Diagnostic Imaging in Veterinary Dental Practice

Ana Nemec William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Amy Fulton William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Natalia Vapniarsky William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Lynelle R. Johnson Department of Medicine and Epidemiology, 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 Findings

A 7-year-old 8.6-kg (18.9-lb) castrated male Pug was evaluated because of chronic nasal discharge. Respiratory signs, which started 3 weeks following ingestion of coffee beans, had been noticed for the past 2.5 years and had developed into respiratory distress. Six months after the onset of clinical signs, the patient developed a mucoid discharge from the left nostril. Rhinoscopy revealed hyperemia and mucus in the left nasal cavity. The mucoid discharge resolved temporarily with the use of amoxicillin–clavulanic acid (14.5 mg/kg [6.59 mg/lb], PO, q 12 h), but occasional treatment with neomycin–polymyxin B–dexamethasone ophthalmic drops (in each nostril, q 12 h) had no effect. Two months prior to evaluation, oral examination by the referring veterinarian revealed a well-healing extraction site (which tooth had been extracted was not reported), and thoracic radiography revealed no abnormalities. Several other teeth were extracted at that time because of advanced periodontal disease involving the right maxillary and right mandibular quadrants. Because there was no improvement in the primary problem, the patient was referred.

Findings on general physical examination were largely unremarkable, apart from stenotic nares, bilateral serous nasal discharge, and reduced nasal airflow on the left (normal on the right). Moderate stertor was evident, and referred upper airway sounds were auscultated over the thorax.

Oral examination revealed several missing teeth and mild generalized gingivitis. Results of a CBC demonstrated mild leukocytosis (15,270 leukocytes/μL; reference range, 6,000 to 13,000 leukocytes/μL), with neutrophilia (10,796 neutrophils/μL; reference range, 3,000 to 10,500 neutrophils/μL) ascribed to chronic inflammation. Results of a serum biochemical profile and urinalysis did not reveal any clinically important findings.

Laryngeal examination revealed a severely elongated soft palate and everted laryngeal saccules. A detailed oral examination and maxillary dental radiography with the patient anesthetized revealed that the right maxillary third and fourth premolar teeth, right maxillary second molar tooth, and left maxillary second, third, and fourth premolar teeth were missing. Periodontal probing revealed no important abnormalities apart from a small nonhealing area of the gingiva at the level of the missing left maxillary third premolar tooth. There was also a root fracture of the left maxillary first premolar tooth with a retained root fragment. At the level of the apex of the left maxillary canine tooth, an opaque structure was noted (Figure 1).

Figure 1—
Figure 1—

Occlusal (A) and left lateral (B) radiographic views of the maxilla of a 7-year-old Pug evaluated because of chronic left-side nasal discharge and occlusal radiographic view following contrast and brightness adjustment (C).

Citation: Journal of the American Veterinary Medical Association 241, 12; 10.2460/javma.241.12.1567

Determine whether additional studies are required, or make your diagnosis, then turn the page

Diagnostic Imaging Findings and Interpretation

On the survey radiographic view of the maxillas, an opaque structure in the shape of the crown of a premolar tooth could be seen in the left nasal cavity at the level of the apex of the left maxillary canine tooth (Figure 2). This finding was consistent with a possible foreign body in the nasal cavity; however, it was not possible to rule out a resorbing unerupted tooth associated with a dentigerous cyst.1 By means of image processing,2 a radiolucent area surrounded by a rim of bone at the level of the left maxillary canine tooth was identified. The retained root tip of the maxillary first premolar tooth had no clinical or radiographic signs of endodontic disease3 and was likely not contributing to the clinical signs.

Figure 2—
Figure 2—

Same radiographic views as in Figure 1. On the occlusal (A) and left lateral (B) radiographic views, there is an opaque structure in the shape of the crown of a premolar tooth at the level of the left maxillary canine tooth (white arrows). In addition, there is mild horizontal bone loss affecting the incisor teeth, partially unerupted right and left maxillary canine teeth with mild associated pericoronitis, a root fragment of the left maxillary first premolar tooth, and rotation of the premolar teeth consistent with the brachycephalic head conformation. Following adjustment of contrast and brightness of the occlusal radiographic view, a radiolucent area surrounded by a rim of bone at the level the left maxillary canine tooth becomes obvious (white arrow; C).

