교정용 각형선재에 부여된 torque가 브라켓에 발생시키는 모멘트에 관한 유한요소법적 분석

The moment generated by the torwue of the orthodontic rectangular wire : Three-dimensional finite element analysis

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiongual movement of the single tooth during finishing stage of the orthodontic treatment. The clincal torque is the sum od the play and the active torque which generates the moment at the bracket. The play is calculated by the formual and the active torqe is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center was calculated. The sizes od seven wires which were used commonly were .016 X .022 , .017 X .022 , .017 X .025 , .018 X .025 , .019 X .025 , .020 X .025 , .021 X .025 . In .018 bracket, .016 X .022 , .017 X .022 , .017 X .025 wires were inserted and in .022 bracket, all the sizes of wires except .016 X .022 were inserted and tested. The follwing conclusions could be drawn from this study 1. The moments generated on the same size of the wires by the same active torque were equal regardless od the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021 X .025 wire was about 1.75 times as large as that on the .016 X .022 wire regardless of material. 3. The moments were increased in the order of the NiTi, TMA, stainless steel. The moment of the TMA wire was 0.35 times as smaall as thst of the stainless steel was 0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the inter bracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.