fa Deflection and stress distribution around mini-screw implants: A finite element investigation into the effect of cortical bone thickness, force magnitude and direction ارتودنسی Orthodontics پژوهشي Research <p> <strong>Objective:</strong></p><p>  The purpose of this investigation was to quantitatively evaluate mini-screw deflection and stress distribution associated with two different cortical bone thicknesses (CBTs) under loading with two applied forces at four different angles. </p><p> <strong>Material and methods:</strong> </p><p> Four finite element models (ANSYS 11) of bone with mini-screws (Dentos) inserted at 90° angulation to the cortical surface were made as follows: model A: CBT 1·5 mm, load 200 g model B: CBT 2 mm, load 200 g model C: CBT 1·5 mm, load 300 g model D: CBT 2 mm, load 300 g. In each model, the loading force was applied at angulations of 70, 90, 110 and 130° to the long axis of the mini-screw. The elastic modulus of the cortical bone, cancellous bone and mini-screw were kept at 15, 1·5 and 114 GPa, respectively. The maximum equivalent stress (MES) distribution and maximum deflection (MD) at the mini-screw to bone interface was evaluated in the four models at each angulation. </p><p> <strong>Results:</strong></p><p>  In each model, MES and MD of the mini-screw decreased when the angulation of loading increased from 70 (MES = 2·81 MPa) to 130° (MES = 1·92 MPa). Mean MES with model A = 2·21 MPa, model B = 1·83 MPa, model C = 3·06 MPa and model D = 2·67 MPa. </p><p> <strong>Conclusions:</strong></p><p>  The MES and MD both decrease as the angulation of mini-screw loading increases, with increasing load differences occur in MD but the MES remains similar, whilst differences were observed in both MES and MD as CBT increased. </p><hr><p></p><p> <strong>Source: </strong>Journal of Orthodontics </p><p> <a href="http://jorthod.maneyjournals.org/content/39/4/249.abstract" target="_blank"><font color="#0000ff">Full Text</font></a></p> Mini-screw, stability ,cortical bone thickness ,maximum equivalent stress 0 0 http://idai.ir/browse.php?a_code=A-10-32-1860&slc_lang=fa&sid=1 Abhishek H Meher 10031947532846008774 10031947532846008774 No Department of Orthodontics, Sharad Pawar Dental College, DattaMeghe Institute of Medical Sciences, Wardha, Maharashtra, India Sunita S Shrivastav 10031947532846008775 10031947532846008775 No Department of Orthodontics, Sharad Pawar Dental College, DattaMeghe Institute of Medical Sciences, Wardha, Maharashtra, India Pavankumar J Vibhute drpavanvibhute@gmail.com 10031947532846008776 10031947532846008776 Yes Department of Orthodontics, Sharad Pawar Dental College, DattaMeghe Institute of Medical Sciences, Wardha, Maharashtra, India Pushpa V Hazarey 10031947532846008777 10031947532846008777 No Department of Orthodontics, Sharad Pawar Dental College, DattaMeghe Institute of Medical Sciences, Wardha, Maharashtra, India