History and Physical Examination Findings
A 3.5-month-old 2.7-kg (5.94-lb) sexually intact female Yorkshire Terrier was evaluated following an episode of chewing on the edge of a wicker dog bed. While disengaging its entrapped teeth from the bedding, the puppy vocalized in a manner suggestive of pain. Following the incident, the puppy was able to eat soft food, but had signs of pain when touched around the head. The client noted that the mouth was not fully closed.
The puppy was evaluated by the referring veterinarian. Initial physical abnormalities included an inability to close the mouth and signs of pain during palpation of the lower jaw. Skull radiographs were obtained but were deemed nondiagnostic. The puppy was referred to the University of Illinois Veterinary Teaching Hospital for additional diagnostic testing and treatment. Findings of a general physical examination were unremarkable. A complete oral examination performed after the puppy was sedated revealed typical deciduous dentition apart from slight mandibular mesiocclusion. There were no palpable mandibular fractures, but there was a slight increase in lateral movement of the mandibles. Radiographs of the skull were obtained (Figure 1).
Left lateral oblique (A) and dorsoventral (B) radiographic views of the skull of a 4-month-old Yorkshire Terrier with signs of jaw pain following trauma.
Citation: Journal of the American Veterinary Medical Association 239, 7; 10.2460/javma.239.7.931
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Diagnostic Imaging Findings and Interpretation
On the left lateral oblique radiographic projection of the skull (Figure 2), there was an increase in space between the mesial aspect of the tooth bud of the permanent left mandibular first molar tooth and the alveolar bone. On the dorsoventral radiographic projection, there were bilateral radiolucent lines through the cortical bone lingual to the permanent tooth buds of the left and right mandibular first molar teeth.
Same radiographic views as in Figure 1. On the left lateral view (A), notice the increase in space between the left mandibular first molar tooth bud and the alveolar bone (arrows). On the dorsoventral view (B), notice the radiolucent lines through the mandibular cortices on the lingual aspects of the first molar tooth buds (asterisks).
Citation: Journal of the American Veterinary Medical Association 239, 7; 10.2460/javma.239.7.931
Dental radiographs were obtained (Figure 3) to supplement the skull radiographs and revealed bilateral incomplete, minimally displaced, irregular transverse fractures of the buccal and lingual aspects of the mandibles in the region of the mesial aspects of the tooth buds of the permanent mandibular first molar teeth. The fractures were classified as greenstick fractures, indicating involvement of all cortices with minimal to no displacement.1 There was rostroventral displacement of the rostral segments of the mandibles, indicated by an increase in space between the mesial aspect of the first mandibular molar tooth buds and the alveolar bone.
Intraoral lateral and occlusal radiographic views of the left and right mandibles of the dog in Figure 1. On the lateral radiographic views of the right (A) and left (C) mandibles, notice the irregular transverse fractures through the mandibles in the region of the mesial aspects of the mandibular first molar tooth buds (black arrows) and the mild rostroventral displacement of the rostral aspect of the mandibles, indicated by an increase in space between the tooth bud and the alveolar bone (white arrows). On the occlusal view (B), notice the fractures of the buccal (white arrows) and lingual (asterisks) mandibular cortices in the region of the mesial aspects of the mandibular first molar tooth.
Citation: Journal of the American Veterinary Medical Association 239, 7; 10.2460/javma.239.7.931
Treatment and Outcome
The dog was anesthetized, and a complete oral examination was performed. The mandibles were rostrally and ventrally displaced; however, the temporomandibular joints appeared stable, and the lateral movement of the mandible was deemed to be normal for a dog of this age. Extraoral and intraoral palpation of the mandibles revealed slight bilateral instability distal to the deciduous fourth premolar teeth in a ventrodorsal direction.
The mandibular fractures were manually reduced, restoring normal occlusion and allowing the mouth to close properly. A soft cloth muzzle was placed loosely enough to allow the patient to lick soft food and water but tightly enough to maintain normal occlusion and reduction of the fractures. An analgesic was prescribed, and the owner was instructed to leave the muzzle and an Elizabethan collar on at all times for 14 days. During a recheck examination 2 weeks later, the dog had normal occlusion, and the mandibles appeared stable during palpation. Dental radiography at 6 months of age was recommended to evaluate development and eruption of the permanent dentition.
Comments
It has been reported that mandibular fractures are most common in dogs < 1 year of age and that the most common cause of mandibular fractures in dogs < 1 year of age is trauma.2 The primary goals of mandibular fracture repair are allowing a rapid return to function, maintaining proper occlusion, establishing effective stabilization, and avoiding additional trauma to the soft tissues and teeth.3,4 In the dog described in the present report, the subtle changes observed on the initial skull radiographs were not sufficient to establish a clear diagnosis and treatment plan. Although skull radiography is a useful technique in some cases of oral and maxillofacial trauma, findings for the dog described in the present report illustrate the importance of dental radiography when evaluating dental or maxillofacial injuries. With the use of dental radiography, the lesions became clear and appropriate treatment could be pursued, which consisted of nonrigid, noninvasive external coaptation and continued monitoring of the involved permanent tooth buds.
Fractures in juvenile patients require special consideration. In young dogs, the mandible is in a rapid growth phase, and hence, rigid fixation is not always desirable because it can lead to growth restriction.5,6 Invasive fixation techniques can also lead to damage to tooth roots or buds.6 For the dog described in the present report, rigid fixation was not required because the fracture was closed and minimally displaced. Healing in a patient of this age is typically rapid, and stabilization is usually required only for a short time. Juvenile patients with mandibular fractures may have tooth buds in the fracture site. Trauma to tooth buds can result in malformation of the permanent teeth or impede eruption of affected developing teeth.7 Follow-up dental radiography should be performed between the ages of 6 and 7 months in patients that have had trauma in the region of developing tooth buds. Another sequela of facial fractures in juvenile patients is facial deformity.4 The location of the fractures in this patient was unlikely to cause facial deformity or a disparity in growth of the mandibles.8
Tape muzzles are an inexpensive and noninvasive way of stabilizing mandibular fractures that are minimally displaced in dogs. A 5- to 10-mm space should be left between the upper and lower incisor teeth to allow the patient to eat and drink with the muzzle in place.3
The present case demonstrates the need for thorough oral examination in conjunction with appropriate diagnostic imaging for dogs with maxillofacial trauma. Skull radiography in this case did not readily provide a clear image of the underlying cause of the mandibular pain and inability to close the mouth, but dental radiography provided information necessary to reach a definitive diagnosis and plan appropriate treatment. Computed tomography is another imaging modality that can be used for patients with maxillofacial injury if dental radiography does not result in a diagnosis.9
References
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