Overview

Impacted wisdom teeth are third molars at the back of the mouth that don't have enough room to emerge or develop normally.

Wisdom teeth are the last adult teeth to come into the mouth (erupt). Most people have four wisdom teeth at the back of the mouth — two on the top, two on the bottom.

Impacted wisdom teeth can result in pain, damage to other teeth and other dental problems. In some cases, impacted wisdom teeth may cause no apparent or immediate problems. But because they're hard to clean, they may be more vulnerable to tooth decay and gum disease than other teeth are.

Impacted wisdom teeth that cause pain or other dental complications are usually removed. Some dentists and oral surgeons also recommend removing impacted wisdom teeth that don't cause symptoms to prevent future problems.

Symptoms

Impacted wisdom teeth don't always cause symptoms. However, when an impacted wisdom tooth becomes infected, damages other teeth or causes other dental problems, you may experience some of these signs or symptoms:

  • Red or swollen gums
  • Tender or bleeding gums
  • Jaw pain
  • Swelling around the jaw
  • Bad breath
  • An unpleasant taste in your mouth
  • Difficulty opening your mouth

When to see a doctor

See your dentist if you experience symptoms in the area behind your last molar that may be associated with an impacted wisdom tooth.

Causes

Wisdom teeth (third molars) become impacted because they don't have enough room to come in (erupt) or develop normally.

Wisdom teeth usually emerge sometime between the ages of 17 and 25. Some people have wisdom teeth that emerge without any problems and line up with the other teeth behind the second molars. In many cases, however, the mouth is too crowded for third molars to develop normally. These crowded third molars become trapped (impacted).

An impacted wisdom tooth may partially emerge so that some of the crown is visible (partially impacted), or it may never break through the gums (fully impacted). Whether partially or fully impacted, the tooth may:

  • Grow at an angle toward the next tooth (second molar)
  • Grow at an angle toward the back of the mouth
  • Grow at a right angle to the other teeth, as if the wisdom tooth is "lying down" within the jawbone
  • Grow straight up or down like other teeth but stay trapped within the jawbone

Complications

Impacted wisdom teeth can cause several problems in the mouth:

  • Damage to other teeth. If the wisdom tooth pushes against the second molar, it may damage the second molar or increase the risk of infection in that area. This pressure can also cause problems with crowding of the other teeth or require orthodontic treatment to straighten other teeth.
  • Cysts. The wisdom tooth develops in a sac within the jawbone. The sac can fill with fluid, forming a cyst that can damage the jawbone, teeth and nerves. Rarely, a tumor — usually noncancerous (benign) — develops. This complication may require removal of tissue and bone.
  • Decay. Partially impacted wisdom teeth appear to be at higher risk of tooth decay (caries) than other teeth. This probably occurs because wisdom teeth are harder to clean and because food and bacteria get easily trapped between the gum and a partially erupted tooth.
  • Gum disease. The difficulty cleaning impacted, partially erupted wisdom teeth increases the risk of developing a painful, inflammatory gum condition called pericoronitis (per-ih-kor-o-NI-tis) in that area.

Prevention

You can't keep an impaction from occurring, but keeping regular six-month dental appointments for cleaning and checkups enables your dentist to monitor the growth and emergence of your wisdom teeth. Regularly updated dental X-rays may indicate impacted wisdom teeth before any symptoms develop.

March 31, 2015
References
  1. Wisdom teeth management. American Association of Oral and Maxillofacial Surgeons. http://myoms.org/procedures/wisdom-teeth-management. Accessed March 9, 2015.
  2. Mettes TG, et al. Surgical removal versus retention for the management of asymptomatic impacted wisdom teeth. Cochrane Database of Systematic Reviews. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD003879.pub3/abstract. Accessed March 9, 2015.
  3. Wisdom teeth. MouthHealthy.org. http://www.mouthhealthy.org/en/az-topics/w/wisdom-teeth. Accessed March 9, 2015.
  4. Coulthard P, et al. Surgical techniques for the removal of mandibular wisdom teeth. Cochrane Database of Systematic Reviews. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004345.pub2/abstract. Accessed March 9, 2015.
  5. Postextraction problems. The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/dental_disorders/dental_emergencies/postextraction_problems.html. Accessed March 9, 2015.
  6. Gingivitis. The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/dental_disorders/periodontal_disorders/gingivitis.html?qt=Wisdom%20teeth&alt=sh. Accessed March 9, 2015.
  7. Toothache and infection. The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/dental_disorders/symptoms_of_dental_and_oral_disorders/toothache_and_infection.html?qt=Wisdom%20teeth&alt=sh. Accessed March 9, 2015.
  8. Bouloux GF, et al. What is the risk of future extraction of asymptomatic third molars? A systematic review. Journal of Oral and Maxillofacial Surgery. In press. Accessed March 9, 2015.
  9. Salinas TJ (expert opinion). Mayo Clinic, Rochester, Minn. March 17, 2015.