15: Radiographic assessment and localization of unerupted maxillary canines

Radiographic assessment and localization of unerupted maxillary canines

Assessment 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:

• To determine the size and shape of the canine and any related disease

• To determine the position of the canine.

Assessment of the canine size and shape and the surrounding tissues

Radiographic views used (see Fig. 15.1)

The usual radiographs used include:

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 .

• Periapicals

• Upper standard occlusal

• Panoramic radiograph.

Radiographic interpretation

The specific features that need to be examined relate to:

• Surrounding structures.

Note: These views, on their own, do not provide information as to the position of the canines.

The crown: Note in particular:

• Crown size (in relation to the space available in the arch)

• Crown shape

• The presence and severity of resorption

• The presence of any related disease, such as a dentigerous cyst

• The effect on adjacent teeth, such as resorption.

The root: Note in particular:

• Stage of development.

Surrounding structures: Note in particular:

• The deciduous canine

– root length

– degree of resorption

• The presence of an odontome or supernumerary

• The condition of the surrounding bone.

Assessment of the position of the canine – localization

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.

Main localization methods

• Parallax in the horizontal plane

• Parallax in the vertical plane

• Cross-sectional tomography

• Cone beam CT (see Ch. 13).

The principle of parallax

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.

Fig. 15.2 The principle of parallax. Photographs of a small black cylinder positioned behind a tooth. From directly in front (F), the tooth and cylinder/>

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Tags: Radiography and Radiology for Dental Care Professionals 3e

Jan 12, 2015 | Posted by mrzezo in Oral and Maxillofacial Radiology | Comments Off

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