 Orthodontics may be required in such circumstances for an individual to achieve a functioning and aesthetic dentition.The permanent dentition begins when the last primary tooth is lost, usually at 11 to 12 years, and lasts for the rest of a person's life or until all of the teeth are lost (edentulism).During this stage, permanent third molars (also called "wisdom teeth") are frequently extracted because of decay, pain or impactions.