Orthodontic appliances, commonly known as “braces” describe the small brackets that are placed on teeth through which little flexible wires are threaded. These small wires place light forces on the teeth, as the wires tend to straighten themselves to their undistorted forms, moving the teeth with them. The reason the teeth move is due to the magical properties of the periodontal ligament (attaches the tooth to the bone). Since the periodontal ligament is elastic — teeth are not set in the bone like pillars in concrete — there is micro-movement of the teeth all the time. Since these tissues are living, they are constantly changing and “remodeling.” When a light and controlled force is placed on a tooth on the “tension” or pulling side, new bone, ligament and cementum are formed. On the pressure side, cells will remove bone and ligament to allow the tooth to move.