What Is an Underbite?
An underbite is a type of malocclusion where the lower front teeth extend forward past the upper front teeth when the mouth is closed. In a normal bite, the upper teeth sit slightly in front of and overlap the lower teeth. When this relationship is reversed, it is classified as a Class III malocclusion.
Underbites range from mild, where the lower and upper teeth meet edge to edge, to severe, where there is a significant gap between the upper and lower front teeth. The severity and underlying cause determine which treatment approach will be most effective.
Dental Underbite
A dental underbite means the jaw bones are reasonably well-positioned, but the teeth are angled incorrectly. The lower front teeth may be tilted too far forward or the upper front teeth tilted too far back. This type is often easier to correct because it involves moving teeth rather than repositioning bone. Braces and sometimes clear aligners can treat dental underbites effectively.
Skeletal Underbite
A skeletal underbite results from a mismatch in jaw size or position. The lower jaw may be too large, the upper jaw too small, or both. This type of underbite is more complex to treat because moving teeth alone cannot compensate for the skeletal discrepancy. In growing children, orthodontists may use appliances to influence jaw growth. In adults whose jaws have stopped growing, surgical correction is typically needed.
What Causes an Underbite?
Underbites are among the most genetically influenced orthodontic conditions. Research shows that jaw size and position are strongly inherited traits. Beyond genetics, several other factors can contribute.
- Genetics: Family history is the strongest predictor. If one or both parents have an underbite, children are more likely to develop one. Certain populations have higher prevalence rates due to inherited jaw growth patterns.
- Lower jaw overgrowth: The mandible (lower jaw) may grow disproportionately large compared to the upper jaw during childhood and adolescence.
- Upper jaw underdevelopment: The maxilla (upper jaw) may not grow forward enough, causing the lower jaw to appear prominent by comparison.
- Childhood habits: Chronic mouth breathing and prolonged tongue thrusting can contribute to underbite development in some cases, though these are less common causes than genetics.
- Injury or tumors: Trauma to the jaw or benign growths can alter jaw alignment, though these causes are rare.
How Is an Underbite Corrected?
Underbite treatment depends on the type (dental vs skeletal), severity, and the patient's age. Treatment approaches range from simple orthodontics for mild cases to combined surgery and braces for severe skeletal underbites.
Braces for Underbite Correction
Braces with elastics (rubber bands) can correct mild to moderate dental underbites. The elastics connect the upper and lower arches in a pattern designed to pull the lower teeth back and the upper teeth forward. For underbites with a skeletal component, braces alone may produce limited improvement.
In cases that border between orthodontics-only and surgical correction, orthodontists sometimes use temporary anchorage devices (TADs), which are small screws placed in the jawbone to provide a fixed point for moving teeth. TADs can expand the range of what braces alone can accomplish.
Clear Aligners for Mild Underbites
Clear aligners can treat some mild dental underbites, particularly those involving minor tooth positioning rather than jaw discrepancy. However, underbites are generally more challenging for aligners than overbites. If your underbite involves a skeletal component or significant tooth movement, braces will typically provide better control and more predictable results.
Jaw Surgery for Underbite Correction
Orthognathic (jaw) surgery is the standard treatment for moderate to severe skeletal underbites in adults. The most common procedure involves moving the lower jaw back, moving the upper jaw forward, or repositioning both jaws. An oral and maxillofacial surgeon performs the surgery, while an orthodontist manages braces before and after the procedure to align the teeth to the new jaw position.
Surgery is typically performed after jaw growth is complete, around age 17 to 19 for females and 18 to 21 for males. The full treatment process, including pre-surgical orthodontics, surgery, and post-surgical orthodontics, typically takes 18 to 30 months.
Early Intervention for Children
For children between ages 7 and 10, orthodontists may use growth modification appliances to address a developing underbite before the jaws finish growing. A reverse-pull headgear (face mask) applies forward force to the upper jaw to stimulate growth. A palatal expander can widen the upper jaw to improve its relationship with the lower jaw.
Early treatment does not guarantee that surgery will be avoided, but in many cases it reduces the severity of the underbite and may eliminate the need for surgical correction later. The American Association of Orthodontists recommends an orthodontic evaluation by age 7 to identify these opportunities.
How Long Does Underbite Correction Take?
Treatment duration depends on severity, treatment method, and patient age. Underbite correction generally takes longer than overbite correction because the mechanics of moving the lower jaw back or the upper jaw forward are more complex.
- Mild dental underbite with braces: 12 to 18 months
- Moderate underbite with braces and elastics: 18 to 24 months
- Underbite with jaw surgery (total process): 18 to 30 months
- Phase 1 early treatment in children: 6 to 12 months of active appliance wear, followed by monitoring during growth
How Age Affects Treatment Time
Children in active growth phases may respond to treatment faster because the orthodontist can redirect jaw growth rather than move fully developed bone. Teens who have recently finished growing respond well to braces for dental underbites. Adults with skeletal underbites face the longest timelines because surgery is typically part of the plan, and bone healing adds recovery time to the overall process.
Underbite Correction Cost
Costs for underbite correction vary significantly depending on the treatment approach and complexity. These ranges represent typical figures, though your actual cost will depend on your specific case, location, and provider.
Braces for a dental underbite typically cost $3,000 to $7,000. If jaw surgery is needed, the surgical component can range from $20,000 to $40,000 before insurance. Medical insurance, rather than dental insurance, may cover a portion of jaw surgery when it is deemed medically necessary for function, not just appearance.
Dental insurance with orthodontic benefits typically covers up to a lifetime maximum of $1,000 to $2,500 for braces. Many orthodontic offices offer payment plans to spread costs over the treatment period. Costs vary by location, provider, and case complexity.
When to See an Orthodontist About an Underbite
If your lower teeth sit in front of your upper teeth, or if you have difficulty chewing, speaking, or experience jaw pain, consult an orthodontist for an evaluation. For children, have an orthodontist assess any noticeable underbite by age 7 so early intervention can be considered while growth is still occurring.
An orthodontist can determine whether your underbite is dental, skeletal, or a combination, and recommend the most appropriate treatment path. For cases requiring surgery, the orthodontist will coordinate with an oral and maxillofacial surgeon to plan the full treatment sequence.
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