An underbite is fixed by moving the teeth, guiding jaw growth, or both. Children are often treated with an expander and reverse-pull facemask while the jaws are still growing. Teens and adults are treated with braces or aligners, and severe skeletal cases with jaw surgery.
What is an underbite?
An underbite is a bite where the lower teeth sit in front of the upper teeth when you close. As our common orthodontic issues page puts it, the lower jaw extends further than the upper jaw. Orthodontists call it a Class III bite. It is the mirror image of an overbite, and it is one of the bite problems we take most seriously in children, because the right timing changes the whole treatment plan.
Dental underbite vs. skeletal underbite
Not every underbite is the same problem. In a dental underbite, the jaws are a reasonable size and position but the front teeth are tipped, so the lower incisors end up in front. In a skeletal underbite, the jaws themselves are out of proportion: the upper jaw is short or narrow, the lower jaw is long, or both. Many people have a mix of the two. Telling them apart is the first job of the exam, because tipping teeth cannot fix a jaw that is the wrong size.
How is it different from a crossbite or an overbite?
With an overbite, the upper front teeth overlap the lower ones too much; our overbite vs. open bite guide covers that pattern. With a crossbite, some upper teeth sit inside the lower teeth, which can affect only one or two teeth or one side of the mouth. A front crossbite on a single tooth can look like an underbite, but it is a smaller and more local problem than a full Class III bite.
What are the signs of an underbite?
A pronounced underbite is easy to see. A mild one often is not, and parents are usually the first to notice something is slightly off in photos or when their child chews.
- Lower front teeth that close in front of the upper front teeth
- A chin and lower lip that look prominent in profile
- Difficulty biting into food with the front teeth, or chewing that looks effortful
- Speech changes, especially with sounds made at the front of the mouth
- Uneven wear on the front teeth, because the teeth do not meet evenly
- Jaw discomfort or a jaw that shifts forward to close
Our practice page notes that an untreated underbite can cause facial imbalance, pain or difficulty chewing and speaking, and premature tooth wear. Those are the reasons it is worth checking even when it does not bother your child yet.
What causes an underbite?
Most skeletal underbites are inherited. Jaw size and growth pattern run in families, so a parent or grandparent with a strong lower jaw is a useful clue. Other contributors include an upper jaw that has not grown forward or wide enough, early loss of baby teeth, missing teeth, and habits such as low tongue posture or prolonged thumb sucking. Facial trauma can also change how the jaws meet. Whatever the cause, the treatment decision depends on how much growth is left.
How is an underbite diagnosed?
A look at the bite is only the start. To separate a dental underbite from a skeletal one, we use the records described on our orthodontic technology page: digital x-rays, PreXion cone beam CBCT imaging where 3D detail is needed, and a TRIOS intraoral scan that builds a precise 3D model of the teeth in a few minutes. Together they show how the jaws relate to each other, how the front teeth are angled, and how much growth may be left, which is what decides between guiding growth, moving teeth, or planning surgery.
What is the best age to fix an underbite?
Earlier is better for skeletal underbites. The American Association of Orthodontists recommends a first orthodontic screening by age 7, and our early intervention approach is built around that check. At that age the upper jaw is still growing, which means it can be guided rather than surgically moved later.
Ages 7 to 10: the growth window
Our orthodontic appliances page describes the reverse-pull headgear, or orthodontic facemask, as especially helpful for young patients ages 7 to 10. It pulls the upper jaw forward and treats underbite conditions that might otherwise require jaw surgery to correct. It is often paired with a palatal expander, which widens a narrow upper jaw first.
Teens
By the teen years, much of the upper jaw’s growth has happened, while the lower jaw can keep growing into the late teens. Dental underbites still respond well to braces or aligners. For skeletal cases, the plan has to account for that late lower-jaw growth, so treatment may be timed or staged rather than started immediately.
Adults
Once growth has finished, the jaws can no longer be guided. Adults with a mild underbite can often be treated by repositioning the teeth alone. Adults with a significant skeletal underbite usually need orthodontics combined with corrective jaw surgery for a stable, balanced result.
