The retraction of anterior teeth is one of the fundamental, methods in orthodontic treatment and a proper position and angulation of anterior teeth after the retraction are very important for esthetics, stability, and function of teeth. In this research we analyzed, by Finite Element Method, the stress distribution on the: periodontal ligament according to the variation of force and moment applied on the crown and predict the pattern of movement of maxillary central incisor. At the same time, the amount of force and moment caused by activation of the loop which was used for retraction of maxillary central incisor was analyzed by Finite Element Method. We observed the , following results:
1) We could control the stress distribution on the periodontal ligament by proper moment/force ratio on maxillary right central incisor and pr-dice the pattern of movement of maxillary right central incisor.
2) The amount of stress on the periodontal ligament as well as the moment/force ratio demanded
by each pattern of movement increased as the destruction of alveolar bone was worse.
3) The moment/force ratio demanded by each pattern of movement decreased as the angle
between the maxillary central incisor and occiusal plane decreased.
4) The force with the open loop was shown to be large compared to that with the closed loop.
Also, the force with the helix decreased by 30% compared to that without the helix.
5) Under the same conditions we observed a larger moment/force ratio when the open loop
and/or the helix were used.
|