Image Gallery: Dental Radiography

Figure 1 Periapical lucency

Periapical lucency develops secondary to bone loss around the tooth root caused by endodontic, neoplastic, or periodontal disease. In this dog, periapical lucency of the maxillary first and second molars (red arrows) developed secondary to periodontal disease. Periapical lucency secondary to endodontic disease (caused by exposure of the pulp from a slab fracture [blue arrow]) is also present surrounding the roots of the right maxillary fourth premolar (white arrow).

Observation of marked mobility of the molars would be expected on anesthetized examination. In this dog, the maxillary fourth premolar would likely not be mobile, as there is still bone surrounding the root apices. Extraction of the maxillary fourth premolar and first and second molars is indicated.

Figure 2 Internal tooth resorption in a dog

Apparent pulp exposure (blue arrow) from a complicated crown/root fracture caused by a dog chewing on deer antlers is visible on the left maxillary fourth premolar crown. Note the evidence of internal resorption of the distal root canal (white arrow). Internal resorption is an unusual condition in which the dentin and pulpal walls begin to resorb centrally within the root canal. In addition, periapical lucency of the distal root (red arrow), consistent with apical periodontitis caused by pulpal necrosis, is evident. Extraction is indicated.

Figure 3A External tooth resorption

External tooth resorption, a common finding in dogs and cats, can be diagnosed clinically and radiographically. The stages of tooth resorption (TR) can be classified anatomically. Note that stage 1, which is characterized by mild dental hard tissue loss, is a microscopic finding and thus not visible on dental radiographs.

Stage 2 (TR 2): Moderate dental hard tissue loss in a cat’s right canine tooth (white arrow)

Figure 3B External tooth resorption

Stage 3 (TR 3): Deep dental hard tissue loss extending to the pulp in a cat’s mandibular fourth premolar, with most of the affected tooth retaining its integrity (white arrows). Note extent of resorption in the left mandibular third premolar approaching TR 4 (red arrows). 

Figure 3C and D External tooth resorption

Stage 4 (TR 4): Extensive dental hard tissue loss in a dog. Note resorption affecting (C) the roots of the left mandibular second, third, and fourth premolars (red arrows) extending to the oral cavity, (D) the right mandibular fourth premolar, and the first molar.  

Figure 3E External tooth resorption

Stage 5 (TR 5): Remnants of dental hard tissue are visible only as irregular radiopacities. Note stage 5 resorption affecting the right mandibular third premolar (white arrow) in a cat, along with stage 4 resorption (red arrow) in the first molar.

Extraction would be indicated on diagnosis of external root resorption extending into the oral cavity.

Figure 4A and B Juvenile dental abnormalities

A. Preoperative intraoral radiograph of the rostral mandible in a 6-month-old dachshund. Multiple abnormalities are apparent:

Impacted canine teeth (red arrows): Impacted teeth are prevented from erupting because of a physical barrier in the path of eruption, such as malpositioned incisors. This includes malpositioned incisors, the likely clinical scenario in this dog. Treatment involves a ventral approach to extract the canine teeth. 

Malpositioned incisors, fracture: Note the malpositioned incisors most likely responsible for interfering with eruption of impacted canine teeth as described above, along with a crown fracture of the right second incisor (yellow arrow). Treatment involves extraction of all incisors.

Retained deciduous teeth (white arrows): Note retention of the right and left mandibular canine deciduous teeth. Treatment involves surgical extraction of deciduous teeth.

B. Postoperative intraoral radiograph after extraction of the incisors and canine teeth. The prognosis for function is excellent. 

Figure 5 Pulpal calcification

Pulpal calcification (red arrow) may be located in the pulp chamber or root canal. The cause is uncertain but does not appear to be related to inflammation. There are 2 recognized types of pulpal calcification: denticles, which occur near the furcation of multirooted teeth, and pulp stones, which form in the coronal portion of the pulp. Fortunately, neither is related to pathology, and both become an issue only if calcification interferes with any future root canal therapy.