Unit Forty
The Development of Contemporary
Fixed Appliances
Angle' s Progression to the Edgewise Appliance
Edward Angle's position as the "father of modern orthodontitics" is based not only on his contributions to classification and diagnosis but also on his creativity in developing new orthodontic appliances. With few exceptions, the fixed appliances used in contemporary orthodontics are based on Angle's design from the early twentieth century. Angle developed four major appliance systems:
The E-Arch. In the late 1800s, a typical orthodontic appliance depended on some soft of rigid framework to which the teeth were tied so that they could be expanded to the arch form dictated by the appliance. Angle' s first appliance, the E-arch, was of this type (Fig. 12-l).
Pin and Tube. The E-arch was capable only of tipping teeth to a new position. It was not able to precisely position any individual tooth. To overcome this difficulty, Angle began placing bands on other teeth and used a vertical tube on each tooth into which a soldered pin from a smaller archwire was placed. With this appliance, tooth movement was accomplished by repositioning the individual pins at each appointment.
Ribbon Arch. Angle's next appliance modified the tube on each tooth to provide a vertically positioned rectangular slot behind the tube. A Ribbon arch of 10×20gold wire was placed into the slot and held with pins (Fig. 12-2).
Edgewise. To overcome the deficiencies of the Ribbon arch, Angle reoriented the slot from vertical to horizontal and inserted a rectangular wire rotated 90 degrees to the orientation it had with the Ribbon arch--thus the name "Edgewise" (Fig. 12-3). The dimensions of the slot were altered to 22×28 mils, and a 22×28 precious metal wire was used. These dimensions, arrived at after extensive experimentation, did allow excellent control of crown and root position in all three planes of space.
• Other Early Appliance Systems
Before Angle, placing attachments on individual teeth simply had not been done, and Angle's concern about precisely positioning' each tooth was not widely shared during his lifetime. In addition to a variety of removable appliances utilizing fingersprings for repositioning teeth, the -major competing appliance systems were the labiolingual appliance, which used bands on first molars and a combination of heavy lingual and labial archwires to which fingersprings were soldered to move individual teeth (Fig. 12-4), and the twin-wire appliance (Fig. 12-5).
Fig. 12-1 B Edward Angle's E-arch, from the early 1900s. Ligatures from a heavy labial arch were used to bring malposed teeth to the line of occlusion.
• Begg Appliance.
Raymond Begg had been taught use of the Ribbon arch appliance at the angle school before his return to Australia in the 1920s. Working independently in Adelaide, Begg also concluded that extraction of teeth was often necessary, and set out to adapt the Ribbon arch appliance so that it could be used for better control of root position.
Fig. 12-2 Angle's Ribbon arch appli，英语论文，英语论文范文 |
