Complicated crown fracture of an unerupted permanent tooth--a case report.

Trauma to primary teeth may result in direct damage to underlying developing permanent teeth because of the close relationship that exists between the apices of the primary teeth and their permanent successors. Injuries to developing teeth have been classified into ten different categories, using a classification that is largely based on developmental alterations to the permanent teeth. However, this classification does not include other types of trauma that may occur to developing teeth, such as crown fractures. Although apparently rare, such injuries can occur by direct contact of the impacting object with a developing tooth, as illustrated by the following case report.