History and Physical Examination Findings
A 3-year-old 5.8-kg (12.8-lb) neutered male Bengal cat was referred for assessment and treatment because of recent trauma causing malocclusion. General physical examination revealed small excoriations on the chin and the nose. On intraoral examination of the awake patient, a superficial wound was observed in the interdental space between the left maxillary third incisor tooth and left maxillary canine tooth; a hematoma was also present in the submucosa of the left mandibular region just caudal to the frenulum of the lip (Figure 1). To assess the occlusion, the mouth was gently closed, and this action resulted in traumatic contact of the left mandibular canine tooth with the gingiva between the left maxillary third incisor and canine teeth. The cat resisted complete closure of the mouth. The referring veterinarian had assessed the cat for other injuries prior to referral, and the remainder of the physical examination was unremarkable. Results of a CBC and serum biochemical analysis were within the respective reference ranges.
Clinical photographs of the rostral facial region and teeth of a 3-year-old Bengal cat that was referred for assessment and treatment following trauma that resulted in malocclusion. The cat was anesthetized for oral examination. A—Small excoriations are present on the chin and the nose, and a superficial wound in the interdental space between the left maxillary third incisor and canine teeth is evident. B—Notice the submucosal hematoma present in the left mandibular region just caudal to the lower lip frenulum.
Citation: Journal of the American Veterinary Medical Association 253, 10; 10.2460/javma.253.10.1259
General anesthesia was induced, and a complete oral examination was performed. The patient had mild generalized gingivitis. There were no missing teeth, crown fractures, or resorptive lesions evident on gross examination. The mandibular symphysis was stable with no evidence of separation. The temporomandibular joints were assessed by palpation, manipulation, and examination of dorsoventral and lateral oblique radiographic views. Full-mouth intraoral radiographs were obtained with size 2 phosphor plates and bisecting angle and parallel techniques. Selected radiographic views are provided (Figure 2).
Intraoral occlusal (A) and lateral (B) radiographic views of the rostral part of the mandibles and rostral mandibular teeth of the cat in Figure 1. The image in panel B was obtained with a bisecting-angle technique.
Citation: Journal of the American Veterinary Medical Association 253, 10; 10.2460/javma.253.10.1259
Determine whether additional studies are required, or make your diagnosis, then turn the page→
Diagnostic Imaging Findings and Interpretation
There were abnormal findings on 2 views of the left mandibular canine tooth (Figure 3). On the occlusal view, a radiolucent line was visible extending from the mandibular symphysis through the apical third of the tooth root. There was a focal enlargement of the periodontal ligament space on the distal aspect of the tooth as well as a widened periodontal ligament space apically. On the lateral view, a more obvious irregular radiolucent line through the apical third of the root was visible. The radiolucent line extended from the distal aspect of the canine tooth root to the mesial root of the left mandibular third premolar tooth. There was disruption of the lamina dura distally. The periodontal ligament space was widened at the alveolar margin with no evidence of bone resorption; these findings indicated displacement rather than periodontal disease. As seen on the occlusal view, the periodontal ligament space was also widened at the apex. One possible diagnosis was an alveolar bone fracture with superimposition of the fracture line over the intact tooth root with subluxation of the tooth root. However, a diagnosis of a horizontal fracture of the apical third of the left mandibular canine tooth root with subluxation of the tooth and a nondisplaced fracture of the alveolar bone could not be ruled out. Further diagnostic imaging to definitively distinguish between these diagnoses was not pursued.
Same radiographic views as in Figure 2. A—A radiolucent line is visible extending from the mandibular symphysis through the apical third of the left mandibular canine tooth root (long black arrow). There is focal enlargement of the periodontal ligament space at the distal aspect of the tooth (short black arrow), and the periodontal ligament space is widened apically (short white arrow). The periodontal ligament space at the alveolar margin on the distal aspect of the left canine tooth (long white arrow) is subjectively wider, compared with that of the contralateral canine tooth. B—In the lateral view, an irregular radiolucent line through the apical third of the left mandibular canine tooth root is seen (short black arrows). The line also extends from the distal aspect of the canine tooth root to the mesial root of the left mandibular third premolar tooth. Disruption of the lamina dura is evident (long black arrow). The periodontal ligament space is widened at the alveolar margin of the left canine tooth (long white arrow) and at the root apex (short white arrow).
Citation: Journal of the American Veterinary Medical Association 253, 10; 10.2460/javma.253.10.1259
Treatment and Outcome
Treatment was performed under the same anesthetic episode as the dental examination. Given that there was no soft tissue trauma other than that seen on the initial examination and no displacement of the rostral aspect of the affected mandible, the decision was made to treat the case as a tooth root fracture. The goal of treatment for a root fracture is to reposition the coronal segment as closely as possible to its normal anatomic position and to maintain the placement with a semirigid splint to allow healing. It is important that treatment is performed as soon as possible after the injury to allow the best alignment of the segments and reduce the risk of complications. Treatment options, prognosis, and potential complications were discussed with the owner.
