Crossbite: Understanding and Treating This Common Issue

Have you ever heard of a crossbite? It's a common dental issue that can affect both children and adults.

Crossbite can occur in any area of the mouth (front or back) and may impact only the teeth' alignment or involve the growth of the jaws as well.

What makes it particularly challenging is that it doesn't resolve on its own. It can even worsen over time, affecting the overall facial development. That's why early treatment is key.

What is a Crossbite?

In a normal bite, your upper jaw should slightly overlap the lower jaw, with the chewing surfaces of your bottom teeth fully hidden behind the upper teeth when you bite down.

However, in a crossbite, the opposite occurs – it's the lower teeth that overlap the upper ones.

Now, you might think it's not a big deal, but this misalignment goes against how your jaws are supposed to work together. Over time, it can cause problems not only with your teeth but also with the joints and muscles involved in chewing.

There are different types of crossbites, depending on the specific teeth involved and the origin of the issue. Let's break it down:

• Anterior Crossbite: This type of crossbite affects the front teeth. It means that your lower front teeth are positioned in front of the upper front teeth when you bite down.
• Posterior Crossbite: When the crossbite is limited to the back teeth, specifically the molars and premolars, it's called a posterior crossbite. In this case, your lower teeth may be positioned on the outer side of your upper teeth when you bite.

Crossbites can also be categorized based on the involvement of one side or both sides of the mouth:

• Unilateral Crossbite: If the crossbite affects only one side of your mouth, either the right or left, it's called a unilateral crossbite.
• Bilateral Crossbite: When the crossbite affects both sides of your mouth, it's known as a bilateral crossbite.

The origin of a crossbite can vary as well. It may be due to:

• Dental Misalignment (Dental Crossbite): In this case, the crossbite is solely related to the position of your teeth. Your jaws have developed normally, but the teeth don't align properly.
• Skeletal Issues (Skeletal Crossbite): A skeletal crossbite involves the growth of your jaws. Either they haven't developed properly or have grown asymmetrically.
• Combination of Dental and Skeletal Factors: Sometimes, a crossbite occurs due to a combination of both tooth misalignment and jaw growth issues.

Dental Crossbite: Alignment Issues

In a dental crossbite, your jaws have developed normally, but the problem lies in the misalignment of your teeth (1).

They may be tilted in the wrong direction, causing the upper and lower teeth to meet incorrectly. Typically, dental crossbite occurs on one side of your mouth when you bite down.

Also, as the lower jaw seeks contact points through the teeth to stabilize itself, it may deviate to one side. This can lead to facial asymmetry.



The good news is that dental crossbite is usually a minor issue and can be easily treated when diagnosed early. However, if left untreated, what starts as a simple dental misalignment can progress and impact normal growth, potentially transforming into a skeletal problem (2).

Skeletal Crossbite: Jaw Development Issues

Unlike dental crossbite, skeletal crossbite involves more than just misaligned teeth. It's a condition where the jaws have become too narrow or asymmetrical (1).

Skeletal crossbite is typically a more severe condition that often affects the alignment of teeth on both sides (bilateral crossbite).

The most common cause of skeletal crossbite is a narrow upper jaw that hasn't grown sufficiently in width. As a result, the palate (the roof of the mouth), becomes narrow and takes on a triangular shape.

In rarer cases, skeletal crossbite can be caused by a malformation of the lower jaw (the mandible). The mandible may have developed excessively on one side or grown asymmetrically, leading to a unilateral crossbite on that side.

Severe forms of skeletal crossbite often require more advanced treatment, which may include surgical intervention to correct the jaw position and alignment.

What causes a crossbite?

Crossbite results from the interaction of multiple factors, including genetics, abnormal oral functions, and certain habits. Let's explore these factors in more detail:

1. Genetics:

Facial growth and development are largely determined by genetics.

Certain syndromes and anomalies can influence jaw growth, making skeletal crossbites more likely. It’s also common for individuals with crossbites to have close relatives dealing with the same malocclusion.

Some genetic conditions commonly linked to crossbites include:

• Maxillary Hypoplasia: Insufficient growth of the upper jaw.
• Mandibular Hyperplasia: Excessive growth of the lower jaw.
• Laterognathia: Asymmetry of the jaw, where one side is larger or positioned differently than the other.

2. Functional Issues and Bad Habits:

Abnormal oral habits and functions — such as mouth breathing, thumb sucking, or tongue thrusting — can interfere with how teeth align and may contribute to a crossbite.

If these habits aren’t addressed early, they can affect facial growth and turn a simple tooth alignment issue into a more serious skeletal malocclusion.

Some oral habits and function issues commonly associated with crossbite include:

• Mouth Breathing: Breathing mostly through the mouth pushes the tongue down, which can affect dental alignment, facial growth, head posture, and overall health.


