History and Physical Examination Findings

A nonambulatory 6-year-old 52-kg female spayed Mastiff was evaluated because of open fractures of the right radius and ulna and puncture wounds on the head, left ear, thorax, abdomen, and limbs after an unwitnessed attack by a presumed large wild animal was also referred for evaluation of dentoalveolar trauma. Oral examination performed with the dog awake revealed missing both maxillary canine teeth and hemorrhage from each respective alveolus, suggestive of dentoalveolar injury. Differential diagnoses for the missing canine teeth included complicated crown root fracture, intrusive tooth luxation, and tooth avulsion.

The dog received supportive treatment and ampicillin-sulbactam (30 mg/kg, IV, once) before undergoing anesthesia for further diagnostic procedures. Regarding findings for the head and mouth, more detailed examination during anesthesia revealed facial symmetry with adequate temporal and masseter musculature, multiple small to moderate-sized lacerations on both cheeks, and bilaterally missing maxillary canine teeth (Figure 1). Uncomplicated crown fractures were present on the left and right mandibular first, second, and third incisor teeth; right mandibular canine tooth; and right maxillary fourth premolar tooth. Contiguous transverse 0.6-mm collimated CT of the head with 3-D volume-rendering (Enterprise Imaging Diagnostic Desktop version 8.1.2; Agfa HealthCare; InVivo5; Anatomage) was performed (Figure 2).

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Photograph of the intraoral occlusal view of the rostral maxillas of a 6-year-old 52-kg Mastiff with bilaterally missing maxillary canine teeth and hemorrhage from the alveoli (arrows) after an unwitnessed attack by a presumed large, wild animal.

Citation: Journal of the American Veterinary Medical Association 259, 9; 10.2460/javma.259.9.988

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Transverse (A) and dorsal (B) plane and 3-D rendered rostrocaudal (C) and dorsoventral (D) perspective CT images of the dog described in Figure 1, with the dog’s right side toward the left in each image. A and B—The images are displayed in a bone window (window width, 2,500 HU; window level, 480 HU) with a 0.6-mm slice thickness. The line across each image represents the plane of the orthogonal image. C and D—The images are displayed in tooth mode (a special setting in the imaging software [InVivo5, Anatomage] used that provided optimal contrast for visualization of teeth).

Citation: Journal of the American Veterinary Medical Association 259, 9; 10.2460/javma.259.9.988

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Formulate differential diagnoses, then continue reading.

Diagnostic Imaging Findings and Interpretation

Both maxillary canine teeth were displaced into the nasal cavity (Figure 3). The alveolar bone surrounding the left maxillary canine tooth was widened, and there was a hypoattenuating lesion along the lingual aspect of this tooth. There was a small, minimally displaced fracture of the alveolar bone mesial to the right maxillary canine tooth, and a few small comminution fragments surrounded the root. The uncomplicated crown fractures identified on physical examination were evident, and subcutaneous emphysema was present over the dorsal aspect of the calvarium and extending caudally on the neck, consistent with the puncture wounds seen on physical examination. The CT diagnosis was complete intrusive luxation of both maxillary canine teeth with a minimally displaced fracture and widening of the surrounding right dental alveolus.

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Same images as in Figure 2 that show the maxillary canine teeth (arrows) severely displaced into the nasal cavity and providing critical information, especially in the 3D-rendered images, beneficial for planning the surgical approach to safely remove the intruded maxillary canine teeth.

Citation: Journal of the American Veterinary Medical Association 259, 9; 10.2460/javma.259.9.988

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Treatment and Outcome

Infraorbital nerve blocks (0.5% bupivacaine; 1.2 mL [5 mg/mL]) was performed bilaterally. Surgical extraction of the maxillary canine teeth was performed through an oral approach. For each maxillary canine tooth, a buccal pedicle mucoperiosteal flap was raised to expose the crown tip, alveolectomy was performed until approximately 70% of the tooth was exposed, then luxators and extraction forceps were used to remove the tooth. Alveoloplasty was performed to remove sharp bone edges, and then each alveolus was irrigated with a copious volume of sterile saline (0.9% NaCl) solution. The mucogingival flaps were closed with 4-0 poliglecaprone 25 in a simple-interrupted pattern. Postoperative intraoral dental radiography (not shown) confirmed that the alveoli of the maxillary canine teeth had been vacated. Hydromorphone (0.05 mg/kg, IV) was given once after surgery. The dog recovered from anesthesia without complication; was hospitalized for treatment of its other wounds, including repair of the right thoracic limb open fractures; and received ampicillin–sulbactam (30 mg/kg, IV, q 8 h) and carprofen (2.2 mg/kg, PO, q 12 h).

