Diagnostic Imaging in Veterinary Dental Practice

G. G. Comet Riggs Dentistry and Oral Surgery Service, William R. Pritchard Veterinary Medical Teaching Hospital.

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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 Findings

An 8-year-old 21.5-kg (47.3-lb) castrated male Australian cattle dog was evaluated after sustaining maxillofacial trauma secondary to biting a horse. The referring veterinarian noted severe dental calculus and suspected a displaced right mandibular fracture. A temporary tape muzzle was placed, and carprofen (2.2 mg/kg [1.0 mg/lb], SC, once), hydromorphone (0.05 mg/kg [0.02 mg/lb], IV, q 6 h), and ampicillin (22.0 mg/kg [10.0 mg/lb], IV, q 8 h) were administered.

Physical examination revealed a body condition score of 5 of 9, mild hypothermia (temperature, 37.3°C [99.1°F] per rectum; reference range, 38° to 39.1°C [100.5° to 102.5°F]), bradycardia (heart rate, 60 beats/min; reference range, 60 to 120 beats/min), and respiratory rate of 18 breaths/min (reference range, 10 to 34 breaths/min). Oral examination revealed lateral luxation of the right maxillary canine tooth (Figure 1), a 12-mm-long mucogingival laceration distal to the right maxillary canine tooth, and swelling at the rostral aspect of the right side of the muzzle. No evidence of mandibular fracture or instability was noted. Thoracic radiography was performed, and findings were consistent with mild bronchopneumonia, possibly secondary to aspiration. Results of a CBC revealed 1,124 band neutrophils/μL with slight to moderate toxic changes and slight toxic changes in the mature neutrophils. There was a mild lymphopenia (756 lymphocytes/μL [reference range, 1,000 to 4,000 lymphocytes/μL]). Serum biochemical analysis revealed slightly low creatinine concentration (0.7 mg/dL [reference range, 0.8 to 1.5 mg/dL]) and slightly high creatine kinase activity (291 U/L [reference range, 55 to 257 U/L). Urinalysis revealed mild proteinuria (75 mg/dL [reference range, 0 to 50 mg/dL]) with a urine specific gravity of 1.048. The remaining hematologic and urological values were within respective reference ranges.

Figure 1—
Figure 1—

Photographs of the laterally luxated right maxillary canine tooth and mucogingival laceration of an 8-year-old castrated male Australian cattle dog that was evaluated because of maxillofacial trauma.

Citation: Journal of the American Veterinary Medical Association 245, 5; 10.2460/javma.245.5.497

The patient was hospitalized overnight for treatment with lactated Ringer's solution (2.3 mL/kg/h [1.0 mL/lb/h], IV), ondansetron hydrochloride dihydrate (0.2 mg/kg [0.09 mg/lb], IV, q 12 h), methadone (0.5 mg/kg [0.23 mg/lb], IV, q 6 h), and ampicillin sodium–sulbactam (40.0 mg/kg [18.18 mg/lb], IV, q 8 h). The dog was anesthetized, and intraoral dental radiography and periodontal charting were performed. Selected radiographic views are provided (Figure 2).

Figure 2—
Figure 2—

Right lateral (A), occlusal (B), and left lateral (C) intraoral radiographic views of the rostral portion of the maxilla of the dog in Figure 1.

Citation: Journal of the American Veterinary Medical Association 245, 5; 10.2460/javma.245.5.497

Dignostic Imaging Findings and Interpretations

Full-mouth dental radiographs revealed a root fracture of the right maxillary canine tooth and an area of decreased radiopacity consistent with external inflammatory root resorption. The pulp cavity of the affected tooth appeared wider than that of the contralateral canine tooth and inconsistent with maturity of the dog, indicating failure of the pulp cavity to narrow. The alveolus of the right maxillary canine tooth was mostly replaced by bone. In addition, the apex of the right maxillary canine tooth appeared round and irregular, compared with the contralateral canine tooth, suggesting a chronic inflammatory process. These findings were supportive of endodontal injury at an earlier age. In addition, the right maxillary canine tooth was luxated laterally and fracture of the ipsilateral maxillary and incisive bones was evident mesially (Figure 3). In the set of full-mouth dental radiographs, mild to moderate semigeneralized periodontitis with a pattern dominated by horizontal bone loss was also seen.

