关键词: 三维有限元, 磨牙控制曲, 位移

Abstract:

Objective    To investigate the distribution and initial displacements of the maxillary first molar under various degree and location of tip back and Toe-in bends by the 3-D finite element method， so as to clarify the biomechanism of those bends. Methods    （1）The whole maxillar 3-D finit element model was successfully constructed. 0.018×0.025 wire was used in this study. Analyze the displacement of upper first molar when there were 15°， 30° and 45° tip back bends in different location. When the forces were loaded in these situations on the model，observe the upper molar displacement on the Z directions. （2）Analysze the displacement of upper first molar when there were 15°， 30° and 45° Toe-in bends in different location. When the forces were loaded in these situations on the model，observe the upper molar displacement on the X and Y directions. Results    （1）With the increase of the tip back bends angle， the magnitude of the bending force increased. As bend location progressively moved toward the molar， the magnitude of the intrusive moment at the molar also progressively increased. When the bend was close to the second premolar，the first molar showed an extensive movement.（2）With the angle of the Toe-in bends increaing， the magnitude of force increased. When the bend was close to the upper first molar， it showed the overall lingual displacement. When the Toe-in was near the second premolars， the upper molar had a clockwise rotation. Conclusion    Tip back bend is critical in controlling vertical dimension of the first molar， and is beneficial to anchorage control and bite opening when located in distal of the second premolar. Toe-in bend is in favour of rotation control of the first molar.

Key words: 3-D FEM, molar control bends, displacement