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All About Underbites: Causes, Complications and Treatment Options

By Dr. Cheng Eng Wah and Dr. Tyler Tay on 23 February 2022

Categories: Braces, Invisalign
3D image of an underbite

An underbite can be identified by lower front teeth that extend beyond one’s upper front teeth. This dental condition is known as a Class III malocclusion and its severity can vary from mild to severe. 

Mild cases may be less noticeable to peers and family members while severe cases are easily visible to others. Underbites can cause pain and significant discomfort. It can also lead to several complications if left untreated.

Learn more about the causes, complications and treatment options for this dental condition below!

  • Underbite

    What it is: 

    This is a Class III malocclusion and occurs when the lower teeth extend further than the upper front teeth.

    This condition may result in a protruding lower jaw or chin.


    Treatment options:

    • Braces
    • Invisalign
    • Surgery
    • Upper jaw expander
    • Reverse-pull headgear
    • Tooth extraction
  • Overbite

    What it is: 

    This is a Class II malocclusion and appears as a vertical overlap of the upper front teeth over the lower front teeth. Thus, a significant part of the lower teeth will be covered by the upper ones when biting.

    With an overbite, your lower teeth may touch the roof of your gum while the upper ones may touch the lower gum. 


    Treatment options:

    • Braces
    • Invisalign
    • Surgery
    • Twin Block


Genetics can play a role in causing an underbite as the shape and size of our teeth as well as facial structure* are inherited from our parents. Thus, the chances of inheriting an underbite are higher if one member of the family suffers from the condition as well.

*Note: Certain individuals may have a unique facial structure that features long lower and short upper jaws. This is known as a Class III jaw and is often accompanied by an underbite.


Childhood Habits

Some habits that we develop in childhood can cause teeth misalignments such as underbites. These include:

  • Pushing on teeth with the tongue
  • Sucking on the thumb
  • Using a pacifier frequently beyond 3 years old
  • Using a bottle for feeding for long periods of time


Facial Injuries

Injuries to the face can damage our jawbones. While surgery can repair the broken or damaged areas, the jawbones may not be able to fit together as well as before, resulting in an underbite.



A tumour in the mouth or on the jawbone can cause the lower jaw to protrude. This can, in turn, result in an underbite.

The issues associated with an underbite vary according to the severity of your condition. Some common ones include:

  • Eating and chewing difficulties
  • Speech difficulties
  • Irregular or crooked teeth
  • Changes to the structure of the mouth and smile
  • Tooth decay
  • Increased risk of gum disease
  • Sleep apnea
  • Snoring
  • Bad breath

Temporomandibular Joint Disorder (TMJ) is another common complication of an underbite. It affects the functioning of your jaw and can result in several other issues and discomforts such as headaches, dizziness and pain in the jaws, ears, neck and shoulders.

Depending on your age and condition, your dentist may recommend different treatment options.


Braces are orthodontic devices used for mild cases of underbites. They help to realign your jaws and address teeth misalignment issues by applying pressure to the teeth.

This treatment method can be used for younger children, teenagers and adults.

Frequency of dental visits: Every 4 weeks
Cost: $3,996 – $7,560 (with GST)


Invisalign is another orthodontic device that can be used to address certain cases of underbites. It helps to align the teeth and jaw by applying consistent pressure on the teeth.

Do note that underbites resulting from issues with one’s skeletal structure will require other forms of treatment such as surgery.

Frequency of dental visits: Every 6 – 8 weeks
Cost: $4,320 – $9,180 (with GST)


For more severe cases of underbites, surgery may be recommended. Through surgery, the lower jaw is reshaped and shortened. The upper jaw may also be extended to align with the lower front teeth if necessary.

To maintain the shape of the jawbone, wires, plates and screws may be used.

Upper Jaw Expander

The upper jaw expander is designed to increase the size of the upper jaw gradually such that it’ll align with the lower front teeth over time.

The device is placed across the palate and widened by a small amount each night using a special key. Once the upper jaw has expanded to the desired size, you’ll be recommended to wear a retainer.

Reverse-Pull Headgear

The reverse-pull headgear is a treatment method recommended for children.

It’s worn for at least 12 hours daily and works to slow the growth of the lower jaw while pulling the upper jaw forward. This allows both jaws to align over time.

Image credit: Miami Orthodontist Group

Tooth Extraction

A treatment option that may be offered for infants and children with an underbite is tooth extraction. To allow the adult teeth to grow straight, their baby teeth may be extracted.

Dentists will typically avoid extracting adult teeth. However, this may be necessary for severe cases  to make room for the movement of teeth.

Note: Depending on each individual’s condition, extraction may or may not correct an underbite.


Your dentist will diagnose your condition through an examination of your teeth, jaw and bite. Contact us to book an appointment today.

No, underbites are caused by jaw misalignment. Thus, your wisdom teeth won’t result in an underbite.

Correcting your underbite as early as possible makes treatment easier and smoother. This is especially so for children as their jawbones are relatively malleable and can be aligned more easily.

Furthermore, widening the upper jaw as a child can allow adult teeth to grow in a better position, reducing the need for jaw surgery in the future.

The treatment duration will depend on the severity of your underbite and the treatment method used.

In general, it takes 1.5 to 2 years to treat the condition. After which, your dentist will advise wearing a retainer.

The time taken to treat an underbite using Invisalign will depend on the severity of your condition. Minor cases may require 3 to 4 months, while more severe cases may require 12 months or more.

After Invisalign treatment, you’re recommended to wear a retainer to maintain your new smile.

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