• Lack of space (crowding)
• Misalignment (tooth is rotated out of position)
• Conflicting position (another tooth has erupted over that position)
• Ankylosis – when other causes of impaction are not corrected in a timely manner, the roots of the impacted tooth can fuse to the surrounding bone, creating a tooth frozen in an unerupted or partially erupted state.

The teeth most likely to become impacted are the third molars, also known as “wisdom teeth.” The first molars are also known as the 6-year molars since they generally erupt at around age 6, and the second molars are also known as the 12-year molars since they generally erupt at around age 12. If the third molars erupted normally, they might be called 18-year molars. But there is rarely enough space to fit these last teeth into the small space left behind the second molars, so the third molars often become impacted.

This panoramic x-ray shows the impacted 3rd molars (wisdom teeth).
The upper wisdom teeth  crowd the sinus cavity and may erode the roots of the 2nd molars. The lower wisdom teeth are impacted sideways and are likely to cause crowding of the lower teeth, leading to malocclusion.

The most important thing to know about impacted teeth is that they almost always require extraction. The longer the extraction is postponed, the longer the tooth roots grow. When the tooth roots of an impacted tooth are allowed to develop, the risk of complication due to extraction increases significantly because the tooth roots may “wrap around” sensitive facial nerves.

The risks of keeping an impacted tooth extend beyond the impacted tooth itself. Any impacted tooth will exert forces on the arch of your smile that may cause unnecessary crowding of your teeth. An impacted tooth below the gum surface may erode the roots of adjacent teeth. An impacted tooth above the gum line may create a “food trap” that’s hard to brush or floss and is likely to lead to decay.

Wisdom Teeth

Wisdom teeth, also known as third molars, are the last teeth to erupt in your mouth. This generally occurs between the ages of 17 and 25, a time of life that has been called the “Age of Wisdom.”
Anthropologists note that the rough diet of early humans resulted in the excessive wear of their teeth. Normal drifting of the teeth to compensate for this wear ensured that space was available for most wisdom teeth to erupt by adolescence. The modern diet, which is much softer, and the popularity of orthodontic tooth straightening procedures produce a fuller dental arch, which quite commonly doesn’t leave room for the wisdom teeth to erupt, thereby setting the stage for problems when the final four molars enter the mouth.

What is an Impacted Tooth?

A tooth becomes impacted when there is a lack of space in the dental arch, and its growth and eruption are prevented by overlying gum, bone or another tooth. A tooth may be partially impacted, which means a portion of it has broken through the gum; or totally impacted and unable to break through the gum at all.

How Serious is an Impacted Tooth?

Impacted and partially impacted teeth can be painful and lead to infection. They may also crowd or damage adjacent teeth or roots.

More serious problems may occur if the sac surrounding the impacted tooth becomes filled with fluid and enlarges to form a cyst. As the cyst grows, it may hollow out the jaw and permanently damage adjacent teeth, the surrounding bone and nerves. Rarely, if a cyst is not treated, a tumor may develop from its walls, and a more serious surgical procedure may be required to remove it.

Despite the considerable concern regarding impacted third molars, a recent study sponsored by the American Association of Oral and Maxillofacial Surgeons, and the Oral and Maxillofacial Surgery Foundation shows that third molars which have broken through the tissue and erupted into the mouth in a normal, upright position may be as prone to disease as those third molars that remain impacted.

When Should I Have My Wisdom Teeth Removed?

Not all problems related to third molars are painful or visible. Damage can occur without your being aware of it.

As wisdom teeth grow, their roots become longer, the teeth become more difficult to remove, and complications become more likely. In addition, partially or totally impacted wisdom teeth are more likely to cause problems as patient’s age.

No one can predict when third molar complications will occur, but when they do, the circumstances can be much more painful and the teeth more difficult to treat. It is estimated that about 85% of third molars will eventually need to be removed.

When Should I Have My Wisdom Teeth Removed?

It isn’t wise to wait until your wisdom teeth starts to bother you. In general, earlier removal of wisdom teeth results in a less complicated healing process. The AAOMS/OMSF study strongly recommends that wisdom teeth be removed by the time the patient is a young adult in order, to prevent future problems and to ensure optimal healing. The researchers found that older patients may be at greater risk for disease, including periodontitis, in the tissues surrounding the third molars and adjacent teeth. Periodontal infections, such as those observed in this study, may affect your general health.

What Happens During Surgery?

Before surgery, your oral and maxillofacial surgeon will discuss with you what to expect. This is a good time to ask questions or express your concerns. It is of particular importance let the doctor know about any illness you have and medications you are taking.

The relative ease with which a wisdom tooth may be removed depends on several conditions, including the position of the tooth and root development. Partially or totally impacted wisdom teeth may require a more involved surgical procedure.

Most wisdom tooth extractions are performed in the oral and maxillofacial surgery office, under local anesthesia, intravenous sedation or general anesthesia. Your oral and maxillofacial surgeon will discuss the anesthetic option that is right for you.

What Happens after Surgery?

Following surgery, you may experience some swelling and mild discomfort, which are part of the normal healing process. Cold compresses may help decrease the swelling, and medication prescribed by your Oral and Maxillofacial Surgeon can help manage the discomfort. You may be instructed to modify your diet following surgery, and later progress to more normal foods.