A palatal expander is used when the upper jaw is constricted or more narrow compared to your lower jaw. An expansion appliance is custom made for you and cemented in your mouth through bands placed on the back molar teeth. A small key is used to turn the device, which slowly widens the upper jaw. This treatment is more effective in younger patients whose top jaws are easier to expand than an adult’s. By the time you become an adult your jaw is not as easily manipulated, which can make the expansion more difficult.