Canine root movement: an evaluation of root springs.

An analysis of the mechanics required for distal movement of canine roots is presented and, on the basis of this analysis, a specific clinical approach is outlined. Three different root spring designs were tested for their ability to meet the previously determined requirements. The only spring that approached the established requirements was spring A-2. Spring types B and C did not meet the established requirements. Angular activations in excess of 20 degrees in 0.018 by 0.025 inch stainless steel wire without benefit of a loop resulted in permanent deformation of the appliance.