Diagnostic Imaging in Veterinary Dental Practice

Marika E. Constantaras Fox Valley Veterinary Dentistry and Surgery, 3123 N Clybourn Ave, Chicago, IL 60618.

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 DVM, MS
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Cynthia J. Charlier Fox Valley Veterinary Dentistry and Surgery, 3123 N Clybourn Ave, Chicago, IL 60618.

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 DVM, DAVDC

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History and Physical Examination Findings

A 6-year-old 5-kg (11-lb) castrated male domestic shorthair cat was evaluated because of a 3-day history of drooling and protusion of the tongue. The cat had generalized stomatitis at 3 years of age, and all premolar and molar teeth were extracted at that time. Intraoral radiographs had not been obtained, and there were no follow-up examinations prior to referral.

Pertinent physical examination findings included a physiologic heart murmur; the remainder of the general physical examination was unremarkable, and results of a CBC and serum biochemical analysis were within the respective reference ranges. Maxillofacial examination revealed that the cat was unable to completely close its mouth and an asymmetric skeletal malocclusion1 was present (Figure 1). The maxillary-mandibular asymmetry was in a side-to-side direction with the mandibles deviated slightly to the right. Mesioversion and palatoversion of the right maxillary canine tooth caused the tooth to occlude on the lingual side of the right mandibular canine tooth. Moderate to severe generalized gingivitis and caudal mucositis1 were evident. Smooth, firm swellings of the buccal alveolar bone associated with both maxillary canine teeth were detected. All 4 canine teeth were partially extruded, with several millimeters of cementum visible coronal to the gingival margin. The right maxillary third incisor tooth had stage 3 mobility,1 and all other teeth were apparently absent.

Figure 1—
Figure 1—

Photograph (occlusal view) of the teeth of a 6-year-old castrated male domestic shorthair cat that was evaluated because of drooling and protrusion of the tongue. Open-mouth dental interlock is evident. Notice the maxillary-mandibular asymmetry with the mandibles deviated slightly to the right and palatoversion of the right maxillary canine tooth. Contact between the right maxillary and mandibular canine teeth as well as buccal bone expansion associated with the right and left maxillary canine teeth can be seen.

Citation: Journal of the American Veterinary Medical Association 243, 12; 10.2460/javma.243.12.1691

The cat was anesthetized, and full-mouth intraoral radiographs were obtained. Occlusal and lateral radiographs of the right and left maxillary canine teeth and an occlusal radiograph of the mandibular canine teeth were obtained by means of the bisecting angle technique with a size 2 sensor (Figure 2). Intraoral examination revealed extrusion of the right and left maxillary canine teeth with 5 mm of cementum visible coronal to the gingival margin, bilateral moderate to severe buccal bone expansion associated with the maxillary canine teeth, and bilateral mild buccal bone expansion associated with the mandibular canine teeth. Periodontal probing revealed increased probing depths consistent with periodontitis. Clinical attachment loss was most severe on the palatal aspects of the maxillary canine teeth and right maxillary third incisor tooth and on the lingual aspects of the mandibular canine teeth. Probing depths of 6 mm on the palatal aspect of the right maxillary canine tooth, 5 mm on the palatal aspect of the left maxillary canine tooth, 4 mm on the lingual aspect of the left mandibular canine tooth, and 3 mm on the lingual aspect of the right mandibular canine tooth were found. A probing depth of 3 mm was detected on the palatal aspect of the right maxillary third incisor, and the tooth had 3 mm of gingival recession and stage 3 mobility.1 The right and left maxillary canine teeth had stage 1 mobility.1

Figure 2—
Figure 2—

Intraoral lateral radiographic views of the right (A) and left (B) maxillary canine teeth and occlusal views of the maxillary canine and incisor (C) and mandibular (D) canine teeth of the cat in Figure 1.

