PROPERTIES OF SUPERELASTIC WIRES AND THEIR RELEVANCE TO ORTHODONTIC TREATMENT

In this study tools were developed to test and compare levelling archw ires that the manufacturers claim to have superelastic properties. As the classic spring model and Hook's law cannot be applied, new paramet ers had to be found. it could be shown that three parameters are neces sary to describe a superelastic archwire adequately: the distinctivene ss of the pseudo-elastic plateau, the deflection at the beginning of t he plateau, and the force level of the plateau. The results showed tha t many materials either did not show any pseudoelastic properties at a ll or that the wire parameters were such that they did not give any ad vantage over conventional work hardened NiTi materials. In many archwi res the beginning of the plateau and thereby the desired characteristi cs began only when the archwire was displaced 1 mm or more. For many a rchwires the force level of this plateau also proved to be rather high with values often above 500 g.