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Dentist Disaster

Crooked teeth & bite

Crossbite

Routine3 treatment options

When some upper teeth bite inside the lower teeth instead of outside. How crossbites affect the jaw and how they are corrected.

How urgent is it? Routine

Not an emergency. Crossbites are one of the problems dentists are advised to refer for orthodontic advice while a child still has a mix of baby and adult teeth.

What it is

In a normal bite the upper teeth sit just outside the lower teeth. In a crossbite, one or more upper teeth close inside the lower teeth instead. It can affect the front teeth, the back teeth, or both, and may be on one side or both sides of the mouth.

A back-tooth (posterior) crossbite usually happens because the upper jaw or teeth are narrower than the lower ones. To get a comfortable bite, the lower jaw may shift to one side, and Cochrane reviewers note that crossbites have been linked to tooth wear, uneven jaw development and jaw joint problems.

Treatment for a posterior crossbite typically involves an appliance that gently widens the upper jaw. A Cochrane review found that in children both fixed and removable widening appliances can correct the crossbite, with a fixed 'quad-helix' appliance working faster and more reliably than a removable plate.

Signs and causes

Common signs

  • Upper teeth closing inside the lower teeth on one or both sides
  • The lower jaw sliding to one side as you close your teeth together
  • A centre line of the lower teeth that does not match the upper teeth
  • Uneven wear on particular teeth

Usual causes

  • An upper jaw or upper dental arch that is narrower than the lower one
  • Individual teeth coming through in the wrong position
  • Differences in how the jaws have grown

Ways to fix it

The options a dentist may discuss with you, and when each one tends to be used. Which one suits you depends on an examination.

  1. Metal braces

    Fixed braces, often with a separate expansion appliance, to widen the upper arch and align the teeth.

    Sometimes on the NHSOrthodontics

  2. Clear aligners

    Mild crossbites of individual teeth in adults, if your orthodontist confirms aligners can achieve the movement.

    Usually private onlyOrthodontics

  3. Retainers

    After correction, to keep the widened arch and the teeth stable.

    Sometimes on the NHSOrthodontics

What you can do now

  • Mention any jaw clicking, pain or shifting bite to your dentist
  • Keep up good cleaning around any expansion appliance or brace

Preventing it

  • Regular check-ups in childhood allow crossbites to be picked up and referred at the most useful time

Common questions

Do crossbites need treating?

Not always, but orthodontists often recommend it, particularly where the jaw shifts sideways to bite. Your orthodontist will explain the likely benefits for your situation.

How common are crossbites?

Cochrane reviewers report that back-tooth crossbites affect somewhere between about 4% and 17% of children and adolescents in Europe and America.

Can I get braces on the NHS?

Children and teenagers under 18 can be assessed for NHS orthodontic treatment, and it is provided free when their need scores highly enough on a standard index called the IOTN. Adults usually pay privately, although NHS treatment is possible in some complex cases, such as when jaw surgery is needed through a hospital service.

Products that may help at home

These support good daily care; they don’t replace treatment from a dentist. Some links may be affiliate links.

OPRO Gold mouthguard for braces

A self-fit sports mouthguard shaped to sit over fixed braces. Braces can change fit over time, so check with your orthodontist –…

Features & who it suits

TePe Bridge & Implant Floss

Pre-cut spongy floss with stiff ends that thread under wires, bridges and around implants – handy for anyone with fixed braces.

Features & who it suits

Sources we used

Checked September 2026. Guidance changes, so always follow the advice of your own dental team. About our sources.