A crossbite can be easy to miss when you look at your smile from the front. One tooth may seem slightly out of position, or one side of your bite may simply look different from the other.
But a crossbite is more than a crooked tooth. It describes the relationship between the upper and lower teeth when you bite together.
Normally, the upper teeth sit slightly outside the lower teeth. In a crossbite, that relationship is reversed in one area, so an upper tooth or group of teeth bites inside the lower teeth instead.
A crossbite tells us where the teeth are meeting incorrectly. The next question is why.
That distinction matters because two crossbites can look similar and come from very different problems. One may be primarily a tooth-position issue. Another may involve the width or position of the jaws. Treatment starts by figuring out which relationship we are actually trying to change.
What is a crossbite?
A crossbite occurs when one or more upper teeth bite inside the corresponding lower teeth rather than slightly outside them.
You can see the difference more clearly when you compare the way the upper and lower teeth fit together.
A crossbite does not have to involve the entire mouth. It can affect a single tooth, several teeth, or a larger section of the dental arch. It may also appear on only one side.
That is why the word crossbite describes a bite relationship, not one specific diagnosis. We still need to identify where it occurs and what is creating it.
What's the difference between an anterior and posterior crossbite?
The names tell us where in the mouth the reversed bite relationship occurs.
Anterior crossbite
The front teeth cross over.
An anterior crossbite occurs when one or more upper front teeth sit behind the lower front teeth when you bite together.
Posterior crossbite
The back teeth cross over.
A posterior crossbite occurs when upper back teeth bite inside the corresponding lower back teeth.
This distinction is important because the movements required to correct a front-tooth crossbite can be very different from those required to correct a posterior crossbite involving the width of the dental arches.
What causes a crossbite?
There isn't one cause behind every crossbite. Sometimes the problem is primarily the position of individual teeth. In other cases, the relationship between the upper and lower jaws plays a larger role.
- The position of individual teeth. A tooth can erupt or move into a position that places it inside the opposing tooth when the bite closes.
- The width of the upper dental arch. If the upper arch is relatively narrow compared with the lower arch, the upper back teeth may bite inside the lower back teeth.
- The relationship between the jaws. The position and growth pattern of the upper and lower jaws can contribute to a crossbite that is broader than a single tooth-position problem.
- How the teeth erupt. Developing teeth do not always come into the dental arch in an ideal position. Their eruption path can contribute to a localized crossbite.
- A combination of factors. Tooth position, arch width, and jaw relationships can all contribute at the same time. That is why the visible crossbite is only the beginning of the diagnosis.
The tooth that looks out of place isn't always the whole problem we're trying to correct.
Why can a crossbite happen on only one side?
A posterior crossbite can be bilateral, involving both sides, or unilateral, appearing on only one side of the mouth.
In some one-sided posterior crossbites, the way the upper and lower dental arches fit together can cause the lower jaw to shift sideways as the teeth come together. In other cases, the asymmetry is more directly related to the position of the teeth or the underlying jaw relationship.
That difference matters. We do not want to look only at the side where the teeth cross over. We want to see how the jaw closes, whether the bite shifts on the way into contact, and how the right and left sides relate to each other.
This is one reason an orthodontic examination is more useful than trying to diagnose the problem from a photograph alone.
Is the crossbite coming from the teeth or the jaws?
One of the most useful questions in treatment planning is whether the crossbite is primarily dental, skeletal, or a combination of both.
Primarily dental
Tooth position is driving the crossbite.
One or more teeth may be tipped, rotated, or positioned so they bite on the wrong side of the opposing teeth.
These relationships can often be changed through orthodontic tooth movement.
Skeletal component
Jaw width or position is part of the picture.
The crossbite may exist within a broader relationship involving the width or position of the upper and lower jaws.
In those cases, moving individual teeth may be only one part of the treatment plan.
Our orthodontic treatment is provided by Dr. Edward Viloria , a board-certified orthodontist who evaluates the entire bite before recommending braces, clear aligners, or another treatment approach.
Does a crossbite need to be fixed?
A crossbite deserves an orthodontic evaluation, but the presence of one does not tell us by itself what treatment you need or how extensive that treatment should be.
We look at which teeth are involved, whether the bite is shifting as you close, whether the relationship is affecting tooth contact or function, and whether the problem is primarily dental or involves the jaws.
- The bite is causing unfavorable tooth contact. Teeth that meet in the wrong relationship can place force on surfaces that were not meant to carry it that way.
- The lower jaw shifts as you bite down. Some posterior crossbites are associated with a sideways shift as the teeth move into their final biting position.
- The crossbite involves more than one tooth. A broader crossbite may reflect an arch-width or jaw relationship that needs to be considered rather than simply moving one tooth.
- Other orthodontic problems are present. Crowding, spacing, rotations, an underbite, or other bite relationships can occur alongside a crossbite and affect the treatment plan.
- The crossbite affects your smile. Esthetics can also be a reason to consider correction. We still want the treatment to make sense for the health and function of the entire bite.
The important part is determining what is creating the crossbite before deciding how it should be treated.
Can a crossbite be corrected?
Many crossbites can be corrected with orthodontic treatment.
