Malocclusion: Definition, Causes, and Treatments

A Comprehensive Guide to Malocclusion: Types, Causes, Treatment Options

If you have crooked teeth or a misaligned jaw, your dentist or orthodontist may have told you that you have a malocclusion. A malocclusion isn’t a one-type condition, and it can be mild or severe, sometimes needing surgery.

It’s important to understand the types of malocclusion, their causes, and how they can be treated. We are detailing everything there is to know about malocclusions, including how it can affect you and when to see a doctor.


Key Takeaways

  • A malocclusion is where the upper and lower teeth do not meet correctly. Sometimes, the upper or lower jaw protrudes in front of the other, or the teeth may be crooked or crowded.

  • Severe malocclusion typically causes difficulty eating, speaking or closing your mouth correctly.

  • Diagnosis and treatment planning requires dental examination and X-rays.

  • Braces, surgery, or a combination of treatments are required to correct malocclusions. 

  • Malocclusion may be genetic where abnormalities in bone development are involved; oral habits and sinus problems are also common causes.


Malocclusion Definition: Types of Malocclusion

The definition of malocclusion is simply “bad bite”. It is a condition where your upper and lower teeth do not meet correctly due to excessive overlap, or one or more teeth cannot touch because of a gap. A malocclusion may be dental, where only the teeth are involved, or skeletal, where your jaw and facial structure affect your bite. 


Malocclusion Pronunciation

Malocclusion is pronounced as mal-ah-clue-zhun; breaking it up into syllables, you get mal-oc-clu-sion. 

“Mal” means “bad”, and “occlusion” refers to the closed state of your mouth at rest or when biting. 

Here are some examples of the different types of malocclusion: 


Class 1 Malocclusion

A Class 1 malocclusion is the most common type, where your upper teeth slightly overlap your lower teeth, but your bite is normal. It is often the least detrimental to your health and quality of life [1]

In general, your molars are aligned in a relatively normal position, but your other teeth may be spaced too far apart, or you could have crooked teeth, crossbite, or overcrowding.


Global Prevalence of Class I Malocclusion Compared to Class II and III


The global prevalence of class I malocclusion ranges between 34.9% to 93.6%


Class 2 Malocclusion

A Class 2 malocclusion is also known as an overbite. Here, your upper teeth overlap your lower teeth. You may have trouble eating or speaking clearly in this case, particularly if the bone structure is involved. 

Skeletal involvement of a Class II malocclusion can feature a smaller lower jaw, typically, giving you a heart-shaped face with a small chin. 

The facial structure seen in overbite involves a smaller angle between your lower jaw and teeth too because they are positioned underneath your upper front teeth. You also have a wider angle between your upper teeth and eyes [2]

If you’re struggling with figuring out how to fix an overbite, click here. 


Class 3 Malocclusion 

Class 3 malocclusions, also known as an underbite, are less common, occurring in less than 5% of the U.S. population [3]. Here, your lower teeth sit forward and overlap your upper teeth. Your lower jaw is positioned forward in more severe cases. It is essentially the opposite of an overbite. 

When there is skeletal involvement in Class III malocclusions, your lower jaw may be larger, creating a “square” or “rectangular” facial shape. 

Have you been diagnosed with Class III malocclusion? Learn how to fix underbite here.


Graph Showing the Prevalence of Class III Malocclusion Worldwide


Class III malocclusion showed to be more common in Asia, with 6.46% of the population affected


What Are the Effects of Malocclusion?

Left untreated, malocclusion can have several negative effects on your oral health and quality of life:


Adverse effects of untreated malocclusion


  • Some types of malocclusion, such as the posterior open bite, may lead to temporomandibular joint (TMJ) dysfunction. This can involve chronic pain from muscle dysfunction or nerve impingement. It is also common to have tight muscles, making it difficult to eat or speak as the jaw can feel stiff or as if it is about to lock. 
  • When teeth severely overlap or do not meet at all, eating hard or chewy foods is often more difficult, especially in cases of open bite. You may find yourself avoiding foods such as steak or nuts, and choosing soft foods like mashed vegetables and soups. 
  • Tooth decay and gum disease are more likely if you don’t correct malocclusion. Your teeth are more difficult to clean or may be partially erupted or impacted [4]


What Causes Malocclusion of Teeth?

Malocclusions are caused by: 


Things that cause malocclusion of teeth


  • Genetic factors
  • Congenital or early lifestyle factors, such as non-nutritive sucking 
  • Other health and lifestyle factors. 

Lifestyle factors mainly have an influence during early childhood, when the upper and lower jaws are still developing.


Genetic Factors

You or your child may have gene variations that affect the development of the jaw and teeth, and this can manifest as a malocclusion. Congenital defects appear during fetal development, and they are typically difficult to predict or prevent. Mouth breathing may reveal a congenital issue with skull growth [3].

