A crossbite in children is when some upper teeth bite inside the lower teeth instead of outside them. It is often caused by a narrow upper jaw, and it is usually easiest to correct while a child is still growing, often with an expander.
Parents tend to notice a crossbite in one of two ways. Either a dentist mentions it at a check-up, or they see their child’s jaw shift to one side when the teeth come together. Either way, the next question is the same: does this need treatment now, or can it wait? The answer depends on the type of crossbite and what is causing it. Here is what parents should know.
What Is a Crossbite?
In a healthy bite, the upper teeth sit slightly outside the lower teeth all the way around the arch. A crossbite is a type of misalignment where some upper teeth don’t line up with the lower teeth and sit either too close to the cheek or too close to the tongue. It can involve one tooth or several, and it can be the result of the teeth themselves or of the bone of the jaw.
Orthodontists usually describe two main types. In a posterior crossbite, one or more upper back teeth bite inside the lower back teeth, on one side or on both. In an anterior crossbite, one or more upper front teeth sit behind the lower front teeth when the child bites down. An anterior crossbite involving the whole front of the mouth can look like an underbite, which is a separate jaw-level problem covered in our article on what causes an underbite.
Crossbites are one of several common bite problems in children. Some resolve as baby teeth are replaced, but many do not, especially when the jaw itself is too narrow.
| Question | Posterior crossbite | Anterior crossbite |
|---|---|---|
| Which teeth are affected? | Upper back teeth bite inside the lower back teeth | Upper front teeth bite behind the lower front teeth |
| Common cause | A narrow upper jaw | Tooth position or a jaw growth difference |
| What parents might notice | The jaw shifts sideways when the teeth close | Lower front teeth show in front of the upper teeth |
| Typical early approach | Expansion to widen the upper jaw | Moving the affected teeth, or guiding jaw growth |
What Causes a Crossbite in Children?
The most common cause of a back-teeth crossbite is an upper jaw that is narrower than the lower jaw. When the upper arch is too narrow, the upper back teeth cannot reach their normal position outside the lower teeth, so one or both sides end up biting inside. Jaw size and shape are partly inherited, so crossbites often run in families.
Habits can contribute too. Thumb or finger sucking and prolonged pacifier use can narrow the upper arch as it develops. Breathing matters as well. Mouth breathing throughout development can negatively affect the way the face grows, and a narrow upper jaw is one of the patterns linked with it.
Front-teeth crossbites are often a question of where a permanent tooth came in. If a baby tooth is lost late or there is not enough room, an upper front tooth can erupt behind the lower teeth and get locked there. Our article on childhood habits that affect the teeth covers what parents can watch for at home.
Why Should a Crossbite Be Treated Early?
A crossbite rarely fixes itself once the permanent teeth start arriving, and leaving it can make it harder to correct later. When the jaw shifts to one side to bring the teeth together, the child’s bite is working around the problem every time they chew. Over time that shift can influence how the jaw develops and cause uneven wear on the teeth that are biting against each other the wrong way.
Front-teeth crossbites carry a different risk. A tooth locked behind the lower teeth can be worn down or pushed out of position, and the gum around the lower tooth can be stressed. Correcting it early protects both teeth and makes room for the rest of the permanent teeth to come in properly.
Early treatment is designed around growth. The goal of phase one treatment is to help the jaw develop in a way that accommodates all of the permanent teeth and to improve how the upper and lower jaws fit together. An upper jaw that is too narrow can be recognized at an early age, and children over the age of six with this kind of jaw discrepancy are candidates for early treatment. The two-phase treatment overview explains how the two stages fit together, and why phase two usually begins once all the permanent teeth have erupted.
How Is a Crossbite Corrected?
For a crossbite caused by a narrow upper jaw, the usual approach is expansion. A palatal expander is an appliance that sits in the roof of the mouth and gently widens the upper jaw while the child is still growing. Expansion is used to help develop the face as well as make room for permanent teeth, and it has also been shown to increase nasal airway volume and improve the ability of children to breathe properly through their noses. You can read more about our approach to palatal expansion.
For children between ages 7 and 10, an orthodontist may recommend interceptive treatments like palatal expanders or space maintainers to guide jaw growth and create room for future teeth. A crossbite involving only one or two front teeth may instead be corrected by moving those teeth with a short course of braces or another appliance.
What If the Crossbite Isn’t Caught Until the Teen Years?
Teens and adults can still have a crossbite corrected, but the options change once growth slows. Braces or aligners can move individual teeth, and some adults are candidates for MARPE, a miniscrew-assisted expander that widens the upper jaw without surgery. When the jaw difference is too large, orthodontics may be combined with jaw surgery.
When Should My Child See an Orthodontist?
The American Association of Orthodontists recommends that children have their first orthodontic evaluation by age 7. At that age, many permanent teeth are still on their way, but the jaw relationship is already visible, so an orthodontist can tell whether a crossbite is likely to resolve or needs treatment. For a closer look at timing, read at what age your child should first see an orthodontist.
Signs worth an exam include a jaw that slides sideways when your child bites, a front tooth that sits behind the lower teeth, uneven wear on the teeth, or a narrow, high palate. Many children simply need to be monitored, and Dr. Clif Speaks, a board-certified orthodontist, will tell you if waiting is the right call.
Frequently Asked Questions
Can a crossbite correct itself?
Occasionally a crossbite involving baby teeth resolves as the permanent teeth erupt. Crossbites caused by a narrow upper jaw usually do not. An exam is the only way to know which kind your child has.
Does a palatal expander hurt?
Most children feel pressure in the upper teeth and nose area after the expander is adjusted, and it usually eases within a short time. Soft foods help in the first few days.
Will my child still need braces after an expander?
Often, yes. Phase one prepares the jaw and makes room for the permanent teeth. A second phase, usually with full braces, places each tooth in its final position once the permanent teeth have come in.
Book an Exam for Your Child’s Bite
If you have noticed your child’s jaw shifting or a tooth biting the wrong way, an early exam gives you the most options. Speaks Orthodontics offers braces for kids in Denver and early treatment when it is needed. Schedule a complimentary exam to find out what your child’s bite needs.