Underbite: causes and how to fix it

Page updated October 14, 2026. Medically reviewed by Dr. Abraham Thomas and Dr. Jennifer Loucks-Buren.

An underbite is when your lower front teeth sit in front of your upper front teeth when you bite down. It's fixed with braces or clear aligners when the cause is the teeth, with growth appliances such as a palatal expander and reverse-pull headgear in children, and with jaw surgery plus braces when the jaws themselves are out of position.

What an underbite is

In a healthy bite, the upper front teeth sit slightly in front of the lower ones. With an underbite that relationship is reversed (AAO); see overbite vs underbite. It's a type of malocclusion, the clinical term for teeth and jaws that don't line up (AAO), and is also called a Class III malocclusion or prognathism (Healthline). Cleveland Clinic describes Class III as the lower teeth sticking out significantly beyond the upper teeth with an overdeveloped jaw, and calls it often the most difficult type to fix (Cleveland Clinic).

Underbites range from barely noticeable to severe, where the lower jaw visibly juts forward. The AAO splits the cause into three groups, and the group decides the treatment (AAO):

• Dental: a tooth positioning problem.
• Skeletal: a problem with the jaw structure.
• A combination of both.

It's the opposite of an overbite, where the upper teeth extend far past the lower ones (Healthline).

Signs of an underbite

Some underbites are obvious; others only show up at an orthodontic exam. Common signs (AAO):

• Lower teeth that sit visibly in front of the upper teeth when biting down
• A lower jaw or chin that looks more prominent than the upper jaw
• Difficulty biting or chewing comfortably
• Speech issues, such as a lisp or trouble with certain sounds
• Jaw discomfort or pain, especially around the joints
• Uneven or faster tooth wear
• Difficulty closing the mouth fully without strain

Severe cases can cause difficulty chewing, problems speaking, and mouth and face pain from jaw misalignment (Healthline). Healthline adds that symptoms of temporomandibular (jaw joint) disorders are common with underbites (Healthline).

What causes an underbite

• Genetics: most often an underbite is inherited, and you're more likely to have one if someone else in your family does (Healthline). Jaw shape, size and bite patterns run in families (AAO).
• Jaw growth: if the upper jaw grows more slowly than the lower, or the lower jaw grows more than expected, the teeth end up out of line (AAO).
• Childhood habits: prolonged thumb sucking, pacifier use, tongue thrusting and chronic mouth breathing (AAO); Healthline adds pacifier use above age 3 and bottle feeding beyond infancy (Healthline).
• Injury or tumors: severe facial injuries, and tumors on the jawbones or in the mouth, can also cause one (Healthline).

How an underbite is diagnosed

An orthodontist looks at the teeth, bite, jaw position and face together. The evaluation may include a clinical exam, digital X-rays of the bone and roots, and photos, 3D scans or impressions of the bite (AAO). From that, they decide whether the underbite is mainly dental, skeletal or both, which shapes every option below (AAO). You don't need a referral from your dentist to see an orthodontist (AAO).

How common bite problems are

Underbites are less common than other bite problems (AAO). Malocclusion of any kind affects around 56% of people worldwide, and up to 93% of children and adolescents have some degree of it, though not every case needs treatment (Cleveland Clinic). Cleveland Clinic says treatment takes about 2 years on average, longer for some people and only a few months of braces for others (Cleveland Clinic).

How to fix an underbite

Treatment depends on your age, how much jaw growth is left, and how severe the underbite is (AAO).

Healthline adds that removing one or more lower teeth can help when crowding contributes, and that a dentist may smooth teeth that stick out (Healthline). Many people can fix an underbite without surgery: mild underbites caught early often are, and surgery is generally kept for severe skeletal cases in adults (AAO).

Can Invisalign fix an underbite? Sometimes. The AAO says aligners can work for mild underbites that are largely dental rather than skeletal (AAO), and aligners in general typically treat light to moderate problems (AAO). Compare prices on Invisalign vs braces.

Underbites in children

Children have more options because their jaws are still growing, and growth appliances can guide jaw development in ways that aren't possible later (AAO). When the underbite comes from jaw development, an orthodontist may use a palatal expander with reverse-pull headgear to encourage the upper jaw forward (AAO); see orthodontic headgear. Healthline mentions a small study suggesting facemask appliances can help ease lower front teeth into place, though a more permanent solution may still be needed later (Healthline).

That's why the AAO recommends a first orthodontic visit by age 7: early treatment can reduce the need for more complex treatment later (AAO), and many orthodontists offer that first check at no cost (AAO). More in braces for kids and teens.

Underbites in adults

Adults can be treated and get excellent results; more severe cases need a more involved plan because jaw growth is complete (AAO). Braces or clear aligners can improve chewing and speech and reduce jaw pain and tooth wear (AAO). When the jaws are substantially out of position, braces alone may not be enough, and jaw surgery is typically done after the jaw has finished growing, with orthodontic treatment before and after (AAO). Healthline says recovery from the surgery takes one to three weeks (Healthline). Read more on jaw surgery cost and recovery and adult braces.

Looking after your teeth with an underbite

An underbite makes it more important to keep teeth clean. Healthline recommends brushing at least twice a day for two minutes with fluoride toothpaste, paying attention to the gumline and the backs of the teeth, flossing, and seeing a dentist at least twice a year (Healthline). Correcting a severe underbite can make teeth easier to clean, lower the risk of decay and gum disease, and ease strain on the teeth, jaws and facial muscles (Healthline).

Questions to ask your orthodontist

• What type of malocclusion do I have, and is it dental, skeletal or both (Cleveland Clinic) (AAO)?
• What are my treatment options, and what does each cost?
• Will I need surgery, and if so, before, during or after orthodontic treatment (Cleveland Clinic)?
• How long will treatment take (Cleveland Clinic)?
• Will my insurance treat this as medically necessary?

How much it costs to fix an underbite

Cost follows the treatment:

Health insurance may cover jaw surgery when the problem causes health issues; Healthline says an insured patient might pay as little as a $100 copay, or $5,000 or more if the plan caps jaw surgery (Healthline). Get a written estimate for your case, and use our braces cost calculator for the orthodontic part.