Underbite

What is an underbite?

An underbite is a dental condition where your lower front teeth protrude (stick out) beyond your upper front teeth. It can happen if your lower jaw extends beyond your upper jaw. An underbite is a class III malocclusion. Malocclusion is a word healthcare providers use to describe misaligned teeth.

If your teeth are aligned, your front teeth should extend slightly beyond your lower front teeth. This positioning allows the molars (back teeth) on your upper and lower jaw to meet when you close your mouth.

You may not notice issues if you have a mild underbite. In more severe cases, the misalignment may affect your appearance and cause symptoms.

How common are underbites?

About 5% to 10% of people have an underbite. This includes people with a slight underbite who don’t need treatment and people with more noticeable misalignment who do.

What are the symptoms of an underbite?

A mild underbite may not cause issues. A severe underbite can cause your jaw to stick out noticeably. The misalignment can cause symptoms, including:

• Trouble opening or closing your mouth all the way.
• Discomfort or pain while speaking or chewing.
• Biting the inside of your mouth.
• Difficulty breathing.
• Jaw pain.
• Bad breath (halitosis).

What are the complications of an underbite?

Over time, an underbite can lead to additional issues, such as:

• Temporomandibular joint (TMJ) disorders. This condition arises when there are problems with the joint connecting your upper and lower jaw and surrounding tissue. It causes symptoms like headaches, earaches and facial pain.
• Dental problems: A misaligned bite creates more spaces for bacteria to hide, increasing your risk of infection. It can lead to dental issues like tooth decay, cavities and gum disease. It can cause your teeth to crack or wear down.
• Sleep apnea: Sleep apnea is a sleeping disorder that causes you to stop breathing during sleep. The temporary pause in breathing starts you awake. Sleep deprivation leads to fatigue, drowsiness and irritability.

What causes an underbite?

Your lower jaw may be bigger than your top jaw, or your top jaw may be underdeveloped. Sometimes, an underbite results from the positioning of your teeth rather than your jaw size or placement.

Regardless of the anatomy, you’re more likely to have an underbite if someone in your family also has an underbite. Certain behaviors and conditions can also play a role.

Causes include:

• Genetics: Genes you inherit from your family determine the shape and size of your jaw and teeth. Most people with teeth misalignment inherit these traits.
• Prolonged childhood behaviors: Actions that place repeated pressure on your teeth while they’re still forming can cause an underbite. These actions include prolonged thumb-sucking, bottle-feeding or pacifier use. Nail-biting and tongue-thrusting, which involves pressing your tongue into your teeth when you speak or chew, can also cause an underbite.
• Injury: An injury to your face or jaw can cause an underbite. Even with surgery, sometimes the jaw bones don’t grow back perfectly aligned.
• Tumors: Tumors in your mouth or jaw can cause a misaligned bite.

How is an underbite diagnosed?

Your dentist will perform a physical exam. They may take dental X-rays to pinpoint the exact spots where your teeth are misaligned.

Depending on the severity of your underbite, you may need to see an orthodontist or an oral surgeon. An orthodontist specializes in aligning your bite and straightening your teeth. An oral surgeon performs surgery on oral structures, like your teeth and jaw.

At what age should you fix an underbite?

It’s best to get treated in childhood, between ages 7 and 10, when the jaw bones are still developing. It’s much easier to modify bone structure at that point without surgery.

What are treatments for underbite correction?

Treatment options depend on the severity of your underbite and your age. Generally, treatments that gradually change bone structures are more common in children and teens, whose bones are still growing. Adults often need surgery.

Braces and retainers

Braces fit onto your teeth and gradually move them into alignment. You may need braces on all your teeth or only those affected by your underbite. Some braces are clear and blend in naturally with your appearance. Afterward, you may need to wear a retainer. Retainers hold your teeth in position after you get braces removed.

Tooth extraction

A healthcare provider may need to remove teeth if having too many (crowded teeth) contributes to your underbite. You may need to have teeth removed before getting braces. This creates more space for your healthcare provider to position your remaining teeth correctly.

Palate expanders and other growth modification devices

Children whose bones are still forming may benefit from devices that gradually align their bite. Your child may need to wear these devices for several weeks or months to correct an underbite.

• Palate expanders fit into the roof of your child’s mouth and gradually widen their top jaw to align more fully with their lower jaw.
• A chin cap is headgear with a chin strap that prevents your child’s jaw from jutting forward.
• Reverse pull headgear attaches to your child’s upper jaw and pulls it forward.

Surgery

Surgery to correct jaw misalignment is more common in adults than in children. You may need reconstructive surgery to align your bite if other, less invasive options haven’t worked and your underbite is severe.

How can I prevent an underbite?

You can’t prevent underbites related to genetics. But parents and caregivers can limit certain behaviors that may cause a child to develop an underbite.

Prevention strategies include:

• Weaning your child from the bottle starting at age 1.
• Scheduling a dental visit by age 1.
• Discouraging thumb-sucking after age 3.
• Discouraging pacifier use after age 3.

What is the outlook for people with an underbite?

The outlook is excellent. If your underbite is mild, you may not notice it or need treatment. Even if it’s severe, an underbite is usually a correctable condition. It doesn’t usually require surgery if treated in childhood.

Do underbites get worse with age?

They can, especially if an underbite in childhood remains unaddressed into adulthood. At that point, jaw bones harden, and an underbite may become more pronounced.

What happens if I don't fix my underbite?

Depending on the severity of your underbite, the misalignment can lead to unpleasant symptoms like jaw pain and difficulty eating and speaking. It can increase your risk of dental problems and conditions like TMJ disorders. Depending on its severity, an underbite may make you self-conscious about your appearance.

Ask your dentist if they recommend treatment for your underbite.

How do I care for myself (or my child)?

Proper oral hygiene is important for everyone, but it’s especially important with an underbite. Misaligned teeth can create hard-to-reach places that are easy to miss while brushing your teeth. They create hiding places for bacteria.

Reduce your risk of infection by brushing at least twice daily and taking care to brush all the places where bacteria may hide. Floss daily. See your dentist every six months.

Follow your dentist’s or orthodontist’s guidance on whether you or your child should wear a mouth guard (night guard) at night. A night guard helps prevent the harmful effects of teeth grinding (bruxism), which causes damage during sleep.

What questions should I ask my doctor?

If you have an underbite, you may want to ask your healthcare provider:

• Does my underbite require treatment?
• What potential symptoms should I be on the lookout for?
• What are my treatment options?
• How long will treatment take?
• How can I care for my teeth with an underbite?

What’s the difference between an underbite and an overbite?

An underbite is the opposite of an overbite. An overbite occurs when your upper front teeth extend beyond your lower front teeth. They share similar causes, but overbites are more common than underbites.

A note from Cleveland Clinic

Regular visits with a dentist are important for your oral health. This includes your bite. Teeth misalignment can increase your risk of infections and painful symptoms like the ones common in TMJ disorders. If you’re an adult with an underbite, ask your dentist if they recommend treatment. If you’re a parent or caregiver, schedule a dental appointment within your child’s first year, and don’t miss regular appointments. Catching and correcting misalignment issues early can prevent your child from having to experience the symptoms of an underbite.