Diagnostic Imaging in Veterinary Dental Practice

Sophie Döring 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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History and Physical Examination Findings

A 7.5-month-old neutered male English Springer Spaniel was evaluated because of unerupted right and left maxillary canine teeth and signs of oral discomfort. The dog had a history of maxillofacial trauma 5 months prior to this examination; at that time, cone-beam CT (CBCT) was performed under general anesthesia. Several maxillofacial fractures as well as fractures of permanent tooth buds were detected, and the patient was treated conservatively with digital fracture reduction, soft tissue repair, and placement of an elastic face mask. At the 2-week recheck examination, stabilization of the fractures and palatal displacement of the deciduous right maxillary canine tooth were observed. The owner was advised to return the dog at 6 months of age to be evaluated for proper exfoliation of the deciduous teeth and eruption of the permanent teeth.

The dog was reexamined at 5 months of age because of a malocclusion, with persistent deciduous right and left mandibular canine teeth causing trauma to the palatal mucosa. The permanent right and left maxillary canine teeth remained unerupted, and the deciduous right maxillary canine tooth was palatally displaced. Dental radiography and CBCT of the anesthetized patient were performed, and the persistent deciduous right and left mandibular canine teeth were extracted. Recommendations were made to return the patient for further evaluation at 8 months of age (after closure of the apices of the canine teeth) or earlier if the owner observed signs of oral discomfort.

Examination of the patient at 7.5 months of age revealed unilateral, moderate, mucoid nasal discharge with marked crusting around the right naris. Airflow was detected bilaterally; however, a pronounced stertor was heard on the right side. The oral examination revealed incomplete adult dentition, with missing right maxillary second and third incisor teeth and right and left maxillary canine teeth. The right maxillary first incisor and first premolar teeth and the left maxillary third incisor tooth had characteristics of odontodysplasia.1 Palpation of a firm, deviated region of the hard palate at midline elicited signs of pain. The dog was considered systemically healthy, and hematologic assessment revealed that the PCV, serum total protein concentration, and blood glucose concentration were within the respective laboratory reference ranges. The dog was anesthetized, and intraoral dental radiography was performed. Selected radiographic views are provided (Figure 1).

Figure 1—
Figure 1—

Selected intraoral radiographic views of a 7.5-month-old English Springer Spaniel with a history of severe maxillofacial injury incurred at 2.5 months of age. The images were obtained with a bisecting angle technique at a follow-up examination 5 months after the initial injury and 2.5 months after removal of retained deciduous right and left mandibular canine teeth that were causing trauma to the palatal mucosa. A—Lateral view of the right maxillary canine tooth. B—Occlusal view of the maxillary incisor teeth. C—Lateral view of the left maxillary canine tooth. D—Occlusal view of the maxillary canine teeth.

Citation: Journal of the American Veterinary Medical Association 248, 12; 10.2460/javma.248.12.1349

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Diagnostic Imaging Findings and Interpretation

Evaluation of dental radiographs revealed multiple abnormalities, including the presence of fragments of the missing right maxillary second and third incisor teeth and malformed left maxillary third incisor, right maxillary first incisor, and right maxillary first premolar teeth. The permanent maxillary canine teeth were retained bilaterally, with displacement of the right maxillary canine tooth (Figure 2).

Figure 2—
Figure 2—

Same radiographic images as in Figure 1. Notice fragmented remnants of the right maxillary second and third incisor teeth (white arrowheads) and malformed left maxillary third incisor, right maxillary first incisor, and right maxillary first premolar teeth (white arrows). The right maxillary canine tooth is retained and palatally displaced (A), and the left maxillary canine tooth is also retained (B and C); both have irregular root margins (black arrows).

