Jaw Fracture Management
Sandra Manfra Marretta, DVM, Diplomate
Management of jaw fractures in dogs can be subdivided into three major categories including preoperative evaluation of patients, selection and utilization of appropriate techniques, and management of postoperative complications.
Prior to correction of jaw fractures the patient must be thoroughly evaluated for other traumatic injuries. Following stabilization of life-threatening injuries jaw fractures can be evaluated under sedation or general anesthesia. The mandible, maxillofacial bones, and temporomandibular joints are palpated both extra- and intraorally for fractures. Radiographs are taken to localize the fracture sites. It is important to assess the full extent of all injuries keeping in mind that multiple fractures may be present.
The teeth need to be evaluated for periodontal and endodontic disease and their relationship to fracture lines must be determined. Previous reports indicate that pathologic fractures may occur in the mandible of dogs with severe periodontal disease through deep periodontal pockets.1,2 These pathologic fractures occur most frequently in the region of the mandibular first molars and canine teeth. Periodontally diseased teeth in a fracture line need to be extracted or hemisected to remove the periodontally affected tooth or root that predisposed the dog to the pathologic fracture. Retension of a periodontally diseased tooth or root in a fracture site inhibits fracture healing. If hemisection is chosen as the method of treatment, the retained root must be treated endodontically. In addition teeth that are fractured with pulpal exposure require endodontic therapy.
Teeth that are not diseased but are located in the fracture site can generally be retained. Prognostic factors of teeth in the fracture site have previously been reported with fractures extending along the periodontal ligament to the apex having the poorest prognosis.3 In general, it is probably best to retain teeth that significantly contribute to fracture stability as long as severe periodontal disease is not present and the fracture is acute.
The presence of multiple or severe jaw fractures in which frequent intraoperative assess of occlusion is necessary may require the utilization of pharyngostomy endotracheal intubation. This technique involves the placement of an endotracheal tube through a pharyngeal incision which is carefully made to avoid cutting major vessels located in this region. This is best accomplished following induction of anesthesia with routine placement of an endotracheal tube. The pharyngeal region is surgically prepared. An index finger is placed intraorally posterior to the caudal aspect of the mandible and anterior to the hyoid apparatus. A skin incision is made over the properly positioned index finger. The remainder of the approach to the oropharynx if made with a curved hemostat which is used to bluntly separate the muscles to the level of the oropharyngeal mucosa. A long curved hemostat is then passed through the oral cavity to the oropharyngeal incision and the mucosa is carefully penetrated with the hemostat and is gently enlarged to permit the introduction of a sterile endotracheal tube. The previously orally placed endotracheal tube is removed and the pharyngeally placed endotracheal tube is placed into the trachea.
Techniques for Jaw Fracture Management
Various techniques can be utilized in the management of jaw fractures. Adherence to basic principles of jaw fracture management can help provide a successful outcome regardless of the technique utilized. These basic principles include the following: (1) restoration of occlusion and anatomic reduction of the fracture, (2) neutralization of forces on the fracture line and stable fixation, (3) avoidance of soft tissue entrapment by the fixation technique, (4) avoidance of further dental trauma, (5) proper assessment of tissue viability, (6) removal of diseased teeth within the fracture, (7) avoidance of excessive elevation of soft tissue from the surface of the bone and covering of exposed bone with soft tissue, and (8) rapid restoration of function.4,5
Numerous techniques for reduction of mandibular and maxillary fractures in small animals have been described previously.5 Techniques frequency utilized in the management of jaw fractures include: (1) tape muzzles, (2) circumferential wiring, (3) acrylic splints, (4) percutaneous skeletal fixation, (5) bone plating, and (6) partial mandibulectomy.
Tape muzzles are an inexpensive, noninvasive technique of aligning and stabilizing jaw fractures. They can be used to temporarily stabilize jaw fractures prior to definitive repair. Tape muzzles can also be utilized as the primary repair technique in minimally displaced stable fractures especially fractures of the mandibular ramus or fractures occurring in young animals in which bone healing occurs rapidly.
