When discussing the role of dental radiography with a pet owner in the exam room, I inform them that the conscious examination provides only half the story of their pet’s oral health. The two most important tools for the dentist are the dental X-ray machine and the periodontal probe/explorer, both of which cannot be used until the patient is under anesthesia. Studies have shown dental radiographs reveal more pathology than a thorough oral examination alone.1,2 In one patient, I may find a nonvital maxillary incisor tooth whose crown looks totally normal on visual inspection.3 In another patient, I may find a “missing tooth” that is actually unerupted and forming a destructive dentigerous cyst within the bone. Dental radiography is essential for developing an individual treatment plan and ensuring successful outcomes. The ability to obtain dental radiographs not only improves your diagnostic capabilities but also improves your therapeutic outcomes. For example, supernumerary roots occur in approximately 10.3 percent of maxillary third premolars in cats,4 and if you do not perform dental radiography, you will not know that you need to extract three roots instead of two. What about other imaging modalities? Skull radiographs are rarely helpful since there is too much superimposition of the maxilla and mandible. Multidetector/multislice computed tomography (CT) has been used for assessing dental and orofacial structures for decades. Its importance has been documented in the morphologic assessment of the temporomandibular joint5 and the assessment of guinea pig dental disease.6 However, conventional CT has been found to have low sensitivity for the detection of tooth resorption in cats.7 Another study in dogs compared the agreement between dental radiography and a 16-slice helical CT scanner in diagnosing radiographic signs consistent with periodontitis and endodontic disease in a group of dogs typical of clinical practice to see if it was necessary to perform both imaging examinations. The frequency of detection of endodontic lesions was 10 percent higher for CT as compared to intraoral radiography. Also, the authors concluded that CT appears to better delineate alveolar margin height than intraoral radiography.8 Over the past decade, cone beam CT (CBCT) has become popular among veterinary dentists. Though not as capable at imaging soft tissue structures as conventional CT, CBCT provides finer spatial resolution of dentoalveolar structures. Image acquisition is rapid, and asymmetry of positioning can be overcome with software. CBCT shines when assessing maxillofacial trauma, where the ability to perform measurements and assess three-dimensional reconstruction for surgical planning. Inka, a female jaguar from the Elmwood Park Zoo, is placed in a CBCT machine for rapid assessment of her dentition. The portability of CBCT is an advantage over conventional CT. Photos courtesy Dr. John R. Lewis CBCT can also provide helpful information for endodontic and periodontal lesions when used together with dental radiography. One study looked at the diagnostic yield of dental radiography compared to CBCT in cats.9 When multiple software models were used, the diagnostic yield of CBCT was found to be significantly higher than that of dental radiography in four of 14 pathologic categories (missing teeth, horizontal bone loss, loss of tooth integrity, and feline resorptive lesions). In nine other categories, CBCT’s diagnostic yield was higher than dental radiography, but not statistically significant. The authors concluded CBCT is better suited than dental radiography for use in diagnosing dentoalveolar lesions in cats. Studies such as this one have driven some veterinary dentists to include CBCT in every patient’s imaging package during anesthetized oral health assessments. Our practice does not currently perform CBCT on every patient, but some practices offer an imaging fee that includes both dental radiography and CBCT. The routine use of CBCT on patients gives us reason to discuss the radiation dose of various modalities. Modern intraoral dental radiography systems require the least amount of radiation exposure. CBCT requires lower radiation exposure than conventional CT scanners, though the dose is protocol dependent. Conventional CT requires an order of magnitude higher of radiation exposure than that of CBCT. Recent human studies have suggested conventional CT scans may have increased the risk of cancer for human patients, so clinicians should be critical in saving CT as a modality for those cases that may have significant benefit from it. John R. Lewis, VMD, DAVDC, Fellow, AVDC OMFS, practices at Veterinary Dentistry Specialists and teaches at Silo Academy Education Center, both in Chadds Ford, Pa. References Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in dogs. American Journal of Veterinary Research 1998; 59(6): 686-691. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in cats. American Journal of Veterinary Research 1998; 59(6): 692-695. Lewis, JR. Why your practice needs dental radiography. Veterinary Practice News 2019: September: 18. Verstraete FJ, Terpak CH. Anatomical variations in the dentition of the domestic cat. Journal of Veterinary Dentistry 1997; 14(4): 137-40. Villamizar-Martinez LA, Villegas CM, Gioso MA, Reiter AM, Patricio GC, Pinto AC. Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography. J Vet Dent. 2016; 33(2): 75-82. Schweda MC, Hassan J, Böhler A, Tichy A, Reiter AM, Künzel F. The role of computed tomography in the assessment of dental disease in 66 guinea pigs. Vet Rec. 2014 Nov 29;175(21):538. Lang LG, Wilkinson TE, White TL, Farnsworth RK, Potter KA. Computed tomography of tooth resorption in cats. Vet Radiol Ultrasound. 2016 Sep;57(5):467-74. Campbell RD, Peralta S, Fiani N, Scrivani PV. Comparing intraoral radiography and computed tomography for detecting radiographic signs of periodontitis and endodontic disease in dogs: an agreement study. Front Vet Sci. 2016;3:68. Heney CM, Arzi B, Kass PH, Hatcher DC, Verstraete FJM. The diagnostic yield of dental radiography and cone-beam computed tomography for the identification of dentoalveolar lesions in cats. Front Vet Sci. 2019 Feb 21;6:42.
