If there is a delay in an adult tooth growing into the mouth it could be that the tooth is missing or it could be that the tooth is impacted.
An impacted tooth is positioned in a way that it cannot grow in normally or there is too much crowding for that tooth to grow in normally.
Orthodontic treatment is almost always necessary to successfully bring an impacted tooth into its normal position.
The most commonly impacted teeth are wisdom teeth, which are normally removed. The next most commonly impacted teeth are the upper canines (third tooth from the centre). Occasionally the lower second molars are impacted.