• Tongue Thrusting: Pushing the tongue against or between the teeth while swallowing can misalign teeth and may cause an open bite — a gap between the upper and lower front teeth when the mouth is closed.


• Thumb Sucking: While normal in young children, prolonged thumb sucking after age five can impact jaw growth and tooth alignment.

Why are oral functions so important in jaw development and dental alignment?

While genetics play a role in facial development and jaw growth, it is primarily abnormal oral function and bad habits that contribute significantly to malocclusion (3). This is particularly the case for posterior crossbite, which is more common in children (7%-23%) (4).

Initially, these functional problems impact tooth alignment. However, if left unaddressed, they can disrupt facial growth and result in deformities of the jawbone (7). Let's delve into why this happens.

During growth, facial bones are connected by sutures, which provide growth potential until puberty. Normal functions (such as chewing, nasal breathing, and swallowing) exert tension on these sutures, stimulating growth and facilitating proper jaw development and tooth alignment.

However, persistent abnormal oral functions, such as mouth breathing, can deprive the sutures of adequate stimulation, resulting in facial deformities.

Furthermore, balanced muscle activity is vital for maintaining proper tooth alignment. When muscles, including the cheeks and tongue muscles, exert uneven pressure on the teeth, it can cause them to shift.

For example, if the cheek muscles work harder than the tongue muscles, the teeth may gradually tilt inward.

Therefore, the rehabilitation and restoration of normal oral function are essential aspects of treatment.

By addressing these functional issues early on, we can prevent the development of long-term skeletal problems that often require complex, long treatment.

Why early treatment is crucial?

Treating a crossbite as soon as possible is crucial for several reasons. Here's why:

• Limited self-correction: Crossbites are unlikely to correct themselves over time. In fact, without intervention, crossbites can worsen and negatively impact jaw growth.


• Early treatment is especially critical for skeletal crossbite. During growth, the width of the jaws is the first dimension to complete its development. By addressing the crossbite early, we can leverage the growth potential and use it for faster and more effective correction.
  Delayed treatment may require more invasive surgery to correct bone deformities, as the growth potential decreases with age.


• Preventing additional problems: Untreated crossbites can contribute to various muscular, joint, and dental issues. These include:
  
  • Temporomandibular joint pain
  • Jaw asymmetry
  • Less efficient chewing
  • Muscle dysfunction
  • Tooth wear

Treating Crossbite: Options for Children and Adults:

Crossbite, like any dental malalignment issue, should be treated as early as possible, especially in childhood. The remaining growth potential allows for faster and more efficient treatment. There are several approaches available to fix a crossbite, including:

In Children:

Treating crossbite in children offers advantages due to their ongoing growth potential. The following treatment options are commonly employed:

1. Palatal Expansion:

This technique involves using orthodontic devices (such as a rapid palate expander) to expand the upper jaw, creating space for proper teeth alignment. This will also help to position the lower jaw correctly, thus preventing muscular and joint problems later on.

2. Rehabilitation of Oral Functions and Elimination of Bad Habits:

An essential step in treatment is rehabilitation and replacing harmful habits with healthier ones. This will help stop the condition from progressing, create favorable conditions for facial growth, and prevent recurrence after treatment. Two primary approaches are used:

• Myofunctional Therapy: Children actively participate in exercises that target breathing, swallowing, phonation, and other functions to develop new, beneficial habits for proper growth.


• Rehabilitation with Orthodontic Devices: Orthodontic devices, such as tongue cribs, tongue spurs, or orthodontic trainers, are utilized to rehabilitate oral function without conscious participation from the child.

In Adults:

Treatment for crossbite in adults may vary depending on the severity and whether it is primarily dental or skeletal in nature.

1. Fixing Dental Crossbite in Adults:

Dental crossbite treatment is relatively simple as it involves only teeth misalignment. It can be addressed using orthodontic appliances such as braces, clear aligners, or palate expanders. Within a few to several months, these can modify tooth positions and establish a healthier bite.

2. Fixing Skeletal Crossbite in Adults:

Treating skeletal crossbite in adults is more complex as growth has already been completed. Treatment options depend on the severity of the condition:

• Minor Cases: Minor skeletal crossbites can sometimes be corrected with orthodontic appliances to restore a normal bite. The idea is to address the misalignment of the jaws by adjusting the teeth's positions.


• Severe Cases: If the crossbite is associated with severe jaw deformity, corrective surgery may be necessary. However, some studies have shown that palatal expansion can still be an effective option for adults.
  By reactivating the palatal suture, it may be possible to achieve jaw correction without the need for surgery. However, this approach is not suitable for everyone and carries potential risks and complications.
  Therefore, a thorough examination and consultation with an orthodontist is necessary to determine the appropriate treatment course.