Diagnostic Imaging in Veterinary Dental Practice

Peter C. Strøm Dentistry and Oral Surgery Service, William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Boaz Arzi Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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History and Physical Examination

A 9-year-old 4.9-kg (10.8-lb) spayed female Jack Russell Terrier was evaluated because of a crown-root fracture of the right mandibular third incisor tooth after chewing a cow bone. The owner had noticed the fracture 1 month prior to this examination. The dog was reluctant to eat on the day of the fracture but had no apparent issues with eating afterward. The patient was also receiving medical treatment from the referring veterinarian for glaucoma of both eyes at the time of referral.

The physical examination revealed a rectal temperature of 37.6°C (99.7°F), heart rate of 72 beats/min, and respiratory rate of 20 breaths/min. Initial oral examination revealed a rostral crossbite, a linguoverted right mandibular first incisor tooth, and generalized mild gingivitis. Focal severe gingivitis was observed buccally at the level of the mesial root of the left mandibular first molar tooth, extending from the free gingiva into the attached gingiva (Figure 1). Plaque was noted at the buccal aspect of the right and left mandibular fourth premolar, first molar, and second molar teeth. The right mandibular third incisor tooth had an uncomplicated crown-root fracture. Complete hematologic evaluation and urinalysis had been performed by the referring veterinarian; prior to anesthesia, a blood sample was collected for additional evaluation of PCV, serum total protein concentration, blood glucose concentration, and estimation of BUN concentration with a reagent strip test. All values were within the respective reference ranges.

Figure 1—
Figure 1—

Photograph depicting the fractured left mandibular first molar tooth (black arrow) and focal gingival inflammation (white arrows) in a 9-year-old Jack Russell Terrier that was evaluated because of a crown fracture of the right mandibular third incisor tooth.

Citation: Journal of the American Veterinary Medical Association 245, 12; 10.2460/javma.245.12.1335

The following day, the dog was anesthetized, and selected intraoral dental radiographs were obtained and periodontal charting was performed. The clinical and radiographic findings were compared with dental radiographs obtained 6 months earlier, when the dog had been treated for previous injuries involving the right maxillary fourth premolar tooth and right mandibular second premolar tooth. Slight mobility (mobility stage 1)1 of the left mandibular first molar tooth was present, with a periodontal probing depth at the fracture of 6 mm on the lingual aspect and 9 mm on the buccal aspect. Ampicillin sodium (20 mg/kg [9.1 mg/lb], IV) was administered intraoperatively. A selected radiographic view obtained at the time of evaluation (Figure 2) is provided, with an additional radiograph of the same tooth obtained 6 months earlier (Figure 3).

Figure 2—
Figure 2—

Left parallel intraoral radiographic view of the caudal left mandibular quadrant of the same dog in Figure 1.

Citation: Journal of the American Veterinary Medical Association 245, 12; 10.2460/javma.245.12.1335

Figure 3—
Figure 3—

Left parallel intraoral radiographic view of the caudal left mandibular quadrant of the same dog in Figure 1, obtained 6 months prior to the examination in the present report.

Citation: Journal of the American Veterinary Medical Association 245, 12; 10.2460/javma.245.12.1335

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Diagnostic Imaging Findings and Interpretation

Evaluation of the radiographs revealed a complicated crown-root fracture of the mesial root of the left mandibular first molar tooth, with a concurrent combined periodontal-endodontic lesion, subclassified as a primary endodontic lesion with secondary periodontal involvement (Figure 4). The fracture extended from between the paraconid (mesiobuccal cusp) and protoconid (mesiolingual cusp) and apically into the apical terminus toward the apical delta. Two well-defined periapical lesions were detected. The periodontal ligaments of both roots were compromised, and the integrity of the lamina dura was affected mesially, distally, and interradicularly, as evidenced by the radiolucent areas. There was also vertical bone loss at the mesial aspect of the left mandibular first molar tooth.

