An underbite, medically termed a Class III malocclusion, is a condition where the lower jaw and teeth sit too far forward relative to the upper jaw when the mouth is closed. This misalignment causes the lower front teeth to overlap the upper front teeth, a reversal of the normal bite relationship. Whether this condition can be corrected without surgery depends heavily on the underlying cause and the patient’s age. While severe cases in adults often require surgery, non-surgical treatment is frequently possible and highly successful, particularly when intervention begins early.
Understanding the Cause and Patient Age
The key to non-surgical success lies in distinguishing between a dental and a skeletal underbite. A dental underbite involves misaligned teeth, where the lower teeth are positioned forward, even though the underlying jawbones are correctly aligned. This type of malocclusion is simpler to correct using only braces or clear aligners, as the issue is confined to the teeth’s positioning.
A skeletal underbite stems from a structural issue where the bones themselves are misaligned, usually because the lower jaw (mandible) is overgrown or the upper jaw (maxilla) is underdeveloped. The severity of this skeletal discrepancy is the most important factor determining the treatment path. While an underbite with a mild skeletal component may be treatable without surgery, a large discrepancy requires surgical intervention.
The patient’s age is the second determinant factor, as the jawbones are still actively growing and malleable during childhood and pre-adolescence. This period offers a valuable window for “growth modification,” a non-surgical approach that physically guides the jawbones into a better position. Once growth is complete, typically in the late teens, true bone-structure correction without surgery is no longer possible.
Non-Surgical Growth Modification for Children
Growth modification is an interceptive orthodontic treatment designed to manage the development of the upper and lower jaws in children. The goal is to encourage the forward growth of the underdeveloped upper jaw and, in some cases, restrict the forward growth of the lower jaw. This treatment is most effective when initiated before the child experiences their pubertal growth spurt, often between the ages of seven and ten.
One common device used is the reverse-pull headgear, also known as a protraction facemask. This removable appliance rests on the forehead and chin and connects to the upper teeth or a palatal expander via elastic bands. The continuous force applied by the facemask gradually pulls the upper jaw forward, correcting the skeletal imbalance over time.
A palatal expander is frequently used in conjunction with the facemask to widen the upper arch. This appliance is fixed to the upper back teeth and is periodically adjusted to apply pressure to the midpalatal suture, effectively widening the upper jaw. Expanding the upper jaw creates a better foundation to accommodate the lower arch and prepares the upper jaw for forward movement.
Another appliance, the chin cap, is sometimes used to restrain the forward and downward growth of the lower jaw, complementing the efforts to advance the upper jaw. The success of these techniques relies heavily on consistent patient compliance, often requiring the devices to be worn for many hours each day.
Non-Surgical Orthodontic Camouflage for Adults
For adults and older teenagers whose jaws have finished growing, non-surgical correction of a mild to moderate skeletal underbite is achieved through orthodontic camouflage. This method avoids changing the jawbone’s position and instead focuses on adjusting the angle and position of the teeth to hide the underlying skeletal discrepancy. The treatment uses traditional braces or clear aligner systems to achieve the necessary tooth movement.
The process involves tilting the upper front teeth forward and the lower front teeth backward, creating a functional bite relationship and improving the appearance of the smile. To create the space needed to retract the lower teeth, the orthodontist may recommend specific tooth extractions, often of the lower premolars. Removing a tooth allows the remaining lower teeth to be moved back significantly enough to meet the upper teeth in a more favorable alignment.
While camouflage treatment can yield excellent aesthetic and functional results for mild skeletal issues, it has limitations. It does not alter the jaw structure itself, meaning the facial profile remains largely unchanged, which may not be ideal for patients with a very prominent lower jaw. Furthermore, excessive tooth tipping can sometimes compromise the long-term stability or health of the teeth. This makes it a treatment reserved for specific, less severe cases.
When Jaw Surgery is the Only Option
Jaw surgery, or orthognathic surgery, is reserved for individuals with a severe skeletal Class III malocclusion, where the difference in size or position between the upper and lower jawbones is too great for non-surgical methods to overcome. Adjusting the teeth alone in these cases would result in an unstable bite or an unacceptable facial appearance.
The procedure involves a maxillofacial surgeon physically repositioning one or both jaws to achieve a correct skeletal and dental relationship. Surgery is always preceded by orthodontic treatment, often lasting 12 to 18 months, to align the teeth properly so they fit together once the jaws are moved. This path is pursued when non-surgical camouflage is insufficient to solve significant functional problems, such as difficulty chewing, chronic jaw pain, or severe aesthetic concerns.