An extraction is the complete removal of a primary or a permanent tooth. The most common reason for surgical extractions is the removal of third molars, often called wisdom teeth. There is often not enough room for the third molars to erupt normally so they must be extracted.
Other reasons for extractions are:
Advanced gum disease. This is the #1 reason adults loose their teeth!
An abcessed tooth that cannot be saved.
A tooth with decay too deep to save the tooth.
A tooth that has broken at the gum line and cannot be saved.
Some Orthodontic cases require that one or more teeth be extracted.