The cat's teeth were scaled and polished. A wire-reinforced bis-acryl composite splint was created for rigid stabilization extending from the right mandibular canine tooth up to and including the left mandibular third premolar tooth. Odontoplasty was performed on the left mandibular canine tooth to prevent continued contact with the traumatized gingiva of the maxilla. The cat recovered well from anesthesia and was discharged from the hospital on the same day. Meloxicam (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) was prescribed for 5 days. The owner was instructed to rinse the affected region of the cat's mouth with 2 mL of 0.12% chlorhexidine mouthwash on a daily basis while the splint was in place, and the technique was demonstrated prior to patient discharge.
At a scheduled recheck appointment 1 week later, the owner reported that the cat was comfortable and eating well. The cat was tolerating the mouthwash, although the owner found it difficult to perform the treatment. Intraoral examination revealed that the splint was in place. The maxillary laceration was still inflamed but healing as expected.
At a follow-up appointment to assess healing and remove the splint 3 weeks later, the cat was anesthetized and radiographs were obtained (Figure 4). No evidence of pulp necrosis was visible radiographically, and the fracture line was healing but still visible. The splint was removed. Moderate gingivitis was present on some of the teeth that were covered by the splint, and the teeth were scaled and polished.
Clinical photograph and intraoral lateral radiographic view of the cat in Figure 1. A—Clinical photograph of the wire-reinforced semirigid bis-acryl composite splint used for fracture stabilization for the cat in Figure 1. The image was obtained at the scheduled appointment for device removal 3 weeks after placement. B—Intraoral lateral radiographic view of the rostral aspect of the mandibles and rostral mandibular teeth obtained with a bisecting-angle technique prior to splint removal. No evidence of pulp necrosis in the left mandibular canine tooth is visible. The healing fracture line is still detectable, particularly at the mesial aspect of the tooth root (arrow).
Citation: Journal of the American Veterinary Medical Association 253, 10; 10.2460/javma.253.10.1259
Another radiograph was obtained for endodontal assessment 6 months after splint removal (Figure 5). The periodontal ligament space was of uniform width around the root and apex. New bone formation was visible at the apex. There was dilaceration of the root at the level of the previous fracture. The healed fracture line was just visible distally. The root canal was not visible in the apical third of the tooth and may have been undergoing obliteration. At this stage, no further treatment was required, but yearly monitoring was recommended.
Intraoral lateral radiographic view of the rostral aspect of the mandibles and rostral mandibular teeth of the cat in Figure 1. The image was obtained with a bisecting-angle technique at a recheck examination visit 6 months after referral and treatment. The periodontal ligament space of the left mandibular canine tooth is of uniform width around the root and apex. New bone formation is visible at the apex. There is dilaceration of the root at the level of the previous fracture (arrow), and the healed fracture line is just visible distally. The root canal is not visible in the apical third of the tooth root and may be undergoing obliteration.
Citation: Journal of the American Veterinary Medical Association 253, 10; 10.2460/javma.253.10.1259
Comments
The authors considered whether the cat of this report had a root fracture of the left mandibular canine tooth or lateral tooth luxation with superimposition of an alveolar bone fracture line over the root. Lateral luxation occurs less commonly for mandibular canine teeth than for maxillary canine teeth.1 The alveolar bone plate covering the roots of canine teeth is much thinner in the maxilla than in the mandible. The axis of each mandibular canine tooth root runs in a lingual-caudal direction, with the buccal bone becoming thicker further apically. In cats, trauma to the rostral aspect of a mandible usually results in the mandible fracturing along the same axis as the canine tooth root, creating a complete vertical or oblique fracture of the rostral mandibular body rather than a horizontal fracture of the rostral aspect of the bone. If the visible radiolucent line was superimposed over the root and reflected lateral luxation and associated alveolar bone fracture, the authors would have expected more soft tissue trauma usually seen in these cases and more displacement of the tooth and bone fragment.2 In the authors’ experience, a lateral luxation and associated alveolar bone fracture usually occur in the coronal half of the buccal bone plate where the bone is thinner. The authors postulate that the trauma caused a subluxation of the root and fracture of the alveolar bone, but owing to the thickness of the buccal bone around the mandibular canine tooth root, root fracture occurred rather than the more common lateral luxation and bone displacement usually seen in these cases of trauma. Surprisingly, there were no crown fractures of the teeth despite the trauma sustained by the cat of this report. Crown fractures are the most common dentoalveolar injury in cats.1 According to the American Association of Endodontists, dental injuries do not always fall into 1 group or category and are often a combination of injuries,3 which was the most likely scenario in this patient. A root fracture is a fracture of the cementum and dentin involving the pulp. These injuries are relatively rare, comprising 0.5% to 7% of dental injuries in people.4,5 Luxation injuries as a group are the most common dental injuries in people, representing 30% to 44% of dental injuries.6 Results of a study1 performed to evaluate the prevalence of traumatic dentoalveolar injuries in 660 dogs and cats revealed frequencies of 3.5%, 0.8%, and 0.3% for tooth root fractures, lateral luxations, and alveolar fractures, respectively. In cases of horizontal root fracture, the coronal segment can be displaced to various degrees depending on fracture location, but the apical segment is generally not displaced. Therefore, pulpal blood supply is not usually disrupted, and pulp necrosis rarely occurs. A horizontal root fracture of the apical third of the root does not usually result in severe displacement of the coronal segment.4,6
Because a root fracture is typically oblique, it is essential that > 1 radiographic view is obtained. This helps to ensure that at least 1 image is obtained where the beam passes directly through the fracture line, making it visible on the radiograph.4,6 Studies7,8 have shown that CT, and specifically cone beam CT, has significantly greater sensitivity for detection of dentoalveolar trauma, compared with radiography. The International Association of Dental Traumatology's guidelines for the management of traumatic dental injures suggest that cone beam CT may be beneficial when used to assess and monitor healing in patients after traumatic dental injuries, especially in cases of lateral luxation and root fracture.9 In this case, cone beam CT was not available but would have been useful to establish a diagnosis.