However, genes only account for 40% of the risk of malocclusion and have greater involvement in skeletal deformities [5]

Neuromuscular conditions such as muscular dystrophy can increase the risk of malocclusion, as dysregulated muscle tone and poor strength place incorrect or insufficient stress on the teeth and jaw bones. 


Non-Nutritive Sucking

Thumb sucking and other types of non-nutritive sucking (e.g. pacifiers, toys, and fingers) can increase the risk of open bite, crossbite and overbite. The sucking motion causes the muscles in your mouth to move in unhealthy patterns, slowly shifting your teeth up and outwards, or causing them to lean back towards your tongue. 

Besides thumb sucking, mouth breathing and tongue thrusting can also put a strain on your mouth and jaw muscles. Mouth breathing can be a consequence of sinus problems, so these must be treated to see long-term success. 

Tongue thrusting is an intermittent or constant forward motion of your tongue, which you may have as a habit because of jaw issues. It is usually too intermittent to have a significant effect on teeth alignment. However, if your tongue is positioned forward for most or all of the time, it can cause irregular teeth alignment as constant light pressure has more of an effect. 

Studies estimate that over 10% of children continue non-nutritive sucking past the age of five, but usually, they replace thumbs and pacifiers with more socially acceptable objects such as a pencil, piece of jewelry, or their finger. Not only can this contribute to poor oral hygiene, but it impairs upper jaw development and prevents adult teeth from moving to the correct position [6]


Other Health and Lifestyle Factors

Besides non-nutritive sucking, other health and lifestyle factors including diet and allergies can increase the risk of malocclusion: 

  • Extended bottle-feeding or pacifier use, typically beyond the age of three, increases the risk of malocclusion in the same way as sucking on thumbs or other objects. 
  • Chronic tonsillitis or enlarged adenoids, as well as allergies, can affect tongue positioning by making it necessary for you to breathe through your mouth [7]
  • Children are more likely to show malocclusion than adults. As adult teeth are larger than baby teeth and take time to settle into their correct position, your child may have a temporary malocclusion that resolves itself over time. 
  • Fat-soluble vitamins play essential roles in the development of your jaw and teeth. While vitamin D enables calcium metabolism, we need vitamin K to shuttle it to the bones. Vitamin A is required for the remodeling of bone tissue from child to adult form [8]
  • Tooth overcrowding can cause issues such as overbite, as teeth grow outwards to find space. 
  • Poor dental care may be another contributing factor, as poorly fitted braces, crowns or even fillings can shift tooth positioning. Tooth loss from insufficient oral hygiene can also contribute to overbite. 


Malocclusion Symptoms and Diagnosis

Depending on the severity of your malocclusion, symptoms can include:


  • Incorrect teeth alignment, including crooked teeth or buck teeth. This is when your two upper front teeth protrude forward, and can sometimes be visible when you close your mouth. 
  • Difficulty or discomfort when eating.
  • Visible changes to your facial appearance, including a long face, forward chin, buck teeth, or an always-open mouth in cases of open bite. 
  • Having to breathe through your mouth instead of your nose, in cases of skeletal malocclusion. 

A malocclusion is typically diagnosed during routine dental examinations. If your dentist suspects issues with bone development, dental X-rays will likely follow to get a clearer picture of your teeth and jaw alignment. 


When Should I See a Doctor?

You should see a doctor if your dentist is unable to treat you on their own. Early treatment is important in order to prevent dental diseases such as tooth decay and gum disease, which are more common in malocclusion. Additionally, prevention of nerve or joint damage is essential to avoid chronic pain or other disability. 

It is also best to see a doctor if you have chronic pain as a result of your malocclusion, or you have difficulty eating, which can lead to malnutrition, or experience a significant speech impairment. 


Malocclusion Treatments

If your malocclusion is severe enough to require treatment, there are several options:


Different ways to treat malocclusion


  1. Orthodontic treatment
  2. Surgery
  3. A combination of both 


Orthodontic Treatment

Orthodontic treatments are known as camouflaging interventions. Both dental braces and lingual braces work by correcting misaligned teeth. However, they do not affect any underlying bone structure issues. For this reason, orthodontic treatment is only a stand-alone intervention for mild malocclusion, but not every case is seen as severe enough for treatment [4]

If you have a milder case of misaligned teeth, teeth aligners may be a more appealing option. These are clear plastic appliances that gradually shift your upper and lower teeth into the correct position without uncomfortable metal wires and brackets. However, aligners are not always suitable for severe malocclusion [9]

The advantage of teeth aligners is that you can remove them to eat and brush your teeth, and you don’t have to worry about irritation or injury to your cheek. This helps to reduce your risk of tooth decay compared to traditional braces, as there are no brackets and wires to work around [10]

Read more on clear aligners such as Invisalign for overbite, here.


