The Impact of an Impacted Tooth
A tooth is considered impacted when it only partially grows through the gums. This can happen because another tooth blocks it, or it grows in crookedly. The third molar typically erupts from age 17 to 21 and is the last tooth to appear, which is why it's the most likely tooth to become impacted - there's usually no room left for it.
Although an impacted tooth does not always lead to pain or discomfort, the impaction can cause other problems. A partially erupted tooth can create an opening in the gum where food and other particles can accumulate, leading to gum infection.