Maxillary expansion appliances are used to widen a top jaw which is too narrow in relation to the lower jaw.

There are numerous types of maxillary expansion appliance – fixed and removable. The most common types are fixed and use an expansion screw (which is turned regularly by the patient) or a wire spring device (which is widened by the orthodontist).

Removable appliances are orthodontic plates with a built-in expansion screw which is turned regularly by the patient.