What is a Crossbite? Causes, Symptoms, and Modern Treatments

A crossbite is a common bite misalignment where one or more teeth sit inside the opposing teeth. This guide explains crossbite causes, symptoms to watch for, when treatment is needed, and the modern options available — including clear aligners.

A crossbite is one of the most common bite misalignments — yet many people live with one for years without realising it. Unlike crowding or spacing, which are visually obvious, crossbite teeth can look relatively straight from the front while the upper and lower jaws are meeting incorrectly from side to side or front to back. Left unaddressed, a crossbite can lead to uneven tooth wear, jaw discomfort, gum recession, and even changes to facial symmetry over time. This guide explains what a crossbite actually is, what causes it, how it's diagnosed, and the modern treatment options available to fix crossbite problems — including when clear aligners may help and when they may not.

📋 What This Guide Covers

Quick answer: what is a crossbite?
Types of crossbite explained
Causes and contributing factors
Symptoms and signs to watch for
Can clear aligners fix a crossbite?
When alternative or combined approaches are needed
Risks of leaving a crossbite untreated
Who clear aligners may not be suitable for
FAQs

Whether you've been told you have a crossbite at a dental check-up, noticed your teeth meeting unevenly when you bite down, or simply want to understand the condition before seeking an orthodontic assessment — this guide gives you a clear, honest overview of what's involved.

Quick Answer: What Is a Crossbite?

A crossbite is a type of dental misalignment (malocclusion) where one or more upper teeth sit inside the lower teeth when you bite down, rather than slightly outside them. It can affect the front teeth (anterior crossbite) or the back teeth (posterior crossbite), and may involve a single tooth or multiple teeth. Treatment depends on the type, severity, and underlying cause — options range from clear aligners for mild-to-moderate cases to fixed braces, expanders, or surgery for more complex situations.

Bite Basics: What Is a Normal Bite — and What Makes a Crossbite Different?

To understand a crossbite, it helps to know what a normal bite looks like. In an ideal bite (Class I occlusion), the upper teeth sit slightly outside the lower teeth all the way around the arch. The upper front teeth overlap the lower front teeth by about 2–4 mm, and the back teeth interlock with the upper teeth sitting just outside the lower ones.

A crossbite reverses this relationship — some of the upper teeth drop inside the lower teeth instead of sitting outside them. Think of it as the teeth being on the "wrong side" of each other.

Types of Crossbite

Crossbites are broadly classified by location and cause:

Anterior Crossbite

One or more upper front teeth sit behind the lower front teeth. This can look similar to an underbite but may affect only individual teeth rather than the entire jaw. Causes range from a single tooth being displaced to skeletal discrepancies in jaw position.

Posterior Crossbite

One or more upper back teeth (premolars or molars) sit inside the lower back teeth. This is the more common type and can affect one side (unilateral) or both sides (bilateral). It often relates to a narrow upper jaw or palate.

Dental Crossbite

Caused by the teeth themselves being tilted or positioned incorrectly, while the jaws are relatively well-aligned. These are often more straightforward to treat with orthodontics alone.

Skeletal Crossbite

Caused by a mismatch in the width or position of the upper and lower jaws themselves. These may require palatal expansion, combined orthodontic and surgical treatment, or specialist referral.

The distinction between dental and skeletal crossbites is clinically important — it determines which treatment options are appropriate. This can only be assessed through a proper clinical examination and, in many cases, X-rays or a 3D scan.

What Causes a Crossbite?

Crossbites develop for a variety of reasons, and often more than one factor is involved:

🧬 Genetics

Jaw size and shape are largely inherited. If one or both parents have a crossbite or a narrow upper jaw, there's a higher likelihood of the same pattern occurring in their children.

👶 Childhood Habits

Prolonged thumb-sucking, dummy use beyond age 3–4, or tongue thrusting can affect how the palate develops, potentially narrowing the upper arch and contributing to a posterior crossbite.

🦷 Delayed or Abnormal Tooth Eruption

If permanent teeth erupt in the wrong position — or if baby teeth are lost too early or retained too long — the adult teeth may settle into a crossbite position. Impacted teeth can also contribute.

🫁 Mouth Breathing

Chronic mouth breathing (often linked to allergies, enlarged adenoids, or nasal obstruction) can alter palatal development during childhood, leading to a narrow upper arch and posterior crossbite.