The actual treatment depends on what needs to change. A localized dental crossbite may require movement of only a few teeth. A posterior crossbite associated with a narrow upper arch may require a different strategy to change the relationship between the upper and lower arches.
Treatment may involve moving individual teeth, coordinating the dental arches, creating or redistributing space, changing tooth angulation, or addressing a broader transverse relationship.
Correcting a crossbite isn't about pushing one tooth outward. It's about creating the right relationship across the bite.
Can braces fix a crossbite?
Yes. Braces can be used to correct many crossbites because brackets and wires give the orthodontist direct control over the position and angulation of individual teeth.
They can also be useful when the crossbite occurs alongside crowding, rotations, or other bite problems that require several movements to happen together.
Our braces are planned by Dr. Viloria around the entire bite rather than simply the tooth or teeth that appear to be crossed.
Can Invisalign fix a crossbite?
Invisalign can correct certain crossbites, particularly when the required correction can be accomplished through predictable orthodontic tooth movement.
Clear aligners can move individual teeth and coordinate the arches, but they are not automatically the right tool for every crossbite. The location of the crossbite, the number of teeth involved, the underlying jaw relationship, and the movements required all matter.
Our Invisalign treatment is also planned by Dr. Viloria, so the decision between aligners and braces begins with the diagnosis rather than which appliance you prefer.
Braces
Fixed control.
Brackets and wires can provide direct control over individual tooth position and are useful when several movements or more complex bite correction need to occur together.
Invisalign
Removable treatment.
Clear aligners can correct selected crossbites while remaining removable for meals, brushing, and flossing. They also depend on consistent wear.
Braces and Invisalign are tools. The crossbite determines what the tool needs to accomplish.
Can adults have a crossbite corrected?
Yes. Many dental crossbites can be treated in adults with orthodontic tooth movement.
The important difference is that an adult's facial growth is complete. If a crossbite has a significant skeletal component, the treatment possibilities and limitations can be different from those of a growing patient.
For adults, we also consider gum health, bone support, existing crowns or other restorations, missing teeth, and previous dental treatment when planning orthodontic movement.
Age alone does not tell us whether a crossbite can be corrected. The type of crossbite and the anatomy creating it are much more useful.
The crossed tooth is only the part you can see.
If you notice that an upper tooth sits behind a lower tooth, or one side of your bite seems to fit differently from the other, it is reasonable to wonder whether you have a crossbite.
But I wouldn't choose a treatment from the appearance alone.
First we need to determine whether the crossbite is anterior or posterior, whether it involves one tooth or a larger part of the arch, whether the jaw shifts when you close, and whether the problem is primarily dental or has a skeletal component.
Once we understand that, we can decide whether correction is useful and whether braces or Invisalign makes sense for the movements your bite requires.
The question isn't simply, "Do I have a crossbite?" It's, "Why are these teeth crossing over, and does that relationship need to change?"
Key takeaways
A crossbite describes the relationship. The cause determines the correction.
- 01 A crossbite occurs when one or more upper teeth bite inside the corresponding lower teeth.
- 02 An anterior crossbite involves the front teeth. A posterior crossbite involves the back teeth.
- 03 Crossbites can involve tooth position, arch width, jaw relationships, or several factors together.
- 04 A unilateral posterior crossbite may be associated with a sideways shift of the lower jaw as the teeth come together.
- 05 Braces and Invisalign can both correct selected crossbites. The movements required help determine which approach makes sense.
- 06 Adults can undergo crossbite treatment, although skeletal maturity and the underlying cause influence what orthodontics can accomplish.
Frequently asked questions
A few questions patients ask most.
What is a posterior crossbite?
A posterior crossbite occurs when the upper back teeth bite inside the lower back teeth rather than outside them. When it affects one side, the lower jaw may shift to one side as the teeth come together.
Will a posterior crossbite correct itself?
It depends on the age and stage of dental development. One longitudinal study found that some posterior crossbites in the primary teeth corrected as the mixed dentition developed. That does not mean an established crossbite should simply be ignored. Whether observation or treatment makes sense depends on the individual bite and stage of development.
Why are some posterior crossbites treated while a child is growing?
Growth can affect both the diagnosis and the treatment options. In children with unilateral posterior crossbite, several early orthodontic approaches have been studied. The appropriate timing and appliance depend on the type of crossbite, the child's stage of development, and the relationship between the dental arches.
Does a unilateral posterior crossbite affect how the jaw functions?
It can. A unilateral posterior crossbite may be associated with functional asymmetry, including differences in chewing and muscle activity. Functional changes after treatment have been studied, particularly in children whose crossbite is associated with a mandibular shift.
Can Invisalign correct an anterior crossbite?
Clear aligners can correct selected anterior crossbites. In a randomized clinical trial involving mixed dentition, both clear aligners and a removable inclined plane were effective for anterior crossbite correction. Whether aligners are appropriate still depends on the cause of the crossbite and the movements required.
How is a posterior crossbite treated?
Treatment depends on what is creating the crossbite. When the upper arch needs to be widened, orthodontic expansion may be part of the plan. A Cochrane review found that several orthodontic approaches can correct posterior crossbites, with the choice of treatment depending on the patient's age, dentition, and bite.
