The Kilroy Spring for impacted teeth.

mechanics have been devised for the eruption of impeded and impacted teeth. One such device, the Monkey Hook,* was recently introduced as a method of applying lateral and vertical eruptive forces.1 The Kilroy Spring* is a new option that produces directional forces without the need for special patient compliance. The Kilroy Spring is a constant force module that is slid onto a rectangular archwire over the site of an impacted tooth (Fig. 1). (The configuration of the Kilroy Spring reminded the designers of the popular “Kilroy Was Here” graffiti of the 1940s.) In the passive state, the vertical loop of the Kilroy Spring extends perpendicularly from the occlusal plane (Fig. 2). To activate the spring, a stainless steel ligature is guided through the helix at the apex of the vertical loop, and the loop is directed toward the impacted tooth. The ligature is then tied to an attachment that has been direct-bonded to the surgically exposed tooth (Fig. 3). A Kilroy Spring can be