Impacted tooth

Alternative names:

dental impaction; tooth, unemerged; unemerged tooth

Definition:

A dental disorder involving failure of a tooth to fully emerge through the gums.

Causes, incidence, and risk factors:

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 17 and 21 years old.

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 trouble; however, in some cases, the impacted tooth pushes on the next tooth and causes it to become misaligned, eventually causing the bite to become shifted. 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.