Citation: Journal of the American Veterinary Medical Association 243, 12; 10.2460/javma.243.12.1691

Determine whether additional studies are required, or make your diagnosis, then turn the page →

Diagnostic Imaging Findings and Interpretation

Mesioversion and palatoversion of the right maxillary canine tooth with occlusion on the lingual side of the right mandibular canine tooth was confirmed. Tooth-to-tooth contact between the right maxillary and right mandibular canine teeth resulted in open-mouth dental interlock. Evaluation of radiographs revealed severe horizontal and vertical bone loss along the mesial, distal, buccal, and palatal aspects of the left and right maxillary canine teeth, consistent with periodontitis (Figure 3). In addition, expansion of the alveolar bone was detected along the buccal aspects of the maxillary canine teeth. Extrusion of the left and right maxillary canine teeth was evident radiographically. There was severe horizontal and vertical bone loss associated with the right maxillary third incisor, with external inflammatory root resorption and a possible root fracture visible. The remaining maxillary and mandibular incisors were absent and were likely lost because of severe attachment loss.

Figure 3—
Figure 3—

Same radiographic views as in Figure 2. On the lateral views (A and B), there is vertical (white arrowheads) and horizontal (black arrowheads) bone loss associated with the right and left maxillary canine teeth and the right maxillary third incisor tooth. External inflammatory resorption of the right maxillary third incisor tooth as well as a possible root fracture with resorbing root tip fragment is evident on multiple views (black arrows; A and C). On the occlusal views, moderate to severe alveolar bone expansion is evident along the buccal aspects of the left and right maxillary canine teeth (white arrows), and palatoversion of the right maxillary canine tooth (white asterisk) can be seen (C). Vertical bone loss is also evident on the buccal, palatal, and lingual aspects of the maxillary and mandibular canine teeth (white arrowheads; C and D).

Citation: Journal of the American Veterinary Medical Association 243, 12; 10.2460/javma.243.12.1691

Vertical bone loss and mild buccal bone expansion was also observed in association with the right and left mandibular canine teeth. All canine teeth had signs of mild external inflammatory root resorption. Assessment of lateral views of the right and left mandibles (images not provided) revealed a retained mesial root of the right mandibular fourth premolar tooth and a retained distal root of the left mandibular molar tooth.

Treatment and Outcome

Following ultrasonic scaling and polishing of all teeth, left and right infraorbital and inferior alveolar nerve blocks were performed with 0.75 mg (0.15 mL) of bupivacainea at each site to provide regional anesthesia. Extraction of the 4 canine teeth, the right maxillary third incisor tooth, the retained mesial root of the mandibular fourth premolar tooth, and the retained distal root of the left mandibular molar tooth was completed by use of standard techniques.2 Buccal osteoplasty was performed to reduce the expanded buccal bone prior to closure of the mucogingival flap. Removal of the tooth roots was confirmed by evaluation of postoperative radiographs. The cat was continued on buprenorphineb (0.01 mg/kg [0.0045 mg/lb]) administered transmucosally for 5 days after surgery. Reexamination 14 days after treatment confirmed that the oral surgery sites had healed and the caudal mucositis had decreased in severity. The client reported that the cat had a good appetite and was no longer drooling.

Comments

Differential diagnoses for a cat that cannot close its mouth include temporomandibular joint luxation or fracture, jaw fractures, displacement of the coronoid process lateral to the zygomatic arch, class I malocclusion1 resulting in dental interlock, tumors, foreign bodies, and neuropathies.3 In the cat of this report, clinical signs of periodontitis were evident on examination in the awake animal and included buccal bone expansion, extrusion of both maxillary canine teeth, and mesioversion and palatoversion of the right maxillary canine tooth (Figure 1). Given the cat's history of an acute inability to close the mouth, the lack of any known trauma, and the clinical findings, dental interlock caused by advanced periodontal disease was considered the most likely diagnosis.

