Crossbite Treatment

What Is a Crossbite?
A crossbite occurs when some of the teeth wind up on the "wrong side of the track," meaning the bottom teeth are shifted to one side or shoved forward or backward. If, for example, when you bite down, your top teeth fall inside your bottom teeth on one side, you have a "unilateral posterior crossbite." If your top front teeth fall behind your lower front teeth when you bite down, then you have an "anterior cross bite," which is similar to an underbite.

What Causes a Crossbite? There are many reasons why crossbites occur. One is jaw size and heredity. Another is delayed loss of baby teeth. Some people keep their baby teeth so long that their permanent teeth come in behind their baby teeth, like a second row of teeth. If this happens in your upper jaw, the permanent top front teeth may wind up sitting behind the lower front teeth when you bite down. This can happen on one side (unilaterally) or on both sides (bilaterally).

Mouth breathing by children can also spur the development of a crossbite. Normally, children breathe through their nose; the mouth is closed, and the tongue sits on the roof of the mouth. This tongue position is very important because it causes the upper jaw to grow out laterally, or sideways, as it should. Children who have big adenoids and tonsils tend to breathe almost exclusively through their mouth, especially while asleep. Snoring is another symptom.

When children are forced to breathe through their mouth all the time, their tongue drops from the roof of the mouth, and lateral growth of the upper jaw becomes inadequate. Adult teeth growing in a narrow upper jaw can become squeezed inward and land inside the bottom teeth whenever the child bites down.

Tipped off by this telltale pattern of malocclusion, an orthodontist often is the first health-care professional to notice that a child's adenoids and tonsils are too large. The orthodontist generally refers the patient to an ear, nose and throat specialist.

Aside from mouth breathing and snoring, parents should suspect a crossbite if their child slides his/her lower jaw to the left or right in order to chew comfortably, or if their child's chin appears off-center.

How Is a Crossbite Treated?
Orthodontic treatment to correct a crossbite in children should begin as early as possible. If enlarged tonsils and adenoids are at the root of the problem, they probably should be removed before orthodontic treatment begins.

The first step, "maxillary expansion," broadens the upper jaw with an appliance called an "expander." Fixed to the roof of the mouth, the expander is widened each night for about 1 or 2 weeks with the turn of a key. The expander remains in the mouth for several more months to allow the bone to harden in its new position. Braces may be put on the top teeth while expansion is going on to eventually close a "gap-tooth grin" that will develop as the upper jaw is being expanded.

Once the expansion is complete, the patient may need to wear a full set of braces for 2 to 2 1/2 years to achieve an ideal bite.

Aside from Cosmetic Concerns, Why Is It Important to Correct Crossbites?
The main reason to correct a crossbite in children is to prevent temporo-mandibular joint disorder (TMJ)--a misalignment or malfunction that causes excess pressure on the jaw joint. TMJ can lead to head and cheek pain, a clicking or popping sound each time you open and close your mouth, limited range of motion of the jaw joint, and other symptoms. In adults, orthodontic treatment can often improve TMJ symptoms.

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