On the use of nomograms to determine the elastic property ratios of orthodontic arch wires.

With an 0.012 inch stainless steel arch wire as the base line, a series of calculating charts which express the strength, stiffness, and range ratios of orthodontic arch wires is introduced. In each case, both the bending and the torsional stress states are computed over a broad range of wire sizes. Three distinct situations are addressed: the over-all spectrum of elastic property ratios among stainless steel, nickel-titanium, and beta titanium wires; the intra- and interproperty relationships of these wire compositions; and the role which elastic property ratios play in the selection of the right arch wire. Via these nomograms, clinicians will have another means available by which the plethora of wire compositions and cross sections may be assessed.