Finite Element Analysis Of Different Load Mode On Tooth Movement In Extraction Space Sliding Closure

Objective: Construct a FEM model to investigate the maxillary dentition biomechanical effects of micro-implant anchorage technique with sliding mechanics on maxillary anter ior teeth retraction under different retraction hook heights and different archwire position.Methods: DICOM image data including maxilla were obtained through cone-beam CT. The three dimensional finite element model was constructed by Mimics software, and brackets and archwire model were constructed by Creo software. The models were instantiated using Pro/Engineer software,and Abaqus finite element analysis software was used to simulate the sliding mechanics by loading 2N force on 9 positions of retraction hook and archwire. Predict rotation of the occlusal plane through the initial displacement and stress distribution of tooth.Results: The force at the archwire level(0mm) induced 0.02° lingual inclination of the maxillary central incisor, 0.005 mm gingival movement of the maxillary first molar, and 0.012°clockwise rotation of the maxillary occlusal plane. In contrast, force application point was located high level of the retraction hook(10mm), the maxillary central incisor was rotated 0.23° to labial, the maxillary first molar was moved to the occlusion side 0.015 mm,and the maxillary occlusal plane was rotated 0.07°anti-clockwise. As the force application point was located posteriorly along the archwire, lingual inclination of the maxillary central incisor were 0.02°、0.018°、0.003°, the trend of the rotation gradually decreased, the buccal displacements of maxillary first molar were 0.0067mm、0.007mm、0.0092 mm, the trend of buccal movement gradually increased.Conclusions: Maxillary anter ior teeth rotation and retraction,vertical and buccal palate displacement of posterior segment and rotation of the occlusal plane can be precisely controlled in the process of extraction space closure with miniscrew sliding mechanics.