The "Tip-Edge" torquing mechanism: a mathematical validation.

The Tip-Edge (TP Orthodontics, LaPorte, Ind) bracket is unique among orthodontic brackets because it can be used in combination with rectangular archwire to torque teeth, not through activation of the archwire itself but through the action of auxiliary springs that are active in the tip plane. The purpose of this report is to describe the way in which a tipping couple generates a secondary torquing couple and the resulting path traced by the root apex and to express those actions mathematically. The magnitude of forces applied by the auxiliary spring to the tooth apex is calculated on the basis of an experiment.