18: The periapical tissues

The periapical tissues

Introduction

This chapter explains how to interpret the radiographic appearances of the periapical tissues by illustrating the various normal appearances, and describing in detail the typical changes associated with apical infection and inflammation following pulpal necrosis. To help explain the different radiographic appearances, they are correlated with the various underlying pathological processes. In addition, there is a summary of the other, sometimes sinister, lesions that can affect the periapical tissues and may simulate simple inflammatory changes.

Normal radiographic appearances

A reminder of the complex three-dimensional anatomy of the hard tissues surrounding the teeth in the maxilla and mandible, which contribute to the two-dimensional periapical radiographic image, is given in Fig. 18.1.

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. 18.2)

The three most important features to observe are:

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 18.5 and 18.6).

Jan 12, 2015 | Posted by in Oral and Maxillofacial Radiology | Comments Off on 18: The periapical tissues
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