Citation: Journal of the American Veterinary Medical Association 248, 12; 10.2460/javma.248.12.1349

In addition to intraoral dental radiographs, CBCTa was performed for further evaluation. Contiguous, 0.25-mm thick, transverse images of the skull processed with a bone algorithm (110 kV; 2.0 mA; field of view, 183×183 mm in a 732×732-pixel matrix) were obtained. Images were viewed by use of commercially available softwareb and were compared with images obtained by the same method at the time of the initial injury (Figure 3). Evaluation of the new CBCT scan results revealed healing and remodeling of the previously seen bilateral comminuted fractures of the incisive and maxillary bones (Figure 4). There was a focal compression and deformation of the rostral aspect of the right nasal cavity at the level of the right maxillary canine tooth. Turbinate loss, which likely resulted from resorption following the previously described trauma, was noted in the rostral aspect of the right nasal cavity. Soft tissue-attenuating material was present adjacent to the nasal septum, consistent with an accumulation of mucoid discharge or the presence of granulation tissue. The right maxillary second and third incisor teeth were unerupted and slightly fragmented and had lesser density than the remaining maxillary incisor teeth. Malformation of the left maxillary third incisor, right maxillary first incisor, and right maxillary first premolar teeth was confirmed. Bilaterally, the permanent maxillary canine teeth were unerupted, with severe malangulation of the right maxillary canine tooth within its alveolus toward the right palatine fissure. Widening of the periodontal ligament spaces surrounding both right and left maxillary canine teeth was evident.

Figure 3—
Figure 3—

A 3D reconstructed CBCT image (A) and a dorsal CBCT view (B) of the skull of the same dog as in Figure 1. The images were obtained for assessment and treatment planning when the patient was bitten by another dog at 2.5 months of age.

Citation: Journal of the American Veterinary Medical Association 248, 12; 10.2460/javma.248.12.1349

Figure 4—
Figure 4—

A 3-D reconstructed CBCT image (A) and selected sagittal (B), transverse (C), and dorsal (D) CBCT views of the skull of the same dog as in Figure 1 at 7.5 months of age. There is evidence of odontodysplasia of the right maxillary first incisor and first premolar teeth (green arrows), and the unerupted, fragmented right maxillary second and third incisor teeth have lesser density (white arrowheads), compared with the remaining incisor teeth. The right and left unerupted permanent maxillary canine teeth are surrounded by eruption widening of the periodontal ligament space (white arrows). The right maxillary canine tooth is present within its alveolus, but palatally displaced and malaligned, obstructing the right palatine fissure. Loss of nasal turbinates and accumulation of soft tissue–attenuating material are evident in the right nasal cavity (white asterisk).

Citation: Journal of the American Veterinary Medical Association 248, 12; 10.2460/javma.248.12.1349

Treatment and Outcome

Under the same anesthetic episode as for CBCT, modified pedicle flaps were raised from the right maxillary first incisor tooth to the right maxillary third premolar tooth and in the region of the left maxillary canine tooth. Alveolectomy was performed to expose the right maxillary second and third incisor teeth and the right and left maxillary canine teeth. The tooth remnants and odontodysplastic teeth were extracted. Alveolectomy was also performed at the right and left maxillary canine teeth (Figure 5). The teeth were carefully luxated and gently extracted laterally out of their alveoli. Moderate to severe intraoperative hemorrhage was controlled by application of hemostats and digital pressure with moist gauze. Both flaps were sutured, without tension, in a simple interrupted pattern.

Figure 5—
Figure 5—

Intraoperative photographs of the same dog as in Figure 1 at 7.5 months of age, showing the unerupted left (A) and right (B) maxillary canine teeth immediately before extraction, after alveolectomy was performed.

Citation: Journal of the American Veterinary Medical Association 248, 12; 10.2460/javma.248.12.1349

The dog recovered routinely after surgery and was hospitalized overnight. An antimicrobial (ampicillin, 20 mg/kg [9.09 mg/lb], IV, q 8 h) and analgesic medication (hydromorphone, 0.05 mg/kg [0.023 mg/lb], IV, q 6 h) were administered. The following day, the dog was discharged from the hospital, and tramadol (2.7 mg/kg [1.23 mg/lb], PO, q 8 to 12 h for 7 days), meloxicam (0.1 mg/kg [0.045 mg/lb], PO, q 24 h for 5 days), amoxicillin-clavulanic acid (13.6 mg/kg [6.18 mg/lb], PO, q 12 h for 10 days), and oral rinse (0.12% chlorhexidine gluconate solution, q 12 h for 2 weeks) were prescribed. A follow-up examination 2 weeks after surgery revealed complete healing of the extraction sites. A moderate stertor was still present on the right side but had subjectively improved since the previous examination. The owner was advised to return to discuss further treatment options if the right-sided nasal stenosis was thought to impair the dog's quality of life.

