A cross bite occurs when a tooth or teeth have a more buccal or lingual position than the opposing tooth or teeth. This means that some teeth are either too close to the cheek or lip or to close to the tongue or the palate. In an anterior crossbite the lower tooth or teeth are positioned closer to the lip than the upper tooth or teeth. In a posterior crossbite, the lower tooth or teeth are positioned closer to the cheek than their antagonist. Potential problems caused by a crossbite can include excessive wear of teeth, uneven distribution of forces during chewing, inefficient chewing, reduced chewing surface area, potential injury to the lip or cheek, and unaesthetic appearance.

An anterior cross bite is typically caused by an overgrowth of the lower jaw. Since the lower jaw is larger than the upper, the lower anterior teeth end up closer to the lip than the upper teeth. A posterior crossbite is typically seen in a patient with a narrow upper jaw and dental arch.

A crossbite is a condition that is corrected during comprehensive orthodontic treatment with the use of braces, brackets and orthodontic wires, a quad helix, clear aligner therapy and other less common ways.