[A three-dimensional finite element study on composite archwire applied in extraction cases].

OBJECTIVE: To explore mechanical properties of the composite archwire (CoAW) applied in extraction cases. METHODS: The mandibular three dimensional model was established by spiral computed tomography scanning and SOLIDWORKS 2001 PLUS software. The archwire model was established by means of ANSYS software. The mechanical analysis and calculation of CoAW were carried out. RESULTS: With the diameter of NiTi part of CoAW gradually augmented (the diameter of stainless steel part kept unchanged), the stress on teeth gradually increased. As the diameter of stainless steel part of CoAW gradually augmented (the diameter of NiTi part kept unchanged), the stress on teeth also gradually increased. The CoAW (0.30 mm NiTi round wire combined with 0.36 mm stainless steel round wire) produced the least force on teeth. There was little contradistinction between six kinds of CoAW and stainless steel wire on the stress of posterior teeth. CONCLUSIONS: The stress on teeth closely correlated with the diameter of the composite archwire.

[Mechanical analysis of composite archwire applied to anterior malocclusion with extraction of bilateral first premolars].

PURPOSE: To optimize the structure of composite archwire applied to anterior malocclusion with extraction of bilateral first premolars. METHODS: The mandibular model was scanned by spiral CT and 30 CT images were obtained, then the mandible finite element model and the archwire model was respectively established by means of SOLIDWORKS software and ANSYS software, mechanics analysis and calculation were carried out. RESULTS: The force produced by composite archwire applied to anteriorly malocclused teeth in the model was greater than by TiNi shape memory alloy but smaller than stainless steel: F(SS)>F(CoAw)>F(NiTi); As the diameter of NiTi in the composite archwire increased (the diameter of stainless steel kept unchanged) , the force on the malocclused teeth gradually increased; As the diameter of stainless steel in the composite archwire increased (the diameter of NiTi kept unchanged),the force on the malocclused teeth increased accordingly. CONCLUSION: The rigidity of the composite archwire increases as the the diameter of NiTi increases; the rigidity of composite archwire also increases as the the diameter of the stainless steel increases.Supported by Research Fund of Jilin Provincial Bureau of Science and Technology (Grant No.20030539-3).