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Causes
By Mayo Clinic staff
Wisdom teeth (third molars) become impacted because they don't have enough room to erupt or grow normally.
Wisdom teeth usually erupt 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 most cases, however, the mouth is too crowded for third molars to develop normally. These crowded third molars become trapped, or impacted.
An impacted wisdom tooth may partially erupt so that a part 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 perpendicular 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
Why do we have wisdom teeth?
Early humans had diets of tough food that probably resulted in enough wear on teeth to make room for the relatively late-emerging wisdom teeth. The softer diets of modern humans — and relatively recent practices of preventive dental care and orthodontic care to straighten teeth — have resulted in mouths that often can't accommodate a third molar.
- Wisdom teeth. American Association of Oral and Maxillofacial Surgeons. http://www.aaoms.org/wisdom_teeth.php. Accessed Feb. 22, 2010.
- Marciani RD. Third molar removal: An overview of indications, imaging, evaluation, and assessment of risk. Oral and Maxillofacial Surgery Clinics of North America. 2007;19:1.
- Bagheri SC, et al. Extraction versus nonextraction management of third molars. Oral and Maxillofacial Surgery Clinics of North America. 2007;19:15.
- Esposito M, et al. Impacted wisdom teeth. Clinical Evidence (Online). 2008. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=19450307. Accessed Feb. 22, 2010.
- Gingivitis. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec08/ch095/ch095c.html. Accessed March 3, 2010.
- Caries. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec08/ch095/ch095b.html. Accessed March 3, 2010.
- Pogrel MA, et al. White paper on third molar data (2007). American Association of Oral and Maxillofacial Surgeons. http://www.aaoms.org/media.php. Accessed Feb. 27, 2010.
- Farish SE, et al. General technique of third molar removal. Oral and Maxillofacial Surgery Clinics of North America. 2007;19:23.
- Postextraction problems. The Merck Manuals: The Merck Manual for Healthcare Professionals. Accessed Feb. 22, 2010.
- Dental anxiety. American Dental Association. http://www.ada.org/public/topics/anxiety.asp. Accessed March 3, 2010.
- Carr AB (expert opinion). Mayo Clinic, Rochester, Minn. March 10, 2010.
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