Diagnostic Imaging in Veterinary Dental Practice

Suzanna L. Hatunen Northeast Veterinary Hospital, Peabody, MA 01960.

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Kevin K. Ng Animalius Vet, Bayswater, WA 6053, Australia.

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Nadine Fiani Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

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History and Physical Examination Findings

An 18-month-old 3.5-kg (7.7-lb) spayed female Burmese cat was referred to the Dentistry and Oral Surgery Department of a veterinary referral hospital for evaluation and treatment of supernumerary teeth. The cat had been evaluated by the referring clinician 3 days earlier because of a few months’ history of severe halitosis. The cat was reportedly not showing signs of oral pain or difficulty with prehension or mastication of food. Results of a CBC and serum biochemical analysis revealed mild neutropenia (1.72 × 109 neutrophils/L; reference range, 2.30 × 109 to 10.29 × 109 neutrophils/L) but were otherwise within respective reference ranges. The referring veterinarian had identified the presence of multiple supernumerary teeth during examination of the oral cavity. The referring veterinarian performed supragingival and subgingival plaque and calculus removal using an ultrasonic scaler, with the patient under general anesthesia and prescribed a course of amoxicillin–clavulanic acid (12 mg/kg [5.45 mg/lb], PO, q 12 h).

The results of a general physical examination performed at the referral hospital were unremarkable. The cat was anesthetized, and a detailed oral examination, including periodontal probing and charting, was performed. Supernumerary left and right maxillary third premolar teeth and supernumerary left and right mandibular fourth premolar teeth were identified on oral examination. Additionally, abnormal dental tissue palatal to the left and right maxillary fourth premolar teeth was identified. Full-mouth intraoral radiographs were obtained. Selected radiographic views are provided (Figure 1).

Figure 1
Figure 1

Selected radiographic images of the maxillary (A and B) and mandibular (C and D) dentition of an 18-month-old Burmese cat that was referred for evaluation and treatment of supernumerary teeth. A and B—Bisecting-angle intraoral radiographs of the caudal portion of the right and left maxillae, respectively. C and D—Parallel intraoral radiographs of the caudal portion of the right and left mandibles, respectively.

Citation: Journal of the American Veterinary Medical Association 258, 8; 10.2460/javma.258.8.843

Diagnostic Imaging Findings and Interpretation

Intraoral radiographs confirmed the presence of several supernumerary teeth. In addition to the supernumerary third premolar teeth in both maxillary quadrants and supernumerary fourth premolar teeth in both mandibular quadrants, the dental tissue palatal to the maxillary fourth premolar teeth appeared to be consistent with supernumerary fourth premolar teeth on the basis of crown morphology (Figure 2). Severe crowding was evident in areas with supernumerary teeth, and there was superimposition of multiple dental structures.

Figure 2
Figure 2

Same intraoral radiographs as in Figure 1. A—Two right maxillary third premolar teeth are present (solid yellow and white arrows). The rostral right maxillary third premolar tooth has a supernumerary root (dotted white arrow), and the roots of this tooth are convergent. The distal root of the anatomically normal right maxillary fourth premolar tooth (white-outlined arrow) is superimposed over a supernumerary right maxillary fourth premolar tooth (dotted black arrow), which appears to have fused or convergent roots. The right maxillary first molar tooth (yellow-outlined arrow) is anatomically normal. B—Two left maxillary third premolar teeth are present (solid yellow and white arrows). The rostral left maxillary third premolar tooth has a supernumerary root (dotted white arrow). The caudal left maxillary third premolar tooth is rotated and also has a supernumerary root (dotted yellow arrow). The left maxillary fourth premolar tooth (white-outlined arrow) and left maxillary first molar tooth (arrowhead) are anatomically normal. The supernumerary left maxillary fourth premolar tooth (black-outlined arrow) appears to have fused or convergent roots. C—A supernumerary right mandibular fourth premolar tooth (arrow) is present. D—A supernumerary left mandibular fourth premolar tooth (solid arrow) is present. There is mild horizontal bone loss (dotted arrows) affecting the left mandibular third and fourth premolar teeth as well as the supernumerary left mandibular fourth premolar tooth. Both fourth premolar teeth have furcation involvement.

Citation: Journal of the American Veterinary Medical Association 258, 8; 10.2460/javma.258.8.843

Multiple teeth with variant radicular anatomy were also identified. These included supernumerary roots affecting 3 of 4 maxillary third premolar teeth and root convergence or fusion of a right maxillary third premolar tooth and the supernumerary left and right maxillary fourth premolar teeth (Figure 2). Radiographic evidence of localized periodontitis was also present, with mild horizontal bone loss affecting the left mandibular third premolar, fourth premolar, and supernumerary fourth premolar teeth.

