The palatal expander "expands" (or widens) your upper jaw by putting gentle pressure on your upper molars each time an adjustment is made. The animation below is a demonstration of how to turn the expander. Your orthodontist will have given you instructions on how many turns, and how often to make the turns to the expander. When you achieve the desired expansion, you will wear the appliance for several months to solidify the expansion and to prevent regression.
As a side note, there are also expanders that are used to widen the lower jaw. They are often made of colored plastic, are removable, and have an expansion screw in the middle of the appliance. They are taken out of the mouth to turn and usually have an indicator arrow showing you the direction to turn.
Adjusting the palatal expander
You can also download these instructions in a printable PDF document.
In a well-lit area, tip the patient's head back.
Place the key in the hole until it is firmly in place.
Push the key toward the back of the mouth. You will notice the fender will rotate and the new hole will appear. The rotation stops when the key meets the back of the expander.
Press back and down toward the tongue to remove the key. The next hole for insertion of the key should now be visible.