Figure 4—
Figure 4—

Same radiographic image as in Figure 2. There is a complicated crown-root fracture of the mesial root of the left mandibular first molar tooth and concurrent combined periodontal-endodontic lesion (subclassified as a primary endodontic lesion with secondary periodontal involvement). Notice the osseous-alveolar lesions of the interradicular area and interproximal alveolar bone distal to the same tooth (arrowheads), the interalveolar pocket formation (white arrows) at the lateral dentotubular canals of the mesial root, and the 2 well-defined periapical lucencies consistent with granulomas (black arrows).

Citation: Journal of the American Veterinary Medical Association 245, 12; 10.2460/javma.245.12.1335

Mild to moderate semigeneralized periodontitis with a horizontal pattern of bone loss was also observed, and an uncomplicated crown fracture of the left mandibular fourth premolar tooth, which had been noted during the previous evaluation, was evident (Figures 4 and 5). Focal severe external root replacement resorption was detected at the distal root of the left mandibular fourth premolar tooth and was also present in the image obtained 6 months prior to the referral evaluation.

Figure 5—
Figure 5—

Same radiographic image as in Figure 3. An uncomplicated crown fracture of the left mandibular fourth premolar tooth (white arrow) is present, and focal external root replacement resorption (black arrows) is evident at the distal root of the left mandibular fourth premolar tooth.

Citation: Journal of the American Veterinary Medical Association 245, 12; 10.2460/javma.245.12.1335

Treatment and Outcome

All teeth were ultrasonically scaled supra- and sub-gingivally. Left inferior alveolar (0.4 mL [2 mg]) and right middle mental (0.2 mL [1 mg]) nerve blocks were performed with bupivacaine hydrochloride (5 mg/mL). The left mandibular first molar tooth was surgically extracted, and the right mandibular third incisor tooth was removed by simple extraction. The extraction sites were sutured with 5–0 poliglecaprone 25. The patient received oxymorphone hydrochloride (0.05 mg/kg [0.023 mg/lb], IV) before and after surgery and meloxicam (0.1 mg/kg [0.045 mg/lb], IV) once after surgery. The patient was discharged with instructions for treatment with tramadol hydrochloride (2.04 mg/kg [0.93 mg/lb], PO, q 8 to 12 h) and chlorhexidine gluconate oral rinse (0.12%, q 8 to 12 h) for 2 weeks. A 2-week follow-up examination revealed that the extraction sites were healed.

Comments

Endodontic and periodontal lesions may occur simultaneously. These pulpal and periodontal lesions are classified according to the pathway of communication and are described as combined periodontal-endodontic lesions. They can be further classified according to their primary origin.

The first subclassification is when the tooth is primarily endodontically compromised.2,3 An infection (anachoresis) via the apex or accessory canals as well as compromised coronal structure may lead to this type of lesion. Often a very narrow drainage canal resulting from lamina dura destruction exists near the gingival margin.2,3 When the pulp becomes inflamed or infected, it elicits an inflammatory response of the periodontal ligament at the apical delta, regions adjacent to openings of accessory canals, or both. These inflammatory lesions cause localized edema and a resulting increase in intrapulpal pressure and cell death.4,5 Increased damage associated with an inflammatory exudate can result in local collapse of the venous part of the local microvasculature. This in turn causes local tissue hypoxia and anoxia with subsequent localized necrosis, the chemical mediators of which cause further localized edema, completing the cycle.6 Destruction of the periapical alveolar bone and progression into the interradicular area may occur as in the dog of this report.

The second type of subclassification is primarily of periodontal origin. In this type of lesion, bacteria from deep periodontal pockets invade the pulp through the lateral canals or through a retrograde pathway at the apical delta. A third subclassification is used when a combination of endodontic and periodontal lesions is found and the primary etiology cannot be determined.

The dog of this report had undergone dental treatment for a complicated crown-root fracture of the right maxillary fourth premolar tooth, also attributed to chewing a cow bone, 6 months prior to evaluation for a fractured incisor tooth. Client compliance in preventing access to inappropriate chewing objects may have prevented any further trauma to the remaining teeth. At the earlier dental treatment, a full-mouth set of dental radiographic images was obtained as part of a comprehensive orodental examination. Full-mouth dental radiographs were important because they allowed detailed assessment of all of the dentoalveolar structures and possible lesions.7,8 In addition, they serve as documentation of a patient's dentoalveolar health status for monitoring of a disease process or for comparative use in a situation where a new disorder emerges. This report exemplifies the value of the full-mouth dental radiographic set, which allowed us to determine that the crown-root fracture of the left mandibular first molar tooth occurred following the previous procedure and that the periapical lesions developed as a result of the tooth fracture.

