Underbite treatment aims to correct the Class III bite problem in which the lower front teeth close in front of the upper front teeth or the lower jaw protrudes in the face. The method is chosen according to the patient's age, the source of the problem (whether the lower jaw has grown too much, the upper jaw has lagged behind, or both) and the size of the discrepancy. In childhood it is possible to guide the development of the upper jaw; in adulthood the options are changing the position of the teeth or jaw surgery. Timing is especially important with this problem, because lower jaw growth is completed later than that of the other facial bones.
Why does the source of an underbite matter?
A picture that looks the same from the outside can arise from different causes, and each requires a different treatment:
- Pseudo (functional) Class III: The jaws are actually in harmony, but a contact between the front teeth shifts the lower jaw forward on closing. This is suspected if the front teeth can meet edge to edge when the jaw is guided back. Once the alignment of the teeth is corrected, the bite often returns to normal.
- Underdeveloped upper jaw: In a significant share of Class III cases, the real problem is that the upper jaw has not grown forward enough. In these patients the middle of the face may look flat.
- Excess lower jaw (true prognathism): The lower jaw is large in size. A similar jaw structure is often seen in the family; heredity plays a clear role.
- Mixed picture: The upper jaw may be set back and the lower jaw forward at the same time; a crossbite in the side teeth may also be present.
This distinction is made with a cephalometric X-ray, facial analysis and a bite examination. You can find what the bite classes mean on our bite classes page, and general information on jaw deformities in our article jaw deformities.
How is an underbite treated in children?
When a reverse bite of the front teeth is noticed, an orthodontic assessment should be done without waiting. Early intervention aims to make use of the upper jaw's growth potential and to prevent wear of the front teeth or damage to the gums caused by the reverse bite. For the general logic of early treatment, see our early orthodontic treatment page.
Expansion and the face mask
In children with an underdeveloped upper jaw, a common approach is to use an appliance that widens the palate together with a face mask (reverse-pull headgear) worn at night and at home. Expansion relieves narrowness in the upper jaw and corrects crossbite in the side teeth, while the face mask applies a forward force to the upper jaw. This treatment generally responds better at around 6–10 years of age, while the growth areas of the upper jaw are more flexible. Wearing the mask every day for the time set by the orthodontist directly affects the result. How the mask is used is explained in our article the orthodontic face mask; for expansion, see our jaw expansion treatment page.
Bone-anchored methods in older children
In children for whom it is too late for a face mask but who are still growing, some centers apply elastic force via small plates or mini-screws placed in the jawbone. This method requires a minor surgical procedure and is not suitable for every patient; the choice is made jointly by the orthodontist and the surgeon.
Does early treatment solve everything?
An important point for families to know is this: even if early treatment is successful, the lower jaw may continue to grow during and after puberty. For this reason, in some children the reverse bite becomes noticeable again in adolescence. Early treatment aims to reduce the treatment that may be needed at a later stage and, in some patients, to eliminate the need for surgery; however, it cannot achieve this in every patient. That is why regular follow-up is planned after treatment.
How is an underbite treated in adults?
In people who have finished growing, the size of the jaws cannot be changed with appliances. The choice is between two main routes.
Orthodontic camouflage
In adults with a mild skeletal discrepancy who are generally happy with their profile, the bite is corrected by adapting the teeth to the jaws. This involves moving the lower teeth backward (with mini-screw support when needed), bringing the upper front teeth slightly forward, Class III elastics or, in some cases, extractions in the lower jaw. In suitable cases these movements can also be planned with the Invisalign system; the limits of aligner treatment in this respect are explained on our can clear aligners fix jaw structure page. Because the lower front teeth are tipped backward in camouflage, the condition of the gums and bone at the lower front is carefully assessed; in patients with thin gums the limits are narrower.
Orthodontics and orthognathic surgery
If the discrepancy is pronounced, if the profile bothers the patient, or if camouflage would force the teeth to the limits of the bone, jaw surgery is planned alongside. In the operation the upper jaw may be moved forward, the lower jaw moved back, or both jaws treated together; which is chosen depends on the source of the problem. The process consists of three stages: pre-surgical orthodontics in which the teeth are prepared for surgery, the surgery performed in a hospital, and post-surgical orthodontics in which the bite is completed. For general information on the surgery, see our article orthognathic surgery.
Why wait for growth to finish before surgery?
The lower jaw is the part of the facial skeleton that completes its growth last, and in people with a Class III tendency this growth can continue until the end of adolescence. If the lower jaw keeps growing forward after an operation performed before growth has ended, the problem can reappear. For this reason, surgery is usually planned after X-ray follow-up has confirmed that growth has finished. During the waiting period, limited orthodontic procedures can be carried out to protect the health of the teeth and avoid complicating future treatment.
Which option suits whom?
- Young children with a reverse bite of the front teeth: First it is determined whether it is a pseudo Class III; if the upper jaw is underdeveloped, expansion and a face mask are considered.
- Teenagers who are still growing: If the discrepancy is mild, preparation for camouflage is discussed; if it is pronounced, growth monitoring and a future surgical plan are discussed.
- Adults with a mild discrepancy: Camouflage with fixed braces or, in suitable cases, clear aligners.
- Adults with a pronounced skeletal discrepancy: Orthodontics combined with jaw surgery.
If a crossbite of the side teeth is also present, you can also see our clear aligners for crossbite page for treatment of that problem.
What questions should you ask when deciding?
Since Class III treatment can be a long process, it is important to clarify the options at the examination. The following questions make the consultation more productive:
- Is the problem caused by an excess lower jaw, an underdeveloped upper jaw, or a shift of the teeth?
- What stage of growth is this; is it better to start treatment now or to wait?
- If camouflage is done, what changes in the profile and what does not?
- If surgery is needed, how are the orthodontic and surgical phases planned, and what is the total duration?
- How often will check-ups be needed after treatment, and how long will the retainer be worn?
To prepare for the examination, you can also use our orthodontic consultation question list page. Since the fee varies depending on the chosen route and duration, it is provided in writing after the examination and planning.
What do follow-up and retention look like after treatment?
In Class III treatment, retention and follow-up are kept longer than for other bite problems. In children, regular check-ups are done until growth is complete; if the bite is seen to worsen again, the plan is updated. In adults, fixed and removable retainers are used together at the end of treatment. After surgery, elastics and retainers are used as directed by the orthodontist until bone healing is complete. If you notice a change in your bite, the position of your front teeth or how your jaw sits in your face between check-ups, reporting it without waiting for the next appointment allows any necessary adjustment to be made early. Details on retainer use are on our retainer after treatment page.