Citation: Journal of the American Veterinary Medical Association 241, 12; 10.2460/javma.241.12.1567

Computed tomography was recommended to plan further diagnostic testing and treatment.4 Contiguous precontrast 1.3-mm collimated transverse images (120 kV; 79 to 131 mA; field of view, 157 × 157 mm in a 512 × 512-pixel matrix) as well as reconstructed 0.6-mm transverse images of the rostral aspect of the skull processed in a bone algorithm were obtained and viewed with a window width of 2,900 Hounsfield units and window level of 600 Hounsfield units. These revealed a hyperattenuating structure representing the crown of a tooth in the ventral aspect of the left nasal passage at the level of the missing left maxillary third premolar tooth (Figure 3). A large amount of soft tissue–attenuating material was noted around the tooth fragment with osteolysis of the lateral aspect of the palatine process of the maxillary bone on the left side at the level of the tooth fragment, suggestive of an abscess. However, an infected cyst or neoplasia could not be ruled out.5 Rhinoscopy was performed in an attempt to remove the foreign body and revealed mucus and inflammation of the nasal turbinates. The suspected foreign body could not be identified. Clindamycin hydrochloride (8.7 mg/kg [3.95 mg/lb], PO, q 12 h for 2 weeks) was prescribed, and the patient was scheduled to return for surgical removal of the intranasal tooth remnant.

Figure 3—
Figure 3—

Computed tomographic images obtained at the level of the maxillary third premolar teeth (which are absent) of the dog in Figure 1. There is a hyperattenuating structure in the shape of the crown of a premolar tooth in the ventral aspect of the left nasal passage (arrow). This structure is surrounded by a soft tissue–attenuating area. There is associated osteolysis of the palatine process of the maxillary bone underlying the foreign body (arrowheads). In the remainder of the left nasal passage, there is a moderate amount of soft tissue–attenuating material and only a small amount of soft tissue–attenuating material in the right nasal passage.

Citation: Journal of the American Veterinary Medical Association 241, 12; 10.2460/javma.241.12.1567

Treatment and Outcome

One week later, the patient underwent transpalatal rhinotomy, tooth remnant removal, and biopsy. An incision was made at the most lateral aspect of the palatal mucosa from the level of the mesial aspect of left maxillary first molar tooth to the palatal aspect of the left maxillary canine tooth. A full-thickness palatal flap was elevated, and the area of missing palatal bone observed on CT images was identified just medial to the previously detected small nonhealing area of the gingiva (Figure 4). A cyst-like cavity was found surrounding the tooth fragment, with no signs of purulent debris, and there was a visible soft tissue connection between the area of the nonhealing gingiva and the soft tissue lining of the cavity. The tooth was removed, and the lining of the cavity was curetted and biopsied. Tangential incision of the wound edges was performed before the wound was sutured without tension. Owing to the lack of signs of active endodontic disease associated with the root of the left maxillary first premolar tooth, it was decided to postpone extraction of the root tip until full periodontal treatment could be performed. Postoperative radiographs were obtained and confirmed removal of the foreign body (Figure 5). Staphylectomy and bilateral sacculectomy were also performed. The dog was hospitalized for supportive care, which included IV fluid, analgesic, and antimicrobial administration. One day after surgery, the dog was discharged, and carprofen (2.9 mg/kg [1.32 mg/lb], PO, q 12 h for 2 weeks), tramadol (2.9 mg/kg, PO, q 8 to 12 h for 1 week), and clindamycin hydrochloride (8.7 mg/kg, PO, q 12 h for 1 week) were prescribed. The owner was also instructed to rinse the dog's mouth with chlorhexidine gluconate. Clinical signs resolved 2 days after surgery, and examination 2 weeks after surgery demonstrated normal healing of the mucosal surgery sites. Nasal airflow was normal bilaterally.

Figure 4—
Figure 4—

Intraoperative photograph of the palate of the dog in Figure 1 showing elevation of a full-thickness palatal flap (A) and a photograph of the surgically removed crown fragment (B). In the intraoperative photograph, a retractor is used to demonstrate the defect in the palatine process of the maxillary bone; a tooth foreign body is present within the cavity.

Citation: Journal of the American Veterinary Medical Association 241, 12; 10.2460/javma.241.12.1567

Figure 5—
Figure 5—

Postoperative occlusal radiographic view of the maxilla of the dog in Figure 1 demonstrating successful removal of the crown fragment.

Citation: Journal of the American Veterinary Medical Association 241, 12; 10.2460/javma.241.12.1567

Histologic examination of the lining of the cavity revealed keratinized epithelium similar to gingival epithelium (Figure 6). Thus, the lesion was considered to represent a gingival inclusion cyst.1

Figure 6—
Figure 6—

Histologic section of the inclusion cyst lining from the dog in Figure 1. Notice the hyperplastic, keratinized stratified squamous gingival epithelium (A) with prominent rete-pegs (arrows). The subepithelium is expanded by a lymphoplasmacytic inflammatory infiltrate (B). The subepithelial stroma (C) contains numerous capillaries lined by reactive endothelium. H&E stain; bar = 50 μm.

