A rapid maxillary expansion appliance (RME), also known as a rapid palatal expander, is used to widen the narrow upper jaw so that the upper and lower teeth will fit together better. The use of an expander is most common in children. We often use brackets (braces) on the upper front teeth in conjunction with the RME to correct minor crowding problems.

The appliance has a screw that is turned each day with a small key until the desired width is achieved.