Comments

When evaluating dogs with maxillofacial trauma, full-mouth dental radiography as the sole form of diagnostic imaging is likely inadequate to provide information on the full extent of the damage and the spatial relationships of the fracture fragments.2 In addition, the presence of developing tooth buds or a mixed dentition in very young dogs renders a complete evaluation of the maxillary and mandibular anatomy on dental radiographs difficult. When conventional radiography cannot supply satisfactory diagnostic information in human dentistry, CBCT is routinely used. Cone-beam CT allows for assessment of anatomic features on 3D images, which dental radiographs fail to provide. Compared with conventional CT, acquisition time and radiation exposure to the patient are substantially decreased with CBCT, and owing to its smaller section thickness, CBCT also provides better image resolution. With specialized CBCT software, additional 3D reconstructions, and panoramic views, the evaluation of CBCT images provides a surgeon with a detailed, comprehensive representation of the lesions present.

For the dog of this report, although maxillofacial fractures could be identified and trauma to the developing tooth buds could be assumed after evaluation of the radiographic views at the time of the injury, the CBCT images provided more detailed information on location and severity of the maxillofacial and dental injuries, and were crucial in providing an accurate prognosis and allowing the clinician to prepare the owner for the necessity of future surgical intervention. The initial conservative treatment of the 2.5-month-old puppy by careful soft tissue repair and placement of an elastic but stabilizing face mask was in accordance with treatment standards for human pediatric maxillofacial surgery.3–5 Long-term follow-up was strongly indicated, because in cases such as this, damaged tooth buds are at risk for resorption, odontodysplasia, tooth retention, formation of dentigerous cysts, or abnormal eruption, and a need for future surgical intervention should be considered likely.1,6

When the dog of this report was reevaluated at 5 months of age, the persistent deciduous right and left mandibular canine teeth were causing trauma to the palatal mucosa. Prior to extraction of deciduous teeth, it is essential to obtain dental radiographs to determine the shape and location of the root and to document the presence and location of the developing permanent tooth.7 A CBCT scan obtained at the same time provided additional information to predict further maxillary tooth development and assess the likelihood and possible sites of eruption of the affected teeth. Further surgical intervention was postponed until closure of the apices of the right and left maxillary canine teeth could be identified by diagnostic imaging and eruptive forces had likely ceased.8

When the patient was 7.5 months of age, there was still no sign of eruption of the right maxillary second and third incisor teeth or the right and left maxillary canine teeth. Dental radiographs revealed the presence of tooth fragments and malformed, displaced, and retained teeth, as well as closure of the apices of both maxillary canine teeth, but could not provide sufficient information on the exact spatial location of the tooth fragments in the area of the right maxillary first and second incisor teeth. Additionally, the dental radiographs did not clearly show whether the right maxillary canine tooth had erupted intranasally or was still confined within the alveolar bone. This was clearly visible on the CBCT scan, and it was the key point for planning the surgical approach. Although antimicrobials are not routinely indicated for dental procedures on young and healthy patients, the intra- and postoperative antimicrobial administration in this patient was justified by the invasive nature of the surgical procedure.

Cone-beam CT was performed in addition to dental radiography of the patient of this report, and was useful in evaluating the extent of damage caused by maxillofacial trauma; forming an appropriate prognosis; monitoring fracture healing, tooth development, and eruption; and surgical planning for all 3 interventions. This report illustrates the need for long-term follow-up and the combination of thorough oral examinations with diagnostic imaging by appropriate modalities in puppies with maxillofacial trauma.

Footnotes

a.

NewTom 5G, QR srl, Bologna, Italy.

b.

InVivo5, Anatomage Inc, San Jose, Calif.

References

  • 1. Slootweg P. Developmental disturbances in tissue structure. In: Dental pathology: a practical introduction. 2nd ed. Heidelberg: Springer, 2013;3554.

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  • 2. 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
  • 3. Boyette JR. Facial fractures in children. Otolaryngol Clin North Am 2014, 47:747761.

  • 4. Gassner R, Tuli T, Hachl O, et al.Craniomaxillofacial trauma in children: a review of 3,385 cases with 6,060 injuries in 10 years. J Oral Maxillofac Surg 2004, 62:399407.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Morris C, Kushner GM, Tiwana PS. Facial skeletal trauma in the growing patient. Oral Maxillofac Surg Clin North Am 2012, 24:351364.

