The term” edgewise” refers to the method by which a rectangular archwire is inserted into the rectangular bracket slot. In1928, the edgewise appliance was Dr.Angle’s final achievement, represented the culmination of many years of effort and many different appliance designs attempting to place the teeth according to his “line of occlusion”.
Edgewise brackets are typically described by the vertical slot dimension into 0.018 or 0.022 inch. The depth of slot is commonly 0.028 inch.
By interaction of archwire with bracket slot, the tooth movement will occur in all three spatial planes. In orthodontics, these are described by the types of bend that are required in an archwire to produce each type of tooth movement:
First-order bends, are made in the plane of archwire to compensate tooth widths and bucco-lingual position (in/out).
Second-order bends, are made in vertical plane to achieve correct mesio-distal angulations or tilt of the tooth (tip).
Third-order bends, are applicable with rectangular archwire only. They are done by twisting of wire so that the wire exerts bucco-lingual force on the tooth apex when inserted into rectangular slot (torque).
In original edgewise appliance, these bends were placed in the archwire during treatment so that the teeth were moved into correct their positions.