What Is a Crossbite?
In a well-aligned bite, the upper teeth sit slightly outside the lower teeth when the jaw is closed. This allows the teeth to meet evenly and distribute biting forces across the dental arches. A crossbite occurs when this relationship is reversed — one or more upper teeth close inside the corresponding lower teeth rather than outside them.
A crossbite differs from an overbite, in which the upper front teeth overlap the lower front teeth vertically by an excessive amount, and from an underbite, in which the entire lower jaw protrudes forward of the upper jaw. A crossbite may involve individual teeth or groups of teeth and can occur on one or both sides of the mouth.
There are two main types. An anterior crossbite affects the front teeth and occurs when one or more upper incisors close behind the lower incisors. A posterior crossbite involves the back teeth and occurs when the upper premolars or molars sit inside the lower back teeth. The type of crossbite influences the approach to assessment and any treatment that may be recommended.
Common Causes of Crossbite
A crossbite can develop for a number of reasons, and the underlying cause varies between individuals. Contributing factors may include:
Jaw Growth Patterns
Differences in the rate or direction of upper and lower jaw growth can result in a mismatch between the dental arches, contributing to crossbite development.
Delayed or Abnormal Tooth Eruption
When permanent teeth erupt later than expected or in an atypical position, they may settle into a crossbite relationship with the opposing teeth.
Childhood Habits
Prolonged thumb sucking, dummy use, or mouth breathing during childhood may influence the development of the dental arches and jaw, potentially contributing to crossbite.
Narrow Upper Jaw
A narrow upper jaw — also known as a constricted maxilla — may not be wide enough to accommodate the lower arch, causing some or all of the upper teeth to sit inside the lower teeth.
Genetic Factors
Jaw size, tooth size, and the overall relationship between the upper and lower dental arches are influenced by hereditary factors. A family history of bite irregularities may increase the likelihood of crossbite.
In many cases, a crossbite results from a combination of factors rather than a single cause. A professional assessment can help identify the contributing elements.
Symptoms and Potential Effects
A crossbite may not always cause noticeable symptoms, particularly if it is mild. However, when present, the following effects may be observed:
Uneven Tooth Wear
When teeth do not meet evenly, certain surfaces may be subjected to greater forces during chewing, leading to accelerated or asymmetric wear patterns over time.
Jaw Discomfort or Pain
A crossbite may place uneven stress on the temporomandibular joint (TMJ) and surrounding muscles, which can contribute to jaw pain, clicking, or stiffness.
Gum Recession in Affected Areas
Teeth positioned in crossbite may experience abnormal loading forces that can, over time, contribute to localised gum recession around the affected teeth.
Difficulty Chewing
Misaligned bite relationships may reduce chewing efficiency, as the teeth do not come together in a way that allows even distribution of biting forces.
Cosmetic Concerns
A crossbite may affect the symmetry of the smile or the alignment of the dental midline. Some patients seek assessment primarily because of the visible appearance of their bite.
The presence and severity of symptoms depend on the type of crossbite, the number of teeth involved, and individual factors. Not all crossbites produce noticeable effects.
Why Professional Assessment Is Important
Bite misalignment, including crossbite, may place uneven pressure on certain teeth and the surrounding structures. Over time, this imbalanced loading can contribute to enamel wear, gum recession, or discomfort in the jaw joint. A professional assessment allows the extent and impact of the crossbite to be properly evaluated.
During an assessment, your dentist or orthodontist may use digital scans, clinical photography, or dental imaging to assess tooth positioning, jaw alignment, and the overall bite relationship. These findings help inform whether treatment is recommended and, if so, which approach may be most appropriate.
Early evaluation — particularly in children and adolescents — may help identify crossbites at a stage when intervention can take advantage of ongoing jaw development. In adults, timely assessment can help prevent progressive wear or functional complications. Treatment planning will always depend on the severity of the crossbite and the individual's dental and medical history.
Orthodontic Treatment Options for Crossbite
The management of a crossbite depends on its type, severity, and the patient's age. Treatment aims to create balanced tooth positioning and may help improve bite alignment. Options may include:
Fixed Orthodontic Appliances
Traditional fixed braces use brackets and wires to gradually reposition teeth into a more favourable bite relationship. They are suitable for a wide range of crossbite types and severities.
Clear Aligners or Invisible Braces
For suitable cases, clear aligner systems may help improve tooth positioning and bite alignment. These removable appliances are often preferred by patients who value discretion during treatment.
Palatal Expansion
Where a crossbite is caused by a narrow upper jaw, a palatal expander may be used to widen the upper arch gradually. This technique is most effective in younger patients whose jaw development is still ongoing.
Retainers Following Correction
After active orthodontic treatment, retainers are typically prescribed to help maintain the corrected tooth positions and prevent relapse. Both fixed and removable retainer options may be considered.
Treatment outcomes depend on individual circumstances, including the complexity of the crossbite and patient compliance. Your orthodontist will discuss what can reasonably be expected based on your specific assessment findings.
Orthodontic Assessment for Crossbite
If you are concerned about bite alignment or uneven tooth contact, a dental assessment can determine whether orthodontic treatment may be appropriate. Your dentist or orthodontist can evaluate the type and severity of any crossbite and discuss the most suitable management options for your individual situation.
Depending on the findings, your clinician may recommend invisible braces for suitable cases, a fixed retainer following correction, or TMJ treatment if jaw discomfort is present.
Orthodontic assessment and crossbite treatment are available at our London clinics. You can attend our South Kensington dental clinic or our City of London clinic near St Paul's for a professional dental evaluation.
