What Is an Underbite?
An underbite is a dental condition where the lower front teeth overlap the upper front teeth when the mouth is closed. Dentists call this a Class III malocclusion. It is the opposite of a normal bite, where the upper teeth slightly cover the lower teeth.[1]
Underbites range from mild to severe. A mild underbite may only show when a person bites down. A severe underbite can change facial shape, push the chin forward, and make eating difficult. According to the American Association of Orthodontists, Class III malocclusions are less common than overbites but more likely to require complex treatment.[1]
Underbites are often noticed in childhood as adult teeth come in. Some cases become more obvious during teenage growth spurts when the lower jaw grows faster than the upper jaw.
What Causes an Underbite?
Most underbites come from a mismatch in jaw size or position, and many cases run in families. Both inherited traits and childhood habits can play a role in how the bite develops.[1]
Genetic and Skeletal Causes
Genetics is the leading cause of underbite. Children often inherit jaw size and shape from their parents. If the lower jaw grows longer than the upper jaw, an underbite forms. In some cases, the upper jaw is too small, which produces the same result.[1]
Certain conditions present at birth can also cause underbite. These include cleft lip and palate and other craniofacial differences. These cases usually need care from a team of specialists.
Childhood Habits and Other Factors
Some habits during early childhood can change how the jaw and teeth grow. The American Dental Association notes that long-term thumb sucking, pacifier use beyond age 3, and tongue thrusting can affect bite development.[2]
- Thumb or finger sucking after permanent teeth come in
- Prolonged pacifier or bottle use
- Tongue thrusting (pushing the tongue against the teeth)
- Mouth breathing related to airway problems
- Early loss of baby teeth without proper spacing care
- Injury to the jaw
Symptoms and Diagnosis
An underbite usually shows clear signs by age 7 to 10, when adult teeth replace baby teeth. A dentist or orthodontist confirms the diagnosis with a clinical exam, X-rays, and bite impressions.[1]
Patients with underbite often notice problems beyond appearance. Chewing tough foods may feel awkward. Some people develop jaw pain, headaches, or trouble with certain speech sounds like 's' and 'sh'. Over time, teeth that hit incorrectly can wear down or chip.[2]
Common Symptoms
- Lower teeth visibly in front of upper teeth
- Difficulty biting or chewing certain foods
- Jaw pain or clicking
- Headaches or facial muscle soreness
- Speech difficulties, especially with 's' sounds
- Mouth breathing or snoring
- Uneven tooth wear or chipping
- Lower lip or chin appearing more prominent
When to Seek Care
The American Association of Orthodontists recommends a first orthodontic evaluation by age 7. Early evaluation does not always mean early treatment. It allows the orthodontist to spot problems while the jaw is still growing, when correction may be simpler.[1]
Adults who notice jaw pain, worn teeth, or new speech changes should also seek evaluation. These signs can mean the bite is causing damage that may worsen without care.
Underbite Treatment Options
Treatment depends on age, severity, and whether the underbite is dental, skeletal, or both. Children often respond to growth-guiding appliances, while teens and adults may need braces, aligners, or surgery.[1]
Early Interceptive Treatment (Ages 7 to 10)
When the jaw is still growing, orthodontists can guide it into better alignment. This is called interceptive or Phase 1 treatment. Common tools include a palate expander, a reverse-pull headgear, or a chin cap. These devices encourage the upper jaw to grow forward or hold the lower jaw back.[1]
Early treatment can reduce the need for surgery later. In many cases, a second phase of braces is still needed once all permanent teeth come in.
Braces and Clear Aligners
For mild to moderate underbites caused mainly by tooth position, braces or clear aligners can move teeth into a normal bite. Braces use brackets and wires. Clear aligners use a series of removable trays. Both can take 12 to 24 months on average, though complex cases take longer.[1]
Braces and aligners work best when the jaws are the right size but the teeth are misaligned. They cannot move the jaw bones themselves. Severe skeletal underbites usually need additional treatment.
Orthognathic (Jaw) Surgery
Adults with severe skeletal underbite often need orthognathic surgery, also called corrective jaw surgery. An oral and maxillofacial surgeon repositions the upper jaw, lower jaw, or both. Braces are usually worn before and after surgery to align the teeth within the new jaw position.[1]
Total treatment time often runs 18 to 36 months including pre-surgical orthodontics, surgery, and recovery. Surgery is performed in a hospital under general anesthesia.
Tooth Extraction or Reshaping
In some mild cases, removing one or more teeth can create space to correct the bite without surgery. Cosmetic reshaping or veneers may improve appearance for very mild underbites, but they do not fix the underlying bite problem.
Recovery and Aftercare
Recovery depends on the treatment used. Braces and aligners require regular checkups but no downtime. Jaw surgery involves a longer healing process with diet and activity changes for several weeks.[1]
After active treatment, retainers are essential. Teeth and jaws can shift back without them. Most orthodontists recommend wearing a retainer full-time at first, then nightly for life.
After Braces or Aligners
Patients can return to normal activity right away. Mild soreness is common after adjustments. Brushing, flossing, and routine dental cleanings are important throughout treatment to protect the teeth.
After Jaw Surgery
Most patients spend one to three days in the hospital. Swelling and bruising typically peak in the first week. A soft or liquid diet is usually needed for 4 to 6 weeks while the jaw heals. Full bone healing takes about 3 to 6 months. Follow-up visits with the surgeon and orthodontist track progress and finalize the bite.
Cost and Insurance
Underbite treatment costs vary widely based on the approach, severity, and location. Costs vary by location, provider, and case complexity, so the figures below are general ranges only.
Many dental insurance plans include partial orthodontic coverage, often with a lifetime maximum benefit. Medical insurance may cover jaw surgery when it is considered medically necessary, such as for severe chewing problems, sleep apnea, or congenital conditions.[2]
- Early interceptive treatment: often a few thousand dollars per phase
- Full braces or clear aligners: commonly several thousand dollars
- Jaw surgery: typically tens of thousands of dollars including hospital and surgeon fees
- Retainers and follow-up: additional cost after active treatment
Insurance and Financing
Patients should ask their orthodontist for a written treatment plan with a fee breakdown. Most offices offer monthly payment plans. Health savings accounts (HSAs) and flexible spending accounts (FSAs) can also help cover qualified expenses.
Specialist vs. General Dentist
A general dentist can spot an underbite during a routine exam, but treatment usually requires a specialist. Orthodontists complete 2 to 3 years of additional training in tooth and jaw alignment after dental school.[1]
Severe skeletal underbites often involve a team. An orthodontist plans tooth movement. An oral and maxillofacial surgeon performs jaw surgery. Children with cleft lip and palate may also work with a pediatric dentist and other specialists. Visit the orthodontics page to learn more about how orthodontists treat bite problems.
Find an Orthodontist
Underbite treatment works best when it starts at the right time and uses the right approach for your case. Search My Specialty Dentist to find a qualified orthodontist in your area who can evaluate your bite, explain your options, and help you choose a treatment plan that fits your needs.
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