Diagnostic Imaging in Veterinary Dental Practice

Holly Burchfield Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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Heather Duncan Upstate Veterinary Specialists, 393 Woods Lake Rd, Greenville, SC 29607.

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Rodney Schnellbacher Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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Joerg Mayer Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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Ira Roth Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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History and Physical Examination Findings

A 5-year-old 4.54-kg (9.99-lb) neutered male capuchin monkey (Cebus sp) was referred to the University of Georgia Veterinary Teaching Hospital for evaluation of facial abscesses and regional lymphadenomegaly. The monkey was privately owned (such ownership is allowed by Georgia state law with appropriate permits1). There was no history of health problems, and the patient had undergone annual tuberculosis testing and was vaccinated against rabies virus, measles virus, and tetanus.

Crown reduction of the canine teeth had been performed 7 months prior to the referral examination. Four months prior to the referral visit, the monkey had been examined by the referring veterinarian because of a nodular swelling with purulent exudate under the left eye. At that time, the patient had a swelling under the left eye, mandibular lymphadenomegaly, and a firm, round swelling over the body of the left mandible. The patient reportedly had febrile episodes (rectal temperature not reported) and was initially empirically treated with systemically and topically administered antimicrobials.

The initial physical examination was conducted with the patient under general anesthesia in accordance with hospital policy for prevention of human exposure to potential zoonoses. The mandibular, superficial cervical, and axillary lymph nodes were subjectively enlarged, and an open draining tract was present below the left eye, producing a small amount of purulent exudate. A firm swelling was also present over the body of the left mandible. The right maxillary canine tooth appeared to be fractured at the gingival margin, with only a small fragment of the tooth crown visible. The crowns of the remaining canine teeth each had a pinpoint and faintly gray discoloration, but no other visible lesions. There was no evidence of gingivitis or intraoral draining tracts on oral examination.

Initial screening for tuberculosis, including CT of the head and thorax, was prioritized because of the patient's clinical signs. No thoracic lesions were identified. Anaerobic and aerobic cultures were performed on samples from abscessed tissue. Staphylococcus epidermis and Bacteroides fragilis were cultured from enrichment broth. The right mandibular lymph node was surgically removed under general anesthesia for histologic examination; no microorganisms were observed within affected tissue. Chronic, diffuse, marked follicular lymphoid hyperplasia was present, consistent with chronic reaction to antigenic stimulation. Results of a CBC and serum biochemical analysis revealed no clinically important abnormalities except for relative monocytosis (8%; reference value, < 1.8%) and mild hypoproteinemia (6.6 g/dL; reference range, 7.5 to 8.7 g/dL).

Intraoral dental radiographs were obtained to further assess the cause for facial abscesses (Figure 1).

Figure 1—
Figure 1—

Intraoral dental radiographs of the site of the missing right maxillary canine tooth (A) and the left maxillary (B), right mandibular (C), and left mandibular (D) canine teeth of a 5-year-old male capuchin monkey (Cebus sp) that was evaluated because of facial abscesses and regional lymphadenomegaly.

Citation: Journal of the American Veterinary Medical Association 249, 9; 10.2460/javma.249.9.1013

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Diagnostic Imaging Findings and Interpretation

Evaluation of dental radiographs confirmed that the right maxillary canine tooth was absent (Figure 2). Mild osteolysis and sclerosis were present within the maxillary bone surrounding the left maxillary canine tooth, and periapical lysis was present around the right mandibular canine tooth root. The pulp cavity of the left mandibular canine tooth contained gas-attenuating foci and debris, and periapical alveolar bone lysis was also present around this tooth. In addition, there was pulp exposure of the 3 remaining canine teeth, and these had subjectively wide pulp cavities, considering the apparent maturation of the adjacent teeth. The canine tooth root apices, which typically close as permanent teeth mature, were open, suggesting that these teeth were nonvital.2

Figure 2—
Figure 2—

Same radiographic views as in Figure 1. In panel A, the right maxillary canine tooth is absent (bracket). The pulp cavities of the remaining canine teeth are exposed at the cusp tips (single-headed arrows) and are subjectively wide (double-headed arrows). Periapical lucency, indicating osteolysis, is present around the canine tooth roots (stars).

Citation: Journal of the American Veterinary Medical Association 249, 9; 10.2460/javma.249.9.1013

Computed tomography findings (not shown) were suggestive of mild multifocal lymphadenomegaly, tooth root abscessation of the 3 remaining canine teeth, osteomyelitis of the lateral aspect of the left maxillary bone, and periapical lysis surrounding the left and right mandibular canine tooth roots. The left aspect of the maxilla had a mild, smooth periosteal reaction. The surrounding soft tissues were enlarged, and a focal fluid-attenuating region was present. The CT appearance of the paranasal sinuses was normal.

