Underbite: Causes, Risks, Treatments, and Correction Surgery

perfect teeth
  • A severe underbite can cause jaw pain, headaches, speech issues, and tooth decay.
  • Treatment options in children are non-surgical and involve orthodontic approaches.
  • In adults, underbite correction generally requires both surgery and braces.

An underbite, or prognathism as dentists call it, is one of the most noticeable of all dental problems. A severe underbite changes the overall shape of the face, distorting features and making one’s chin stick out. It can also lead to a host of chronic health conditions.

Fortunately, prognathism is treatable. Depending on the condition’s severity, various options can be pursued to help sufferers regain their self-confidence and quality of life.

What is an underbite?

An underbite is a type of malocclusion, or bite abnormality, which occurs when the lower jaw extends upwards and out beyond the upper row of teeth.

When underbite sufferers close their mouths, their chins are forced forwards and tend to protrude outwards. This can make a face appear long and flat, with the chin seeming larger and more pronounced than normal.

Why are underbites bad?

The negative effects of having an underbite depend on how severe the condition is. Somewhere between 5%-10% of the population suffers from some degree of underbite. Some are barely detectable while other, more serious underbites are extremely noticeable and can have strong, negative effects on self-image and quality of life.

Aside from the aesthetic issues associated with having an underbite, underbites are responsible for a variety of negative health effects:

  • TMJ pain — The temporomandibular joint (TMJ) connects the jawbone to the skull. Underbites put extra pressure on this joint, which in turn can cause chronic aches and pains. TMJ pain caused by an underbite can also radiate to the surrounding areas, causing facial pain, ear pain, and headaches.
  • Tooth decay and gum disease — An underbite causes teeth to wear down unevenly, leading to tooth decay, gum disease and an eventual loss of tooth enamel.
  • Altered alignment of teeth — The abnormal stresses that an underbite places on teeth can alter their alignment and make them crooked over time.
  • Problems chewing and swallowing — Our ability to chew depends on the proper alignment of the upper and lower jaw. In severe cases, a misalignment makes chewing and swallowing more difficult.
  • Speech problems — Speech issues can also develop as the positions of the tongue and teeth are altered by the bite abnormality. Underbite sufferers can speak with a lisp and/or slur certain words.
  • Sleep apnea and snoring — Severe underbites can contribute to snoring, apnea, and other difficulties breathing during sleep.

What causes an underbite?

In the most simple terms, an underbite is a misalignment of the teeth where the lower teeth make contact with the upper teeth at a point that is too far forward. But what causes this misalignment to happen in the first place?

Most of the time, the simple answer is genetics.

According to research conducted at the University of Florida, garden variety heredity is the primary cause of most underbites. If your mother or father had an underbite, there’s a better than average chance you will too.

Aside from genetics, certain childhood practices are also commonly to blame. Underbites can form in childhood due to thumb sucking and too much time spent with a bottle or pacifier. Using a pacifier or bottle for too many years can delay the turnover of baby teeth. When some of our adult teeth emerge too slowly, it can contribute to future alignment issues.

After childhood, a range of other, somewhat less likely causes can also contribute to the development of an underbite. These range from lost teeth and impacted teeth to poor fitting dental fillings and braces. However, no cause is as likely as the simple roll of the dice that genetics plays.

Will an underbite go away by itself?

An underbite in a child may be self-correcting. As our teeth develop in childhood, it is not uncommon to experience a temporary malocclusion.

Adult underbites, on the other hand, are a different story. If the issue persists throughout childhood, it may become more pronounced in the late teens and early twenties.

“Underbites tend to get worse,” explains K. Shaikh of Royal Dental in Houston. “The lower jaw grows later and for a longer duration than the rest of the body. And since the lower jaw dictates the position of the lower teeth, things generally don’t get better with time.”

What are the treatment options for correcting an underbite?

