RESUMO
<p><b>OBJECTIVE</b>To explore mechanical properties of the composite archwire (CoAW) applied in extraction cases.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>The stress on teeth closely correlated with the diameter of the composite archwire.</p>