by Shen-Li Lee

Created on: February 26, 2010   Last Updated: March 01, 2010

What is an Impacted Tooth?

An impacted tooth is a tooth that is unable to fully erupt into the mouth due to blockage of its path of eruption by other teeth, bone or soft tissues.  Impacted teeth may be remain fully embedded in the gums or they may be partially erupted where only part of the crown is visible above the gumline.

What are the Causes of an Impacted Tooth?

Impacted teeth are usually caused by a mismatch between the size of the teeth and the size of the jaw arch.  Sometimes the teeth are too large for the space available in the jaw arch which lead to a condition called crowding.  The malalignment of teeth may result in tooth impaction.   Impacted teeth can also be caused by a layer of bone or hard cover of gum that blocks the path of eruption of the tooth.  A tooth may also be impacted because it grows in an abnormal position or in an abnormal direction.

The most commonly impacted teeth are the third molars.  Historically, human diets were very abrasive.  The abrasiveness of food eaten would wear away the biting edges of the teeth.  Since teeth are narrower at the neck of the tooth (the part of the tooth near the gum line), the wearing down of the biting surfaces would create gaps between the teeth.  The back teeth would then migrate forwards in a process called “mesial migration” to close gaps between the teeth thus creating space for the third molars to erupt at the back of the mouth.

In modern times, our diets have become softer and less abrasive which preserve the biting edges of our teeth.  This results in the third molars becoming redundant through changes in our lifestyles and diet.  In some individuals, the third molars become impacted due to the lack of space in the dental arch.

What are the Effects of an Impacted Tooth?

Impacted teeth do not necessarily cause problems in the mouth.  Impacted teeth that are fully submerged can remain submerged without an individual even being aware of having an impacted tooth.  Occasionally submerged teeth may cause problems, such as root resorption (breaking down of the roots) of the adjacent teeth.

There is also a belief that impacted teeth push on adjacent teeth which pushes other teeth.  The end result is malalignment of the teeth.  There are two schools of thought on this theory – the oral surgeons that do not believe a single tooth can be the cause of crooked teeth and the orthodontists who believe that

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