Underbite: Causes, Signs & Treatments

An underbite is a common orthodontic condition where the lower front teeth sit in front of the upper front teeth when the mouth is closed. In a healthy, well-aligned bite, the upper teeth should overlap the lower teeth slightly. An underbite reverses this relationship, and the result can affect everything from the way you chew and speak to the balance of your facial profile.

So what is an underbite, exactly? It is a type of malocclusion — a misalignment of the teeth and jaw — that causes the lower jaw or lower teeth to project forward beyond the upper teeth. Underbite teeth may appear noticeably out of alignment, with the lower front teeth sitting visibly ahead of the uppers. The condition can range from a mild discrepancy that is barely noticeable to an extreme underbite that significantly affects function and appearance.

Underbites are seen in both children and adults. Whether caused by genetics, jaw growth imbalance, or childhood habits, early assessment is valuable because timely intervention — particularly during childhood development — can simplify treatment and improve outcomes. This guide covers everything you need to know: causes, symptoms, diagnosis, and the full range of treatment options available.

Underbite vs Overbite — What's the Difference?

Understanding the difference between an overbite and underbite is important because they are essentially opposite conditions, and each requires a different treatment approach. If you have ever wondered “how do I know if I have an overbite” or “how do you know if you have an overbite”, the answer lies in observing where your teeth sit when your jaw is fully closed.

In a normal bite, the upper front teeth sit slightly in front of and overlap the lower front teeth by around 2–4mm. This small degree of overlap is healthy and allows for comfortable biting and chewing.

An overbite occurs when the upper teeth overlap the lower teeth excessively — often covering them significantly or even contacting the gum. An underbite is the reverse: the lower teeth and jaw project forward, sitting in front of the upper teeth.

How to know if you have an overbite versus an underbite? Look at your bite in a mirror when you close your mouth naturally. If your lower teeth sit visibly in front of your upper teeth, you likely have an underbite. If your upper teeth cover a large proportion of your lower teeth, you may have an overbite.

What Causes an Underbite?

Underbites develop for a variety of reasons, and the underlying cause determines the most effective treatment approach. In many cases, more than one factor contributes to the condition.

Causes in Children

• Genetics — The most common cause of underbite is hereditary. Jaw size and shape are largely inherited, and a child may develop an underbite simply because the lower jaw is genetically larger or grows further forward than the upper jaw. A family history of underbite significantly increases the likelihood
• Jaw growth differences — During childhood development, the upper and lower jaws may grow at different rates. If the lower jaw outpaces the upper, the lower teeth gradually move forward, creating an underbite jaw discrepancy that becomes more apparent over time
• Thumb sucking and oral habits — Prolonged thumb sucking, tongue thrusting, or dummy use can influence the developing jaw, altering the position of the teeth and potentially contributing to a bad underbite as the child grows

Causes in Adults

• Untreated childhood bite issues — An underbite that was not addressed during childhood can persist and worsen in adulthood as the jaw finishes developing. What may have been a mild underbite in childhood can become a more pronounced underbite jaw problem over time
• Jaw growth imbalance — In some adults, the lower jaw is naturally larger or more forward-positioned than the upper jaw, resulting in a skeletal underbite that affects both tooth alignment and facial balance
• Tooth loss — Missing upper teeth can allow the lower teeth to drift forward, creating or worsening an underbite. Without the opposing teeth providing balance, the bite can shift over time

Signs and Symptoms of an Underbite

The symptoms of an underbite can range from subtle to significant, depending on the severity. A mild underbite may cause few noticeable issues, while a severe underbite or extreme underbite can have a substantial impact on both function and appearance.

