Impacted Teeth

Impacted teeth are teeth that have not broken through the gum at all or that have not fully emerged from the gum.

An impacted tooth, also called an unemerged tooth, an unerupted tooth, or a dental impaction, is a tooth that does not emerge through the gum in the correct position. There are two types of impacted teeth. A fully impacted tooth is one that exists in the jaw under the gum line but never breaks through the gum. A partially impacted tooth is one that breaks through the gum line (a process called eruption) but does not fully emerge. Although any tooth may become impacted, the most common teeth to have this condition are the third molars, more commonly known as the wisdom teeth. These are the grinding teeth that are farthest back in the jaw. They normally emerge sometime in the late teens or early 20s.

Researchers are not sure why so many people develop impacted wisdom teeth, but there are several theories. One is that early humans had a larger jaw with enough space for the wisdom teeth. Over the centuries, as humans began to cook food and their diet became softer, less chewing was needed. As the chewing muscles became smaller, so did the jawbones to which these muscles are attached. Another theory is that the diet of early humans wore down the teeth enough that space was created in the jaw by the time the wisdom teeth were ready to erupt.

Teeth can be impacted in several ways. In the most common type of impacted tooth, a mesial impaction, the third molar (wisdom tooth) comes in at an angle so that it is blocked from erupting by the second molar, which is in front of it in the jaw. Impacted teeth can also be positioned in the jaw in a number of other ways ranging from vertical to completely horizontal, so that their eruption through the gum is prevented either by bone or by other teeth. Some impacted teeth are able to partially emerge before they are blocked, whereas others are unable to break through the gum line at all.

Sometimes impacted teeth cause no pain or visible problem, whereas other times they can lead to tooth decay, infection, and gum disease. Normally, partially impacted wisdom teeth cause more health problems than fully impacted teeth. When a tooth partially emerges from the gum, it creates a tiny opening between the gum and the tooth that cannot be cleaned out through brushing or flossing. Bacteria can then enter this space, reproduce, and cause an infection that dentists call pericoronitis, which causes the gum to become tender and swell. The condition can be very painful and also can cause bad breath and a bad taste in the mouth. Pericoronitis is usually treated with antibiotics to kill the bacteria causing the infection, but the disease may return repeatedly if the partially impacted tooth remains in place.

A partially impacted tooth is obvious to the dentist on examination. The dentist must then determine whether the tooth is in the process of emerging normally or if it is stuck in position and impacted. A dental x-ray that shows what is happening below the gum line may help the dentist decide whether the tooth is impacted. An x-ray is the only way to confirm the presence of a fully impacted tooth, since in some people wisdom teeth never develop in the jaw. Most dentists take x-rays on a regular basis to help detect tiny cavities and other dental abnormalities. These x-rays are safe and expose people to a very low level of radiation, although special precautions must be taken with women who are or might be pregnant.

The treatment for an impacted tooth is extraction, which is performed by either a dentist or an oral surgeon. An oral surgeon is a person who has graduated from dental school and then had a minimum of four years of hospital-based training in dental, jaw, and related surgery. Extractions can be done using local or general anesthesia or intravenous * sedation depending on the complexity of the extraction and the patient's preferences. The patient is usually given antibiotics * to combat infection and medication to manage pain following the extraction.

Although dentists agree that extraction is the appropriate treatment for an impacted tooth that is causing health problems, there are two philosophies on whether impacted wisdom teeth should be routinely removed. One school of thought is that impacted wisdom teeth are likely to cause health problems and that they should be removed before these health problems arise. The dentists supporting this position point out that wisdom teeth are much easier to remove and healing is much faster in adolescents than in older individuals, because younger people have more flexible bones. The other philosophy is that although some wisdom teeth should be removed, all wisdom teeth do not need to be routinely extracted when no problems have occurred. People who support this position note that not all impacted wisdom teeth cause problems. People with impacted wisdom teeth should discuss their individual situation with their dentist and review the pros and cons of extraction of teeth that are not yet causing health problems before making treatment decisions.

See also Cavities • Mouth Disorders: Overview

* intravenous (in-tra-VEE-nus), or IV, means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.

* antibiotics (an-tie-by-AH-tiks) are drugs that kill or slow the growth of bacteria.