📐 Jaw Growth Discrepancies

Uneven growth between the upper and lower jaws — either the upper jaw being too narrow, the lower jaw being too wide, or asymmetric growth — can create a skeletal crossbite.

🦴 Trauma or Previous Dental Work

Injury to the jaw or face, or dental restorations that change tooth height or shape, can sometimes shift the bite into a crossbite pattern over time.

Symptoms and Signs of a Crossbite

Many crossbites are asymptomatic in the early stages — particularly if only one or two teeth are affected. However, the following signs may indicate a crossbite is present or causing problems:

Common Signs of a Crossbite

Uneven bite: teeth don't meet evenly when you bite down, or you shift your jaw to one side to make them fit
Jaw pain or clicking: discomfort in the temporomandibular joint (TMJ), particularly when chewing
Uneven tooth wear: certain teeth show more wear than expected, or wear patterns are asymmetric
Gum recession: teeth in crossbite may develop localised gum recession due to abnormal forces
Difficulty biting or chewing: food doesn't break down evenly, or you avoid chewing on one side
Facial asymmetry: in more pronounced cases, the lower jaw may appear shifted to one side
Headaches or neck tension: sometimes associated with compensatory jaw positioning
Tooth sensitivity: teeth under abnormal stress may become more sensitive

Important Note

Many of these symptoms can also be caused by other conditions. Only a clinical examination by a qualified dental professional can confirm whether a crossbite is present and whether it's contributing to any symptoms you're experiencing.

Can Clear Aligners Fix a Crossbite?

In some cases, yes — but suitability depends entirely on the type and severity of the crossbite, the underlying cause, and the overall clinical picture.

When Clear Aligners May Be Suitable

Clear aligners can be effective for treating crossbites where:

The crossbite is dental — caused by tooth position rather than jaw structure
Only a few teeth are involved — particularly single-tooth anterior crossbites or mild posterior crossbites
The arch width discrepancy is small — minor expansion of the upper arch may be achievable with aligners in adult patients
The patient has good compliance — aligners must be worn 20–22 hours per day for bite correction with aligners to be effective

Modern aligner systems can incorporate features that help with crossbite correction:

Attachments and Elastics

Small tooth-coloured attachments bonded to specific teeth provide grip points for the aligner, enabling more controlled and predictable tooth movements. In some cases, attachments and elastics (such as class II elastics aligners) can be combined to address bite relationships more effectively than aligners alone.

Cross-Bite Elastics

Some aligner systems use small elastic bands attached between upper and lower trays to help guide crossbite teeth into the correct position. These require specific attachment placement and careful treatment planning.

Sequential Arch Expansion

Aligners can be programmed to gradually widen the upper arch through controlled tipping of the back teeth outward. This works within limits — significant skeletal expansion cannot be achieved with aligners alone in adults.

An orthodontic assessment is essential to determine whether your specific crossbite is suitable for aligner treatment. This typically involves a clinical examination, X-rays, and a 3D scan to understand the position of the teeth and the underlying jaw relationship. You can read more about crossbite and aligner suitability on our conditions page.

What Affects Treatment Duration

If clear aligners are suitable for your crossbite, the treatment timeline depends on several factors:

Factor	Impact on Treatment Time
Number of teeth in crossbite	Single-tooth crossbites may resolve in 3–6 months; multi-tooth involvement typically takes longer
Severity of the crossbite	Mild crossbites requiring small movements are quicker; significant repositioning extends treatment
Compliance	Wearing aligners for 20–22 hours per day is essential. Reduced wear time delays progress and may compromise the result
Refinements needed	Most crossbite cases need at least one round of refinement trays to fine-tune the bite relationship
Additional tooth movements	If crowding, spacing, or rotated teeth are also being addressed alongside the crossbite, the overall plan takes longer

Note: Typical treatment times for mild-to-moderate dental crossbites range from approximately 6–18 months, but this varies significantly by case. Only a clinical assessment can provide a realistic estimate for your situation.