Figure 3—
Figure 3—

Same radiographic views as in Figure 2. The pulp cavity of the right maxillary canine tooth (black arrowheads; A and B) has failed to narrow and appears wider than that of the contralateral canine tooth (C). Traumatic lateral luxation of the right maxillary canine tooth has resulted in fracture of the maxillary and incisive bones mesially (white arrowheads). In panel A, notice decreased radiopacity consistent with external inflammatory root resorption as well as an ill-defined root fragment (black arrow). White arrows indicate the region where the right maxillary canine tooth alveolus should be located. In panel B, root fracture and lateral luxation of the right maxillary canine tooth are evident.

Citation: Journal of the American Veterinary Medical Association 245, 5; 10.2460/javma.245.5.497

Computed tomography of the skull was performed to evaluate the patient for other possible maxillofacial injuries. Gas opacities were observed within the pulp cavity and within the remaining periodontal space of the right maxillary canine tooth, consistent with acute trauma. A slightly displaced fracture of the right incisive bone was detected rostrally. Palatally, a small, slightly displaced maxillary bone fracture was seen. There was loss of bone around the root of the right maxillary canine tooth at the caudal aspect of the fracture that was not consistent with acute trauma. A separated fragment of dental tissue, thought to represent a fragment of the fractured tooth root, was observed apical to this region (Figure 4). Computed tomography further supported the radiographic findings by revealing that the right maxillary canine tooth had a blunted, irregular root and a wider than normal pulp cavity.

Figure 4—
Figure 4—

Computed tomographic images of the head of the dog in Figure 1. A—Sagittal image obtained at the level of the right maxillary canine tooth. B—Sagittal image obtained at the level of the left maxillary canine tooth. In panel A, notice the blunted and irregular root of the right maxillary canine tooth. The pulp cavity appears wider than normal (arrowhead). Gas opacities within the pulp cavity and within the widened periodontal space are consistent with acute trauma. A fragment of dental tissue, thought to represent a part of the right maxillary canine tooth root, is evident apical to the tooth (arrow). The remnant of the alveolus is indicated with an asterisk.

Citation: Journal of the American Veterinary Medical Association 245, 5; 10.2460/javma.245.5.497

Treatment and Outcome

With the patient anesthetized, all teeth were sonically scaled above the gingival margin and pumice polished. A right infraorbital nerve block was performed with 0.5% bupivacaine hydrochloride solution (0.23 mg/kg [0.10 mg/lb]). The right maxillary canine tooth was surgically extracted, and the attached buccal alveolar bone and fragments of the maxillary and incisive bones were removed. Alveolectomy was performed, and the remnant of dental tissue detected on CT images was removed. On the day following surgery, the dog appeared to be comfortable and was discharged home. The owner was instructed to administer amoxicillin-clavulanic acid (17.5 mg/kg [8.0 mg/lb], PO, q 12 h) for 2 weeks, famotidine (1.0 mg/kg [0.45 mg/lb], PO, q 12 h) for 7 days, sucralfate (46.5 mg/kg [21.1 mg/lb], PO, q 8 h) for 10 days, maropitant citrate (1.5 mg/kg [0.68 mg/lb], PO, q 24 h) for 4 days, tramadol (2.5 mg/kg [1.14 mg/lb], PO, q 8 to 12 h) for 5 days, and carprofen (2.5 mg/kg, PO, q 12 h) for 7 days. The owner was also instructed to rinse the dog's oral cavity with chlorhexidine gluconate 0.12% oral rinse solutiona (q 12 h, after meals) for 2 weeks. On follow-up examination 2 weeks after surgery, the extraction site had healed. No swelling of the affected region of the muzzle was noted. Urinalysis showed no further proteinuria. Examination of thoracic radiographs revealed resolution of the previous mild bronchopneumonia.

