If a tooth fails to fully erupt, it is considered to be impacted. Wisdom teeth, the last teeth to erupt, are the most common teeth to become impacted. Without treatment, an impacted tooth remains stuck in the bone or gum tissue.

There are various reason why teeth may become impacted. There may be no room for the emerging tooth due to overcrowding. It may also be that teeth become tilted as they erupt, resulting in impacted teeth.

Impacted wisdom teeth are very common. They are often painless and cause no apparent trouble. Partially emerged teeth can be difficult to clean properly, giving way to gum inflammation, known as pericoronitis, and bad breath.

Impacted upper canine teeth are also relatively common and often require surgical exposure so that the orthodontist can then move them into the arch. These canine teeth are often impacted in the palate.