Periodontitis is inflammation that involves tissues of the periodontium and indicates irreversible loss of tooth supporting structures.4 Alveolar bone loss is a common sequela of periodontitis and may be evident radiographically as vertical or horizontal bone loss, or both.5 Feline buccal bone expansion is a widening of the alveolar bone on the buccal aspect of the canine teeth.5–7 This bulbous alveolar swelling, also described as alveolar osteitis,6 often develops bilaterally, and moderate to severe buccal bone expansion is associated with periodontal disease.5–7 The underlying process by which buccal bone expansion develops has not been investigated, but results of 1 study5 suggested that a buccal bone width > 2 mm is correlated with advanced periodontal disease because 10 of 11 cats with moderate to severe buccal bone expansion of 1 or more canine teeth also had severe vertical bone loss associated with those teeth. Radiographically, this appears as bone loss immediately adjacent to the root with expansile alveolar bone growth.5,6 The buccal bone expansion in the cat of the present report appeared clinically and radiographically to be associated with advanced periodontitis, as evidenced by the tooth mobility, deep periodontal pockets, and a substantial degree of vertical bone loss. Treatment includes extraction of the affected tooth, curettage, rinsing of the alveolus with sterile saline (0.9% NaCl) solution, and reduction of the alveolar expansion via osteoplasty before flap closure.7

Buccal bone expansion of the canine teeth is also often seen in conjunction with tooth extrusion, which is evident by the cementoenamel junction being several millimeters coronal to the alveolar margin and causing the canine teeth to appear elongated.8 Tooth extrusion, also described as supereruption, has been associated with periodontitis,6 although it may be also associated with tooth resorption or be found in the absence of either of these conditions.8 It has been postulated that alveolar bone expansion, tooth extrusion, and tooth resorption may have a common cause.8 Signs of periodontitis, buccal bone expansion, tooth extrusion, and tooth resorption were all present in the cat of the present report.

Because radiographs are 2-D, radiographic evidence of loss of the bony support along the buccal, palatal, or lingual alveolar bone plates is not readily seen on lateral views. The occlusal radiographic view is necessary for evaluation of lingual and buccal alveolar margin height, and the lateral view is necessary to evaluate the mesial and distal alveolar margin heights.4,5 In a study4 that compared the diagnostic values of occlusal and lateral views of the maxillary canine teeth with periodontal probing depths, there was no correlation between the alveolar margin height on the palatal aspect of the maxillary canine teeth as determined radiographically and the clinical attachment level. Dental probing as part of the clinical examination will detect bone loss affecting the palatal aspect of the maxillary canine tooth, and the morphology of an infrabony defect indicative of vertical bone loss must also be determined on the basis of clinical examination findings.4,5,9 Intraoral occlusal and lateral radiographic views, in conjunction with a complete intraoral examination including dental probing, are necessary to detect early periodontitis. Moderate to severe buccal bone expansion, which can be detected during an awake examination, has been shown to be a reliable predictor of periodontitis.5 Further investigation is warranted to evaluate whether mild buccal bone expansion or subtle tooth extrusion is a reliable predictor for the development of periodontitis or clinical tooth resorption because detection and treatment of vertical bone loss during the early stages of periodontal disease may slow the progression of periodontal disease.

According to the medical record, the cat of the present report underwent extraction of all maxillary and mandibular premolar and molar teeth at 3 years of age as treatment for generalized stomatitis. Full-mouth intraoral radiographs and complete dental charting were obtained to determine whether retained tooth roots were present and to evaluate for the presence of tooth resorption and the severity and extent of periodontal disease. Following oral surgery to extract the periodontally diseased teeth and retained tooth roots, there was substantial clinical improvement in the gingivitis and caudal mucositis in this cat.

The periodontal attachment loss associated with the right maxillary canine tooth resulted in extrusion and mobility of the tooth, allowing mesioversion and palatoversion and causing it to occlude on the lingual side of the right mandibular canine tooth. The tooth-to-tooth contact between the right maxillary and right mandibular canine teeth resulted in open-mouth dental interlock. Following oral surgery to extract the teeth, the cat's occlusion was considered normal. A thorough oral examination and early treatment of periodontal disease may have reduced the risk of development of advanced periodontitis, tooth extrusion, and open-mouth dental interlock.

a.

0.5% Marcaine, Hospira Inc, Lake Forest, Ill.

b.

Buprenex, Reckitt Benckiser Pharmaceuticals, Richmond, Va.

References

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  • 4. Tsugawa AJ, Verstraete FJ, Kass PH, et al. Diagnostic value of the use of lateral and occlusal radiographic views in comparison with periodontal probing for the assessment of periodontal attachment of the canine teeth in dogs. Am J Vet Res 2003; 64:255261.

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