The findings in the patient of this report confirm the need for dental radiography when assessing signs of oral pain, even if obvious tooth fracture is observed clinically. Having previous full-mouth dental radiographs as a part of a comprehensive oral and physical examination is particularly beneficial for appropriate localization and identification of disease processes, treatment planning, and determination of prognosis.

References

  • 1. American Veterinary Dental College. Tooth mobility. Available at: www.avdc.org/nomenclature.html#mobility. Accessed Apr 21, 2014.

  • 2. Herbert F, Wolf EM, Klaus H, et al. Color atlas of dental medicine: periodontology. 3rd ed. New York: Thieme, 2005.

  • 3. Guldener PH. The relationship between periodontal and pulpal disease. Int Endod J 1985; 18: 4154.

  • 4. Czarnecki RT, Schilder H. A histological evaluation of the human pulp in teeth with varying degrees of periodontal disease. J Endod 1979; 5: 242253.

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  • 5. Glickman GN. Endodontic and periodontal interrelationships. In: Kenneth M, Hargreaves SC, eds. Cohen's pathways of the pulp. 10th ed. St Louis: Mosby Elsevier, 2011;655670.

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  • 6. Soames JVSJ. Oral pathology. 3rd ed. Oxford, England: Oxford University Press, 1998.

  • 7. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in dogs. Am J Vet Res 1998; 59: 686691.

  • 8. 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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  • Figure 1—

    Photograph depicting the fractured left mandibular first molar tooth (black arrow) and focal gingival inflammation (white arrows) in a 9-year-old Jack Russell Terrier that was evaluated because of a crown fracture of the right mandibular third incisor tooth.

  • Figure 2—

    Left parallel intraoral radiographic view of the caudal left mandibular quadrant of the same dog in Figure 1.

  • Figure 3—

    Left parallel intraoral radiographic view of the caudal left mandibular quadrant of the same dog in Figure 1, obtained 6 months prior to the examination in the present report.

  • Figure 4—

    Same radiographic image as in Figure 2. There is a complicated crown-root fracture of the mesial root of the left mandibular first molar tooth and concurrent combined periodontal-endodontic lesion (subclassified as a primary endodontic lesion with secondary periodontal involvement). Notice the osseous-alveolar lesions of the interradicular area and interproximal alveolar bone distal to the same tooth (arrowheads), the interalveolar pocket formation (white arrows) at the lateral dentotubular canals of the mesial root, and the 2 well-defined periapical lucencies consistent with granulomas (black arrows).

  • Figure 5—

    Same radiographic image as in Figure 3. An uncomplicated crown fracture of the left mandibular fourth premolar tooth (white arrow) is present, and focal external root replacement resorption (black arrows) is evident at the distal root of the left mandibular fourth premolar tooth.

  • 1. American Veterinary Dental College. Tooth mobility. Available at: www.avdc.org/nomenclature.html#mobility. Accessed Apr 21, 2014.

  • 2. Herbert F, Wolf EM, Klaus H, et al. Color atlas of dental medicine: periodontology. 3rd ed. New York: Thieme, 2005.

  • 3. Guldener PH. The relationship between periodontal and pulpal disease. Int Endod J 1985; 18: 4154.

  • 4. Czarnecki RT, Schilder H. A histological evaluation of the human pulp in teeth with varying degrees of periodontal disease. J Endod 1979; 5: 242253.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Glickman GN. Endodontic and periodontal interrelationships. In: Kenneth M, Hargreaves SC, eds. Cohen's pathways of the pulp. 10th ed. St Louis: Mosby Elsevier, 2011;655670.

    • Search Google Scholar
    • Export Citation
  • 6. Soames JVSJ. Oral pathology. 3rd ed. Oxford, England: Oxford University Press, 1998.

  • 7. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in dogs. Am J Vet Res 1998; 59: 686691.

  • 8. 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.

    • Crossref
    • Search Google Scholar
    • Export Citation

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