Functional Symptoms

• Difficulty chewing — When the lower teeth sit in front of the upper teeth, biting into food and chewing efficiently becomes challenging. Patients with severe underbites often compensate by chewing on one side or tearing food rather than biting cleanly
• Speech challenges — An underbite can affect the way certain sounds are formed, particularly “s”, “f”, and “th” sounds, potentially causing a lisp or unclear pronunciation
• Jaw discomfort — The misaligned bite places strain on the jaw joints and muscles, leading to aching, clicking, or tension — particularly after eating or during periods of stress
• Tooth wear — Underbite teeth that do not meet correctly place uneven force on certain areas, causing premature wearing, chipping, or even fractures over time

Aesthetic Concerns

• Prominent chin or lower jaw — A noticeable underbite can cause the chin and lower jaw to appear more prominent or forward-positioned than expected, affecting the side profile
• Facial imbalance — In more pronounced cases, the relationship between the upper and lower face may appear out of proportion, though the degree of visible impact varies from person to person
• Visible reversed bite — When the lower teeth sit clearly in front of the upper teeth, this may be visible when smiling or speaking, which can affect confidence in social situations

How Is an Underbite Diagnosed?

Diagnosing an underbite involves a thorough clinical examination of your teeth, bite, and jaw. Your dentist will assess how your upper and lower teeth meet when you close your mouth naturally and evaluate the overall relationship between your jaws.

The assessment typically includes:

• Clinical bite examination — Observing the position of the teeth when you bite down naturally to identify whether the lower teeth sit in front of the upper teeth and by how much
• Visual assessment — Evaluating the overall alignment of the underbite teeth and noting any visible asymmetry or reversed bite relationship
• Measurement of jaw alignment — Assessing the spatial relationship between the upper and lower jaws to determine whether the underbite is dental (caused by tooth positioning) or skeletal (caused by jaw size discrepancy)
• Underbite jaw positioning evaluation — Determining whether the lower jaw is naturally larger, further forward, or both, which helps classify the severity and guide the treatment plan

Can an Underbite Be Fixed Without Surgery?

One of the most common questions patients ask is how to fix an underbite — and specifically whether underbite correction can be achieved without surgical intervention. The answer depends entirely on the type and severity of the condition.

When non-surgical treatment is possible: Many underbites — particularly mild to moderate cases caused primarily by tooth positioning — can be corrected without surgery. Orthodontic treatment with braces, clear aligners, and bite-correcting elastics can reposition the teeth and improve the bite relationship effectively. How to correct underbite without surgery is achievable for a significant number of patients through these approaches alone.

When more complex care may be needed: An extreme underbite or severe skeletal underbite caused by a significant jaw size discrepancy may not be fully correctable through orthodontics alone. In these cases, corrective jaw surgery (orthognathic surgery) may be recommended alongside orthodontic treatment to reposition the jaw and achieve a stable, functional result.

Age factors: In children, early intervention during jaw development may harness natural growth to guide the jaw into a more favourable position, potentially avoiding the need for surgery later. In adults whose jaw growth is complete, the treatment options are determined by the degree of skeletal involvement.

Braces for Underbite Correction

Fixed braces are one of the most effective and widely used treatments for correcting an underbite. Do braces fix underbite? Yes — and they remain a gold-standard approach for a wide range of underbite severities.

How Braces Correct an Underbite

Underbite braces work by bonding brackets to the teeth and connecting them with an archwire that applies controlled, continuous force. This gradually moves the teeth into improved positions, correcting the reversed bite relationship. Can braces fix an underbite? Absolutely — and the precise control offered by fixed braces makes them suitable even for more complex cases.

Elastics and Bite Correction

Braces for underbite correction frequently incorporate orthodontic elastics — small rubber bands that attach to the upper and lower brackets. These elastics apply directional forces that help pull the lower teeth back and the upper teeth forward, working to close the reversed bite. Consistent wear of elastics as directed is critical for achieving the desired result.

Treatment Timeline

The duration of underbite braces treatment varies depending on the severity of the condition. Mild cases may be corrected in a shorter timeframe, while more complex underbites require longer treatment to achieve stable results. Your dentist will provide a realistic estimate based on your individual case during your consultation.

Can Invisalign Fix Underbite?