When Alternative or Combined Approaches Are Needed

Clear aligners are not always the right tool for crossbite correction. In the following situations, alternative or combined approaches may be more appropriate:

Skeletal Crossbite (Significant Jaw Discrepancy)

When the upper jaw is significantly narrower than the lower jaw, palatal expansion may be needed before or alongside orthodontic treatment. In growing children and adolescents, a palatal expander can widen the upper jaw. In adults, surgically assisted expansion (SARPE) may be necessary for significant skeletal discrepancies.

Complex Multi-Tooth Posterior Crossbite

Multiple teeth in crossbite on both sides (bilateral posterior crossbite) may require fixed braces, possibly combined with a palatal expander, to achieve reliable correction. Aligners alone may not generate sufficient force for this type of movement.

Crossbite With Severe Bite Issues

If the crossbite exists alongside a significant overbite, open bite, or overjet, the combined complexity may exceed what aligners can predictably manage. A specialist orthodontist may recommend fixed appliances or combined treatment.

Cases Requiring Orthognathic Surgery

Severe skeletal crossbites — particularly those causing significant facial asymmetry or functional impairment — may require jaw surgery combined with orthodontic treatment. This is typically managed by a specialist orthodontist and maxillofacial surgeon.

A good clinician will be transparent about the limits of what aligners can achieve for your case. If your crossbite requires a different approach, that should be identified during the initial orthodontic assessment rather than mid-treatment.

Risks of Leaving a Crossbite Untreated

Not every crossbite requires treatment — a single tooth in mild crossbite with no symptoms may be monitored rather than actively treated. However, crossbites that are functional, progressive, or symptomatic carry risks if left untreated:

⚠️ Potential Consequences of an Untreated Crossbite

Uneven tooth wear: teeth in crossbite meet at abnormal angles, accelerating enamel wear on specific surfaces
Gum recession: abnormal bite forces can push teeth out of the bone, leading to localised gum recession that may require treatment
TMJ problems: compensating for a crossbite by shifting the jaw can lead to temporomandibular joint pain, clicking, and dysfunction
Tooth fracture: teeth under abnormal stress are more susceptible to fractures, particularly teeth with existing restorations
Facial asymmetry: in growing individuals, an untreated crossbite can influence how the jaw develops, potentially increasing asymmetry over time
Bone loss: chronic abnormal forces on teeth can contribute to localised bone loss around the affected teeth
Difficulty with dental restorations: an untreated crossbite complicates crown, bridge, and implant planning by creating an unstable bite foundation

Key Consideration

The decision to treat a crossbite should be based on clinical assessment, not assumption. Some crossbites are stable and asymptomatic; others are actively causing damage. Your clinician can assess whether your crossbite is progressing, stable, or already causing problems — and whether the benefits of treatment outweigh the risks of leaving it.

Who Clear Aligners May Not Be Suitable For

Even when a crossbite is dental rather than skeletal, clear aligners aren't appropriate for everyone. They may not be suitable if:

🚩 When Aligners May Not Be the Right Choice

Active gum disease: periodontal health must be stable before any orthodontic treatment
Significant bone loss: moving teeth through compromised bone carries substantial risk
Severe skeletal discrepancy: aligners cannot reposition the jaws themselves
Unrealistic expectations about compliance: bite correction with aligners requires strict 20–22 hours daily wear — more so than cosmetic alignment alone
Untreated decay or infection: these must be resolved before starting orthodontic treatment
Complex combined malocclusions: when crossbite exists alongside other significant bite issues, fixed braces may offer more predictable results
Growing patients who need skeletal expansion: children and adolescents with skeletal crossbites often benefit more from palatal expanders and/or fixed braces during their growth phase

A responsible clinician will discuss these factors openly during your orthodontic assessment and recommend the approach most likely to achieve a stable, healthy result — even if that means referring you to a specialist.

Safety and Compliance Notes for UK Patients

Clinical Assessment Before Treatment

Under GDC guidance, patients should receive a thorough clinical examination before starting any orthodontic treatment. For crossbite correction, this is particularly important because the type of crossbite (dental vs. skeletal) determines which treatment options are appropriate and safe. A clinical exam, X-rays, and ideally a 3D scan are needed to make this distinction.

Direct-to-Consumer Aligner Services

The GDC has published specific patient guidance about aligners sent directly to your home. For crossbite cases in particular, mail-order services that lack in-person examination and X-rays may miss the skeletal component of a crossbite, potentially leading to treatment that moves teeth without addressing the underlying cause. This can result in an unstable result or, in some cases, worsening of the condition.

