A Rapid Palatal Expander (RPE) is an appliance used to widen the upper jaw in growing children. By gently expanding the palate, it creates more space for permanent teeth, helps correct crossbites, and supports proper jaw and facial development. The expander sits on the roof of the mouth and is adjusted gradually at home following the orthodontist’s instructions. Expansion typically occurs over a few weeks, and the appliance remains in place afterward to allow new bone to stabilize. RPEs are a simple, effective way to guide early growth and often make future orthodontic treatment easier.