Feline dental radiography and radiology: A primer

Abstract

Practical relevance: Information crucial to the diagnosis and treatment of feline oral diseases can be ascertained using dental radiography and the inclusion of this technology has been shown to be the best way to improve a dental practice. Becoming familar with the techniques required for dental radiology and radiography can, therefore, be greatly beneficial.

Clinical challenges: Novices to dental radiography may need some time to adjust and become comfortable with the techniques. If using dental radiographic film, the generally recommended 'E' or 'F' speeds may be frustrating at first, due to their more specific exposure and image development requirements. Although interpreting dental radiographs is similar to interpreting a standard bony radiograph, there are pathologic states that are unique to the oral cavity and several normal anatomic structures that may mimic pathologic changes. Determining which teeth have been imaged also requires a firm knowledge of oral anatomy as well as the architecture of dental films/digital systems.

Evidence base: This article draws on a range of dental radiography and radiology resources, and the benefit of the author's own experience, to review the basics of taking and interpreting intraoral dental radiographs. A simplified method for positioning the tubehead is explained and classic examples of some common oral pathologies are provided.

Figure 1

Veterinary dental unit control pad.

Figure 2

Dental radiographic film

Figure 3

Digital dental systems. (a) Direct digital sensor (DR). (b) Indirect phosphor plate (CR)

Figure 4

(a) Dorsal recumbency for imaging the mandibular canines and incisors. (b) Lateral arecumbency for imaging the maxillary cheek teeth

Figure 5

(a) Parallel (90º) technique for imaging the mandibular premolars and molars and (b) the resultant radiograph. Courtesy of VetDentalRad.com

Figure 6

(a) Bisecting angle (45º) technique for imaging the maxillary premolars and molars and (b) the resultant radiograph. Courtesy of VetDentalRad.com

Figure 7

Bisecting angle (20º) technique for imaging the mandibular canines and incisors (a) and the maxillary incisors (b). The resultant images are (c) and (d), respectively. Courtesy of VetDentalRad.com

Figure 8

The position indicator device (PID) (arrow) on the tubehead

Figure 9

(a) Dual bisecting angle (20º vertical and 20º lateral) for the left maxillary canine (204) and (b) the resultant image. Courtesy of VetDentalRad.com

Figure 10

(a) Bisecting angle technique (45º) to image the apex of the left mandibular third premolar (307) and (b) the resultant image. Courtesy of VetDentalRad.com

Figure 11

(a) Extraoral technique for imaging the right maxillary premolars and molars without interference from the zygomatic arch and (b) the resultant image. Courtesy of VetDentalRad.com

Figure 12

Poor film quality due to use of a developing solution not specific for dental radiography

Figure 13

Chairside developer

Figure 14

Film clip on the edge of an analog film

Figure 15

Dental radiograph of the left maxilla of a cat. Note the three-rooted fourth premolar (208; white arrow) and radiodense line (red arrows)

Figure 16

Dental radiograph of the left mandible of a cat. A large two-rooted molar (309; white arrow), the mandibular canal (red stars) and ventral cortex (yellow arrows) can be seen

Figure 17

Dental radiograph of the right mandible of a cat. The teeth get larger the further distal they are; white arrow = third premolar (407), yellow arrow = fourth premolar (408), red arrow = first molar (409)

Figure 18

Dental radiograph of the maxillary incisors of a cat. The red arrow points to the right third incisor (103)

Figure 19

Normal mandibular dental radiograph. The periodontal ligaments appear as thin black lines around all the teeth (red arrows). The mandibular canal is demonstrated by the white stars

Figure 20

Normal dental radiograph of the rostral mandible. The central black line (red arrow) is the fibrocartilaginous mandibular symphysis

Figure 21

Normal dental radiograph of the rostral maxilla. The paired radiolucent areas distal to the intermediate incisors are the palatine fissures (red arrows)

Figure 22

Alveolar bone loss is evidenced by radiolucency in the coronal area of the bone. Horizontal bone loss (a,b) appears as generalized bone loss of a similar level across all or part of an arcade (red arrows). Vertical (angular) bone loss (c,d) has the radiographic appearance of one area of recession below the surrounding bone (white arrows). Note also in (d) the fractured third incisor (103; blue arrow) and retained root tip of the second incisor (102; red arrow)

Figure 23

(a) Periapical rarefaction secondary to a type 1 tooth resorption lesion (red arrow). (b,c) Widened endodontic space. The root canal of the left maxillary canine (204) (b) is narrower than the right (104) (c). This indicates that the right canine is non-vital. (d) Internal resorption (red arrow). (e) External resorption (red arrow). Figures (b) and (c) courtesy of Dr Jerzy Gawor

Figure 24

(a) Type 1 tooth resorption in the left mandibular first molar (309): note the significant coronal resorption (red arrow) without replacement and normal periodontal ligament space (yellow arrows). (b) Type 1 tooth resorption in the left mandibular fourth premolar (308): again there is significant coronal resorption (white arrow) without replacement and normal endodontic systems (red arrows). (c) Type 2 tooth resorption on the mandibular canines (304 and 404) (red arrows). There is significant replacement resorption and no identifiable endodontic system or periodontal ligament space. Crown amputation is acceptable for these teeth. (d) Complete root resorption (ghost roots) of the left mandibular third premolar (307) (red arrows). Crown amputation is likewise acceptable for this tooth.

Figure 25

(a) Radiographic appearance of a benign growth on the right mandible of a cat. Note the smooth bony margins. (b,c) Radiographic appearance of a malignant neoplasm (squamous cell carcinoma) in the left mandible (a) and right maxilla (b) of a cat. Note the mottled bone loss in both cases as well as the periosteal reaction in (b) (red arrows) and apical root resorption in (c) (blue arrow). Figure (a) courtesy of Dr Jerzy Gawor.