Crossbite

A crossbite is an irregular bite relationship in which one or more upper teeth do not meet the lower teeth in the expected position when the mouth closes. It can affect a single tooth, several teeth, or a larger part of the dental arch. Depending on where it occurs, a crossbite may involve the front teeth, the back teeth, or both.

In a posterior crossbite, one or more upper back teeth usually bite inside the corresponding lower teeth rather than slightly outside them. The pattern may be unilateral, affecting one side, or bilateral, affecting both sides. In some people, the lower jaw shifts sideways as the teeth come together in order to find a more comfortable position. This is known as a functional mandibular shift and is particularly important to assess in growing children.

How crossbite can appear and feel

Some crossbites are clearly visible, while others become apparent only when the bite is examined carefully. A person may notice that the teeth on one side do not fit together like those on the other side, that one or more front teeth close behind the lower teeth, or that the jaw moves slightly to one side during closure.

A crossbite does not necessarily cause pain. However, depending on its type and severity, it may be associated with:

• difficulty biting or chewing evenly on both sides;
• a feeling that the teeth do not meet comfortably;
• uneven tooth contact or localized tooth wear;
• one or more teeth meeting in an unusual position;
• a visible shift of the lower jaw as the mouth closes;
• occasional irritation of the gums or supporting tissues when teeth contact unfavorably.

Not every person with a crossbite develops facial asymmetry, jaw-joint symptoms, or significant functional problems. These findings need to be assessed individually rather than assumed from the presence of a crossbite alone.

Anterior and posterior crossbite

Anterior crossbite

An anterior crossbite involves one or more front teeth. An upper front tooth may close behind a lower front tooth instead of in front of it. When several lower front teeth sit ahead of the upper front teeth, the appearance may overlap with what patients describe as an underbite or reverse bite. The two concepts are related, but they are not identical.

A broader sagittal jaw relationship in which the lower dental arch or jaw is positioned ahead of the upper one is assessed separately and may lead to a pathway such as reverse bite correction. This page focuses primarily on the abnormal crosswise relationship between opposing teeth, particularly posterior crossbite.

Posterior crossbite

A posterior crossbite affects premolars, molars, or the corresponding primary teeth in children. It can involve one tooth, several teeth, one side of the mouth, or both sides. A unilateral appearance does not always mean that the underlying problem exists only on one side. In some children, a relatively narrow upper arch together with tooth contacts can cause the lower jaw to shift to one side when the bite closes.

Common factors associated with crossbite

Crossbite can arise from different mechanisms, and identifying the mechanism is important because treatment is not the same for every patient.

Dental factors

A dental crossbite may result from the position, inclination, rotation, or eruption path of individual teeth. The underlying jaw width may be broadly appropriate, while one or several teeth are positioned too far toward the tongue or cheek. Available space in the dental arch can also influence how teeth erupt and meet.

Skeletal factors

A skeletal crossbite involves the relationship between the underlying jaws. For example, the upper jaw may be relatively narrow compared with the lower jaw. More complex cases may include transverse, sagittal, or combined jaw discrepancies. These cases require assessment of facial growth, skeletal maturity, dental compensation, and the overall relationship between the upper and lower jaws.

Functional factors

Sometimes the teeth first contact in a position that causes the lower jaw to move sideways before the patient reaches a comfortable bite. This functional shift is particularly relevant during growth because the orthodontist needs to distinguish the position in which the jaw naturally closes from the position the patient habitually adopts when the teeth interlock.

Dental, skeletal, and functional factors can occur together, so a crossbite should not be classified only from a photograph or from the appearance of one tooth.

When crossbite should be assessed

Crossbite is usually not an emergency, but an orthodontic assessment is useful when the bite is visibly uneven, the lower jaw shifts during closure, chewing is uncomfortable, or tooth wear appears to be progressing.