Treatment and Outcome

The patient returned 4 days later for surgical extraction of the 3 remaining canine teeth under general anesthesia. Local nerve blocks (mental and infraorbital) were performed with 2% lidocaine solution. The teeth were extracted, and the extraction sites were sutured with 4-0 poliglecaprone-25 in a simple interrupted pattern. The extracted teeth had abnormally large pulp cavities containing purulent material. Complete removal of the canine teeth and tooth roots was confirmed by dental radiography after the extractions. No fractures of the mandible or maxilla were evident radiographically. The patient was discharged from the hospital with clindamycin (selected on the basis of susceptibility testing of the S epidermis isolate; 10 mg/kg [4.5 mg/lb], PO, q 12 h for 21 days) as well as meloxicam (0.1 mg/kg [0.45 mg/lb], PO, q 24 h) and tramadol (2.0 mg/kg [0.91 mg/lb], PO, q 24 h) as needed for signs of pain.

Comments

Multiple canine tooth root abscesses were diagnosed in the monkey of this report. These lesions likely resulted from exposure of the pulp cavities caused by reduction of the canine teeth several months prior to the referral examination. Dental radiographs were valuable as a means to evaluate pathological changes of the affected teeth and bones prior to treatment and to ensure complete tooth removal and evaluate the patient for alveolar bone fractures after extractions were performed. Computed tomography allowed visualization of the extent to which the abscesses involved tooth roots and sinuses and also allowed assessment of the enlarged lymph nodes. Although dental radiographs would have been sufficient to characterize the dental lesions in this patient, CT was prioritized for initial imaging to scan for additional lesions in the head, neck, and thorax that might have been indicative of tuberculosis to help ensure the safety of hospital personnel.

Among New World primates, males typically have larger canine teeth than do females.3 The canine teeth of captive male nonhuman primates are commonly reduced or blunted to lessen the chance of injury to conspecifics and human handlers. Reduction can be achieved under general anesthesia by use of the finishing cone on a low-speed dental drill.4 This procedure is typically repeated throughout the life of the patient because normal occlusion sharpens the canine teeth.4 Coronal reduction of the canine teeth can cause thermal damage, exposure of the pulp cavity, or both, predisposing treated teeth to become nonvital and infected. If the pulp is exposed, a pulpotomy (partial coronal pulpectomy), root canal treatment, or extraction is warranted.5

An alternative to (and more appropriate treatment than) repeated coronal reduction is crown reduction with vital pulp therapy (partial coronal pulpectomy) or root canal treatment. In this procedure, the canine teeth are reduced to the level of the incisal edge of the incisors. A portion of the coronal pulp is removed and a biocompatible material such as calcium hydroxide paste or mineral trioxide aggregate is placed, followed by a composite restoration.6,7 However, in 1 study,8 partial coronal pulpectomy was associated with pulp necrosis and chronic inflammation in 8 of 21 (38%) adult male rhesus monkeys (Macaca mulatta), even under optimal conditions in which sterile equipment and aseptic technique were used by veterinarians properly trained in the procedure. Therefore, annual dental radiographic examination is indicated to monitor tooth vitality following this procedure.4

When tooth root abscesses develop secondary to dentin and pulp exposure, surgical and medical treatment is necessary. In late stages, tooth root abscesses can cause clinical signs such as swellings and draining tracts in the region of the jaw or below the eyes. Abscesses should be thoroughly flushed. Affected teeth should be treated by extraction or endodontic treatment, and systemic antimicrobial treatment is warranted.4

The lesions observed in the monkey of this report were severe, and progression of the pathological changes following coronal reduction of the canine teeth was rapid. The risks and benefits of canine tooth reduction should be carefully evaluated on a case-by-case basis. In the case of this particular patient, the authors speculate that if the canine teeth had been treated with vital pulp therapy at the time of reduction, the teeth might have remained vital and the severe dental disease and abscessation could have been avoided. In 1 study,9 7 rhesus monkeys underwent crown reduction of the canine teeth, followed by vital pulp therapy, with 26 of 27 (96%) treated teeth considered viable on the basis of radiographic and histomorphologic evaluations 19 weeks after the treatment, indicating that crown reduction with vital pulp therapy, when done promptly and correctly, may be an appropriate means of reduction of primate canine teeth.

The AVMA indicates opposition to removal or reduction of healthy teeth in captive nonhuman primates or exotic and wild (indigenous) carnivores, except when required for medical treatment or scientific research approved by an institutional animal care and use committee.10 The AVMA policy points out that animals may still cause severe injury with remaining teeth and that to minimize injury, behavioral assessment and modification, environmental enrichment, changes in group composition, and improved animal housing and handling techniques are recommended as alternatives to this type of dental surgery.10 This policy also acknowledges that removal or reduction of teeth for nonmedical reasons can lead to pathological oral conditions.10 On the basis of the findings in this case, the authors strongly caution against the reduction of canine teeth in capuchin monkeys without appropriate means for endodontic repair in the event that pulp is exposed, and emphasize that such a reduction should be considered only in cases of medical necessity or approved scientific research. Primate canine tooth reduction, with vital pulp therapy, should be considered an advanced procedure that is best performed by an experienced veterinary dentist.

