Tr. Meling et al., ON MECHANICAL-PROPERTIES OF SQUARE AND RECTANGULAR STAINLESS-STEEL WIRES TESTED IN TORSION, American journal of orthodontics and dentofacial orthopedics, 111(3), 1997, pp. 310-320
Forty different sizes and types of square and rectangular stainless st
eel wires, supplied by five different manufacturers, were tested in to
rsion. The study simulated the situation occurring when torque is appl
ied to an individual tooth. We used standard brackets with 0.018-inch
slot heights, with an interbracket distance of 4 mm. The results show
that variation in cross-sectional dimension and edge bevel leads to va
riable torsional play (third-order clearance). As an example 0.016 x 0
.022-inch wires have a mean torsional play of as much as 18.5 degrees,
with a range of 16.6 degrees to 20.4 degrees. We have shown that when
0.016 x 0.022-inch wires are used, one must apply from 24.6 degrees t
o 29.2 degrees of twist to get 20 Nmm of torsional moment. This variat
ion is mostly due to a rather wide range in torsional play. As a resul
t, the prediction by which a predetermined torsional moment can be del
ivered becomes uncertain, The results show that because the working ra
nge in torsion of stainless steel wires is somewhat limited, precise d
elivery of torsional moment, based on the condition present in the ora
l cavity, is difficult. Torsional stiffness varies considerable within
the various dimensional groups, this being the result of variation in
cross-sectional geometry and material properties.