Underbite Treatment

If the patient is an adult, and the underbite is skeletal, surgery is usually required. Braces are worn for about 1 1/2 years before surgery and for 9 to 12 months afterward.

During the operation, the surgeon pushes the lower jaw backyards, pulls the upper jaw forward, or both.

If the underbite is confined to the teeth and there is no skeletal involvement, the malocclusion can potentially be corrected with braces alone.

If the patient is under age 8, and if the lower jaw is outgrowing the upper jaw, surgery may be avoided. The treatment typically begins with an upper jaw expander. This molded plastic and wire device is fixed to the roof of the mouth for about a year. Each night for the first few weeks, the parent uses a key to open the expander slightly. Once the proper jaw width is achieved, the expander remains in place for several more months before being replaced with a retainer. This helps ensure that the upper jaw hardens in its new position.

At around age 8 or 9, the child is fitted with a "reverse-pull face mask," which is worn after school and at night. The mask is anchored to the mouth with rubber bands, which are attached to hooks near the corners of the mouth or to metal bands around the top back molars. The gentle but steady pressure exerted by the rubber bands on the upper jaw encourages bone growth. In effect, the upper jaw is "pulled out" like a dresser drawer.

If the underbite is mild or moderate, the lower jaw is left alone. In severe cases where growth of the lower jaw needs to be restrained, the child may also, wear a chin cup. The cup wraps around the chin and the top of the head. How long the child wears the face mask and chin cup depend on the severity of the underbite; a year is fairly typical.

While the reverse-pull face mask treatment obviates the need for surgery in the majority of cases, sometimes the discrepancy between the lower and upper jaws is so great that surgery is still needed.

After treatment with the face mask or surgery, the child may still need to wear standard braces for 2 to 3 years, followed by a retainer for another 2 years or longer, to achieve and maintain an ideal bite.

What Is the Long-Term Success Rate for Correcting an Underbite?
The success rate of surgical and nonsurgical correction of an underbite are both extremely high. Parents who have undergone surgery for their underbite are usually thrilled to learn that their children can avoid surgery if orthodontic treatment begins early.

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