1. Lack of Space
The most common reason for third molar extraction is IMPACTION which means difficulty in complete erruption due to lack of space or abnormal position of third molar.
2. Dental Caries that is difficult to restore
When the third molar has a deep cavity which is difficult to restore and maintain, it leads to poor prognosis. Also if the opposite third molar is missing, so it is advisable to extract it.
3. Abnormal Position of Wisdom Tooth
Sometimes the wisdom tooth errupts in an abnormal direction which leads to impaction (difficulty in complete erruption) .
This can cause vague dull aching continuous pain in the jaw or trauma to the second molars. At such instances it is better to remove the third molar.
4. Recurring Pericoronitis
An errupting or impacted third molar can cause repeated occurence of inflammation of gums leading to swelling of gums or a flap of gums over the tooth in that area. This makes it painful and also difficult to clean causing more inflammation. In such cases sometimes it is advisable to extract the tooth.
5. Trauma to the adjacent tooth
An abnormally positioned third molar might create pressure on adjacent second molar leading to its resorption or cavity (due to food lodgement) causing pain and sensitivity. In order to prevent damage to second molar which is a more important tooth for biting, it is advised to extract the third molar.
6. Cyst or any other abnormality
Third molars might be associated with cysts or any other pathologies that sometimes are asymptomatic and come to notice only as a radiographic finding. These cysts can become painful or get infected at a later stage. Therefore it is better to remove such pathological third molars in time.