Comments

Tooth luxation is defined as a partial displacement of the tooth in a lateral direction (lateral luxation), into the alveolus (intrusive luxation), or out of the alveolus (extrusive luxation).1 Lateral luxation is usually accompanied by comminution or fracture of the alveolus and laceration of the mucogingival tissues, as occurred in the dog of this report. Lateral luxation is the most commonly diagnosed type of periodontal injury of traumatic origin in dogs.2–4 Radiographic signs include widening of the periodontal ligament space and displacement of the lamina dura. These changes may not be visible depending on the angle of the x-ray beam and the position of the radiographic plate, sensor, or film relative to the tooth.5–7 In our patient, CT allowed better visualization of the remaining periodontal ligament space and alveolus. The root fragment evident on CT was not easily visualized on dental radiographs. On reevaluation of the dental radiographs, the root fragment could be partially seen, but it may have been overlooked if the CT scan had not been performed. In dogs and cats, CT has been proven to be a superior modality for imaging of the skull, compared with radiography.8 Combining dental radiography and CT scan findings can contribute to the diagnosis and treatment of maxillofacial and dental trauma.

Full-mouth radiography and CT often reveal unexpected and clinically important lesions that are not apparent during an oral examination. In the dog of the present report, the right maxillary canine tooth was luxated laterally and clinically appeared to be an appropriate candidate for tooth splinting.9 However, radiographic findings were indicative of a nonvital tooth, extensive inflammatory root resorption, and root fracture; therefore, extraction was performed rather than splinting. Although the type of tooth resorption can only be definitively identified through histologic examination,10 the radiographic appearance with blunting of the tooth root and replacement of the alveolar bone were supportive of external inflammatory resorption. External inflammatory resorption is characterized by a loss of dental tissues adjacent to areas with loss of alveolar bone secondary to inflammatory conditions (eg, endodontal disease, periodontal disease, or both).10 The frequency of this type of tooth resorption increases with age, which is consistent with the prevalent nature of endodontal and periodontal disease in adult dogs. Almost all endodontically compromised teeth have some degree of external inflammatory resorption.10

Treatment of this type of resorption is targeted to resolve the underlying disease process such as the extraction of the right maxillary canine tooth in the dog of this report. Together with a comprehensive oral and physical examination, both dental radiography and CT were beneficial for diagnosis and treatment planning in this patient.

a.

CET, Virbac Animal Health Inc, Fort Worth, Tex.

References

  • 1. Andreasen JO, Andreasen FM, Andersson L, et al. Textbook and color atlas of traumatic injuries to the teeth. 4th ed. Ames, Iowa: Blackwell Munksgaard, 2007.

    • Search Google Scholar
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  • 2. Gracis M, Orsini P. Treatment of traumatic dental displacement in dogs: six cases of lateral luxation. J Vet Dent 1998; 15: 6572.

  • 3. Kraaijenhagen P. Luxation of a canine tooth with fracture of the alveolar wall of the maxilla in a dog [in Dutch]. Tijdschr Diergeneeskd 1986; 111: 12601261.

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    • Export Citation
  • 4. Ulbricht RD, Manfra Marretta S, Klippert LS. Mandibular canine tooth luxation injury in a dog. J Vet Dent 2004; 21: 7783.

  • 5. White SC, Pharoah MJ. Trauma to teeth and facial structures. In: White SC, Pharoah MJ, eds. Oral radiology: principles and interpretation. 4th ed. St Louis: Mosby, 2004; 615638.

    • Search Google Scholar
    • Export Citation
  • 6. Mulligan TW, Aller MS, Williams CA. Atlas of canine and feline dental radiography. Trenton, NJ: Veterinary Learning System, 1998.

  • 7. Powers MP, Quereshy FA, Ramsey CA. Diagnosis and management of dentoalveolar injuries. In: Fonseca RJ, Walker RV, Betts NJ, et al, eds. Oral and maxillofacial trauma. 3rd ed. St Louis: Elsevier Saunders, 2005; 427477.

    • Search Google Scholar
    • Export Citation
  • 8. Bar-Am Y, Pollard RE, Kass PH, et al. The diagnostic yield of conventional radiographs and computed tomography in dogs and cats with maxillofacial trauma. Vet Surg 2008; 37: 294299.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Startup S. Wire-composite splint for luxation of the maxillary canine tooth. J Vet Dent 2010; 27: 198202.

