What is it ?
A tooth which is very decayed or damaged, or loose because of gum disease, may have to be extracted.
Wisdom teeth sometimes have to be extracted if they have come through at an awkward angle and are causing problems (such as decay in adjacent teeth or, being difficult to clean, and causing infections).
Teeth are sometimes taken out from children’s mouths to help other teeth which are crowded to grow straight, (usually on the advice of an orthodontist).
Source: BDA Leaflet