Failure of teeth to emerge completely from the gum and grow into their normal position, usually due to lack of room
Teeth usually become impacted when there is not enough room in the mouth for them to grow into their correct positions. Impacted teeth may sometimes remain entirely buried in the jawbone, producing few or no symptoms, or they may only partly erupt through the gum. Impaction may also occur if a tooth starts to grow in the wrong direction and pushes against other teeth or the jawbone.
Wisdom teeth are the most likely to become impacted, followed by the upper canines. The wisdom and upper canine teeth emerge at a later stage of life than other teeth, and often there is insufficient room in the mouth for them to erupt normally. Impacted teeth most frequently occur in adolescents and young adults when the teeth are still emerging.
Impacted teeth may cause pain and inflammation. A partly erupted tooth may be covered by a flap of gum under which plaque (a sticky deposit of food particles, saliva, and bacteria) accumulates, leading to inflammation of the gum and gradual decay of the tooth (see Dental caries).
Your dentist will check at each visit (see Dental checkup) whether any emerging teeth are likely to become impacted. He or she may also take X-rays to look at unerupted teeth. One or more teeth may be extracted to allow room for other teeth to come through. You may also need orthodontic treatment to straighten the teeth.
Wisdom teeth that are impacted are not routinely removed unless they frequently become infected or are causing other problems. If canines are impacted, they may be fully exposed by removing gum tissue. An orthodontic device is then applied to guide the teeth into position.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.