Circumferential wiring involves placing a wire around a bone or bones to achieve stabilization of a fracture. The most common indication for circumferential wiring in small animal jaw fractures is symphyseal fractures. Circumferential wiring can also be utilized in combination with acrylic splints in edentulous areas where interdental wiring is not possible.
Intraoral acrylic splints are an easy, noninvasive, versatile, and inexpensive technique for repairing jaw fractures. The splints are ideal for the repair of fractures rostral to the first molars. The use of hard dental acrylics such as Jet Repair Acrylic (Lang Dental Manufacturing Company, Chicago, IL) is recommended for the fabrication of intraoral splints.5 Pink acrylic is recommended rather than clear acrylic because of the ease of visualization of the pink acrylic during application and removal. Acid etching of the teeth with 40% phosphoric acid gel prior to splint application enhances retention of the splint to the teeth. Prior to direct splint application, a perimeter of dental wax can be applied around the proposed splint site to facilitate splint fabrication. The splint is easily created directly on and around the teeth with application of a small amount of powder that is then saturated with the liquid. Small amounts of powder and liquid are alternatively applied to the fixation site. The fracture is held in reduction until the desired splint thickness is attained and the splint becomes hard.
An alternative to fabrication of the acrylic splint in layers involves premixing the acrylic splint material and transfering the precured acrylic to a syringe and applying the premixed material to the teeth. In larger animals where a thicker splint is required a significant amount of heat may be generated while the splint is curing. Cool water can be flushed over the splint if excessive heat production occurs to prevent thermal injury to the teeth and gingiva.
Other materials have been recommended for the fabrication of interdental splints include Triad acrylic splint material and Protemp Garant (Premier). When using Triad acrylic for fabricating interdental splints either the sheets or ropes can be utilized. The material can be cut to the necessary shape and size and molded interdentally between and along the teeth and light cured. Protemp Garant, a self curing Bis Acryl-composite material, can also be used for fabrication of interdental acrylic splints.
Interdental acrylic splints are removed following radiographic confirmation of fracture healing. The splint is removed by sectioning the splint intradentally with a bur and removing the splint in segments using an extraction forceps in a shearing motion similar to the technique used to shear off heavy dental calculus from teeth. Following removal of the acrylic splint the teeth are polished.
Many types of percutaneous skeletal fixation devices have been used in the repair of jaw fractures. These techniques are particularly useful in fractures in which there is a large amount of soft tissue trauma, fractures that are comminuted, and fractures in which a defect is present. Stability can be achieved with these techniques despite the loss of bone and teeth. A versatile, easy to apply, and inexpensive technique for the repair of maxillary and mandibular fractures using an external acrylic bar involves the placement of Kirschner wires and/or Steinmann pins into each fracture fragment and embedding the exposed cut ends of the pins into an acrylic (methylmethacrylate) bridge. Healing usually occurs in 4-6 weeks. The pins are removed by cutting the pins close to the acrylic bridge and then pulling the pins from the bone once the bridge has been removed.
Utilization of bone plates in the management of jaw fractures has several advantages and disadvantages. The advantages of bone plates includes rigid stabilization of the fracture and rapid return to normal function. Fractures stabilized with bone plates heal with little or no callus formation. However, there are multiple disadvantages associated with the utilization of bone plates for jaw fractures. Specialized expensive equipment and increased surgical expertise is required for bone plating. Significant soft tissue elevation is necessary for the placement of bone plates which may further comprise the blood supply to the fractured bone. It is also difficult to apply a bone plate to a fractured mandible or maxilla without further traumatizing tooth roots or neurovascular structures. It is very difficult to achieve normal postoperative occlusion using plates for jaw fracture repair because even slight errors in reduction of a fracture particularly in caudal fractures will result in a significant malocclusion with inability of the patient to close its mouth.
Miniplates have been recently utilized in the repair of mandibular and maxillary fractures in dogs and cats.6 The small size of these implants allows placement close to the alveolar border and the screws may be angled to avoid impingement on tooth roots.
