Biomechanics of upper molar uprighting with Tomas microimplant: a finite element study

Objective To investigate the effects of combined force for maxillary second molar uprighting with micro-implant anchorage system. Methods Maxillary second molars with mesiobuccally tipping were included in the study and Helix CT scanning was taken.Three-dimensional finite element model for maxillary second molar with periodontal tissues was established by 3D modeling software.The effect of embedding position of micro-implant,orientation and level of the loading force on the displacement of periedontal tissne were investigated.Results With the micro-implant located in mesiobuccal alveolar bone of second molar,the molar presented with distal tipping and palatal rotation; when located in mesio-occlusal or mesio-palatal alveolar,the molar presented with distal tipping and buccal rotation.Conclusions Complex force is effective for maxillary second molar uprighting. Key words: Micro-implant;  Torque;  Upright molar;  Three-dimensional finite element