Wisdom Teeth

Wisdom teeth are another name for any one of four third molars found in the permanent dentition. These teeth are the last or most posterior teeth in the dental arch. Although most people have wisdom teeth, it is possible for the third molar to never develop or become impacted (not normally erupted through the gums) under the gingival tissue.

You know if you have wisdom teeth by examining your mouth and finding three permanent molars in each dental quadrant. However, if the tooth is impacted under the tissue, presence of the tooth needs to be verified by a radiograph. A panoramic X-ray is usually preferred to help assess the angle of eruption and state of development of the tooth. Most wisdom teeth can be visualized erupting through the gingiva in early adulthood, between the ages of 16 to 23. Your general dentist will often inform you of the condition of these teeth.

Not all wisdom teeth need to be extracted. When a wisdom tooth erupts cleanly through the tissue without compromising the adjacent tooth, the wisdom tooth can be retained in the mouth with little concern. However, removal of the wisdom tooth is indicated if the tooth has partially erupted through the gingival tissue causing inflammation and at times infection. A soft tissue growth over a partially erupted wisdom tooth is referred to as an operculum. If bacteria are trapped under the operculum, swelling with an associated bad taste can occur; this is called a pericoronitis. The wisdom tooth can also erupt at an angle such that the adjacent molar can become difficult to keep clean and free of dental caries. If the third molar has erupted through the tissue but is without opposing occlusion (contact with other teeth), extraction should still be considered. Considering the posterior position of an erupted wisdom tooth, these teeth are often difficult to keep clean.

Source: MedicineNet.com
http://www.medicinenet.com/wisdom_teeth/article.htm