Examination of changes in upper canine distalization by using finite element analysis

Today, anchorage control is an important factor in the success of orthodontic treatment and various anchorage techniques have been designed for canine distalization. The purpose of this study was to evaluate the initial changes following force application during canine distalization with two different anchorage units by using a 3-dimensional (3D) finite element analysis (FEA).Two 3D ? nite element models were generated to simulate the distalization of maxillary canine by sliding mechanics and any associated movement of the anchor teeth and anchorage units. In the first model consisting of 111141 elements with 22549 nodes, mini-screws were used as skeletal anchorage units and 150-gr force was applied distally from the vertical hook placed in the middle of the canine bracket to the mini-screw. In the second model consisting of 109320 elements with 23400 nodes, two transpalatal arches were used as anchorage units and 150-gr force was applied distally from the vertical hook placed in the middle of the canine bracket to the vertical hook placed in the middle of the first molar tube. Three-dimensional (3D) features of displacement and stress distribution were analyzed following application of orthodontic force.The results of this study showed that the mini-screws displaced towards the direction of force and the highest stress areas in the loaded miniscrews appeared around the neck. The presence of transpalatal arches (TPA) did not prevent the initial molar movement. In the first model, the crowns of posterior teeth displaced distally. Also while intrusion was observed in the mesio-incisal aspects of central and lateral incisors, extrusion was observed in the disto-incisal aspects of the canines and laterals. In the second model, the crowns of posterior teeth displaced mesially and intrusion was observed in all anterior teeth mostly in central and lateral incisors. In both models, the canines rotated distopalatally.In conclusion, initial changes at the time of force application during canine distalization with two different anchorage systems were determined in the present dissertation by using finite element analysis.