Mandibulectomy for treatment of fractures associated with severe periodontal disease

Abstract

Six cases of mandibular fractures associated with severe periodontal disease that had been treated by mandibulectomy, due to intense bone loss, were evaluated retrospectively. The dogs were mainly older, small breed dogs that had suffered a traumatic event. Four dogs had a bilateral mandibulectomy and 2 a unilateral mandibulectomy.

Mandibular fractures represent approximately 1.5% to 2.5% of all fractures observed in dogs (1–3). The patients are typically young, approximately 50% are < 1 year of age (1,3,4). The goal of mandibular fracture treatment is to reestablish a functional dental occlusion (3,5). Tape muzzling, wiring techniques, plate repair, dental bonding, intraoral splints, and external skeletal fixation are the methods most commonly used to stabilize mandibular fractures in dogs (1,3,5,6). The type and site of the fracture, degree of contamination, presence of intact teeth, and age are factors to consider when choosing a method (1,3,6). Other less commonly utilized options include mandibulectomy, which has been used in cases of non-unions or malunions, severe comminution, osteomyelitis, failure of primary fixation, or pathologic fracture (1,7–9).

Periodontal disease has a high prevalence in dogs and an increased occurrence in small or toy breeds (10,11). There are 4 stages of periodontal disease, each of which is based on the severity of clinical and radiographic lesions as follows: Stage 1 — gingivitis, Stage 2 — early periodontitis, Stage 3 — moderate periodontitis, Stage 4 — advanced periodontitis (11–13). In the advanced stages pathologic mandibular fractures may occur due to bone loss (9,10) and fracture healing is problematic because of reduced bone quality, difficulty in achieving stable fixation, and decreased oxygen tension (9). Thus, the purpose of this retrospective study was to evaluate cases of mandibular fractures associated with severe periodontal disease that were treated by mandibulectomy.

Patient signalment (breed, gender, age, body weight), body condition, laboratory data, probable causative agent of the fracture, site and type of fracture shown by radiographs of the skull, type of mandibulectomy, and postoperative results were assessed for cases during a period of 2.6 y (Table 1).

Table 1.

Fracture cause, fracture site, type of fracture, and mandibulectomy procedure used in 6 dogs with open mandibular fractures associated with severe periodontal disease

Case number	Dog signalment	Cause	Fracture site	Type of fracture	Mandibulectomy procedure
1	3.9 kg 10-year-old female, mixed breed	Dogfight	Rostral to left mandibular first molar	Simple transverse	Unilateral including rostral and central areas
2	8.5 kg 7-year-old male, mixed breed	Hit by a car	Rostral to left and right mandibular first molar teeth	Simple transverse	Bilateral including rostral and central areas
3	16.3 kg 6-year-old male, cocker spaniel	Dogfight	Between roots of mandibular right canine and first premolar	Comminuted	Unilateral rostral
4	5.2 kg 15-year-old male, mixed breed	Hit by a car	Rostral to left and right mandibular first molar teeth	Simple oblique	Bilateral including rostral and central areas
5	3.0 kg 11-year-old female, poodle	Fall from height	Rostral to left and right mandibular first molar teeth	Simple transverse	Bilateral including rostral and central areas
6	2.2 kg 12-year-old male, Yorkshire terrier	Unknown cause	Rostral to left and right mandibular first molar teeth	Simple oblique (right side) and simple transverse (left side)	Bilateral including rostral and central areas

Six dogs (4 males and 2 females) were studied: 3 were mixed breed, 1 poodle, 1 Yorkshire terrier, and 1 cocker spaniel. The ages of the dogs varied from 6 to 15 y (mean: 10 y). The body weights ranged from 2.2 to 16.3 kg (mean: 6.5 kg); 3 dogs weighed < 4 kg. All dogs were well-conditioned (body condition score 3/5: ribs palpable without excess fat covering, waist observed behind ribs, abdomen tucked up). The diet consisted of commercial pet food for 5 dogs and homemade food for 1. The most significant laboratory findings were anemia in 2 dogs (dogs 1 and 4); neutrophilic leukocytosis in 2 (dogs 2 and 3); elevated levels of urea in 2 dogs (dogs 3 and 4); elevated levels of urea, creatinine, and alkaline phosphatase in 1 dog (dog 1).