  • 10. Peralta S, Verstraete FJM, Kass PH. Radiographic evaluation of the types of tooth resorption in dogs. Am J Vet Res 2010; 71: 784793.

  • Figure 1—

    Photographs of the laterally luxated right maxillary canine tooth and mucogingival laceration of an 8-year-old castrated male Australian cattle dog that was evaluated because of maxillofacial trauma.

  • Figure 2—

    Right lateral (A), occlusal (B), and left lateral (C) intraoral radiographic views of the rostral portion of the maxilla of the dog in Figure 1.

  • Figure 3—

    Same radiographic views as in Figure 2. The pulp cavity of the right maxillary canine tooth (black arrowheads; A and B) has failed to narrow and appears wider than that of the contralateral canine tooth (C). Traumatic lateral luxation of the right maxillary canine tooth has resulted in fracture of the maxillary and incisive bones mesially (white arrowheads). In panel A, notice decreased radiopacity consistent with external inflammatory root resorption as well as an ill-defined root fragment (black arrow). White arrows indicate the region where the right maxillary canine tooth alveolus should be located. In panel B, root fracture and lateral luxation of the right maxillary canine tooth are evident.

  • Figure 4—

    Computed tomographic images of the head of the dog in Figure 1. A—Sagittal image obtained at the level of the right maxillary canine tooth. B—Sagittal image obtained at the level of the left maxillary canine tooth. In panel A, notice the blunted and irregular root of the right maxillary canine tooth. The pulp cavity appears wider than normal (arrowhead). Gas opacities within the pulp cavity and within the widened periodontal space are consistent with acute trauma. A fragment of dental tissue, thought to represent a part of the right maxillary canine tooth root, is evident apical to the tooth (arrow). The remnant of the alveolus is indicated with an asterisk.

  • 1. Andreasen JO, Andreasen FM, Andersson L, et al. Textbook and color atlas of traumatic injuries to the teeth. 4th ed. Ames, Iowa: Blackwell Munksgaard, 2007.

    • Search Google Scholar
    • Export Citation
  • 2. Gracis M, Orsini P. Treatment of traumatic dental displacement in dogs: six cases of lateral luxation. J Vet Dent 1998; 15: 6572.

  • 3. Kraaijenhagen P. Luxation of a canine tooth with fracture of the alveolar wall of the maxilla in a dog [in Dutch]. Tijdschr Diergeneeskd 1986; 111: 12601261.

    • Search Google Scholar
    • Export Citation
  • 4. Ulbricht RD, Manfra Marretta S, Klippert LS. Mandibular canine tooth luxation injury in a dog. J Vet Dent 2004; 21: 7783.

  • 5. White SC, Pharoah MJ. Trauma to teeth and facial structures. In: White SC, Pharoah MJ, eds. Oral radiology: principles and interpretation. 4th ed. St Louis: Mosby, 2004; 615638.

    • Search Google Scholar
    • Export Citation
  • 6. Mulligan TW, Aller MS, Williams CA. Atlas of canine and feline dental radiography. Trenton, NJ: Veterinary Learning System, 1998.

  • 7. Powers MP, Quereshy FA, Ramsey CA. Diagnosis and management of dentoalveolar injuries. In: Fonseca RJ, Walker RV, Betts NJ, et al, eds. Oral and maxillofacial trauma. 3rd ed. St Louis: Elsevier Saunders, 2005; 427477.

    • Search Google Scholar
    • Export Citation
  • 8. Bar-Am Y, Pollard RE, Kass PH, et al. The diagnostic yield of conventional radiographs and computed tomography in dogs and cats with maxillofacial trauma. Vet Surg 2008; 37: 294299.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Startup S. Wire-composite splint for luxation of the maxillary canine tooth. J Vet Dent 2010; 27: 198202.

  • 10. Peralta S, Verstraete FJM, Kass PH. Radiographic evaluation of the types of tooth resorption in dogs. Am J Vet Res 2010; 71: 784793.

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