Citation: Journal of the American Veterinary Medical Association 241, 12; 10.2460/javma.241.12.1567

Comments

Differential diagnoses for chronic nasal disease in dogs have been well described and include nasal neoplasia, inflammation (eg, lymphocytic plasmacytic rhinitis), foreign body, and fungal infection.6,7 However, chronic nasal discharge can also result from periapical disease such as a dental abscess or oronasal fistula.7,8 In the dog of the present report, the lack of nasal airflow in association with a unilateral nasal discharge was most concerning for an atypical fungal infection, nasal or nasopharyngeal foreign body, or neoplasia. Given the history of indiscriminate ingestion in conjunction with the possibility of regurgitation into the nose, a foreign body or chronic inflammation with secondary bacterial component was considered to be the most likely differential diagnosis.

Detailed oral examination with radiography is an essential part of a comprehensive diagnostic workup for dogs with nasal disease.8 The use of image-processing tools in conjunction with digital radiography allows for more information to be extracted from radiographic images.2 However, CT should be considered to better assess the structures of the nasal cavity and spatial relationships because it eliminates superimposition of overlying structures and offers superior contrast resolution, compared with conventional radiography.4,9

An extraction site that seems to not be healing ≥ 7 days after surgery is abnormal, and retained root tips are a common cause.10,11 In this case, however, the retained root fragment of the left maxillary first premolar tooth had no other signs of endodontic disease3 and was not associated with the clinically observed small, nonhealing region. Given that no associated oronasal fistula was detected, the lesion was considered to possibly represent a draining tract, especially because results of CT were suggestive of a foreign body–associated intranasal abscess with osteolysis of the palatine process of the maxillary bone at the level of the nonhealing area. However, following removal of the tooth fragment, the nonhealing area was found to represent 1 end of a connection to the soft tissue lining of the bony cavity, which was more consistent with a cyst.1,5 The cyst-like cavity was curetted and biopsied, revealing a gingival inclusion cyst.

Gingival inclusion cysts are related to a traumatic event (eg, tooth extraction, screw placement, or free gingival graft) resulting in implantation of the superficial epithelium into the underlying tissues1,12,13 and are rare in dogs.1 In the absence of any history of dental or maxillofacial trauma or treatment, the cause of the gingival inclusion cyst in this dog remains unknown. It could be speculated that the left maxillary premolar teeth were affected by severe periodontitis with bone loss, which could have allowed intrusive luxation of this tooth even with a minor or unnoticed trauma. Also, trauma to the left maxilla was likely, given the root fracture of the left maxillary first premolar tooth. Complete removal of a gingival inclusion cyst by means of enucleation and curettage is curative.1 The present case demonstrates the need for a comprehensive oral and nasal examination complemented by dental radiography and CT to better plan biopsy and treatment and to offer a prognosis on dental and related nasal disease in dogs.

References

  • 1. 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
  • 2. van der Stelt PF. Better imaging: the advantages of digital radiography. J Am Dent Assoc 2008; 139(suppl 3):7S13S.

  • 3. Fiani N, Arzi B. Diagnostic imaging in veterinary dental practice. Endodontic disease. J Am Vet Med Assoc 2010; 236:4143.

  • 4. Johnson EG, Wisner ER. Advances in respiratory imaging. Vet Clin North Am Small Anim Pract 2007; 37:879900.

  • 5. Fulton A, Fiani N. Diagnostic imaging in veterinary dental practice. Dentigerous cyst with secondary infection. J Am Vet Med Assoc 2011; 238:435437.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6. Tasker S, Knottenbelt CM, Munro EA, et al. Aetiology and diagnosis of persistent nasal disease in the dog: a retrospective study of 42 cases. J Small Anim Pract 1999; 40:473478.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Lobetti RG. A retrospective study of chronic nasal disease in 75 dogs. J S Afr Vet Assoc 2009; 80:224228.

  • 8. Marretta SM. Chronic rhinitis and dental disease. Vet Clin North Am Small Anim Pract 1992; 22:11011117.

  • 9. 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
  • 10. Smith MM. Exodontics. Vet Clin North Am Small Anim Pract 1998; 28:12971319.

  • 11. Gottrup F, Storgård Jensen S, Andreasen JO. Wound healing subsequent to injury. 4th ed. Oxford, England: Blackwell Munksgaard, 2007;144.

    • Search Google Scholar
    • Export Citation
  • 12. Adachi M, Matsui Y, Iwai T, et al. Epithelial inclusion cyst after intermaxillary screw placement: a case report. J Oral Maxillofac Surg 2011; 69:11171119.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13. de Castro LA, Vencio EF, Mendonca EF. Epithelial inclusion cyst after free gingival graft: a case report. Int J Periodontics Restorative Dent 2007; 27:465469.

