Underbite: Causes, Symptoms & Treatment

Key Takeaways

• Definition:

An underbite, or Class III malocclusion, happens when the lower teeth extend beyond the upper teeth, affecting bite, function, and appearance.

• Prevalence:

Around 5–10% of people experience some degree of underbite, ranging from mild to severe.

• Causes:

Common causes include genetics, childhood habits (thumb-sucking, tongue-thrusting), jaw trauma, congenital conditions, and, rarely, jaw tumors or growths.

• Symptoms:

  Mild: Slight misalignment, minimal discomfort.

  Moderate: Difficulty chewing, speech problems, jaw pain.

  Severe: Visible jaw protrusion, TMJ disorders, and breathing issues.

• Diagnosis:

Dentists use physical exams, X-rays, cephalometric analysis, and 3D imaging to determine severity and treatment needs.

• Treatment Options:

  Orthodontic: Braces, clear aligners, expanders, reverse-pull headgear.

  Surgical: Orthognathic surgery, bone grafts, or implants for severe skeletal cases.

  Early Intervention: Growth modification devices in children can prevent worsening.

• Complications if Untreated:

Can lead to tooth wear, gum disease, TMJ pain, difficulty chewing, speech problems, sleep apnea, and reduced self-esteem.

• Prevention & Detection:

Early dental checkups (by age 7) and addressing harmful habits can help reduce severity.

• Living with an Underbite:

Requires good oral hygiene, dietary adjustments, and emotional support during treatment.

• Prognosis:

With timely intervention, an underbite is highly treatable, restoring both function and confidence.

Generally, a smile tends to be one of the first characteristics that a person notices about you, as it helps your appearance while also making a great first impression on others. Malocclusions are now seen in individuals of all ages. An underbite is a type of malocclusion, along with an Open Bite , overbite, Crossbite , or crooked teeth that many experience. An underbite occurs when your lower teeth extend past your upper teeth while you bite. In this blog, let’s find out everything you need to know about an underbite: its causes, types, and how to correct underbite.

What is an Underbite?

An underbite, clinically referred to as Class III malocclusion, is a dental condition where the bottom front teeth overlap or project past the top front teeth. Unlike a slight misalignment, an underbite can impact not only appearance but also jaw function. Detecting it early is crucial, since untreated cases may result in jaw pain, speech problems, tooth damage, gum issues, or even breathing difficulties.

Types of Underbite

Before you ask, can an underbite be fixed? You need to know that not every underbite is the same. Knowing the type helps decide the right treatment plan.

Dental Underbite

• Happens due to tooth position, not jawbone structure.
• Occurs when teeth erupt at the wrong angle or crowding pushes them forward.
• Easier to fix with orthodontic devices such as braces or aligners.

Skeletal Underbite

• Caused by jawbone irregularities, often inherited.
• The bottom jaw grows too far forward, or the top jaw grows too far back.
• Usually requires orthodontics combined with jaw surgery.

Functional Underbite

• Forms due to habits in childhood or temporary growth issues.
• Typical triggers include thumb-sucking, tongue-thrusting, or long-term pacifier use.
• Early treatment in children can often reverse or reduce this form.

Symptoms of an Underbite

Symptoms vary depending on the severity of misalignment.

Mild Symptoms

• Slight upper and lower tooth misalignment.
• Little to no discomfort.
• May not notice issues unless chewing tough foods.

Moderate Symptoms

• Chewing problems from poor alignment.
• Jaw pain or stiffness.
• Speech challenges such as lisping or unclear words.
• Noticeable tooth enamel wear.

Severe Symptoms

• Visible protrusion of the lower jaw (facial imbalance).
• Frequent tongue or cheek biting.
• Breathing issues, especially during sleep.
• Higher likelihood of TMJ disorders (jaw clicking, pain).
• Emotional stress or self-consciousness about looks.

Causes of an Underbite

Underbites rarely stem from just one reason; they usually result from genetics, habits, and growth factors. Here are the main causes:

Genetics

Genetics plays the largest role. If either parent had an underbite, their child is more likely to inherit similar jaw traits. DNA influences bone size, shape, and alignment. Common inherited features include:

• Large lower jaw (mandibular prognathism) or unusually small upper jaw.
• Uneven jaw growth rates, where the bottom jaw grows faster.
• Tooth crowding from narrow jawbones.

Childhood Habits

Early habits affect jaw growth. If they continue beyond age 3 or 4, they may cause lasting effects. Examples:

• Thumb-sucking and pacifiers: Constant sucking pushes lower teeth forward.
• Tongue-thrusting: Pressing the tongue against teeth during swallowing moves them forward.
• Mouth breathing: Ongoing nasal blockage can shift jaw position.

Injury or Trauma

Serious accidents affecting the jaw or facial bones may cause misalignment during healing. For instance:

• A broken jawbone may heal unevenly, pushing the lower jaw forward.
• TMJ damage may alter bite patterns.

Congenital Conditions

Some birth conditions affect jaw development:

• Cleft lip and palate can cause abnormal upper jaw growth, raising underbite risk.
• Disorders such as Crouzon or Treacher Collins syndromes disrupt craniofacial growth, often leading to severe skeletal underbites.

Tumours or Abnormal Growths

Though rare, tumors in the jawbone can shift growth. A growth may push one section forward or block another, creating an imbalance.

Diagnosis of an Underbite

Diagnosing an underbite involves more than just checking how the teeth look. Dentists and orthodontists use a mix of physical exams, dental imaging, and monitoring jaw growth to figure out how serious the condition is and what treatment will work best. This evaluation also helps determine whether the issue comes from dental misalignment, skeletal problems, or both.

