Malocclusion of the Teeth: Types, Causes & Treatment

What is Malocclusion?

Malocclusion is the medical term for a bad bite, where someone’s teeth are misaligned and don’t make proper contact. There may be an underlying issue with the upper or lower jaw.

With an ideal bite, the top and bottom teeth fit well together when your mouth is closed. The backs of your top front teeth should sit gently in front of your bottom front teeth.

Many people have varying degrees of malocclusion. Their teeth don’t quite fit together in an ideal way. Depending on the type and severity of the malocclusion, health problems can result, including sleep apnea and gum disease.

What Causes Malocclusion?

Malocclusions include overbites, underbites, and several other conditions. There are multiple possible causes of malocclusion, and they may overlap:

• Genetic factors — Jaw shape and size are partly inherited, and some people are predisposed to develop misaligned teeth
• Diet — An excessively soft diet, or a diet low in vitamins such as vitamin K, can contribute to a weaker jaw and misaligned teeth
• Childhood habits — Thumb sucking, mouth breathing, and tongue thrusting are all habits that can affect tooth and jaw development over time
• Injury or illness — Fractures, dislocations, or diseases that affect the jaw or teeth can all contribute to misalignment

Whatever the underlying cause, orthodontic treatment and/or surgery can generally correct the issue, creating (or restoring) a perfect bite.

Symptoms of Malocclusion

The symptoms of malocclusion are usually obvious, but some are subtle and may include:

• Crowded or crooked teeth
• Altered facial appearance
• Jaw or teeth discomfort when biting and/or chewing
• Mouth breathing
• A lisp or other speech problems
• Biting your cheeks, tongue, or lips often
• Lips that don’t close fully

Different Types of Malocclusions

There are three different classes of malocclusion, referred to as class I, II, and III:

• Class I — The back teeth (molars) are aligned, but the front teeth are overlapping, overcrowded, or rotated. This is the most common kind of malocclusion.
• Class II — The upper teeth overlap the lower teeth excessively, making the lower jaw appear smaller.
• Class III — The lower jaw is pushed forward, and the lower teeth overlap the upper teeth. This is commonly called an underbite.

Within these three classes, there are seven common types of malocclusion. Orthodontic treatment options also vary depending on age and the type and severity of the malocclusion.

Crowded Teeth

Dental crowding occurs when there isn’t enough space in the mouth for the permanent teeth to grow in straight. Crowding often only affects the front teeth, making it a class I malocclusion.

Crowding can be caused by a person’s jaw not being big enough to fit all of their teeth properly, or by alignment issues from when they first lost their baby teeth.

Dental Crowding Treatment Options

Common treatment options for dental crowding include:

• Dental braces, clear aligners & retainers (for both children and adults)
• Veneers (for adults only with mild cases)
• Dentofacial orthopedics (best for children)

Excessive Overbite

An excessive overbite is a class II malocclusion, where the upper teeth are too far forward compared to the lower teeth. When a person’s mouth is closed, the top front teeth come straight down, but they cover more of the bottom teeth than they should.

An excessive overbite should be treated as soon as possible. If left untreated, breathing problems, jaw disorders, and oral health issues can develop.

Excessive Overbite Treatment Options

Common excessive overbite treatment options include:

• Baby tooth extractions (for children only)
• Dental braces, clear aligners & retainers (for both children and some adults)
• Cervical pull headgear (for children only)
• Jaw surgery (typically only for adults with fully developed jaws and teeth)

Excessive Overjet

An excessive overjet is a class II malocclusion, similar to an excessive overbite.

The difference between an excessive overbite and an excessive overjet is that an overjet is horizontal rather than vertical. The top front teeth protrude at an angle and don’t make contact with the bottom front teeth.

Excessive overjets are often caused by thumb sucking or tongue thrusting in childhood. Untreated excessive overjets can result in temporomandibular joint disorder (TMD).

Excessive Overjet Treatment Options

Common treatment options for excessive overjets include

• Dental braces, clear aligners & retainers (for both children and adults)
• Carriere appliance (for children or young adults with developing jaws)
• Cervical pull headgear (for children only)

Crossbite

A crossbite is a class II malocclusion that occurs when a few bottom teeth are located outside the upper teeth when the mouth is closed.

