An impacted tooth is a tooth that gets blocked as it is pushing through the gum into your mouth (erupting). Wisdom teeth often are impacted.
Wisdom teeth usually begin to come in between the ages of 17 and 21. Dentists call these teeth third molars. They may become impacted because there's not enough room in your mouth for them. A wisdom tooth also might be trying to come in sideways. Or, it might be tilted in your jaw.
An impacted tooth can be painless. You may not even realize it's there. However, when an impacted wisdom tooth tries to come in, the flap of gum on top of it can become infected and swollen. This can hurt. You might even feel pain in nearby teeth, or in the ear on that side of your face.
An impacted tooth can lead to an infection called pericoronitis. If untreated, this infection can spread to the throat or into the neck. Severe infections require a hospital stay and surgery.
Impacted teeth also can get cavities. An impacted tooth can push on the neighboring molar. This can lead to tooth movement, decay or gum disease. It also can change the way your teeth come together. Rarely, impacted teeth can cause cysts or other growths in the jaw.