What Is A Crossbite? | Misaligned Teeth

A crossbite occurs when the upper jaw is too narrow for the lower jaw. When this happens, the upper teeth sit inside the lower teeth. Sometimes, the opposite can also occur where the lower jaw may be too small for the upper jaw. Either way, a crossbite can occur on either on the left or right side of the mouth (unilateral), or on both sides (bilateral).

What Causes Crossbites?

Most often, crossbites are inherited, however crossbites can also occur because of other factors including: thumb sucking, pacifier use, or large tonsils. Some studies have also shown that those who have been intubated during infancy have a significantly higher risk of developing a crossbite.

How Does A Crossbite Function?

When the upper jaw is too narrow for the lower jaw, in order for the back teeth to touch, the lower jaw has to shift either to the right or the left so that the back teeth can touch together and function for chewing food or for speaking. However, if the lower jaw has to compensate for the size of the upper jaw, this means that it is not sitting properly within its joint cavities, the chin will either be to the right or the left – resulting in a face that is nonsymmetrical. Because the lower jaw is not sitting properly in its joints, this may also lead to TMJ or other oral health issues with the joints of the lower jaw. Many studies show that if left untreated, muscle, skeletal and joint adaptations can occur which can lead to permanent growth alterations.