How is an underbite treated?
The right treatment depends on age, how much of the problem is skeletal, and what you want from the result. The table below sets out the main options we use at our offices.
| Treatment | Typically used for | What it does |
|---|---|---|
| Palatal expander | Children with a narrow upper jaw | Widens the upper jaw gradually so the upper teeth can sit outside the lower teeth |
| Reverse-pull facemask | Children roughly ages 7 to 10 | Pulls the upper jaw forward while it is still growing |
| Braces | Dental underbites at any age; part of most skeletal plans | Moves teeth into a correct bite, often with elastics |
| Clear aligners | Mild to moderate dental underbites | Moves teeth with removable trays and elastics where needed |
| Braces plus jaw surgery | Severe skeletal underbites after growth | Repositions the jaw bones, then braces finish the bite |
Expanders and facemasks for growing children
The expander is bonded to the upper molars and activated with a small key, widening the palate a little at a time. The facemask attaches to the expander with elastics and rests on the forehead and chin, and it is usually worn at home and overnight rather than at school. Because this works with growth instead of against it, it is the phase where dentofacial orthopedics makes the biggest difference. Dr. Battle has over 20 years of experience in both orthodontics and dentofacial orthopedics.
Braces and clear aligners
Braces and aligners correct the tooth part of an underbite. Elastics are commonly used to help draw the upper and lower teeth into a better relationship, which is why consistent wear matters so much. In a mild skeletal case, an orthodontist may plan tooth movement that disguises the jaw difference, sometimes called camouflage treatment. Whether that is appropriate depends on your profile and on how far the teeth can safely move.
Corrective jaw surgery
When the jaw difference is too large for teeth alone, surgery repositions the jaw bones. Our corrective jaw surgery page explains that the surgery is performed by an oral and maxillofacial surgeon, usually in a hospital, with about a two-week recovery. Braces typically continue for 6 to 12 months afterward, followed by a custom retainer.
Can an underbite be fixed without surgery?
Often, yes. Dental underbites and many mild skeletal underbites are corrected without surgery. In children, early treatment with an expander and facemask is specifically aimed at reducing the chance that surgery will be needed later. Surgery is generally reserved for adults with a significant skeletal difference, where moving teeth alone would leave the bite unstable or make the profile worse.
Does an underbite get worse with age?
A skeletal underbite can become more noticeable through the teen years, because the lower jaw may keep growing after the upper jaw has slowed. In adults the jaws stop growing, but the effects of the bite continue: front teeth wear down, chewing stays inefficient, and jaw strain can build. That is why an underbite is rarely something we recommend waiting on without at least monitoring.
Monitoring when treatment is not needed yet
Not every child with a developing underbite needs an appliance right away. If the timing is not right, children can join our Kids Club for regular check-ins, so we can follow their growth and start treatment at the point where it will do the most good.
Frequently asked questions
Will my child have to wear the facemask at school?
Usually not. The facemask is typically worn in the evenings at home and overnight. The exact wear schedule is set at the start of treatment and checked at each visit.
Can Invisalign or clear aligners fix an underbite?
Clear aligners can correct many mild to moderate dental underbites, often with elastics. They cannot change the size of the jaws, so a skeletal underbite needs a different plan.
How long does underbite treatment take?
It depends on the type of underbite and the treatment used. Full braces or aligner treatment commonly runs 12 to 36 months, and cases involving surgery include extra time before and after.
Is a mild underbite worth treating?
Often, yes, because even a mild underbite can wear the front teeth and strain the jaw over time. An exam will tell you whether it needs treatment now, later, or simply monitoring.
Book a complimentary exam in Winter Springs, Oviedo or Waterford Lakes
If you have noticed your child’s lower teeth closing in front, or you have lived with an underbite yourself, an exam is the quickest way to know what kind it is. Dr. Battle is a board-certified orthodontist who sees patients in Winter Springs, Oviedo and Waterford Lakes. Request a complimentary exam and we will walk you through every option.
