An impacted tooth is a tooth that fails to fully pass through the gums.

Teeth emerge through the gums during infancy, and when the primary (baby) teeth are replaced by the permanent teeth. If a tooth fails to emerge, or emerges only partially, it is impacted. Because they are the last teeth to emerge, the most common teeth to become impacted are the wisdom teeth (the third set of molars), which normally emerge between the ages of 17 and 21.

An impacted tooth remains embedded in soft gingiva (gum) tissue or bone beyond its normal eruption time. The cause may be overcrowding, often because the jaw is too small to fit the third set of molars. Teeth may also become twisted, tilted, or displaced as they try to emerge, resulting in impacted teeth.

Impacted wisdom teeth are very common. They are often painless and cause no apparent trouble. However, some professionals believe an impacted tooth pushes on the next tooth, which pushes the next tooth, eventually causing a misalignment of the bite. A partially emerged tooth can trap food, plaque, and other debris in the soft tissue around it, leading to inflammation and tenderness of the gums and unpleasant mouth odor. This is called pericoronitis.

• Pain or tenderness of the gums (gingiva) or jaw bone
• Unpleasant taste when biting down on or near the area
• Visible gap where a tooth did not emerge
• Bad breath
• Redness and swelling of the gums around the impacted tooth
• Swollen lymph nodes of the neck (occasionally)
• Difficulty opening the mouth (occasionally)
• Prolonged headache or jaw ache

Your dentist will look for enlarged tissue over the area where a tooth has not emerged, or has emerged only partially. The impacted tooth may be pressing on adjacent teeth. The gums around the area may show signs of infection, such as redness, drainage, and tenderness. As gums swell over impacted wisdom teeth and then drain and tighten, it may feel like the tooth came in and then went back down again.

Dental x-rays confirm the presence of one or more teeth that have not emerged.