Radiographic assessment and localization of unerupted maxillary canines
The upper canines are often misplaced and fail to erupt as a result of their long path of eruption, the timing of their eruption and the frequency of upper arch overcrowding. Many of the factors that influence the treatment of this anomaly can be obtained from the radiographic assessment, the purpose of which is two-fold:
Fig. 15.1 Examples of the radiographs used typically to assess unerupted canines and the surrounding structures. A Periapical showing unerupted with retained. B Upper standard occlusal showing both upper canines unerupted, a dentigerous cyst associated with , extensive destruction of the alveolar bone and resorption of . C Panoramic radiograph showing unerupted and .
Note: These views, on their own, do not provide information as to the position of the canines.
There are several methods available for localization. They can be used for canines and other unerupted teeth as well as odontomes and supernumeraries. Although emphasis in this section is on canines, examples of localization of other unerupted developmental anomalies are also shown.
Parallax is defined as the apparent displacement of an object because of different positions of the observer. In other words, if two objects, in two separate planes, are viewed from two different positions, the objects will appear to move in different directions in relation to one another, from one view to the next, as shown in Fig. 15.2.