What Is a Crossbite?
Normally, your upper teeth are wider and sit on the outside of your bottom teeth. Each upper tooth touches the matching lower tooth so that the force from chewing or clenching is evenly spread across your mouth. If you have a crossbite, these movements may cause irregular wear and damage to your teeth.
There are two general types of crossbite:
Posterior crossbite. This happens when your upper back teeth sit inside your bottom teeth. The teeth look almost tilted in toward your tongue instead of lined up straight and fitting into each other.
Anterior crossbite. This happens when one or some of your upper front teeth sit behind your lower front teeth. This is different from an underbite, which happens when all of your top teeth are behind your bottom teeth.
What Causes a Crossbite?
A crossbite is usually caused by a dental or skeletal problem, or a combination of both. These problems may be caused by habits, tooth growth delays, bone structure problems, upper airway problems, or genetics.
Specific crossbite causes can include:
- Pacifier, finger, or thumb sucking that pushes teeth
- Tongue thrust during swallowing
- Missing teeth
- Baby teeth that don’t fall out
- Early baby tooth loss that causes teeth to drift
- Small jaw that can’t fit all your teeth
- Teeth too big to fit well for proper alignment
- Cleft palate
- Cleft lip
- Mouth breathing
Teeth and bones can be pushed and twisted out of shape. If teeth are missing or are late coming in, other teeth will drift and shift, which can cause structural and alignment problems.
What Are Crossbite Symptoms?
The main symptom of a crossbite is teeth that don’t line up. The way they look depends on the severity and where your teeth are affected. For example, one tooth may be tucked in behind another, or you may have several teeth that aren't touching properly.
If your crossbite is left untreated, it can lead to other problems. These include:
What Is the Treatment for Crossbite?
Crossbites don’t straighten out on their own, so early treatment is important to stop jaw and dental problems. It’s best to treat a crossbite in childhood, when the jaw and face are still growing. An adult can also have a crossbite corrected.
If you notice that your young child has a crossbite, their orthodontist will likely wait until they are age 7 or 8 to start treatment. The treatment plan will depend on the cause and the severity of the crossbite.
Crossbite treatment can include:
Palatal expander. This is an appliance that is attached to your upper teeth and sits against the roof of your mouth. Your orthodontist will adjust it periodically to slowly widen your palate and jaw.
Braces. These appliances put pressure on your bones and teeth to move your teeth into the correct position. You might have a palate expander and braces at the same time.
Removable appliances. If you have an upper front tooth behind your bottom teeth, your orthodontist might use a removable appliance with a spring. The spring puts pressure on your tooth and moves it forward while the appliance keeps your other teeth in place. This option works best for younger children whose jaws are still growing.
Clear aligners. These are removable braces made of clear plastic that can be used in some cases to fix misaligned teeth.
Sometimes, part of crossbite correction may include stopping or treating habits. These options can include:
Fixed palatal crib. This is a mouth appliance to stop thumb or finger sucking. Most young children stop sucking habits on their own or with parent coaching between ages 2 and 4. If the habit persists or nothing else works, your orthodontist might use this crib to stop the habit.
Myofunctional therapy. This is a type of therapy that teaches you how to chew and swallow so that your tongue doesn’t push your teeth out of place. It can also help you learn to breathe through your nose instead of your mouth. You might have therapy before or along with other treatments.
A crossbite isn’t a medical emergency. If it’s left untreated, it may lead to jaw problems and affect your facial features. Crooked teeth are also harder to clean, which may lead to cavities and other problems. If you or your child have misaligned teeth, talk to your dentist or orthodontist about next steps.