A Rapid Maxillary Expander (RME) is a custom-made orthodontic appliance which is bonded to the upper back teeth and is used to widen the upper jaw. The Maxilla (upper jaw bone) has a midline suture (a joint between the bones) in the palate which will usually close at around the age of 16 years in females and 18 years in males. Before this time, maxillary expansion can be simply achieved with an expander appliance alone. After the suture has closed (eg in non growing patients) a surgical procedure may be required to re-open the suture to allow expansion. Maxillary expansion is used for patients with a narrow upper jaw. When indicated, widening the upper jaw will achieve a better relationship between the upper and lower jaws for normal function and wear, allow for ideal dental and skeletal development and can also create space for crowded teeth.