This patient has bilateral posterior crossbites and an anterior open bite associated with chronic mouth breathing. The adenoids and tonsils were removed as a treatment for obstructive sleep apnoea. There are a number of baby (deciduous) teeth still present. In these situations, a device to move the upper teeth and jaws laterally (rapid maxillary expander or RME) can be used to treatment the crossbite. This also results in extra space for the eruption of the upper teeth.