The outcome for treatment of horizontal root fractures is generally favorable.6 The location of the fracture in the cat of this report meant that there was minimal dislocation or coronal fragment mobility, so the prognosis was favorable. Prognosis also improves with prompt treatment, close reduction of the root segments, and semirigid splinting for 2 to 4 weeks.10 Four types of injury response patterns in radiographic images of horizontal root fractures have been described6: healing with calcified tissue, in which the fracture line is just visible radiographically but the fragments are in close contact; healing with interproximal connective tissue, in which the fragments appear separated by a narrow radiolucent line and the fractured edges appear rounded; healing with interproximal bone and connective tissue, in which the fragments are separated by a distinct bony ridge; and interproximal inflammation without healing, in which widening of the fracture line, development of radiolucency corresponding to the fracture line, or both become apparent. The latter result is typically seen when the coronal segment loses its vitality. Long-term follow-up evaluation is needed to assess pulp vitality. As with all traumatic dental injuries, follow-up at 3 months, 6 months, and annually thereafter is recommended.10
References
1. Soukup JW, Hetzel S, Paul A. Classification and epidemiology of traumatic dentoalveolar injuries in dogs and cats: 959 injuries in 660 patient visits (2004–2012). J Vet Dent 2015;32:6–14.
2. Gracis M, Orsini P. Treatment of traumatic dental displacement in dogs: six cases of lateral luxation. J Vet Dent 1998;15:65–72.
3. American Association of Endodontists. Endodontics: colleagues for excellence. The treatment of traumatic dental injuries. Available at: www.aae.org/specialty/wp-content/uploads/sites/2/2017/06/ecfe_summer2014-final.pdf. Accessed Jul 3, 2018.
4. Andreasen JO, Andreasen FM, Cvek M. Root fractures. In: Andreasen JO, Andreasen FM, Andersson L, eds. Textbook and color atlas of traumatic injuries to the teeth. 4th ed. Copenhagen: Blackwell Munksgaard, 2007;337–371.
5. Andreasen JO, Hjorting-Hansen E. Intraalveolar root fractures: radiographic and histologic study of 50 cases. J Oral Surg 1967;25:414–426.
6. Trope M, Barnett F, Sigurdsson A, et al. The role of endodontics after dental traumatic injuries. In: Hargreaves KM, Cohen S, eds. Cohen's pathways of the pulp. 11th ed. St Louis: Mosby-Elsevier, 2011;758–789.
7. Likubo M, Kobayashi K, Mishima A, et al. Accuracy of intraoral radiography, multidetector helical CT and limited cone beam CT for the detection of horizontal tooth root fracture. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:e70–e74.
8. Kamburoglu K, Ilker Cebeci AR, Gondahl HG. Effectiveness of limited cone beam computed tomography in the detection of horizontal root fracture. Dent Traumatol 2009;25:256–261.
9. Diangelis AJ, Andreasen JO, Ebeleseder KA, et al. International Association of Dental Traumatology guidelines for the management of traumatic dental injuries: 1. Fractures and luxations of permanent teeth (Erratum published in Dent Traumatol 2012;28:499). Dent Traumatol 2012;28:2–12.
10. Andreasen JO, Andreasen FM, Mejare I, et al. Healing of 400 intra-alveolar root fractures. 2. Effect of treatment factors such as treatment delay, repositioning, splinting type and period of antibiotics. Dent Traumatol 2004;20:203–211.
