Few dental patients have a perfectly balanced bite, but for most, treatment is unnecessary. However, an uneven bite can cause significant problems like teeth-clenching, jaw misalignment, and speech issues. One of the most common bite problems is an underbite when the lower jaw protrudes past the upper teeth. Though not as common as an overbite, about one in every 20 people has the condition. For many individuals with underbites, mild to severe TMJ can result in clicking and pain in the jaw, teeth-grinding at night, and worn-away enamel, a precursor to tooth decay. Underbites can be corrected if necessary. The method of correction depends on the severity of the patients age, misaligned bite, and financial cost. Generally, the earlier an overbite is treated, the less invasive the procedure is. We take a look at what an underbite is and how it can be treated.

What is an underbite?
An underbite, clinically called prognathism, is the malocclusion or “bad bite” that happens when lower teeth overlap the upper teeth. Severity can vary between a mild underbite, where the two rows of teeth almost meet; and a situation wherein the teeth don’t meet at all because the gap is so wide. It can give the impression you’re expressing emotion that isn’t intended, and it is therefore a common social issue that many are eager to eliminate for good.

What causes an underbite?
The main cause of an underbite is a misalignment of the lower jaw, which is usually present at birth. Patients with hereditary Crouzon syndrome or basal cell nevus syndrome might show signs of an underbite, or it can develop as a result of conditions such as gigantism or acromegaly. Heredity plays a key role in the formation of an underbite. Did you or one of your parents have an underbite? If so, the chances are greater that your child might develop one as well. Some ethnic backgrounds are more likely to suffer from prognathism than others.

Apart from genetics, other common causes of underbites in children include thumb sucking, constant thrusting of the tongue against the teeth and extended use of a pacifier or bottle. Because underbites can inhibit chewing and cause strain in the teeth and jaw muscles, treating them as soon as possible is recommended.

What complications can an underbite cause?
The problems associated with an underbite depend on how pronounced it is. If the gap is wide, it can cause:

  • Eating difficulties
  • Challenges with speaking
  • Chronic jaw or joint (TMJ) pain, as well as head- and earaches
  • Tooth decay from excessive wear of the tooth enamel
  • Chronic mouth breathing, halitosis and bacterial infections
  • Sleep apnea, snoring and other nighttime breathing difficulties

How can an underbite be fixed?
Several methods exist for correcting an underbite, from jaw surgery to a range of orthodontic appliances. If steps are taken while the patient is young, the right appliance is often just the thing to resolve the problem. This highlights the importance of early orthodontic screening in children, which should be explored by the age of seven. Some methods and appliances used are:

  • Braces:The most common way to correct an underbite is through braces. If your child is self-conscious about how he will look with metal braces, he can choose clear braces, which are less noticeable than their all-metal counterparts.
  • An upper jaw expander:This is a wire-frame device the orthodontist fits across the patient’s palate. Every night, a special key is used to widen the expander a tiny amount. The process gradually causes the upper jaw to widen until the lower teeth no longer close against the outside of the uppers. Patients usually wear the expander for about a year, and then replace it with a retainer.
  • The “reverse-pull” face mask:It resembles braces headgear in appearance. It wraps around the child’s head and pulls the upper jaw back into the right position using metal bands fastened to the upper back teeth.
  • Surgery:In extreme cases or older patients, underbite correction might require orthognathic jaw surgery. In this process, an oral and maxillofacial surgeon separates the bone in the rear part of the jaw from the front part, and modifies it. This enables the part of the jaw carrying the lower teeth to be repositioned further back.
  • Cosmetic approach:In mild cases, a new method of cosmetic dentistry is used to reshape the lower teeth and then fit veneers to the uppers.This makes it possible for the lower teeth to close behind the uppers, and avoids the need for surgery or wearable appliances. “Facelift” technology doesn’t physically resolve the problem, but it makes it less visible and sufficiently improves the jaw’s functionality.


Bite alignment is seldom perfect, especially at a young age, but treatments abound to make the adjustments needed to bring out the smile you were born with. Ask your dentist about what’s available at your next regular cleaning.


If you have any questions about underbites, call Winning Smiles to schedule an appointment with your dentist 716-332-2444.

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