References

  • 1. Official code of Georgia. Title 27. Game and fish. Subsections 27-5-5 to 12. Available at: www.legis.ga.gov/Legislation/en-US/GeneralStatutes.aspx. Accessed Mar 28, 2016.

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  • 2. Dupont GA, DeBowes LJ. Endodontic disease. In: Dupont GA, DeBowes LJ, eds. Atlas of dental radiography in small animal practice. St Louis: Saunders-Elsevier, 2009; 150.

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  • 3. Swindler DR. Family Cebidae. In: Strier KB, ed. Primate dentition: an introduction to the teeth of non-human primates. Cambridge, England: Cambridge University Press, 2002;103106.

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  • 4. Johnson-Delaney CA. Nonhuman primate dental care. J Exotic Pet Med 2008; 17: 138143.

  • 5. Wiggs RB, Hall B. Nonhuman primate dentistry. Vet Clin North Am Exot Anim Pract 2003; 6: 661687.

  • 6. Paranjpe A, Zhang H, Johnson JD. Effects of mineral trioxide aggregate on human dental pulp cells after pulp-capping procedures. J Endod 2010; 36: 10421047.

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  • 7. Holmstrom SE, Fitch PF, Eisner ER. Endodontics. In: Veterinary dental techniques for the small animal practitioner. 3rd ed. Philadelphia: Saunders, 2004;350352.

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    • Export Citation
  • 8. Lommer MJ, Verstraete FJ. Results of crown-height reduction and partial coronal pulpectomy in rhesus monkeys (Macaca mulatta). Comp Med 2001; 51: 207.

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    • Export Citation
  • 9. Coman JL, Fortman JD, Alves M, et al. Assessment of a canine crown reduction technique in nonhuman primates. Contemp Top Lab Anim Sci 1998; 37: 6772.

    • Search Google Scholar
    • Export Citation
  • 10. AVMA. Removal or reduction of teeth in nonhuman primates and carnivores. Available at: www.avma.org/KB/Policies/Pages/Removal-or-Reduction-of-Teeth-in-Non-Human-Primates-and-Carnivores.aspx. Accessed Jan 10, 2016.

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  • Figure 1—

    Intraoral dental radiographs of the site of the missing right maxillary canine tooth (A) and the left maxillary (B), right mandibular (C), and left mandibular (D) canine teeth of a 5-year-old male capuchin monkey (Cebus sp) that was evaluated because of facial abscesses and regional lymphadenomegaly.

  • Figure 2—

    Same radiographic views as in Figure 1. In panel A, the right maxillary canine tooth is absent (bracket). The pulp cavities of the remaining canine teeth are exposed at the cusp tips (single-headed arrows) and are subjectively wide (double-headed arrows). Periapical lucency, indicating osteolysis, is present around the canine tooth roots (stars).

  • 1. Official code of Georgia. Title 27. Game and fish. Subsections 27-5-5 to 12. Available at: www.legis.ga.gov/Legislation/en-US/GeneralStatutes.aspx. Accessed Mar 28, 2016.

    • Search Google Scholar
    • Export Citation
  • 2. Dupont GA, DeBowes LJ. Endodontic disease. In: Dupont GA, DeBowes LJ, eds. Atlas of dental radiography in small animal practice. St Louis: Saunders-Elsevier, 2009; 150.

    • Search Google Scholar
    • Export Citation
  • 3. Swindler DR. Family Cebidae. In: Strier KB, ed. Primate dentition: an introduction to the teeth of non-human primates. Cambridge, England: Cambridge University Press, 2002;103106.

    • Search Google Scholar
    • Export Citation
  • 4. Johnson-Delaney CA. Nonhuman primate dental care. J Exotic Pet Med 2008; 17: 138143.

  • 5. Wiggs RB, Hall B. Nonhuman primate dentistry. Vet Clin North Am Exot Anim Pract 2003; 6: 661687.

  • 6. Paranjpe A, Zhang H, Johnson JD. Effects of mineral trioxide aggregate on human dental pulp cells after pulp-capping procedures. J Endod 2010; 36: 10421047.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Holmstrom SE, Fitch PF, Eisner ER. Endodontics. In: Veterinary dental techniques for the small animal practitioner. 3rd ed. Philadelphia: Saunders, 2004;350352.

    • Search Google Scholar
    • Export Citation
  • 8. Lommer MJ, Verstraete FJ. Results of crown-height reduction and partial coronal pulpectomy in rhesus monkeys (Macaca mulatta). Comp Med 2001; 51: 207.

    • Search Google Scholar
    • Export Citation
  • 9. Coman JL, Fortman JD, Alves M, et al. Assessment of a canine crown reduction technique in nonhuman primates. Contemp Top Lab Anim Sci 1998; 37: 6772.

    • Search Google Scholar
    • Export Citation
  • 10. AVMA. Removal or reduction of teeth in nonhuman primates and carnivores. Available at: www.avma.org/KB/Policies/Pages/Removal-or-Reduction-of-Teeth-in-Non-Human-Primates-and-Carnivores.aspx. Accessed Jan 10, 2016.

    • Search Google Scholar
    • Export Citation

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