  • 6. Verstraete FJ, Zin BP, Kass PH, et al.Clinical signs and histologic findings in dogs with odontogenic cysts: 41 cases (1995–2010). J Am Vet Med Assoc 2011, 239:14701476.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Fulton AJ, Fiani N, Verstraete FJ. Canine pediatric dentistry. Vet Clin North Am Small Anim Pract 2014, 44:303324.

  • 8. Legendre LFJ. Management of unerupted teeth. In: Verstraete FJ, Lommer MJ, eds. Oral and maxillofacial surgery in dogs and cats. Edinburgh: Elsevier, 2012;525529.

    • Search Google Scholar
    • Export Citation
  • Figure 1—

    Selected intraoral radiographic views of a 7.5-month-old English Springer Spaniel with a history of severe maxillofacial injury incurred at 2.5 months of age. The images were obtained with a bisecting angle technique at a follow-up examination 5 months after the initial injury and 2.5 months after removal of retained deciduous right and left mandibular canine teeth that were causing trauma to the palatal mucosa. A—Lateral view of the right maxillary canine tooth. B—Occlusal view of the maxillary incisor teeth. C—Lateral view of the left maxillary canine tooth. D—Occlusal view of the maxillary canine teeth.

  • Figure 2—

    Same radiographic images as in Figure 1. Notice fragmented remnants of the right maxillary second and third incisor teeth (white arrowheads) and malformed left maxillary third incisor, right maxillary first incisor, and right maxillary first premolar teeth (white arrows). The right maxillary canine tooth is retained and palatally displaced (A), and the left maxillary canine tooth is also retained (B and C); both have irregular root margins (black arrows).

  • Figure 3—

    A 3D reconstructed CBCT image (A) and a dorsal CBCT view (B) of the skull of the same dog as in Figure 1. The images were obtained for assessment and treatment planning when the patient was bitten by another dog at 2.5 months of age.

  • Figure 4—

    A 3-D reconstructed CBCT image (A) and selected sagittal (B), transverse (C), and dorsal (D) CBCT views of the skull of the same dog as in Figure 1 at 7.5 months of age. There is evidence of odontodysplasia of the right maxillary first incisor and first premolar teeth (green arrows), and the unerupted, fragmented right maxillary second and third incisor teeth have lesser density (white arrowheads), compared with the remaining incisor teeth. The right and left unerupted permanent maxillary canine teeth are surrounded by eruption widening of the periodontal ligament space (white arrows). The right maxillary canine tooth is present within its alveolus, but palatally displaced and malaligned, obstructing the right palatine fissure. Loss of nasal turbinates and accumulation of soft tissue–attenuating material are evident in the right nasal cavity (white asterisk).

  • Figure 5—

    Intraoperative photographs of the same dog as in Figure 1 at 7.5 months of age, showing the unerupted left (A) and right (B) maxillary canine teeth immediately before extraction, after alveolectomy was performed.

  • 1. Slootweg P. Developmental disturbances in tissue structure. In: Dental pathology: a practical introduction. 2nd ed. Heidelberg: Springer, 2013;3554.

    • Search Google Scholar
    • Export Citation
  • 2. 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
  • 3. Boyette JR. Facial fractures in children. Otolaryngol Clin North Am 2014, 47:747761.

  • 4. Gassner R, Tuli T, Hachl O, et al.Craniomaxillofacial trauma in children: a review of 3,385 cases with 6,060 injuries in 10 years. J Oral Maxillofac Surg 2004, 62:399407.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Morris C, Kushner GM, Tiwana PS. Facial skeletal trauma in the growing patient. Oral Maxillofac Surg Clin North Am 2012, 24:351364.

  • 6. Verstraete FJ, Zin BP, Kass PH, et al.Clinical signs and histologic findings in dogs with odontogenic cysts: 41 cases (1995–2010). J Am Vet Med Assoc 2011, 239:14701476.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Fulton AJ, Fiani N, Verstraete FJ. Canine pediatric dentistry. Vet Clin North Am Small Anim Pract 2014, 44:303324.

  • 8. Legendre LFJ. Management of unerupted teeth. In: Verstraete FJ, Lommer MJ, eds. Oral and maxillofacial surgery in dogs and cats. Edinburgh: Elsevier, 2012;525529.

    • Search Google Scholar
    • Export Citation

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