Pre- Adjusted Edgewise Appliance
Dr. Lawrence F. Andrews introduced pre-adjusted Appliance to Orthodontic profession in 1972, and called it straight wire appliance. In this modern bracket system, the average values for tip and torque built into the bracket slot itself, and the bracket base are of differing thicknesses to produce an average buccolingual position. These pre-adjusted systems have advantage that the amount of wire bending required is reduced. However, they do not eliminate the need for wire adjustment since average values do not always suffice. These characteristics for each tooth are called the “appliance prescription”.