What is wagon wheel effect in orthodontics?

Wagon Wheel Effect also called as the "torque on torque" effect in orthodontics is:

"When teeth are in alignment, the bracket slot is parallel to the line of the archwire with the exception of mesiodistal angulation. When brackets are first placed on mesiodistally angulated teeth, the slot axis will no longer be parallel to the archwire. In such instances, the slot and wire can be thought of as acting as two parallel lines that can be brought to alignment by rotating one of the lines around its long axis. If a continuous round archwire is used, the line represented by the wire can only rotate around its axis if the arch is deflected laterally. As the arch is deflected, the segment of the arch with which it is in contact acts as a rotation component. Thus the force is applied to the root of the tooth while the crown tips in an opposite direction. This produces bodily movement. As alignment progresses, the slot in the bracket begins to parallel the archwire. At this point the force from the wire is directed increasingly to the crown as less deflection of the arch is necessary to bring the slot and the archwire into alignment."

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