<p>The jackscrew and the cemented band provide individual control of the teeth and the most precise method of calculating pressure at each adjustment. The 120 threads per inch provide minute adjustments &ndash; one complete turn of the nut will move the teeth one quarter of a millimeter when the pressure is expanded. Each adjustment will exert pressure and then retains the improvement. The intermittent pressure thus provides for periods of movement and rest. Proper circulation and minimal discomfort is assured&nbsp;<br />
<br />
For unilateral applications, where premature loss of second primary molars has resulted in insufficient space for the second premolar. Jackscrew appliances are always under control and will only open the space to the point of adjustment of the nuts. After improvement, the appliance can be locked in position to retain.</p>

<p><img alt="Jackscrew Design 1 - Click to Enlarge" src="https://www.ordont.com/images/frequently-prescribed/Fixed-Jackscrew-Sp-Reg.jpg" style="float:right; height:210px; width:220px" />When distal movement of the first permanent molar is required with no movement of the first premolar, a lingual retaining arch can be included in the jackscrew design. Where tight contact points prevent band placement, rubber or wire separators can be placed one week prior to appliance insertion. This opens the contact points for band placement.</p>

<p>Bilateral distal movement of first molars can be effected by a double jackscrew configuration. Anchorage is provided by a soldered lingual arch. Alternating the jackscrew adjustments, left then right, will provide cross-arch anchorage. The distal nut is rotated gently toward the tube until contact is made and slight pressure is exerted. The first nut is then held firmly in place with one wrench, while the second nut is carefully turned until it locks against the first.</p>

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<p><img alt="Jackscrew Design 2 - Click to Enlarge" src="https://www.ordont.com/images/frequently-prescribed/Fixed-Jackscrew-w-Reg.jpg" style="float:right; height:214px; width:220px" />Jackscrew Lingual Sagittal appliances are preferred for labial movement of lower anterior segments. The tube and sliding wire combination prevent any ride-up effect on the lingual of the anteriors. The nuts are usually adjusted twice each month. For each adjustment, the distal nut should be held firmly while the lock nut is loosened. Then, the distal nut may be gently rotated one full turn to reactivate the appliance. Avoid turning both nuts at the same time as this will strip the threads.</p>
