Tr. Meling et J. Odegaard, ON THE VARIABILITY OF CROSS-SECTIONAL DIMENSIONS AND TORSIONAL PROPERTIES OF RECTANGULAR NICKEL-TITANIUM ARCH WIRES, American journal of orthodontics and dentofacial orthopedics, 113(5), 1998, pp. 546-557
Twenty-five rectangular superelastic or conventional work-hardened nic
kel-titanium alloy wires, commonly used in the 0.018-inch edgewise tec
hnique, supplied by seven different manufacturers, along with one brai
ded nickel-titanium and two beta-titanium wires, were studied with res
pect to wire dimensions, edge bevel, and mechanical properties in long
itudinal torsion at 37 degrees C. The wires were twisted 25 degrees an
d studied in deactivation, simulating application of torque to an indi
vidual tooth. Standard Siamese brackets. with stated slot heights of 0
.018 inches and measured slot heights of 0.0187 inches, were used. Mos
t wires were within +/-0.0005 inches of the stated dimensions, but had
more edge bevel than previously reported for stainless steel and chro
me-cobalt alloy wires, Variations in wire dimensions and edge bevel le
d to variable torsional (third-order) clearance. The torsional stiffne
ss varied among manufacturers within the various wire sizes, this bein
g the result of differences in actual cross-sectional geometry and mat
erial properties. None of the tested wires exhibited superelastic prop
erties under the current conditions, and only one wire had a superelas
tic tendency.