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Under Bite

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Most people have some degree of overjet where upper front teeth overlap in front of lower teeth. An underbite, also known as a Class III malocclusion, is an abnormal relationship between the upper and lower teeth, in which the lower front teeth overlap in front of the upper teeth.

A person with an underbite may be described as having a ‘strong chin’ or has a ‘moon-face’ side facial profile due to the chin being more forward than the rest of the face.

Underbites are usually genetic in origin. Underbite may be a result of a small upper jaw with a normal sized lower jaw, or normal sized upper jaw with a large lower jaw, or a combination of small upper jaw with large lower jaw.

In some cases, underbite may be a result of crooked teeth, which forces the person to push the lower jaw forward to bite more comfortably.

Besides aesthetic issues, if left untreated, underbite may result in uneven toothwear, gum disease involving gum recession and bone loss, and difficulties with eating and chewing.

Underbite does not normally self-correct.

If left untreated, underbite tends to worsen during teenage years. This is because the lower jaw grows forward at a later age and for a longer duration than the upper jaw.

It is recommended that an initial orthodontic assessment be performed at the first sign of orthodontic problems or around age 7. At this age, the adult molars would have erupted and changing between milk teeth and adult teeth begins. Not everyone is suitable to receive orthodontic treatment at this stage, but a thorough examination can help the orthodontist determine the best time to begin orthodontic treatment for your child.

The jaws of a growing child are more easily manipulated into proper alignment compared to adults. One of the benefits in getting an early orthodontic assessment is that, in many cases, the earlier treatment begins, the simpler and less expensive it can be.

Treatment modality for underbite depends on the nature and severity of underbite, as well as the age of patient when treatment begins.

The Australian Society of Orthodontists recommends that children be evaluated by an orthodontist at age 7. Underbite is one of the few types of malocclusion that may be treated when diagnosed early.

Treatment options for underbite include:

Reverse pull facemask

Used in growing children. It is customized and designed to fix the discrepancy between the upper and lower jaws by moving the upper jaw forward.


Braces are designed to straighten malaligned teeth. It does not correct jaw discrepancies. In some patients, selective extraction of adult teeth may be required to correct the underbite.

Combined braces with jaw surgery

Severe jaw discrepancy can only be corrected with surgery. This treatment is only carried out in late teenage years or in adults.

Are you suffering from this condition? See one of our specialist orthodontists for an assessment.