Assessment during childhood can be particularly helpful because the orthodontist can evaluate the developing dental arches and jaw growth. This does not mean that every child with a crossbite needs immediate orthodontic treatment. In some cases, monitoring is appropriate. In others, treatment during growth may be considered because the type of crossbite, functional shift, available space, or jaw width makes earlier intervention useful.

Adults can also be assessed and treated for crossbite. Because adult jaw growth is largely complete, the evaluation may place greater emphasis on tooth position, periodontal support, skeletal relationships, previous dental treatment, and whether the discrepancy can be managed orthodontically alone or requires a broader interdisciplinary plan.

Dental care should not be delayed when there is significant tooth or gum trauma from the bite, rapidly increasing pain, swelling, difficulty closing the mouth after an injury, or another acute dental problem. These findings may require assessment beyond routine orthodontic planning.

How crossbite is usually diagnosed

A detailed orthodontic examination is the main starting point. The orthodontist evaluates how the teeth meet, whether the crossbite affects one or several teeth, whether it is anterior or posterior, and whether a posterior crossbite is unilateral or bilateral.

The examination may include assessment of:

• the width and shape of the upper and lower dental arches;
• tooth position, inclination, rotation, and available space;
• dental midlines and whether they change as the patient closes the mouth;
• possible functional movement of the lower jaw;
• jaw relationships and facial growth pattern;
• chewing function and areas of uneven tooth contact;
• tooth wear and the health of the gums and supporting tissues.

Digital intraoral scanning can provide an accurate three-dimensional record of the dental arches and bite. Clinical photographs may also be useful. Panoramic, cephalometric, or other imaging is used when it is clinically indicated and when the additional information is expected to influence diagnosis or treatment planning. More complex skeletal cases may require additional imaging or interdisciplinary assessment.

What the next step may involve

The appropriate next step depends on whether the crossbite is primarily dental, functional, skeletal, or a combination of these factors, as well as the patient's age and growth status.

For a localized dental crossbite, treatment may focus on moving one or several teeth into a more appropriate relationship. Depending on the case, this may involve fixed braces, selected removable appliances, or clear aligners. Aligners can be useful in some crossbite cases, but they are not suitable for every type or severity of crossbite.

If insufficient width of the upper arch contributes to the problem, some form of expansion may be considered. It is important to distinguish dental expansion from skeletal expansion. Dental expansion primarily changes tooth position and the surrounding dentoalveolar structures. Skeletal expansion aims to increase the transverse width of the upper jaw and depends strongly on growth and skeletal maturity. These are different therapeutic objectives and should not be presented as interchangeable procedures.

In selected growing patients, expansion of the upper jaw or arch may therefore form part of treatment. In adults, significant skeletal transverse discrepancies may require a different approach, sometimes including skeletal anchorage or combined orthodontic and maxillofacial assessment. An interdisciplinary evaluation is particularly relevant when a crossbite forms part of a more complex skeletal jaw discrepancy.

ZagrebMed already includes a dedicated pathway for crossbite correction. The actual treatment method should be selected only after the orthodontist has established the type of crossbite and the structures responsible for it.

What to prepare before a medical appointment

Before an orthodontic assessment, it helps to note when the bite difference was first noticed, whether it has changed over time, whether chewing feels uneven, and whether the lower jaw appears to move sideways when closing. For children, information about dental development, previous dental examinations, and any earlier orthodontic monitoring can be useful.

If available, bring previous dental X-rays, orthodontic records, photographs, digital scans, dental reports, and information about previous braces, aligners, extractions, restorations, or jaw treatment. Adults should also mention crowns, bridges, implants, gum treatment, or previous orthodontic therapy because these can affect treatment planning.

If you are unsure whether the bite pattern represents a crossbite or what type of assessment is appropriate, you can send ZagrebMed a short description of the concern together with any existing dental records. ZagrebMed can help connect the problem with an appropriate orthodontic examination or bite-correction pathway in Zagreb.