Intraoral Radiographic Anatomy of the Dog

CHAPTER 2 Intraoral Radiographic Anatomy of the Dog


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FIGURE 2-1 Anatomy of the teeth and supporting structures. A and B, Radiograph of a left mandibular fourth premolar tooth. The third premolar tooth on the left and the first molar tooth on the right are partially imaged. C (facing page bottom), Prepared mandible sectioned to expose the internal anatomy. Intraoral radiographs clearly depict the anatomy of the teeth and the surrounding structures. Significant variability exists between individuals. A structure may be absent, be difficult to identify, or appear unusual in any particular individual radiograph. Note that the lamina dura, the white line around the root made by the compact bone of the alveolus (the tooth socket), is visible in some areas but absent in others. The bony plate of the alveolus is more apparent in areas where it is either parallel to the x-ray beam or is superimposed over other radiodense structures and much less apparent where it is perpendicular or tangential to the x-ray beam or is superimposed over radiolucent structures. There is significant variability in lamina dura density and presence between individuals. It is separated from the root by a radiolucent line that represents the periodontal ligament space. Enamel, the densest material in the tooth, covers the tooth crown and is also the most radiopaque material. It can appear as a narrow white line bordering the crown of a tooth, an effect that is enhanced on surfaces that are oriented more parallel to the axis of the x-ray beam. The enamel is often difficult or impossible to visualize on a radiograph because it is generally less than 0.6 mm thick. In many cases, the enamel only diffusely adds to the radiopacity of the crown. Dentin forms the majority of the mature tooth. It is less radiodense than enamel, but the roots appear to have a similar radiodensity to the enamel-covered crowns due to the superimposition of alveolar bone over the roots. The cervical area of the tooth, between the enamel of the crown and the alveolar bony margin, has neither enamel nor bone superimposed and is therefore less radiodense. This is referred to as “cervical burn-out” and should not be mistaken for caries or dental resorption. The bone of the alveolar margin should be relatively horizontal and positioned 1 to 2 mm apical to the cementoenamel junction. The interradicular marginal bone often has a slightly convex contour, filling the furcation area and closely approximating the contour of the furcation. In contrast, the interalveolar marginal bone (margin of septal bone) can have a horizontal, a slightly concave, or a slightly convex contour depending on the proximity of the adjacent roots and the particular region in the arch. The pulp cavity includes the root canal, found in the center of each root, and the pulp chamber in the crown. It appears radiographically as a comparatively radiolucent area within the tooth.


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FIGURE 2-2 Normal incisor teeth. A, Radiograph of the incisor teeth and rostral maxillary region of a young adult dog. B, Dorsal view of prepared skull. C, Palatal (mirror) view of skull. D, Same radiograph as A. The crowns of the incisor teeth are foreshortened due to a projection angle that makes an image of the roots without elongation artifact (see Chapter 12).


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FIGURE 2-15 Normal dog canine tooth A, Radiograph of the skull of a young dog showing the canine tooth and surrounding structures. B, Dorsal view of prepared skull. C, Ventral (mirror) view of skull. D, Same radiograph as A.


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FIGURE 2-23 Normal maxillary premolar teeth The facial and palatal region of the dog consists of 36 bones designed to provide a large surface area for the sense of smell and to hold the teeth. The premolar teeth are all within the alveolar process of the maxilla. However, radiographs of the premolar teeth may project through the nasal, frontal, palatine, and zygomatic bones. A, Radiograph of the left maxillary premolar region of a young dog. B, Buccal (vestibular) view of prepared skull. C, Nasal surface of maxilla. D, Same radiograph as A. Correct use of the bisecting angle technique makes an image with accurate root length. The apical anatomy, however, will be slightly enlarged due to an increased object-to-film distance at the apex.

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May 27, 2016 | Posted by in ANIMAL RADIOLOGY | Comments Off on Intraoral Radiographic Anatomy of the Dog

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