What to Know About Dental Underbites

By Premier Dental of Ohio

How an underbite affects your jaw and teeth

Everything You Need to Know about Underbites

An underbite is a complicated orthodontic issue that is relatively rare. The prevalence of this type of bite varies by ethnicity, with people of Southeast Asian descent having the highest rate at over 15%. It is a difficult orthodontic problem to treat, and it can cause many complications over the patient’s lifetime.

If you or a loved one suffers from an orthodontic underbite, read this article. It will explain many of the details regarding the orthodontic situation and help you make an informed decision about potential treatment options.

What is a Dental Underbite?

An underbite is a type of malocclusion, officially called a class III malocclusion. A malocclusion is the term dentists use to describe situations in which the upper and lower jaws do not come together in the correct relationship. In an underbite, or class III, the lower jaw protrudes further than the upper jaw.  

This often includes lower teeth overlapping the upper teeth in a crossbite. In a “perfect” bite, the upper teeth should fit over the lower teeth like a lid on a box. In a class III malocclusion, that situation is reversed.  

In addition to the relationship of the teeth, a class III malocclusion affects the appearance of the face. Even with the lips closed, you can often detect an underbite due to the concave nature of the profile. The lower jaw appears to protrude too far outward, and the middle portion of the face is retruded.  In most cases, the lower jaw is actually normal, and the upper jaw in the middle of the face is too small. The relatively small size of the upper jaw and its concave nature in the profile makes the lower jaw look too large when it is not.

What Causes an Underbite?

Many underbites are caused by problems with the growth and development of the upper jaw. This can be the result of genetic influences or habits during childhood that influence the shape of the upper jaw.  

For example, chronic habits like thumb sucking can alter the shape of the upper jaws and inhibit its natural growth. This may lead to an entrapment of the upper jaw by the lower teeth.  

In most cases, though, we do not know the underlying cause of the way the jaws grow. An underbite typically shows evidence very early in life, so we can provide interceptive treatment to aid the proper growth and development of the jaws.

Are Underbites Genetic?

Many people ask this question because they see families in which there is a strong predisposition toward underbites. You can often follow multiple generations in a single family with consistent class III malocclusions.

This strongly suggests a genetic component to the growth and development of the jaws. This would account for different prevalence rates among different populations.

There are also genetic disorders that carry a high propensity for class III malocclusions. For example, people with Downs Syndrome have a much higher prevalence of underbites: more than forty percent.

Why is an Underbite a Problem?

Underbites are problematic for several reasons. Not only does a class III malocclusion create the cosmetic problem of an unaesthetic profile, it can cause functional problems, too.

When an upper jaw is too small, it affects the airway. Typically, a restricted airway in the upper nasal passages accompanies an underbite. Some patients are unable to close their lips together over the underbite, which leads to mouth breathing. This is a source of dry mouth, which greatly increases the risk for dental diseases like gum disease and cavities. 

Many patients with underbites do not have a good bite relationship between the upper and lower teeth. This means they often have trouble properly chewing and digesting food. Chewing is the essential first step in the digestive process. Chewing provides, not only mechanical breakdown of large food particles, but also chemical breakdown through salivary enzymes. People who cannot chew properly often have digestive problems for life.

How Do You Fix an Underbite?

Your dentist can help you receive the necessary dental treatment to fix an underbite. We typically address class III malocclusions in two ways.

Interceptive Treatment

Interceptive treatment involves the use of orthodontic appliances to guide any future growth and development of the jaws. This means that interceptive treatment must begin while a child still has growth potential, which is at a relatively early age.

Interceptive treatment will help promote the upper jaw’s growth to reach full development, while holding back the lower jaw if necessary. Many patients need intervention at an early age with a device called a palatal expander. This orthodontic appliance prevents the lower teeth from “trapping” the upper teeth within the lower arch and preventing natural growth.

In order to detect and intervene early enough to promote healthy growth, all children should have an orthodontic evaluation by a dentist, pediatric dental specialist or orthodontist by age six to seven years old.

Surgical Correction

Once there is no longer the potential for jaw growth, the appropriate treatment for an underbite is surgical correction. This type of surgery is called orthognathic surgery. Performed by an oral and maxillofacial surgeon who works in conjunction with an orthodontist, this surgery will realign the upper and lower jaws into the appropriate relationship.

Orthodontics (braces) is also necessary to align and stabilize the teeth when orthognathic surgery is the treatment of choice.  

Inappropriate Treatment for Underbites

It is important to understand that orthodontic appliances alone only work to correct underbites during active growth. Fully-grown adults cannot expect to fix an underbite with orthodontics alone. Many direct-to-consumer aligner companies promote the use of clear aligners to correct any matter of malocclusion, but this is not only incorrect. It’s actually dangerous.  

By attempting to move the teeth in correction of an underbite, you could move them outside of their natural place within the jawbone. This leads to a loss of the foundational attachment between tooth and bone. Patients can even lose their teeth when treated incorrectly.

Why Should I Fix my Underbite?

Some people are able to function well with an underbite for their entire lives. Others struggle with airway problems, digestive issues, and lack of confidence due to cosmetic concerns for life.

Only you can decide whether correcting your underbite (or that of a child in your care) is necessary. Our dentists are happy to walk you through the decision making process with all of your options.

More Questions about Underbites?

Call your nearest Premier Dental of Ohio location today to schedule a consultation with one of our expert dentists. We can answer your other questions about underbites and assess your specific situation. We work closely with highly skilled orthodontists and oral surgeons to help our patients with underbites receive the correction they need.  


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