Stress analysis of the staggered and straight placement of implants in the mandibular posterior region under the localized load / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the stress distribution of the staggered and straight placement of implants in the mandibular posterior region.</p><p><b>METHODS</b>Using three-dimensional finite element approach to analyze the stress distribution and variance regularity under the localized load.</p><p><b>RESULTS</b>Under vertical load, the stress peak value reduced when wide implant was placed straight (min: 3.70 MPa), but slightly increased when normal implant was placed staggered (max: 8.32 MPa); under the inclined load from buccal to lingual direction, the stress peak value reduced when the wide implant was placed in straight line (min: 12.29 MPa) or normal implant was placed staggered with buccal offset configuration (min: 15.48 MPa), but increased with lingual offset configuration (max: 23.60 MPa).</p><p><b>CONCLUSIONS</b>Wide implant (> or = 4 mm) with straight placement should be adopted to reduce the stress peak value and improve stress distribution, when the buccolingual diameter of the alveolar ridge in the mandibular posterior region was wide.</p>

A three-dimensional finite element study on composite archwire applied in extraction cases / 中华口腔医学杂志

<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>