Can Invisalign fix underbite? In many cases, yes. Invisalign and other clear aligner systems can be effective for correcting mild to moderate underbites, particularly those caused by tooth positioning rather than significant skeletal jaw discrepancy.

Clear aligners work by applying controlled pressure through a series of custom-made removable trays. Each set moves the teeth gradually toward their target position. For suitable underbite cases, they offer a discreet and comfortable underbite treatment alternative to fixed braces.

However, Invisalign may not be suitable for all underbites. Severe or skeletal underbites that involve a significant jaw discrepancy may require fixed braces — or a combined orthodontic and surgical approach — for effective correction.

How to Fix Underbite Naturally — Is It Possible?

Many patients search for how to fix underbite naturally, hoping that exercises, jaw positioning techniques, or lifestyle changes can correct the condition without professional treatment. It is important to address this topic honestly and responsibly.

The reality: Exercises and jaw movements alone cannot correct a structural underbite. An underbite is caused by the physical position of the teeth, the size and shape of the jaw, or both. These are anatomical factors that require orthodontic intervention to change. No amount of jaw exercises, facial stretching, or self-directed techniques can reposition the bones or move the teeth into a corrected alignment.

What may help: In young children whose jaws are still developing, early orthodontic intervention can help guide jaw growth in a more favourable direction. This is not a “natural” fix in the way many online sources suggest, but it does use the body's natural growth process to support correction. Growth-guidance appliances and early orthodontic assessment are the most effective way to take advantage of this window.

What Happens If an Underbite Is Left Untreated?

A bad underbite that is left unaddressed does not typically improve on its own — and in many cases, it worsens progressively over time. The longer a severe underbite or extreme underbite goes without treatment, the greater the risk of complications.

• Jaw strain and TMJ discomfort — The misaligned bite places chronic strain on the jaw joints and muscles, leading to pain, clicking, locking, and tension headaches over time
• Accelerated tooth wear — Teeth that do not meet correctly bear uneven force, causing premature wearing of the enamel, chipping, and potential fractures
• Speech problems — An untreated underbite can cause or worsen speech difficulties, affecting clarity and confidence in communication
• Facial imbalance — As the bite worsens, the visual impact on the facial profile can become more pronounced, with the lower jaw appearing increasingly prominent
• Worsening alignment — Without correction, the teeth and jaw can continue to shift, making eventual treatment more complex and potentially requiring more invasive intervention

When to See a Private Dentist in London

If you are experiencing any of the following, it is worth having your bite assessed by a qualified dental professional:

• Difficulty biting into food or chewing comfortably
• Jaw pain, clicking, or tension — particularly after eating
• Speech concerns such as a lisp or unclear pronunciation
• Lower teeth sitting visibly in front of upper teeth when your mouth is closed
• Concerns about your facial profile, chin prominence, or smile
• A child or teenager showing signs of an underbite developing

At St Paul's Medical & Dental, our experienced GDC-registered dental team offers thorough bite assessments at our private dentist in the City of London practice. We will evaluate your bite, explain your options clearly, and create a personalised underbite treatment plan if correction is needed.

Prevention & Early Management

While some underbites are strongly genetic and cannot be entirely prevented, there are practical steps that can help reduce the risk of an underbite developing or becoming more severe:

• Early orthodontic assessment — Having a child's bite assessed at an early age allows the dentist to identify any developing underbite and recommend appropriate monitoring or intervention
• Monitoring jaw growth in children — Regular dental visits during childhood allow for ongoing assessment of jaw development, so any emerging underbite can be tracked and managed proactively
• Avoiding habits affecting jaw growth — Gently discouraging prolonged thumb sucking, tongue thrusting, and extended dummy use beyond the recommended age can help support healthy jaw development
• Replacing missing teeth promptly — In adults, replacing lost teeth helps maintain bite stability and prevents the remaining teeth from shifting in ways that could create or worsen an underbite

Frequently Asked Questions About Underbite