Impacted teeth are those which fail to erupt from a non-functional position in the alveolar bone into the occlusal plane within a normal developmental period. The third molars are the most commonly impacted teeth, followed by maxillary canines, maxillary second molar, mandibular second premolar, and mandibular second molar.
Terminology
The term 'unerupted' is more general and refers to a tooth which has not risen into the occlusal plane regardless of whether or not this is developmentally appropriate 1,2.
Radiographic features
Impacted teeth are first assessed by orthopantomogram which displays their relationship to surrounding structures (adjacent teeth, alveolar canals and occlusal plane) as well as their angulation (mesioangular, distoangular, horizontal or vertical).
CBCT
Cone beam CT (CBCT) allows for more detailed examination of 1,3:
impacted tooth anatomy, e.g. root dilaceration
proximity to other teeth
proximity to other structures, e.g. inferior alveolar canal, incisive canal
assess for both extrinsic and intrinsic root resorption