Byte clear aligners can correct mild to moderate misalignments in 2-4 months



Jaw surgery is a necessary malocclusion treatment when there are underlying issues with bone development.

For example, the surgery used to treat severe overbite is called a mandibular osteotomy. Here, your surgeon cuts behind the teeth of your lower jaw, in order to avoid every tooth socket. Then, your jaw is pulled forward, and titanium plates or screws are used to keep it in the new position [11]

Besides orthognathic surgery, you may need sinus surgery to prevent the need for mouth breathing [12]. This is why careful treatment planning is essential before getting started, to avoid unnecessary procedures. Surgical reshaping takes several months to recover from, as it essentially involves deliberate jaw fractures

If you have issues with a crowded mouth, extraction may be necessary if your teeth cannot be straightened. The nearby teeth can then move into a straighter position, but you will likely need braces to ensure they are properly aligned. 

Learn more about overbite surgery here.


Combination of Both

Surgery and orthodontic treatment are commonly used together in treating malocclusion. You may wear braces for several months leading up to surgery, in order to begin moving your teeth into the properly aligned position

For example, in a case study of a man who initially saw successful treatment of his malocclusion, but then suffered a relapse, a combination of surgery, braces, and habit correction was necessary [12]


Can I Prevent Malocclusion?

If you have a family history of malocclusion, it is likely that the issue is genetic for you. 

There are ways you can reduce the risk of your child developing malocclusion, like discouraging thumb sucking from an early age, as well as sucking other objects such as pacifiers and toys [6].

Malocclusions don’t usually develop later in life as your skull and jaw bone have already finished growing, and your permanent teeth have erupted and moved into place. Except for injuries such as certain jaw fractures, you are very unlikely to develop a malocclusion as an adult. 



In summary, what are malocclusions, and how are they fixed? 


What Is Malocclusion of the Teeth?

What Are the 3 Types of Malocclusion?

How Do You Fix Malocclusion?

What Is an Example of a Malocclusion?



Malocclusion can range from barely noticeable to debilitating, but many cases are preventable in childhood. Healthy oral habits such as hygiene and avoiding sucking objects; getting proper nutrition, particularly fat-soluble vitamins; and treating conditions that affect breathing can go a long way in preventing issues with malocclusion. 

The different types of malocclusion are treatable with orthodontic interventions and surgeries. However, even if you have been successfully treated, correct breathing and oral habits are essential to prevent relapse.



  1. Gallois R. (n.d.). Classification of malocclusion.
  2. Bhateja, Nita Kumari et al. “Deep Bite Malocclusion: Exploration Of The Skeletal And Dental Factors.” Journal of Ayub Medical College, Abbottabad : JAMC vol. 28,3 (2016): 449-454.
  3. Moreno Uribe, L M, and S F Miller. “Genetics of the dentofacial variation in human malocclusion.” Orthodontics & craniofacial research vol. 18 Suppl 1,0 1 (2015): 91-9. doi:10.1111/ocr.12083
  4. [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. Misaligned teeth and jaws: Overview. 2020 Jan 16. Available from:
  5. Cakan, Derya Germec et al. “The genetic basis of facial skeletal characteristics and its relation with orthodontics.” European journal of dentistry vol. 6,3 (2012): 340-5.
  6. Doğramacı, E. J., & Rossi-Fedele, G. (2016). Establishing the association between nonnutritive sucking behavior and malocclusions. The Journal of the American Dental Association, 147(12), 926–934.e6. doi:10.1016/j.adaj.2016.08.018
  7. Majorana A, et al. (2015). Timetable for oral prevention in childhood — developing dentition and oral habits: A current opinion.
  8. Lin, Steven. “Crooked teeth and nutrition: A surprising link.” Ortho Town. December 2017,
  9. Haouili, Nada et al. “Has Invisalign improved? A prospective follow-up study on the efficacy of tooth movement with Invisalign.” American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics vol. 158,3 (2020): 420-425. doi:10.1016/j.ajodo.2019.12.015
  10. Boke, Fatma et al. “Relationship between orthodontic treatment and gingival health: A retrospective study.” European journal of dentistry vol. 8,3 (2014): 373-380. doi:10.4103/1305-7456.137651
  11. Khechoyan, David Y. “Orthognathic surgery: general considerations.” Seminars in plastic surgery vol. 27,3 (2013): 133-6. doi:10.1055/s-0033-1357109
  12. Gracco, Antonio et al. “Multidisciplinary correction of anterior open bite relapse and upper airway obstruction.” Korean journal of orthodontics vol. 45,1 (2015): 47-56. doi:10.4041/kjod.2015.45.1.47


Leave a Reply

Your email address will not be published. Required fields are marked *

13 + 19 =