Responses of 3-dimensional arch wires to vertical v-bends: comparisons with existing 2-dimensional data in the lateral view.
The mechanics of V-bends in orthodontic arch wires have been described almost exclusively in terms of bending forces in two-dimensional (2-D) single plane terms. When a rectangular arch wire enters a third dimension, a more complex wire deformation pattern develops from both torsion and bending during the activation of the V-bends. The necessity for a rectangular three-dimensional (3-D) arch wire to undergo torsion during activation results in a greater resistance to deformation at those points in the wire where the torsion is greatest. This is especially apparent with 2 x 2 long span arch wires. This study used finite element analysis to model the force systems produced by activation of V-bends in 3-D arch wires. In both 2-D and 3-D data, greater moments are present as any V-bend is moved toward either adjacent bracket. In 3-D systems, however, a V-bend at the molar produces significantly less moment and associated equilibrium forces than the same V-bend located the same distance from the incisor. Moreover, the reversal of the direction of the moments at either bracket does not occur when the V-bend location is two thirds of the distance toward that tooth as reported with 2-D studies.
Isacson
R J
RJ
Department of Orthodontics, Virginia Commonwealth University, Richmond 23298-0566, USA.
Lindauer
S J
SJ
Conley
P
P
D003198:Computer Simulation; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D008963:Molar; D009716:Numerical Analysis, Computer-Assisted; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D014092:Tooth Root; D019415:Torque