Dental & oral health

How an Underbite Gets Fixed

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An underbite is the least common type of malocclusion and, more often than an overbite or a crossbite, tends to involve the jaw bones themselves rather than just tooth position — which is why it is treated differently at different ages. This covers how an underbite is diagnosed, why early treatment changes the options, and what correction looks like for a teenager or adult whose jaw has already finished growing.

Last updated: July 2026

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What Makes an Underbite Different From Other Bite Problems

An underbite happens when the lower front teeth close in front of the upper front teeth, the reverse of a normal bite, and it is one of several types of malocclusion along with an overbite and a crossbite. Dentists sometimes call it a Class III bite relationship, and compared with an overbite or crossbite, an underbite more often involves an actual mismatch in jaw size or position — either a lower jaw that grew too far forward, an upper jaw that grew too far back, or some combination of both — rather than simply teeth that erupted in the wrong spot.

That skeletal tendency is the main reason underbite treatment is discussed differently than the other bite problems: the earlier a true jaw-growth mismatch is caught, the more treatment options remain open, because some of them only work on a jaw that has not finished growing.

Why Catching It Early Changes Everything

The American Association of Orthodontists recommends every child have an orthodontic check-up by age 7, once enough permanent teeth are in for a dentist to judge how the jaws are developing relative to each other 1. An underbite is one of the clearer reasons for that early visit, since a lower jaw growing forward faster than the upper jaw is a pattern that is often visible well before all the permanent teeth have erupted.

Most 7-year-olds seen for a routine evaluation need nothing more than monitoring, but a child with a developing underbite is more likely than most to be a candidate for early, growth-guided treatment 2 — treatment that becomes unavailable once the jaws have finished growing, typically by the late teens.

Growth Appliances for a Child's Developing Underbite

When a child's underbite comes from the upper jaw growing behind where it should, an orthodontist may use a removable or fixed appliance designed to encourage forward growth of the upper jaw while the child still has active growth to work with — commonly a facemask-style device worn largely at home, since it relies on hours of daily wear against the forehead and chin to apply gentle forward pressure on the upper jaw. If the cause is instead a lower jaw growing too far forward, a different family of appliances aims to restrain or redirect that growth.

These devices only work on a growing skeleton, which is why a child treated this way is typically re-evaluated periodically through the remaining growth years, since an underbite pattern caused primarily by jaw growth can continue to progress even after an early appliance phase, sometimes requiring a second phase of treatment as a teenager.

When Braces or Aligners Are Enough

A mild underbite that comes mainly from tooth position on jaws that are reasonably well matched in size can sometimes be corrected with braces or clear aligners alone, moving the upper and lower teeth into a normal relationship without addressing the jawbones themselves. This is far less common for an underbite than it is for crossbite correction or overbite correction, precisely because a true skeletal mismatch is more often the driver behind a reversed bite.

An orthodontist determines which category a given underbite falls into with a clinical exam and imaging that measures jaw position, not by how pronounced the underbite looks in the mirror — a subtle-looking underbite can still be primarily skeletal, and a more visible one can sometimes be corrected with braces alone.

Jaw Surgery for a Skeletal Underbite in Teens and Adults

Once jaw growth is complete, a genuinely skeletal underbite — one where the lower jaw is meaningfully larger or more forward than the upper jaw — usually cannot be corrected by moving teeth alone. Orthognathic jaw surgery repositions the jawbone itself, typically preceded by a period of braces to align the teeth in preparation for surgery and followed by more orthodontic work once the jaw has healed to fine-tune the final bite.

This surgical path is why an underbite noticed for the first time in a teenager or adult, after growth has finished, is worth a specialist evaluation sooner rather than later: the earlier a genuinely skeletal case is identified, the more time there is to plan a combined orthodontic-and-surgical approach rather than attempting a tooth-only fix that will not hold.

