Intrusion of palatally displaced maxillary lateral incisors using nickel titanium closed-coil springs.

eral incisors. EW springs were then bonded to anchor-wire segments as described above (Fig. 3). Three months later, the upper lateral incisors had been significantly intruded (Fig. 4). After the intrusion auxiliaries were removed, a bracket was bonded to the left lateral incisor for incorporation into the main archwire; an .008" ligature wire was bonded to the surface of the right lateral incisor and tied to the archwire to bring the tooth into alignment (Fig. 5). Four weeks later, a conventional bracket was bonded to the upper right lateral incisor for final adjustments (Fig. 6). I patients with maxillary anterior crowding, the upper lateral incisors are often inclined palatally; moreover, such incisors are almost always extruded due to lack of contact with the opposing teeth. The resulting crossbite limits accessibility for bracket placement, so that initial alignment requires adequate space to be opened before the teeth are intruded and labial root torque is added.1 Although nickel titanium closed-coil springs are routinely used to intrude lateral incisors in these situations, most commercially available springs apply forces greater than 100g. A new spring* developed in our clinic at Ewha Womans University, called the EW spring, exerts a light, continuous force of less than 50g.