Partial mandibulectomy can be utilized in the management of mandibular fractures when extensive trauma or infection preclude reduction or adequate fixation.7 Partial mandibulectomy techniques should be limited to cases in which primary fracture repair is likely to fail or cases in which primary fracture repair has resulted in an inability to eat and drink.5
Bilateral pathologic caudal mandibular fractures can be an infrequent but severe complication of advanced periodontal disease. These pathologic fractures may occur in the region of the first mandibular molars and often occur following minimal bony stress. These types of fractures tend to occur most frequently in geriatric, small breed dogs and have been described as "orthopedic disasters."8 A salvage procedure involving bilateral partial central hemimandibulectomies with bilateral advancement of the commissures of the lips has recently been described for the management of these difficult cases.9,10 It is recommended that this technique be reserved for bilateral mandibular fractures with poor bone quality in the region of the first molars in which more conservative mandibular fracture repair techniques have been unsuccessful. This technique involves the extraction of all diseased teeth and removal of the avascular ends of the fractured hemimandibles with rongeurs resulting in 1-2 cm of bone loss bilaterally. The fracture sites are flushed and mucoperiosteal flaps are elevated and sutured over the exposed bone ends using 3-0 Monocryl. The mandibular and maxillary lip margins are removed from the level of the commissures of the lip to the distal aspect of the mandibular canine extraction sites. The buccal mucosa is closed bilaterally in a simple interrupted pattern using 3-0 Monocryl. The skin is closed with 3-0 Nylon in a simple interrupted pattern. This advances the commissures of the lips to the previous location of the distal aspect of the mandibular canine teeth. This technique results in a smaller oral aperture, provides support for the rostral mandible and permits adequate alimentation of a soft diet.
Postoperative complications associated with the management of jaw fractures includes malocclusion, osteomyelitis, bone sequestration, delayed union, nonunion, facial deformities, oronasal fistulas, and various forms of dental abnormalities.5
Postoperative malocclusion, a serious complication of jaw fracture management, can be prevented by careful and frequent assessment of proper occlusion during reduction and stabilization of the fracture site. Treatment options for postoperative malocclusion include immediate removal of the fixation device, followed by proper reduction. Selective extraction of maloccluded teeth can permit the patient to close the mouth postoperatively in poorly reduced fracture fixation procedures but is considered a significant compromise for poor surgical technique.
Osteomyelitis and bone sequestration may occur following jaw fractures. Diseased teeth in the fracture site may predispose to these complications. These complications are often associated with delayed and nonunions and are diagnosed radiographically. Removal of bone sequestra and disease teeth often results in bony union.
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2. Manfra Marretta S: The common and uncommon clinical presentations and treatment of periodontal disease in the dog and cat. Seminars in Veterinary Medicine and Surgery (Small Animal) 2:230, 1987.
3. Schloss AJ, Manfra Marretta S: Prognostic factors affecting teeth in the line of mandibular fractures. J Vet Dent 7(4):7, 1990.
4. Chambers JN: Principles of management of mandibular fractures in the dog and cat. J Vet Orth 2:26, 1981.
5. Manfra Marretta S, Schrader SC, Matthiesen DT: Problems associated with the management and treatment of jaw fractures. Prob Vet Med (Dentistry) 2:220, 1990.
6. Boudrieau RJ, Kudisch M: Miniplate fixation for repair of mandibular and maxillary fractures in 15 dogs and 3 cats. Vet Surg 25(4):277, 1996.
7. Lantz GC, Salisbury SK: Partial mandibulectomy for treatment of mandibular fractures in dogs: Eight cases (1981-1984). J Am Vet Med Assoc 1987;191:243-245.
8. Harvey CE, Emily PP: Oral surgery. In Harvey CE, Emily PP (eds): Small Animal Dentistry. St. Louis, Mosby, 1993, 312.
9. Manfra Marretta S: A salvage procedure for bilateral pathologic mandibular fractures in the dog. In Proceedings of the 4th World Veterinary Dental Congress, Vancouver, BC, 1995, 128.
10. Manfra Marretta S: Maxillofacial surgery: Vet Clin North Amer (Canine Dentistry) 28:1285, 1998.