    • Search Google Scholar
    • Export Citation

Contributor Notes

Address correspondence to Dr. Arzi (barzi@ucdavis.edu).
  • Figure 1—

    Occlusal (A) and left lateral (B) radiographic views of the maxilla of a 7-year-old Pug evaluated because of chronic left-side nasal discharge and occlusal radiographic view following contrast and brightness adjustment (C).

  • Figure 2—

    Same radiographic views as in Figure 1. On the occlusal (A) and left lateral (B) radiographic views, there is an opaque structure in the shape of the crown of a premolar tooth at the level of the left maxillary canine tooth (white arrows). In addition, there is mild horizontal bone loss affecting the incisor teeth, partially unerupted right and left maxillary canine teeth with mild associated pericoronitis, a root fragment of the left maxillary first premolar tooth, and rotation of the premolar teeth consistent with the brachycephalic head conformation. Following adjustment of contrast and brightness of the occlusal radiographic view, a radiolucent area surrounded by a rim of bone at the level the left maxillary canine tooth becomes obvious (white arrow; C).

  • Figure 3—

    Computed tomographic images obtained at the level of the maxillary third premolar teeth (which are absent) of the dog in Figure 1. There is a hyperattenuating structure in the shape of the crown of a premolar tooth in the ventral aspect of the left nasal passage (arrow). This structure is surrounded by a soft tissue–attenuating area. There is associated osteolysis of the palatine process of the maxillary bone underlying the foreign body (arrowheads). In the remainder of the left nasal passage, there is a moderate amount of soft tissue–attenuating material and only a small amount of soft tissue–attenuating material in the right nasal passage.

  • Figure 4—

    Intraoperative photograph of the palate of the dog in Figure 1 showing elevation of a full-thickness palatal flap (A) and a photograph of the surgically removed crown fragment (B). In the intraoperative photograph, a retractor is used to demonstrate the defect in the palatine process of the maxillary bone; a tooth foreign body is present within the cavity.

  • Figure 5—

    Postoperative occlusal radiographic view of the maxilla of the dog in Figure 1 demonstrating successful removal of the crown fragment.

  • Figure 6—

    Histologic section of the inclusion cyst lining from the dog in Figure 1. Notice the hyperplastic, keratinized stratified squamous gingival epithelium (A) with prominent rete-pegs (arrows). The subepithelium is expanded by a lymphoplasmacytic inflammatory infiltrate (B). The subepithelial stroma (C) contains numerous capillaries lined by reactive endothelium. H&E stain; bar = 50 μm.

  • 1. 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
  • 2. van der Stelt PF. Better imaging: the advantages of digital radiography. J Am Dent Assoc 2008; 139(suppl 3):7S13S.

  • 3. Fiani N, Arzi B. Diagnostic imaging in veterinary dental practice. Endodontic disease. J Am Vet Med Assoc 2010; 236:4143.

  • 4. Johnson EG, Wisner ER. Advances in respiratory imaging. Vet Clin North Am Small Anim Pract 2007; 37:879900.

  • 5. Fulton A, Fiani N. Diagnostic imaging in veterinary dental practice. Dentigerous cyst with secondary infection. J Am Vet Med Assoc 2011; 238:435437.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6. Tasker S, Knottenbelt CM, Munro EA, et al. Aetiology and diagnosis of persistent nasal disease in the dog: a retrospective study of 42 cases. J Small Anim Pract 1999; 40:473478.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Lobetti RG. A retrospective study of chronic nasal disease in 75 dogs. J S Afr Vet Assoc 2009; 80:224228.

  • 8. Marretta SM. Chronic rhinitis and dental disease. Vet Clin North Am Small Anim Pract 1992; 22:11011117.

  • 9. 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
  • 10. Smith MM. Exodontics. Vet Clin North Am Small Anim Pract 1998; 28:12971319.

  • 11. Gottrup F, Storgård Jensen S, Andreasen JO. Wound healing subsequent to injury. 4th ed. Oxford, England: Blackwell Munksgaard, 2007;144.

    • Search Google Scholar
    • Export Citation
  • 12. Adachi M, Matsui Y, Iwai T, et al. Epithelial inclusion cyst after intermaxillary screw placement: a case report. J Oral Maxillofac Surg 2011; 69:11171119.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13. de Castro LA, Vencio EF, Mendonca EF. Epithelial inclusion cyst after free gingival graft: a case report. Int J Periodontics Restorative Dent 2007; 27:465469.

    • Search Google Scholar
    • Export Citation

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