A Rapid Palate Expander (RPE) is a fixed appliance which which is cemented to the upper molars and gradually widens the palate. There is a screw in the center of the device. When you insert the expander key into the screw and turn it, it makes the device a tiny amount wider. Usually, you turn the screw once or twice a day to gently and gradually widen the palate. The space created by the widening naturally fills with new bone.
You turn the key of the RPE for several weeks, until the necessary amount of expansion has occurred. After that, you don’t turn the key anymore. The device stays in your mouth for about three more months to allow the new bone to solidify, then it is removed.
Photo of Leone Expander courtesy of OSE Company.