Self-Ligating Brackets: An Overview

The specialty of orthodontics has continued to evolve since its advent in the early 20th century. Changes in treatment philosophy, mechanics, and appliances have helped shape our understanding of orthodontic tooth movement. In the 1890‘s, Edward H. Angle published his classification of malocclusion based on the occlusal relationships of the first molars. This was a major step toward the development of orthodontics because his classification defined normal occlusion. Angle then helped to pioneer the means to treat malocclusions by developing new orthodontic appliances. He believed that if all of the teeth were properly aligned, then no deviation from an ideal occlusion would exist. Angle and his followers strongly believed in non-extraction treatment. His appliance, (Fig. 1), consisted of a tube on each tooth to provide a horizontally positioned rectangular slot. Angle’s edgewise appliance received its name because the archwire was inserted at a 90-degree angle to the plane of insertion. The rectangular wire was tied into a rectangular slot with steel ligatures (Proffit, 2000). A later shift in thought occurred when one of his pupils, Charles Tweed, observed that some of the patients formerly treated by Angle exhibited a noticeable amount of relapse. Tweed then re-treated a number of these cases by extracting four bicuspids to resolve the crowding and in turn, developed his own treatment mechanics. Another shift in orthodontics occurred when Larry Andrews introduced the straight wire appliance. Instead of bending wires to place teeth in the proper orientation with an edgewise bracket, Andrews‘ appliance had the angulation and torque values built into the brackets commonly known as the appliance prescription. In theory, these pre-adjusted brackets eliminated the need to repeatedly bend first, second, and third order bends each time the patient progressed to the next wire. The straight wire appliance revolutionized orthodontics by making the bracket much more efficient. Since then, many orthodontic companies have developed their own bracket systems with specific prescriptions, treatment philosophies, and mechanics. However, they all shared one common characteristic – ligatures must be placed around tie wings on brackets to hold arch wires in the bracket slot.