The treatment options for correcting an underbite depend on whether the sufferer is a child or an adult. While it’s never too late to start treating an underbite, it’s easier to fix in childhood than later in life. A child’s jaw is easier to manipulate because it’s still in the process of growing.

Underbite treatments fall into two categories: surgical and nonsurgical.

Fixing an underbite in children

For children, correction methods consist of:

  • Braces — Braces can be worn at any age, but it’s a better idea to start early for aesthetic and social reasons — and because adjusting teeth alignment is easier in children.
  • Upper jaw expanders — An “upper jaw expander” is a mechanical device which is fitted to the upper jaw. The device is expanded daily to slowly pull the lower jaw into the correct alignment.
  • Chin caps — A chin cap is an external device which physically limits the growth of the lower jaw. Chin caps consist of a cup-like device which wraps around the chin and connects with straps around the back of the head. Chin caps can be worn while sleeping.
  • Reverse face masks A reverse face mask, also called a reverse-pull face mask (RFM), is another external device which connects to the top row of teeth. The mask device pulls the upper row of teeth forwards into the correct position while placing inverse pressure on the lower jaw and upper face.

Correcting an underbite for adults

For adults whose jaws are less easy to manipulate, the options are slightly different:

  • Tooth extraction — Dentists often remove teeth in order to decrease the pressure caused by tooth overcrowding, enabling them to correct the alignment of the remaining teeth.
  • Surgery — Dentists may recommend surgery to correct an underbite. By physically shifting the relative position of the jaws, the misalignment can be corrected.
  • Braces — Braces are commonly used in conjunction with both of the above procedures. The alignment of the teeth is often prepared by wearing braces for a period of time prior to underbite surgery.  Some adults opt to use clear aligners such as Invisalign or Smile Direct to straighten their teeth and fix their underbite without anyone noticing.

When is surgery necessary to correct an underbite?

Orthognathic surgery, or corrective jaw surgery, is required only when orthodontic, non-surgical approaches are insufficient. Only your orthodontist can make this decision.

“In some patients, there is an imbalance in the positions of the upper and lower jaws,” explains Shaikh. “If the lower jaw is much further forward than the upper jaw, the result is a skeletal underbite. In such situations, your orthodontist will work along with an oral maxillofacial surgeon to correct the positions of the teeth as well as the underlying skeletal imbalance.”

Typically, underbite surgeries are only performed on adult patients. For underbites in children, a non-surgical approach is preferred.

“When we see teenagers or adults who have underbites, depending on the severity, they may not be correctable by orthodontics alone,” informs orthodontist Seth Newman of Newman Orthodontics. “Sometimes jaw surgery is needed in conjunction with orthodontics, but surgery cannot be performed until growth is completed, which usually happens at age 18 or 19 with females and 21 or 22 for males.”

What are the risks of underbite surgery?

All surgeries carry some level of risk. The risks of orthognathic surgery include nerve damage and numbness in the lower jaw and chin, and the possibility that TMJ pain will be worse after surgery. There is also the risk that the jaw will return to its original misaligned position.

“The risks of surgery are like any other surgical intervention,” explains Dr. Ken Danyluk of Hidden Braces Boutique in Scottsdale, AZ. “Although minimal chances of these events occurring exist, excessive bleeding, nerve structure effects in the area of the surgery, and some initial swelling are some of the areas always reviewed prior to any surgery.”

Do you have to treat an underbite?

Whether or not you treat an underbite is largely a quality of life question. If your underbite is causing low self-esteem, pain, or creating oral health issues, then you should absolutely consult with your dentist or orthodontist.

“There are the cosmetic aspects to consider,” notes Newman. “Aesthetically, facial features look better when they are corrected. Dentally, when there are underbites, teeth are not meeting properly and have adverse pressures on them which can lead to chipping or excessive wear.”

If your underbite isn’t pronounced or causing problems, however, you may wish to wait. As Newman is quick to point out, “many people with underbites lead perfectly healthy and functional lives.”

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