Overview of Malocclusion

Symptoms, Cause, Diagnosis, and Treatment

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Malocclusion is a term commonly used by orthodontists that simply means that the teeth are not aligned the way they should be. The upper teeth should land slightly over the lower teeth when a person bites their teeth together. Each molar should fit properly in the grooves of its opposite molar (upper fitting into the lower molar and vice-versa). 

Why is this important? Though many people prefer the upper and lower teeth fitting together properly for aesthetic (visual) purposes, this is also optimal placement of the teeth as it prevents dental problems, like shifting of the teeth.   

A person with malocclusion often consults with an orthodontist directly or after receiving a referral from a general dentist. Orthodontists are dentists who have specialized training in correcting and preventing irregular teeth, correcting an abnormal bite and problems originating with the jaws (such as TMJ). Additional types of specialized training that orthodontists have include diagnosing irregularities in facial structure as well as facial abnormalities.

Malocclusion treatments
Verywell / Emily Roberts 


The symptoms of malocclusion differ depending on the classification, but some common symptoms may include misaligned teeth, abnormal signs of wear on chewing surfaces of the teeth, problems chewing or biting food, mouth or jaw pain, and/or frequently biting the inside of the cheek when chewing. In addition, a person may have a malformation of facial features and could even develop a lisp (or other speech problems).


There is no single cause of malocclusion. Many times, malocclusion is hereditary. The underlying cause may be a size difference between the upper and lower jaws, or it could result from thumb sucking (after age five). The shape of the jaw could be the cause of malocclusion, or it might result from a birth defect of the mouth—such as cleft lip or cleft palate.

Children who have very little space between their baby teeth are at high risk for malocclusion because often there is not enough space when the permanent teeth come in. Malocclusion may occur due to:

  • overcrowding of teeth
  • an abnormal bite pattern
  • thumb sucking
  • pacifier use or prolonged use of a bottle for babies (beyond age three)
  • the presence of extra teeth
  • lost teeth (from accidents or injuries)
  • impacted teeth (such as impacted wisdom teeth)
  • abnormally shaped teeth
  • ill-fitting crowns, dental appliances, retainers or braces
  • extra teeth
  • jaw fractures or a misaligned jaw (from an accident or injury)
  • tumors of the mouth or jaw

Malocclusion Categories

There are various types of malocclusion, therefore, several categories have been identified.

Class 1 Malocclusion

This is the most common type of malocclusion where the bite is normal, but the teeth slightly overlap the lower teeth more than they normally should.

Class 2 Malocclusion

This is commonly referred to as an overbite. This occurs when the upper jaw and teeth severely overlap the bottom teeth. 

Class 3 Malocclusion

Class 3 is commonly referred to as underbite, or prognathism (in dental terminology). This type of malocclusion happens when the lower jaw juts forward, causing the lower teeth to overlap the upper teeth.

Each type of malocclusion requires a different type of orthodontic device to correct the problem. There are several common types of malocclusions, including:


This is a common type of malocclusions caused by a lack of space that results in overlapping, crooked teeth. This is the most common type of malocclusion that prompts adults to seek orthodontic treatment.


This results when the top teeth extend too far beyond the bottom horizontally. This condition is not considered an overbite; it can result in problems with normal eating and speech.


This type of malocclusion occurs when the overlap of the lower front teeth extends beyond what is considered normal. If this type of problem is severe, it could cause the front teeth to hit the gums when a person bites their teeth together.


This occurs when the upper teeth bite down inside the lower teeth; it can occur on one or both sides of the jaw and can involve the anterior (front) or posterior (back) teeth.

Anterior Crossbite

This is also known as an underbite, this is a crossbite that impacts the front teeth.


This involves open spaces between one or more teeth. It can be caused by missing teeth, tongue thrusting, teeth that are too small, thumb sucking, or an impacted tooth, which is unable to erupt normally through the gum.

Open Bite

This occurs when the front teeth do not properly overlap the lower teeth (in the front, this is called anterior open bite).


Malocclusion is usually officially diagnosed by the dentist or orthodontist. Procedures that help to diagnose malocclusion may include X-rays, impressions (imprints of the teeth poured with plaster to make a model of the mouth—this is used to evaluate malocclusion) and digital scans of the teeth and bite. A proper diagnosis is crucial in establishing treatment goals.


The exact type of treatment that is ordered for malocclusion is determined by the treating dentist or orthodontist on an individual basis. Several factors are considered, including the age of the person/child, their overall health, their medical history, as well as the severity of the condition.

In addition, the person's tolerance of the patient to endure various treatment modalities (including procedures and therapies) are taken into account in addition to the patient’s or parent’s expectations.

Treatment for malocclusion is often done in phases. 

For example, the initial phase may involve extractions to create more space, the second phase could include braces, and the final phase could involve a functional appliance to keep the teeth in place after treatment.

There are several different treatment modalities for malocclusion, depending on the type of malocclusion and the severity of the problem, these include:

  • fixed appliances (braces) to fix the incorrect position of the teeth
  • tooth extraction to alleviate overcrowding
  • capping, bonding, or reshaping teeth
  • surgery to shorten the jaw or reshape it (performed by a maxillofacial surgeon)
  • plates or wires to stabilize the jaw bone
  • removable mouth appliances to maintain a new position of the teeth (such as after braces), or in some cases to promote the growth of the jaws for an improvement in the alignment of the bite

A Word From Verywell

The National Institutes of Health reports that very few people have perfectly aligned teeth, but in most instances the malocclusion is so minor, that treatment is not needed. Many orthodontists recommend getting an initial consultation by age seven, if a child is suspected of having malocclusion. This is when problems such as overcrowding, or an uneven bite may be diagnosed. Waiting too long could result in fewer options for treatment as the child gets older. 

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.