Treatment and Outcome

With the patient under general anesthesia, bilateral infraorbital and inferior alveolar nerve blocks were performed (0.2 mL [1 mg]/site) with bupivacaine hydrochloride (5 mg/mL). The caudal right and left maxillary third premolar teeth, supernumerary right and left maxillary fourth premolar teeth, right and left maxillary fourth premolar teeth, right and left maxillary first molar teeth, and supernumerary right and left mandibular fourth premolar teeth were surgically extracted through envelope mucogingival flaps. Variant radicular anatomy was taken into account when tooth sectioning was performed for multirooted teeth. Notably, the caudal left maxillary third premolar tooth was sectioned into 3 individual crown-root segments rather than 2 because of the presence of a third root, and the supernumerary right and left maxillary fourth premolar teeth were not sectioned owing to fusion of the usual 3 roots into a single, large root. Preservation of the right and left maxillary fourth premolar teeth would have been preferred; however, examination of the lingual aspect of the furcations of these teeth after extraction of the supernumerary counterparts revealed substantial periodontitis. Extraction of the left and right maxillary first molar teeth was also performed to facilitate closure of the extraction sites.

A single perioperative injection of meloxicam (0.1 mg/kg [0.045 mg/lb], SC) was administered. The patient recovered well after the procedure and was discharged from the hospital. Syringes of buprenorphine hydrochloride (0.02 mg/kg [0.01 mg/lb], oral transmucosal administration, q 8 h for 5 days) were dispensed for postoperative analgesia. Additional instructions included feeding the patient only wet food for a period of 2 weeks and restricting the patient from chewing any toys during this time to allow for healing of extraction sites. Evaluation of the extraction sites 14 days after surgery revealed uncomplicated healing, and the owner reported that the cat had resumed eating normally.

Comments

The dental formula for the normal permanent dentition of a cat is I 3/3, C 1/1, P 3/2, M 1/1 = 30. Supernumerary teeth, a condition also known as hyperdontia or polyodontia, is defined as the presence of a greater-than-normal number of teeth.1 The presence of supernumerary teeth can result in overcrowding and tooth malalignment, leading to an increase in plaque retention and predisposing to periodontal disease. This was evident in the left mandibular quadrant and at the lingual aspects of the left and right maxillary fourth premolar teeth in the cat of this report. Although not observed in this case, supernumerary teeth have been associated with tooth impaction in a dog.2 The etiopathogenesis of supernumerary teeth is unknown, but in people, various influences have been suggested such as disturbances in tooth bud development (eg, extreme growth of the dental lamina), atavism, and certain genetic defects.3,4,5 The prevalence of supernumerary teeth appears to be low in cats, with studies6,7,8 reporting 1.4% to 3.7% of cats affected in various populations. Two studies6,9 indicate that, in cats, the premolar teeth are most frequently affected by this condition, with the supernumerary counterpart most commonly located immediately mesial to the maxillary second and mandibular third premolar teeth. In the cat of the present report, supernumerary maxillary third and fourth premolar teeth, as well as supernumerary mandibular fourth premolar teeth lingual to their normal counterparts, were present bilaterally. The supernumerary teeth in this case were first identified when the cat was 18 months of age; a thorough oral examination at an earlier age (eg, 6 months) would have identified the dental abnormalities and allowed for strategic extractions to alleviate crowding and prevent the development of periodontitis.

Supernumerary roots develop as a result of inappropriate formation of the epithelial diaphragm during root development.3,4 Odontogenic plasticity is greater during tooth formation, allowing for various morphological changes.3 Although the exact etiopathogenesis of supernumerary roots is uncertain, predisposing factors in people have been proposed, such as genetic causes, local trauma, external pressure, and developmental anomalies.3 Variations in the number of tooth roots are relatively common in cats, with the maxillary second premolar and first molar teeth reported to have 1 or 2 roots or, in some cases, an intermediate variation consisting of partially fused roots.6,9 Supernumerary roots are also frequently found for the maxillary third premolar tooth,6,8,9 with a prevalence of 1.7% to 10.3%,6,9,10 and have been reported for mandibular fourth premolar and first molar teeth at lower frequencies.6 Supernumerary roots may develop unilaterally or bilaterally.9 The supernumerary roots of maxillary third premolar teeth reportedly vary in size and shape from normal (ie, similar to the anatomically normal roots) to slender.6,8,9 Although these additional roots may potentiate periodontal support by increasing attachment to the alveolar bone, their presence may also contribute to development of complicated furcations and distortion of the gingival margin, forming an environment for microbes to evoke local disease.3 Variations in tooth root anatomy are also clinically important if extraction or endodontic therapy is to be attempted. For example, in the present case, identification of supernumerary roots guided tooth sectioning, helping to avoid potential complications such as root fracture or root retention. Conversely, identification of convergent or fused root anatomy that prevented the need for tooth sectioning allowed for a simple extraction technique, thus reducing surgical trauma and saving time.

The case described here demonstrated the importance of dental radiographs for the diagnosis of supernumerary teeth and variant radicular anatomy, as well as for treatment planning. Identification and, if indicated, extraction of supernumerary teeth in cats at an early age may help prevent the early onset of periodontitis and allow for the preservation of adjacent teeth.

Acknowledgments

The authors declare that there were no conflicts of interest.

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