Physical Exam

The first step is a physical exam. Here, the dentist observes how the top and bottom teeth meet when you bite down. They also check jaw movement, noting if it shifts abnormally, makes clicking sounds, or causes discomfort. Since a skeletal underbite can affect facial harmony, they also evaluate overall facial balance to see if the jaw position impacts appearance.

Dental X-rays

X-rays give a detailed look beneath the surface. They show tooth alignment, root health, and jawbone condition. These images can also reveal hidden issues such as overcrowding, extra teeth, or abnormal eruptions that may contribute to an underbite.

Cephalometric X-ray

In more complex cases, orthodontists may use a cephalometric X-ray. This type of head X-ray shows the exact relationship between the teeth, jaws, and skull. It’s especially useful when planning treatment for moderate to severe underbites, as it highlights the skeletal imbalances that need correction.

3D Imaging and Digital Scans

With modern technology, advanced tools like Cone Beam Computed Tomography (CBCT) and digital scans are now available. CBCT provides highly detailed 3D images of the jaw, which are especially helpful when planning surgery for severe skeletal underbites. Digital scans, on the other hand, allow orthodontists to design precise treatment plans for clear aligners, giving patients a more customized and comfortable option.

Child Growth Monitoring

For children, monitoring growth is a key part of diagnosis. Orthodontists track jaw development over time to spot early signs of imbalance or unusual growth. When addressed early, treatment is more effective since bones are still flexible. This can guide proper jaw development and, in many cases, reduce or even prevent the need for surgery later in life.

How to Fix Underbite

Treatment varies by age, severity, and cause. Children usually have more options since their jaws are still developing, while adults often need advanced care. After a thorough examination of your case, your dentist will suggest the best treatment for you. The options include:

• Orthodontic devices (Braces, aligners, etc.)
• Early prevention in children
• Surgery for severe cases

Orthodontic Devices for an Underbite

Braces

Traditional braces are composed of metal brackets and wires that are fixed on the surface of the teeth. They exert pressure over time to move teeth to a desirable position. They can be very effective for treating malocclusions, including an underbite.

Clear Aligners

Aligners for Teeth Straightening have emerged as a popular alternative to traditional braces. They are invisible and can be easily removed to ensure oral hygiene and routine meals.

Palatal Expanders

Palatal expanders are used to widen the top jaw in children to align it with the bottom.

Early Treatment in Children

Growth Devices

Orthodontic appliances can guide jaw growth in children, helping the upper and lower jaws align properly as they develop. Starting early often reduces the need for more invasive treatments later on.

Habit Appliances

These devices are designed to stop habits like thumb-sucking or tongue-thrusting, which can make an underbite worse. Correcting such habits early supports healthier bite development.

Regular Orthodontic Visits

Dentists recommend that children have an orthodontic evaluation by age 7. Early checkups help track jaw growth and catch problems before they become more serious.

Surgery (For Severe Adult Skeletal Underbites)

In adults, where jawbones have fully developed, surgery may be needed for severe underbites. This procedure repositions the jaws to improve both function and facial balance.

Risks if Left Untreated

Ignoring an underbite may cause long-term issues for oral health and daily life.

Dental Problems

• Tooth Wear: Misaligned bite erodes enamel, raising sensitivity and decay risk.
• Gum Disease: Harder to clean crowded teeth, increasing infection risk.
• Tooth Loss: Uneven pressure can loosen teeth.

Functional Problems

• Chewing Difficulty: A Poor bite affects digestion.
• Speech Issues: Lisping, unclear sounds, or difficulty pronouncing words.

TMJ Disorders: Jaw strain causes pain, popping, and headaches.

Aesthetic Effects

• Facial Imbalance: A Protruding jaw creates asymmetry.
• Confidence Issues: Many struggle socially or emotionally with appearance.

Breathing & Sleep Problems

• Severe underbites may contribute to sleep apnea.
• Chronic mouth breathing may also occur.

Prevention & Early Detection

While genetics can’t be avoided, good habits and early checks help reduce risks.

• Parental Role: Limit pacifier and thumb-sucking after age 3.
• Healthy Habits: Teach proper chewing and swallowing.
• Dental Visits: First orthodontic exam at age 7 (per AAO).
• Growth Checks: Regular monitoring for early detection.

Living with an Underbite

During treatment, lifestyle changes help manage symptoms.

Oral Care

• Brush twice daily and floss carefully around crowded teeth.
• Use fluoride products for added protection.
• Wear night guards if teeth grinding occurs.

Diet Tips

• Avoid sticky, hard, or chewy foods.
• Eat softer foods during orthodontic treatment.

Emotional Support

• Underbites can hurt confidence—therapy or support groups may help.
• Stay in communication with orthodontists for reassurance.

Overbite vs. Underbite

Both are malocclusions, but opposite in nature. An overbite happens when the top teeth extend far over the bottom teeth, often appearing as “buck teeth.” Mild overbites are common and usually harmless, but deep overbites can cause enamel wear, gum recession, and jaw discomfort. An underbite occurs when the bottom teeth extend beyond the top teeth, pushing the jaw forward. Overbites are generally easier to correct with orthodontics, while underbites—especially skeletal ones—may need surgery plus orthodontics. Both affect chewing, speech, and appearance if untreated, but underbites are more complex due to the bone growth links.

Fixing an Underbite

An underbite is more than a cosmetic concern; it impacts how teeth, jaws, and face work together. Though caused by genetics, habits, or trauma, today’s dentistry provides effective treatments from aligners and braces to surgery for severe cases. Detecting it early, especially in kids, makes treatment easier and prevents problems like jaw pain, speech issues, and dental damage. Adults also benefit from modern orthodontics and surgery for lasting improvement. If you see signs of an underbite in yourself or your child, visiting an orthodontist is the best next step. With timely care, you can improve both oral health and self-confidence.