Sliding resistance of rectangular vs. beveled archwires in two self-ligating brackets: a finite element study.

The aim of this study was to use a 3-D finite element method (FEM) to compare the sliding resistance of 0.019"x0.025" stainless steel conventional archwires versus 0.019"x0.025" stainless steel beveled archwires in active (In-Ovation® Dentsply) and passive (SmartClip®, 3M) self-ligating brackets with 0.022" x 0.028" slots. A model was designed for each kind of bracket-archwire system and the following parameters were introduced in the models: friction coefficient calculated for stainless steel bracket-wire: 0.7 pm; Poisson ratio for stainless steel wire: 0.3, and elastic module: 205 GPa for bracket and 190 GPa for archwire. Static structural analysis was applied for homogeneous, linear and isotropic properties considering contacts between wire and bracket as frictional. The results indicate that the beveled archwire generates less stress than the rectangular wire in SmartClip® and In-Ovation® brackets. Comparing brackets, SmartClip® generated less stress than InOvation®. It is concluded that beveled rectangular arch wires provide the advantage of reduced sliding resistance, which is better in some clinical situations to improve orthodontic mechanics.