Dw. Raboud et al., 3-DIMENSIONAL EFFECTS IN RETRACTION APPLIANCE DESIGN, American journal of orthodontics and dentofacial orthopedics, 112(4), 1997, pp. 378-392
The clinical importance of the three-dimensional effects of the force
systems supplied by appliance designs used for retraction has long bee
n appreciated. However, quantification of these force systems is not a
s well known. In this work, a numerical method is used to provide quan
titative insight into three-dimensional effects for typical appliance
designs. One problem that occurs clinically is the axial rotation of a
single rooted tooth as a result of the forces being applied by the re
traction device on the tooth's buccal surface. An out-of-plane preacti
vated bend can be used to counteract this rotation. The proposed numer
ical method can accurately determine the force systems resulting from
this out-of-plane preactivation as well as the in-plane force systems.
It is shown that the out-of-plane effects are independent of the in-p
lane behaviour so that the usual forces and moment to force ratios are
maintained.