance introduced the concept of placing a rectangular wire into bracket slots to allow for three dimensional tooth movement. The summary also mentions some of the key innovators that influenced Angle and the parts of the edgewise appliance like brackets, tubes, and instruments used.