Teeth don’t come together properly when there is a crossbite. Examples would be the upper arch of teeth being too narrow in the back (posterior crossbite), the lower front teeth being ahead of the upper front teeth (anterior crossbite or Class III bite), or one or two teeth in the upper arch that came into the mouth too far back and are trapped there by the lower teeth.
Posterior crossbites can cause imbalance in the jaw joints. Anterior crossbites can be corrected easiest in very young children but become more difficult to correct as a child becomes older. Single teeth in crossbite can sometimes even be corrected by the child with no orthodontics!