The effects of third-order torque and self - Saint Louis University
The effects of third-order torque and self - Saint Louis University
The effects of third-order torque and self - Saint Louis University
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
friction with active <strong>torque</strong> present in the wire <strong>and</strong>/or slot<br />
was also evaluated.<br />
Materials <strong>and</strong> Methods<br />
<strong>The</strong> posterior maxillary right quadrant with a first<br />
premolar extracted <strong>and</strong> canine retracted was simulated to<br />
evaluate the friction produced in a buccal segment during<br />
retraction <strong>of</strong> the half-incisal segment; <strong>third</strong>-<strong>order</strong> <strong>torque</strong><br />
was generally activated at the second premolar position. A<br />
0.019- by 0.025-inch stainless steel wire was selected for<br />
this study because it is frequently selected as the<br />
retraction archwire. <strong>The</strong> two independent variables<br />
controlled in this study were the bracket ligation design<br />
<strong>and</strong> the <strong>third</strong>-<strong>order</strong> <strong>torque</strong> angle at the second premolar<br />
bracket. <strong>The</strong> dependent variable was the kinetic friction<br />
generated in the appliance when a wire was slowly pulled<br />
posteriorly through the crown-attachments.<br />
<strong>The</strong> friction testing device is described in the<br />
Master’s thesis by Bunkall. 58 <strong>The</strong> device consists <strong>of</strong> a<br />
series <strong>of</strong> aluminum cylinders (“teeth”) mounted into a base-<br />
plate in an archform representing a maxillary quadrant.<br />
Through each cylinder is an adjustable stainless steel rod<br />
with an attached brass faceplate that simulates the facial<br />
56