A recheck examination of the oral cavity 3 days after oral surgery revealed no evidence of dehiscence at the extraction sites. The dog had been seen eating well and showed no signs of oral pain or respiratory distress. Ten days after admission, the dog was discharged with prescriptions of carprofen (2.2 mg/kg, PO, q 12 h, for 7 days) and amoxicillin-clavulanate (14.4 mg/kg, PO, q 12 h for 21 days) for its other injuries. Home-care instructions included feeding a soft diet to the dog for 2 weeks.

The dog was reevaluated 4 weeks after oral surgery. Findings included healed extraction sites, no nasal discharge, and progressive healing of its other injuries. The owners reported the dog was doing well. Pertaining to the dog’s oronasal health, the owners were instructed to have the dog reexamined if clinical signs of oral or nasal disease occurred; otherwise, the dog should return for an annual examination and periodontal treatment.

Comments

For the dog of the present report, the use of CT led to the diagnosis of intrusive luxation of the maxillary canine teeth into the nasal cavity, secondary to trauma. Intrusive luxation, a type of traumatic dentoalveolar injury (TDI), is defined by displacement of the tooth in an apical direction into the alveolar bone.^1,2 This rare injury accounts for 0.2% of TDI in dogs and cats,³ with incisor and canine teeth most commonly affected because of animal fights,⁴ car accidents,⁵ and falls from heights.⁶

The type, extent, and presentation of TDI can be affected by external factors (eg, the impact force and direction and the impacting object’s resilience and shape) and internal factors (eg, the resilience of the impacted animal’s periodontal structures).⁷ Clinically, intruded teeth are displaced axially and immobile^1,2 and may involve alveolar fracture. In severe cases, affected teeth may appear clinically missing because of partial or complete displacement into the nasal cavity, sinuses, or recesses as was seen with the dog of the present report. Common complications of intrusive luxation are root canal obliteration, pulpal necrosis, and root resorption,⁸ likely secondary to disruption of the local neurovascular supply to the tooth and periodontal structures. As a result of teeth intrusion into the nasal cavity, temporary or permanent damage may manifest as rhinitis, nasal discharge, and signs of pain or discomfort. Treatment options for intrusive luxation are either extraction or repositioning with stabilization followed by root canal treatment.^2,9 The decision depends on the stage of root development, degree of intrusion, duration of time between the injury and treatment, integrity of the periodontal structures and adjacent teeth, general health of the patient, and owner preference.^1,2 For the dog of the present report, the degree of intrusive luxation was severe, damaged the periodontal ligament, fractured the alveolar bone, and distorted the nasal architecture; therefore, extraction was considered the most appropriate treatment.

Diagnostic imaging is essential for diagnosis and treatment planning of TDI.^1,2 Imaging findings suggestive of intrusive luxation include lack of periodontal ligament space for all or part of the intruded tooth root, cementoenamel junction of the intruded tooth located more apically than in the adjacent intact teeth,¹ or displacement of a tooth resulting in total or partial tooth embedment in the maxillofacial structures apical to the alveolus, alone or in combination depending on the severity of injury.

Generally, skull radiography is inadequate to identify maxillofacial fractures and details of TDI, such as root fracture, periodontal disease, or focal bone loss.¹⁰ Conventional dental radiography with multiple projections and angulations may give an adequate diagnostic yield of focal TDI.¹ However, advanced imaging is preferred with multifocal TDI and when other maxillofacial structure involvement is suspected. In dogs and cats, the prevalence of TDI with concurrent maxillofacial fracture is reported as approximately 70% (31/43 [72%]¹¹ and 10/14 [71%]⁶), which underscores the importance of advanced imaging in addition to dental radiography. With CT and cone-beam CT, imaging the region of interest is performed at once, which eliminates magnification, distortion, and superimposition of structures and enables precise evaluation of fractures,^12,13 dental luxations, and surrounding structures. For the dog of the present report, CT of the skull confirmed no other clinically important trauma to the maxillofacial region, and our use of 3-D rendered CT images helped in planning surgical treatment. Findings for the dog of the present report emphasized the importance of advanced imaging in the diagnosis and treatment of TDI.