21: The periapical tissues

The periapical tissues

Normal radiographic appearances

A reminder of the complex three-dimensional anatomy of the hard tissues surrounding the teeth in the maxilla and mandible, which contributes to the two-dimensional periapical radiographic image, is given in Fig. 21.1.

The appearances of normal, healthy, periapical tissues vary from one patient to another, from one area of the mouth to another and at different stages in the development of the dentition. These different normal appearances are described below.

The periapical tissues of permanent teeth (Fig. 21.2)

The three most important features to observe are:

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Fig. 21.2 Periapical radiographs of A image, B image, C image (compare with Fig. 21.1Bi) showing the normal radiographic anatomy of the periapical tissues in different parts of the jaws. Note the continuous radiolucent line of the periodontal ligament shadow and the radiopaque line of the lamina dura outlining the roots.

These features hold the key to the interpretation of periapical radiographs, since changes in their thickness, continuity and radiodensity reflect the presence of any underlying disease, as described later.

The effects of normal superimposed shadows

Normal anatomical shadows superimposed on the apical tissues can be either radiolucent or radiopaque, depending on the structure involved.

Radiolucent shadows

Examples include:

Such cavities in the alveolar bone decrease the total amount of bone that would normally contribute to the final radiographic image, with the following effects:

• The radiolucent line of the periodontal ligament may appear MORE radiolucent or widened, but will still be continuous and well demarcated

• The radiopaque line of the lamina dura may appear LESS obvious and may not be visible

• There will be an area of radiolucency in the alveolar bone at the tooth apex (see Figs 21.5 and 21.6).

Radiopaque shadows

Examples include:

Such radiopacities complicate periapical interpretation by obscuring or obliterating the detailed shadows of the apical tissues, as shown in Fig. 21.7.

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Jan 12, 2015 | Posted by in Oral and Maxillofacial Radiology | Comments Off on 21: The periapical tissues
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