Skip to main content

Cross Bite

What is a Crossbite?

Overbites and underbites are well known to most who have some knowledge of what’s going on with their teeth and smile. A crossbite, however, may not be as familiar a term.

First, let’s explain a malocclusion. This is when there is a misalignment between your upper and lower teeth as you close your mouth. 

A crossbite refers to a type of malocclusion where your teeth, or just one tooth, are not matched up in a position to the corresponding tooth on the lower or upper jaw. The tooth is either closer to the cheek or tongue then it should be.

Main Causes of Crossbite

The causes of crossbite have been researched and predominantly narrowed down to hereditary reasons, delayed tooth eruption or an abnormally erupted tooth.


Genetically, a crossbite can occur if the lower jaw bone is wider than the upper jaw bone. 

If you imagine what that would look like, you can easily see where there would be a misalignment of the upper and lower jaw teeth.

Delayed and/or Abnormal Tooth Eruption

Normal tooth eruption, where baby teeth are lost and adult teeth come in, can be delayed for a number of reasons. 

When this occurs, the corresponding adult teeth on the opposite jaw (be it upper or lower) do not meet with their “partner”.

Thumb Sucking

When a child sucks their thumb the width of the palate is made smaller and the upper bone of the pallet can be deformed. 

More often or not, this cannot be reversed naturally and orthodontic assistance is required to correct the issue.

Mouth Breathing

We all breathe through our mouths from time to time. In some rare cases during development, children breathe through their mouths all the time instead of through their noses. 

This is usually due to other complications such as enlarged tonsils. 

When we breathe through our nose, our tongue rests on the upper palate and during development this assists in growing the jaw laterally. However, when we breathe through our mouths, the tongue moves away from the palate, hindering this growth.


The best time for fixing a crossbite is as a child or teenager, but there are treatment options available to adults.

Correcting a crossbite involves adjusting the teeth, palate or jaw with orthodontic appliances.

Palatal or maxillary expander: 

An orthodontist attaches a device that is placed on the palate and attached to the upper teeth that gradually widens the upper palate by the regular turns of a special key on the device.

Removable expander

A device that adults can wear at night to widen the upper palate when only minimal expansion is needed.

Surgically assisted rapid palatal expansion: 

A surgeon conducts a surgical procedure to intentionally break the jaw bone in several places, and after surgery, the patient wears a custom-made device. 


As a treatment by itself or after palatal expansion, braces straighten and fix the upper and lower teeth to achieve an aligned bite. Both adults and children can wear braces.

For more information on orthodontic treatments to correct misaligned bites, and specifically fixing a crossbite, visit I Song Orthodontics in Berkeley. At I Song, your smile is in good hands.