Impacted wisdom teeth

Teeth that do not fully grow out of the gums due to being blocked by other teeth

Impacted wisdom teeth is a condition where the third molars (wisdom teeth) are prevented from erupting into the mouth. This can be caused by a physical barrier, such as other teeth, or when the tooth is angled away from a vertical position. Completely unerupted wisdom teeth usually result in no symptoms, although they can sometimes develop cysts or neoplasms.

From Wikipedia, under CC BY-SA. More on occurri.