All 6 dogs had advanced periodontal disease (stage 4) and open fractures. The radiographs showed that 6 of the 10 fractures were simple transverse, 3 were oblique, and 1 was comminuted. In all cases there was bone loss in the mandible due to generalized periodontal disease. Alveolar bone loss was evident in most of the mandibular teeth. In addition, most dogs had loss of teeth, especially the incisors and premolars, due to periodontal disease (Figure 1).

Figure 1.

Lateral (a,b) and dorsoventral (c) views of the mandibular fractures, rostral to the right (a) and left (b) first molar teeth. Observe the bone loss and loss of the incisor and premolar teeth due to advanced periodontal disease.

Therapeutic antibiotics, cephalexin and metronidazole, were administered to all animals before and after surgery. Enteral nutrition via esophagostomy tube feeding was used in dog numbers 1 and 5 for 5 d after surgery. By 10 to 15 d after surgery, all dogs had made a good functional recovery and were eating soft food. However, 2 of the dogs had small areas of oral wound dehiscence. In both cases the antibiotic therapy was maintained until healing occurred. The owners were satisfied with the cosmetic appearance despite lateral protrusion of the tongue in all dogs except dog number 3.

The clients were interviewed at various times after the surgery. Dogs 4, 6, and 2 died for reasons unrelated to the procedure, at 15 d, 1 mo, and 9 mo after surgery, respectively, whereas dogs 1, 5, and 3 were still alive at 1.5 y, 1.2 y, and 2.4 y after surgery.

Discussion

Poodles and Yorkshire terriers are among the breeds predisposed to periodontal disease (10,11). Two of the dogs in the present study were from these breeds, but 3 were mixed breed. Several other factors may influence the development of the disease, including age, skull shape, effects of chewing, disorders of the immune system or immunosuppression, general health, genetic predisposition, saliva volume, oral microbial flora, routine dental cleaning, food texture and type of diet (9,11,12).

Signs of advanced periodontal disease are most commonly observed in senior pets which have lacked adequate dental care throughout their lives (13). In the present study, the individual ages varied from 6 to 15 y, but 4 dogs were aged at least 10 y. None of the dogs had received dental care; the diet consisted of commercial pet food in 5 of the 6 cases. The periodontal disease may cause distant organ effects (9,10). The laboratory results for 4 dogs suggest the presence of systemic dysfunction, despite the well-conditioned body status.

Trauma is the most common cause of mandibular fractures in dogs and cats, especially due to vehicular accidents, falls, fights with other dogs, or gunshot wounds (2,4,6). However, non-traumatic causes such as periodontal, neoplastic, and metabolic diseases are also relevant (2,4,9). Mild trauma, dental extraction or simply eating may result in fracture in dogs with severe periodontal disease (9). Besides advanced periodontal disease, 2 of the dogs in the current study had a history of fighting with other dogs, 2 had been hit by cars, 1 had fallen from a high place, and 1 showed pathological fracture. Thus, in 5 of the 6 cases a traumatic event was a coadjuvant of the bone loss due to advanced periodontal disease.

Fractures in the premolar region are considered common in dogs (6). However, pathological fractures due to periodontal disease in small dog breeds occur most frequently in the area of the mandibular first molar because the tooth is larger in proportion to the mandible (9). In the present study, 4 of the fractures occurred bilaterally and 2 unilaterally, and 9 of the 10 fractures were in the middle third of the mandibular body. Despite the available methods for stabilization of mandibular fractures (1,3,6), mandibulectomy was considered the best option for the patients in the current study due to severe bone loss and problems with owner compliance. The classification of the mandibulectomy procedures is based on the part of mandible that is removed (14). In the current study, a unilateral mandibulectomy was used in 2 cases and bilateral mandibulectomy in 4 cases. However, different portions of the mandible body were removed based on the fracture site and bone loss.

The placement of a feeding tube through esophagostomy may be necessary in dogs that refuse to eat (15). This technique was used in 2 dogs to provide nutritional support due to a history of hyporexia before the fracture. Despite the risks of complications after mandibulectomy such as swelling, infection, dehiscence, and functional complications (7,14,15), only 2 of the dogs had oral wound dehiscence.

In conclusion, this retrospective study found that most of the dogs with pathologic mandibular fractures due to severe periodontal disease that had a mandibulectomy, were older small breed dogs that had suffered a traumatic event. CVJ