Genetics, mouth breathing, delayed permanent teeth eruption, and childhood habits (e.g., thumb sucking) can cause this malocclusion.

A crossbite may involve the front teeth (anterior crossbite), with one or more lower teeth coming out in front of the upper teeth. This can look like a partial underbite.

An underbite can also occur together with a crossbite, so all the bottom teeth (front and back) are outside the top teeth.

Crossbite Treatment Options

Common crossbite treatment options include:

• Dental braces, clear aligners & retainers (for both children and adults)
• Reverse-pull face mask (for children only)
• Rapid palate expander (for children or young adults with developing jaws)
• Jaw surgery (typically only for adults with fully developed jaws and teeth)

Underbite

An underbite is a class III malocclusion that occurs when the lower teeth are in front of the lower teeth.

If an underbite is skeletal, the bones of the jaw are involved. Either the lower jaw is overdeveloped, or the upper jaw is underdeveloped.

Some underbites are dental and only affect the teeth. They may occur together with a crossbite.

Like an overbite, an underbite should be treated as early as possible to prevent health problems.

Underbite Treatment Options

Common underbite treatment options include:

• Baby tooth extractions (for children only)
• Dental braces, clear aligners, and retainers (for children and some adults)
• Reverse-pull face mask (for children only)
• Upper jaw expander (for children or young adults with developing jaws)
• Jaw surgery (typically only for adults with fully developed jaws and teeth)

Open Bite

An open bite is the rarest form of malocclusion. It occurs when the upper and lower teeth slant outwards and do not touch when the mouth is closed. An open bite can affect the front or back teeth.

This condition may be caused by genetic factors or teeth that don’t erupt properly. Habits like thumb sucking can also cause an open bite. Untreated open bites typically result in speaking problems, as well as issues tearing and chewing food.

Open Bite Treatment Options

Common treatment options for open bites include:

• High-pull headgear (for children only)
• Vertical chin cup (for children only)
• Roller appliance (for children only)
• Bite block (for children only)
• Jaw surgery (typically only for adults with fully developed jaws and teeth)

Diastema (Gapped Teeth)

A diastema is when there is a space or gap between two or more teeth. Gaps can range in size, with some being barely noticeable and others being more prominent. A midline diastema, which appears as a gap between the two upper front teeth, is the most common form of diastema.

Diastema Treatment Options

Common treatment options for spaced teeth include:

• No treatment (the gap may be small, and some people consider it an attractive feature)
• Braces, clear aligners & retainers (for children and adults)
• Dental bonding (for children and adults)
• Veneers (for adults only)

Malocclusion Complications

A mild malocclusion may not cause health problems, especially if it doesn’t involve jaw misalignment. However, it may pose a cosmetic issue, affecting a person’s self-image and social life.

On the other hand, malocclusion may involve severe dental crowding and/or jaw alignment issues. In cases like these, early treatment can prevent further complications, such as:

• Breathing problems (including sleep apnea, which can be life-threatening)
• Periodontal disease, which can eventually lead to bone and tooth loss
• Temporomandibular joint disorders (TMDs), which affect the jaw joint
• Tooth decay
• Long-term damage to tooth enamel
• Difficulty eating and speaking
• Oral hygiene difficulties, which can lead to some of the above

Prognosis

Children and adults alike can receive effective treatment for malocclusions of all kinds. Many treatment options are available, allowing people to receive care tailored to their specific needs.

For children, early treatment with braces, clear aligners, and other orthodontic devices can resolve tooth and jaw alignment problems before adulthood.

Adolescents and adults, in particular, may require orthognathic (jaw-correcting) surgery to fully address severe malocclusions.

Summary

Malocclusion refers to cases where a person’s teeth and/or jaw are misaligned (a bad bite). Many people have some degree of malocclusion.

Genes, childhood diet and habits, illnesses, and injuries can all play a role in malocclusions. Some are mild and may not need treatment, but there is often a risk of complications if the condition is left untreated.

Various treatments can be used for malocclusions for children and adults alike. Talk to your dentist or orthodontist if you or your child have misaligned teeth or jaws.