The wisdom teeth or third molar teeth normally erupt into the mouth between the ages of 16-25 years of age. They can erupt earlier or later than this. Not everyone develops all their wisdom teeth, and some people develop none. Also some wisdom teeth stay buried in the jaw bone and never erupt into the mouth; usually they cause no problems.
Sometimes when the wisdom teeth erupt into the mouth it can cause pain. This is often short lived and the pain disappears.
Lots of wisdom teeth only partially erupt in the mouth, leaving a flap of gum over the top. This flap of gum can then become infected and cause a lot of pain, you may need antibiotics to help the pain to settle. This infection is called pericorinitis.
To help prevent infection of the tissues around the wisdom teeth (pericorinitis) then make sure you clean under the flap of gum with a small toothbrush.
Not all wisdom teeth that cause problems need to be removed. Often they go through a phase when they become painful, and then they can often be managed with good oral hygiene, good diet, use of hot salt-water mouthwash and occasional antibiotics. Many troublesome wisdom teeth may eventually erupt sufficiently to give no further problems, or to give rarer, milder problems.
Only if the bouts of pain are severe, or frequent, or causing significant interference with other life commitments should they be considered for removal.
NICE have reviewed the evidence on this subject and have produced guidelines on this subject. You can download the guidelines from NICE website.