Informed Consent and Advertising Standards

Under ASA/CAP advertising standards, providers should not make claims about crossbite correction that are not supported by evidence, or use before-and-after images that imply guaranteed outcomes. Patients should receive clear information about what treatment can and cannot achieve, the risks involved, and alternative options, as part of informed consent.

Frequently Asked Questions

What is a crossbite?

A crossbite is a type of bite misalignment where one or more upper teeth sit inside (rather than outside) the corresponding lower teeth when you bite down. It can affect the front teeth (anterior crossbite) or back teeth (posterior crossbite), and may involve the teeth, the jaws, or both.

How do I know if I have a crossbite?

Some crossbites are visible — you may notice a tooth or teeth meeting on the wrong side when you bite together. Others are less obvious and may be detected during a routine dental examination. Signs can include uneven bite, jaw clicking, asymmetric tooth wear, or chewing difficulty. A dental professional can diagnose a crossbite through clinical examination and X-rays.

Can you fix a crossbite with clear aligners?

Clear aligners can fix crossbite cases that are dental in origin (caused by tooth position) and mild to moderate in severity. They work by gradually repositioning the crossbite teeth using attachments and elastics where needed. However, aligners cannot reposition the jaws themselves, so skeletal crossbites or severe cases may require fixed braces, palatal expansion, or surgery.

How long does it take to fix a crossbite?

Treatment time depends on the type and severity of the crossbite, the treatment approach used, and patient compliance. Mild single-tooth crossbites may be corrected in as little as 3–6 months with aligners. Multi-tooth or more complex crossbites typically take 9–18 months. Cases requiring expansion or combined treatment may take longer. These are estimates — your clinician will provide a realistic timeline based on your specific case.

Is crossbite correction painful?

Most patients experience mild discomfort or pressure when new aligners or adjustments are applied — this is normal and usually settles within a few days. Significant pain is not expected. If you experience persistent or worsening pain, contact your treating clinician.

What happens if a crossbite is not treated?

Not all crossbites require treatment, but those that are functional or progressive can lead to uneven tooth wear, gum recession, TMJ problems, tooth fracture, and in growing individuals, worsening jaw asymmetry. A clinical assessment can determine whether your crossbite is causing problems or is likely to in the future.

Are crossbites common?

Yes — crossbites are one of the most common types of malocclusion. Studies suggest that posterior crossbites affect approximately 5–8% of the population, though prevalence varies by study and population. Many people have a crossbite without being aware of it.

Is a crossbite the same as an underbite?

Not exactly. An underbite (Class III malocclusion) is a specific type of anterior crossbite where the lower jaw protrudes forward, causing the lower front teeth to sit in front of the upper front teeth across the entire arch. A crossbite is broader — it can affect individual teeth, groups of teeth, or the entire arch, and can occur at the front or back of the mouth.

Can adults get crossbite treatment?

Yes — adults can undergo crossbite treatment. However, adult treatment may be more limited than treatment in growing patients, particularly for skeletal crossbites where jaw growth can no longer be guided. For adults with dental crossbites, clear aligners or fixed braces are often effective. For significant skeletal discrepancies, surgical options may be discussed.

📚 References and Further Reading

NHS — Orthodontics Overview
GDC — Aligners or Braces Sent Directly to Your Home
GDC — Guidance on Advertising
ASA/CAP — Dental Advertising Guidance
British Orthodontic Society — Patient Information and Resources
British Orthodontic Society — Patient Information: Retainers (PDF)
British Dental Association — Patient Information Hub
Lombardo L, et al. — Clear aligner treatment of crossbites: a systematic review, Progress in Orthodontics (2021)

Wondering Whether Your Crossbite Can Be Treated With Aligners?

Book a consultation and we'll assess your bite, explain what's happening, and let you know whether clear aligners are a suitable option — or recommend the right next step if they're not.

Book Your Consultation

Disclaimer: This article is for general information only and does not constitute dental or medical advice. A crossbite can only be diagnosed and assessed through an in-person clinical examination by a GDC-registered dental professional. Treatment suitability, timelines, and outcomes vary by individual case. No specific results are guaranteed.