Why an In-Person Evaluation Is Especially Important Here

The American Association of Orthodontists has warned that moving teeth is a medical procedure that should be supervised in person by a licensed professional, and that direct-to-consumer aligner kits are not built to distinguish a tooth-position bite problem from a skeletal one; in an AAO member survey, 77% of orthodontists reported treating patients who needed retreatment after a course of direct-to-consumer aligners 3.

That distinction matters more for an underbite than for most other bite problems, given how often the underlying cause is skeletal rather than purely dental. An aligner kit marketed for cosmetic straightening is not designed to evaluate jaw position, and using one on a true skeletal underbite can leave the actual mismatch unaddressed even if the front teeth look somewhat straighter afterward.

What an Untreated Underbite Can Lead To

An underbite that is never addressed does not typically resolve on its own, and a pronounced one can make chewing and biting into food genuinely difficult, since the front teeth are not meeting the way they are meant to. Over years, an untreated underbite can also concentrate uneven wear on certain teeth and contribute to jaw joint strain, since the jaw is working from an altered position on every bite.

There is also a visible dimension some people are simply used to living with — a pronounced underbite changes the profile of the lower face — and while that alone is not a medical reason to treat it, plenty of people pursue correction for that reason combined with the functional ones. None of this makes an underbite an emergency at any age, but it is a reason to raise it with a dentist rather than assume nothing can be done once childhood has passed.

Common questions

Yes — dentists use 'Class III malocclusion' as the clinical term for what is commonly called an underbite, where the lower front teeth sit in front of the upper front teeth instead of behind them. The terms describe the same bite relationship; 'Class III' is simply the classification a dentist or orthodontist writes in a chart.

Yes, though the options differ from a child's. Growth appliances no longer work once jaw growth is finished, so adult correction relies on braces or aligners for milder, tooth-position cases, and on jaw surgery paired with orthodontics when the underbite is genuinely skeletal.

That determination is made by an orthodontist through imaging that measures jaw position and growth pattern, not by how the bite looks. An evaluation around age 7 is the recommended starting point, since it identifies whether the pattern is likely to be skeletal well before growth is finished.

Most children report some pressure or mild soreness when a growth appliance is first worn or adjusted, similar to the adjustment period with braces, but not sharp pain. Persistent pain, sores that do not heal, or an appliance that is cutting into the gum or cheek is worth reporting to the orthodontist.

An underbite more frequently involves a true mismatch in jaw size or position rather than just tooth placement, compared with an overbite, which is more often correctable with braces alone. That tendency toward a skeletal cause is why surgery comes up more often in underbite treatment discussions.

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When an Underbite Needs Prompt Attention

  • —difficulty biting into or chewing food that is worsening over time
  • —a bite that changes suddenly rather than gradually, especially after facial trauma
  • —jaw pain, clicking, or difficulty opening the mouth fully alongside a known underbite
  • —speech that is affected by how the front teeth meet

This article is educational and does not replace a clinical exam and treatment plan from a licensed dentist, orthodontist, or oral surgeon.

References

  1. 1.American Association of Orthodontists (2024). The Milestone Visit: Why Age 7 is The Best Age For Orthodontic Treatment. American Association of Orthodontists. linkThe AAO recommendation that children have an orthodontic check-up by age 7, used to frame when a developing underbite is typically first identified.
  2. 2.American Association of Orthodontists (2024). What Are the Benefits of Early Orthodontic Treatment?. American Association of Orthodontists. link ✓The rationale and limits of interceptive early treatment, used to explain why a child with a developing underbite is a stronger candidate for early, growth-guided treatment than most 7-year-olds.
  3. 3.American Association of Orthodontists (2024). AAO Highlights Health Risks of Mail-Order Orthodontics. American Association of Orthodontists. link ✓The professional-supervision position and the 77% retreatment survey figure, used to explain why an in-person diagnosis matters for distinguishing a tooth-position underbite from a skeletal one.

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — citations link their sources. Editorial policy

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