An underbite is an orthodontic condition that results in the lower teeth approximating or landing in front of the upper teeth. There is a deep bite in the mandible, which often juts out more than it is supposed to, affecting the placement of the teeth. Ideally, the mandibular teeth are supposed to lie behind the incisors of the upper jaw. The underbite can affect just the incisors but more commonly affects the entire bite, including the molars. The lower jaw appears more prominent than it is supposed to look.
What causes underbite?
The causes of an underbite are mostly genetic. There are some acquired reasons why a child may develop an underbite, including the prolonged use of infant pacifiers, excess pressure on the lower jaw by the tongue and excessive thumb sucking. Children who must mouth breathe because of enlarged adenoids or allergies can also develop an underbite. Bad habits in chewing foods results in a worsened underbite.
Underbites need to be treated as soon as they begin to occur because they tend to worsen over time. Parents must stop their child’s thumb sucking and diminish other behaviors that are making the underbite worsen. Orthodontics may be necessary early in life to prevent worsening of the condition.
Underbite Symptoms:
The symptoms of an underbite include pain and difficulty chewing, headaches and eventual temporomandibular joint syndrome. This is an inflammation and arthritis of the temporomandibular joint near the temples, which is the joint between the mandible (the lower jaw) and the rest of the head. You can get a “long face syndrome” in which the bite is open and the face appears long. In addition, you can have a “toothless smile” in which the upper jaw is smaller than the lower jaw and the lower lips cover the teeth when smiling.
Complications
The major complication of an underbite is temporomandibular joint syndrome. The TMJ or temporomandibular joint begins to wear away from an abnormal chewing experience. The cartilage eventually wears away and then the bone begins to wear onto bone. The resultant problem causes grinding when chewing, chronic headaches and jaw pain. If severe, it needs to be treated surgically with replacement of the temporomandibular joint.
An underbite can wear at the gingiva in an abnormal way so that you can get gingivitis and periodontal disease. This can undermine the entire structure and function of the mouth so that tooth loss is more likely and damage to the gingiva can occur.
Underbite Prevention:
An underbite may not be preventable if it is genetic. If a child is showing tendencies toward having an underbite, you need to eliminate things like the pacifier, tongue thrusting behaviors and thumb or finger sucking.
Treatment Options:
The best age to treat an underbite is when the child is about 8 years old. Reshaping of the jawbone is easier to accomplish because the bone is more malleable. At eight years old or less than that, surgery might not be required and orthodontic appliances can be used. An expander is used similar to a turnkey that gradually reforms the bone so that the underbite is resolved. The expander is not worn permanently but is worn for a certain number of hours each day for around two to three months, if the underbite isn’t bad.
If the child is between eight and nine years of age, an expander may not work. The orthodontist may need to use a “reverse-pull face mask” that looks like a catcher’s mask. It is worn for several hours per day after school or when sleeping. It can reverse the underbite in several months. For a deep underbite, a chin cap is required. This holds back the growth of the child’s mandible and is used along with or before a reverse-pull face mask. Braces may still be required for an additional two to three years. After the braces have done their work, the child may need a retainer for two or more years to keep the bite in its perfect shape.
Adults with an underbite often need surgery. The underbite has become skeletonized and a piece of bone is required to be removed and reset so the jaw fits perfectly after the surgery. The adult with an underbite also needs to wear a year’s worth of braces before surgery and about 6-9 months of braces after surgery.