Orthodontic spring appliance and spring clip therefor

An orthodontic treatment assembly for applying repositioning forces to teeth in a patient's mouth comprising, in combination, means suitable for insertion in the mouth to produce a tension force, said tension producing means comprising a resilient element that produces a stable and predictable force upon elongation of said element, said resilient element having a first end and a second end opposite to said first end, wherein both of said ends are capable of being retained when force is applied thereto, at least one of said ends comprising a force determining element consisting essentially of a substantially straight wire having a plurality of positioning elements thereon, said positioning elements being located on said substantially straight wire at predetermined intervals spaced from each other whereby the amount of elongation of said tension producing means and the force generated thereby is dependent upon which of said positioning elements is inserted in and retained by a retention device, and means for retaining both ends of said resilient element, at least one of said retaining means comprising a retention device, said retention device adapted to be mounted on a stable support and having a slot therein constructed and arranged to permit a substantially straight wire shaped end of said force determining element to be inserted therein and constructed and arranged to retain said straight wire shaped end therein when said resilient element is under tension by retaining said positioning element.