Underbite Problems – Causes & Treatments

Ranging from mild to severe, underbites are a type of malocclusion where the lower teeth or jaw extend beyond the upper front teeth.

This dental issue, which affects approximately 5% to 10% of the population, can impact your ability to chew food properly, speak clearly, maintain good jaw health, and feel confident about your smile.

In this article, we take a look at the most common causes, help you recognise the symptoms, and discuss effective orthodontic treatment options for underbite correction.

What is an Underbite?

An underbite is a type of malocclusion (misaligned bite) where the lower teeth project beyond the upper teeth.

It's sometimes called a Class III malocclusion, simply referring to the category of the bite to help differentiate it from other types of bites.

The back-to-front misalignment is most commonly caused by an upper jaw deficiency, which makes the lower jaw appear more prominent than it should be.

The condition ranges from mild (when only a few lower teeth overlap) to severe (when the entire jaw sits noticeably forward). The extent of an underbite is usually measured by the gap between the upper and lower teeth:

• Mild: Less than 2 mm

• Moderate: approx 2.5 mm to 3.5 mm

• Severe: More than 3.5 mm

Mild cases may only cause slight cosmetic concerns.

"However, more pronounced cases, typically caused by skeletal issues, can interfere with normal chewing, speech, and jaw comfort."

Dr. Joyti Vasudev

Symptoms of Underbite

In most people, the most visible sign of an underbite is bottom teeth that sit in front of the upper teeth when the mouth is closed.

Over time, the misalignment caused by an underbite can lead to jaw pain, speech problems, and other issues.

Some of the most common symptoms include:

• One or more teeth biting the wrong way around

• Crowded upper teeth

• Difficulty biting and chewing food

• Jaw discomfort and pain

• Clicking sounds when moving the jaw

• Difficulty cleaning teeth, leading to poor oral health and even tooth decay

• Reduced confidence when speaking or smiling

• Tooth enamel corrosion and uneven wear

• Speech difficulties, such as a lisp

• Facial imbalance caused by a more prominent lower jaw

• Mouth breathing, sleep apnea, and trouble closing the mouth properly

Causes of Underbite

Underbites can develop for many different reasons, most of which relate to genetics, growth patterns, or childhood habits.

Let's take a closer look at some of the most common underbite causes.

• Genetics – Jaw size and shape are strongly influenced by genetics. If one or both of your parents have an underbite, there's a high likelihood that you have one too.

• Childhood habits – Excessive thumb sucking, pacifier use beyond infancy, and tongue thrusting can all contribute to bite misalignment.

• Jaw growth imbalance – Sometimes, the lower jaw grows faster than the upper jaw, creating an imbalance. This usually begins in childhood and becomes more pronounced in adolescence.

• Trauma or injury – Accidents and injuries to the jaw area can impact jaw growth and tooth position, potentially leading to an underbite.

• Medical conditions – Conditions like cleft lips, cleft palates, and tumours affecting the jawbone may alter the alignment of the jaw.

Dental Treatments for Underbite

Several factors, including the severity of the case and the patient's age, determine the best correction method for an underbite.

For perfectly aligned teeth, timing and accurate diagnosis are very important.

Modern orthodontists typically make use of one or more of the following treatment options:

Growth modification braces

Removable or fixed expander braces are often used to widen the upper jaw in younger patients.

These devices may be used alongside reverse-pull headgear or face-mask therapy, which gently pulls the upper jaw forward and corrects jaw misalignment.

Functional appliances

Functional braces offer the convenience of being removable while still influencing jaw growth by encouraging better alignment.

While they are most often used to treat children, adults can also benefit in some cases.

Fixed braces or aligners

Ceramic or metal braces provide an effective solution for guiding misaligned teeth into the correct position.

Invisalign clear aligners are a great choice for mild to moderate cases.

Tooth extraction

When underbites are caused by overcrowding, removing specific teeth can make space to reposition the remaining teeth correctly.

Surgical options

Jaw surgery may be necessary for adults with severe underbites caused by skeletal issues.

Your Oral & Maxillofacial surgeon will reposition the jaw to ensure the teeth align perfectly.

In many cases, underbite surgery is recommended alongside orthodontic treatment.