<p>Expansion Screws are frequently the auxiliary of choice due to their versatility, durability and precision. The gear mechanisms usually have expansion ranges from five to ten millimeters, depending on application. Many Doctors instruct their patient to adjust the gears at home, with the usual adjustment one-quarter turn or 90 degrees activation which is equal to &frac14; mm. Arrows indicate direction of adjustment for each gear. When subsequent visits of the patient display lack of appliance retention, the gear should be reversed slightly. The patient is instructed to increase wearing time to keep pace with adjustments or reduce the frequency of adjustments.</p>

<p><img alt="Labial Movement of an Individual Anterior - Click to Enlarge" src="https://www.ordont.com/images/frequently-prescribed/Anti-Crossbite-with-Gear---.jpg" style="float:right; height:204px; width:220px" />Labial movement of an individual anterior can result from pressure provided by a small, but effective, expansion screw. The gear is placed immediately lingual to the tooth to be moved. As the gear is activated, the acrylic is displaced labially against the tooth. Reciprocal anchorage is provided by the main body of acrylic and retentive clasping.</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p><img alt="Labial Movement of Two or More Anteriors - Click to Enlarge" src="https://www.ordont.com/images/frequently-prescribed/P3152873.jpg" style="float:right; height:217px; width:220px" />Two or more anteriors can be moved to the labial by selectively sectioning the acrylic. A larger gear may be used depending on available space and number of teeth to be repositioned. The loops on the labial bow can be periodically opened to allow advancement of the anteriors and avoid restriction of movement. Typically, one millimeter of space is provided between the labial bow and the anteriors at each visit of the patient.</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p><img alt="Distal Movement of an Individual Posterior - Click to Enlarge" src="https://www.ordont.com/images/frequently-prescribed/Distalization-with-Gear.jpg" style="float:right; height:218px; width:220px" />Distal movement of an individual posterior can be effected by positioning the screw as detailed. In this instance, the clasp remains part of the sectioned acrylic, providing sufficient grasp of the tooth necessary to overcome appliance displacement. Depending on survey, bite blocks or planes may be included to enhance retention and/or to remove interferences.</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p><br />
&nbsp;</p>

<p><img alt="Distal Movement of an Individual Posterior 2 - Click to Enlarge" src="https://www.ordont.com/images/frequently-prescribed/Gear-to-Regain-Sp-P80.jpg" style="float:right; height:220px; width:220px" /></p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>&nbsp;</p>

<p>Individual or groups of posteriors can be moved to the buccal by an expansion screw positioned and sectioned accordingly. When more movement is required on a particular tooth, the acrylic can be removed from the lingual of adjacent posteriors at the outset of treatment. Once the single posterior has advanced sufficiently, all posteriors will continue to move as a unit to complete the case.</p>
