Types of Malocclusions And Orthodontic Treatments Available

Mouth with Crooked Teeth

Malocclusions are the reason many people find themselves sitting in the orthodontist’s chair. Simply put, a malocclusion is a misalignment of the teeth or jaws that affects appearance and functionality. About 80 percent of people develop some type of malocclusion as their permanent teeth grow in. The American Association of Orthodontists has identified the seven most treated malocclusions across three categories, and we will explore each briefly here.

Class I Malocclusions

Class I dental malocclusions affect more than half of orthodontic patients. They also are the easiest to correct, as they involve misalignment of the teeth only, with normal bone, tissue, and jaw structures. A Class I malocclusion can present as overlapping or crowded teeth, rotated teeth, gaps between teeth, or improper angling.


Crowding typically occurs when there is not enough space in the mouth to allow teeth to align. Overcrowding can be mild, moderate, or severe depending on how many teeth are affected and how far out of place they are. Though genetics is the main predictor of crowding, it also can be caused by the premature or delayed loss of primary teeth.

Overcrowded teeth can create difficulties in brushing and flossing properly, leading to the buildup of plaque and bacteria. This increases susceptibility to cavities and gum disease. This risk is heightened if the crowding is moderate to severe. Straight teeth are easier to brush and floss, which facilitates better dental health. Poor oral hygiene can lead to health problems over time, including a weakened immune system and heart disease.

Patients suffering from crowding alone have many options for orthodontic correction. In most cases, the orthodontist can use ceramic braces, traditional metal brackets, or alternatives such as clear aligners or lingual braces. Dental veneers also can mask mild to moderate crowding for adult patients.


Teeth spacing is a condition in which gaps appear between some or all of the teeth. This typically occurs when teeth are too small or too much space exists in the mouth. An overgrowth of the tissue that borders the gum line and the upper front teeth also can cause spacing, and the tissue can sometimes bulge between the teeth.

If the gums above the two upper front teeth overextend and cause a gap, you might need surgery to remove excess tissue. If your orthodontist diagnoses you with gum disease, she will have to treat that before she corrects the spacing.

Braces are commonly used to fix spacing, and your orthodontist can help you determine whether traditional braces, clear braces, removable braces, or lingual braces are right for you. Other methods of filling in gaps include veneers and bonding. These cosmetic procedures improve the appearance of your alignment by applying resin (bonding) or porcelain (veneers) to the teeth to manipulate their appearance.

Class II Malocclusions

Class II malocclusions refer to protrusions of the upper teeth. This class is somewhat less common than Class I, comprising about one-third of orthodontic patients. Protrusions require more intervention to correct because the orthodontist must fix the misalignment of the bite in addition to the teeth.


An overbite occurs when the top front teeth excessively overlap the bottom when the mouth is closed. This stresses the teeth, causing them to grind and wear down prematurely. It also increases the risk of tooth decay. An overbite might cause a patient to frequently bite into the roof of the mouth, causing painful sores and ulcers to develop.

If untreated, a child’s overbite will allow the teeth to crowd each other and grow crooked if there is too little room or create too much space between teeth if the jaw area is too large. This can eventually cause significant jaw pain, facial pain, and headaches. Orthodontists can correct a mild or moderate overbite in children and teens with braces and growth modification devices such as blocks, repositioning appliances, or headgear.

Braces can only correct mild overbites in adults. Because the jaw has finished growing, appliances can no longer help shape or adjust it. Therefore, significant overbites typically involve invasive procedures such as tooth extraction or jaw surgery.


An overjet occurs when the upper front teeth protrude. In a normal bite, the upper front teeth should rest relatively snuggly over the bottom front teeth when the mouth is closed (about 2 millimeters apart). However, in an overjet, the teeth grow at a more horizontal angle.

Several treatment options exist to correct overjets. Braces, the most popular method, can correct the angle of the front teeth. Different types of braces are available for an overjet, including traditional metal braces and removable clear aligners.

Another option to correct an overjet is to extract the set of premolars in order to change the dental arch and guide the front teeth into place. For patients suffering from a deficiency in jaw development, surgery often becomes the most feasible option.

Class III Malocclusions

Class III malocclusions typically affect about 10 percent of patients, occurring when the lower jaw protrudes and causes the lower teeth to overlap the upper ones. This is the most difficult malocclusion class to treat, as it involves the most manipulation and movement of the jaw bones.


An underbite occurs when the lower teeth extend beyond the top teeth. Your front teeth are naturally designed to fit over your bottom teeth when you close your mouth or chew, so this condition can cause problems both cosmetically and medically.

Patients suffering from underbites often suffer from jaw pain. Underbites can cause chronic mouth breathing, which can lead to halitosis (bad breath) and bacterial infections. This type of malocclusion also can cause excessive wear of tooth enamel, leading to decay. Sufferers of underbites can experience sleep disruptions, snoring, and sleep apnea.

An orthodontist can correct an underbite at any life stage, but it’s best to fix this malocclusion early. The bone is still malleable in younger patients, so an orthodontist can often achieve the desired realignment using appliances. The most common apparatus used to aid the correction of underbites are upper jaw expanders and reverse-pull headgear.

Adults with underbites will usually require surgery either to lengthen the upper jaw or shorten the lower jaw by cutting, reshaping, or repositioning the jawbone. Screws, plates, wires, and rubber bands hold the jaw in place after surgery. In very mild cases where the underbite is only causing cosmetic concerns, a dentist can apply veneers to the upper teeth to create the appearance of a corrected bite.


A crossbite occurs when the top teeth and bottom teeth do not come together or they bite into an incorrect overlapping position. An anterior crossbite is similar to an underbite but affects only some of the teeth. A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth.

Crossbites make teeth more difficult to clean, which facilitates the overgrowth of bacteria and plaque, leading to cavities. Improper tooth position also can accelerate gum recession, exposing the tooth roots.

Braces are capable of fixing most mild crossbites. The type of braces available will depend on the location and severity of the teeth affected by your crossbites, but clear aligners are often an option for many patients, along with traditional metal brackets.

In children, additional appliances may be needed, especially in more severe cases. Rapid palatal expanders or reverse-pull headgear might be used to expand or shift the upper jaw to align the teeth. In adults, veneers may be capable of fixing mild crossbites, but more severe cases will require jaw surgery.

Open Bite

An open bite occurs when the upper and lower front teeth do not meet when the mouth is fully closed. This can strain the back teeth and make them more susceptible to damage and decay. The inability to bring the teeth together also can make eating difficult.

In adolescents, braces can typically provide successful treatment for an open bite. Patients older than 18 may require jaw surgery.

While it’s ideal to catch malocclusions early, you can seek treatment at any age. If you’re concerned you might have a misalignment of your teeth or a problem with your bite, schedule a free consultation with one of our board-certified orthodontists today.


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