Also known as: posterior crossbite, front crossbite, reverse bite, teeth biting inside, uneven bite, shifted bite

A crossbite happens when one or more upper teeth bite inside the lower teeth instead of fitting slightly outside them. It can affect the front teeth, back teeth, one side of the mouth, or both sides. Parents may notice that the bite looks uneven, that the upper arch seems narrow, or that the child shifts the jaw to one side when closing the teeth together.

Crossbites can involve tooth position, jaw development, or both. A posterior crossbite is often associated with an upper jaw that is too narrow for the lower jaw, which is why early orthodontic evaluation can be helpful while a child is still growing. Correcting the underlying width problem can improve how the arches fit together and reduce the chance that an uneven functional jaw shift becomes more established over time.

Possible Causes of a Crossbite

Crossbites may be associated with:

  • A narrow upper jaw – When the upper arch is too narrow, the back upper teeth may sit inside the lower teeth instead of outside them.
  • Genetics and jaw growth – Differences in upper- and lower-jaw development can affect how the teeth meet.
  • Tooth eruption or position – An individual tooth that erupts too far inward or outward can create a localized crossbite even when overall jaw width is normal.
  • Persistent oral habits – Long-term thumb sucking or pacifier use can influence arch development and is associated with posterior crossbite.

Treatments for a Crossbite

Depending on whether the crossbite involves the teeth, jaw width, or both, treatment may include:

  • Airway Orthodontics – When a crossbite is caused by a narrow upper jaw, palatal expansion can widen the upper arch and improve how it fits with the lower jaw.
  • Braces – Braces can reposition individual teeth and refine the bite when tooth alignment is part of the crossbite.
  • Invisalign® – Some dental crossbites and accompanying alignment concerns may be treated with clear aligners when the child is an appropriate candidate.

Palatal expansion is one of the most common treatments for a transverse upper-jaw problem associated with posterior crossbite.

When to See an Orthodontist

Consider scheduling an evaluation if your child:

  • Has upper teeth that visibly bite inside the lower teeth
  • Shifts the jaw sideways when closing the mouth
  • Has an uneven bite or seems to chew primarily on one side
  • Has a crossbite along with crowding or a noticeably narrow upper arch
  • Is developing an increasingly asymmetric-looking bite

Related Symptoms

Concerned About a Crossbite?

A crossbite can involve either tooth position or the way the jaws are developing, so early evaluation helps us identify the underlying cause. We’d love to evaluate your child’s symptoms and determine whether monitoring, palatal expansion, or another orthodontic treatment makes the most sense. Schedule an appointment today and get the answers you need.