Objectives: The aim of this study was to clarify the effect of the play between the bracket and the archwire on anterior tooth movement subjected to the retraction force from various lengths of power arms in sliding mechanics.
Materials and methods: A three-dimensional finite element method was used to simulate en masse anterior tooth retraction in sliding mechanics. The displacements of the maxillary incisor and the archwire deformation were calculated when the retraction force was applied.
Results: When a play did not exist, bodily movement was obtained at 5.0 mm length of power arm. In case a play existed, bodily movement was observed at the power arm length of 11.0 mm.
Conclusions: In the actual clinical situation, a bracket/archwire play and the torsion of the archwire within the bracket slot should be taken into consideration to prescribe an optimal power arm length and to achieve effective anterior tooth movement.
Keywords: Play; deformation of archwire; finite element method; power arm; sliding mechanics.