Teeth are impacted when they fail to emerge through the gums, or emerge only partially, at the expected time.
Wisdom teeth do not always emerge (erupt) into the mouth properly because there may not be enough room in the mouth for them to fit. Sometimes, a part of the tooth may remain covered by a flap of gum. Food particles and bacteria can get trapped under this flap and cause a mild irritation, a low-grade infection called pericoronitis and swelling. This usually happens with the lower wisdom teeth.
Your wisdom teeth (third molars) usually start to erupt (enter your mouth) during late adolescence. Sometimes, there's not enough room for them, and they come in partially or not at all. This condition can lead to pericoronitis, inflammation of the tissue surrounding the tooth.
A few people are born without wisdom teeth or have room in their mouths for them, but like Jen and her brother, many of us get our wisdom teeth taken out during our college years. And like Patrick, many of us are first alerted to the problem when our wisdom teeth don't emerge (erupt) into the mouth properly because there is not enough room for them to fit.