A palatal expander is an appliance that is used to widen the palate(roof of the mouth). This appliance is more commonly used for younger patients with a narrow jaw that makes it challenging to accommodate the incoming permanent teeth. When the jaw is too narrow for the adult teeth, crowding and bite misalignment may develop.
If a narrow upper jaw is left untreated and crowding and bite problems occur, one may have difficulty with chewing, speech and other functions. It could also create more dental work that would be needed as an adult.