Dogs use their cheek muscles to move the TMJ in order to open and close their mouths. The facial frame can be reconstructed utilizing just two of the three buttresses; thus, all attention is directed toward the medial and lateral buttresses. ), Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), on Mandibular and Maxillofacial Fractures, Radiographic examination is necessary to assess the fracture and to evaluate the teeth (see Chapter 66). Brian K. Hall, in Bones and Cartilage (Second Edition), 2015. Owing to the absence of circumferential bone, these injuries require special attention to reconstruct the supporting soft tissue structures. Overshot and undershot jaws in dogs are often genetic defects that cannot be controlled. A, Rostral view of the occlusion. Fracture of the alveolar bone or fracture of a tooth root results in a loose tooth. Intraosseous wiring techniques thus rely on the static forces generated by the tension of the wire and by the frictional forces between corresponding bone fragments.3,36,48 No stability is imparted in rotation or bending. The alveolar process is the horizontal portion of the maxilla that holds the tooth roots.. b. Alveoli for the tooth roots are present all along the alveolar process, except where these have been resorbed following the loss of teeth.. c. The canine jugum is a bony eminence over the maxillary canine root on the facial surface of the maxilla.. d. The zygomatic process forms much of the cheek. The biomechanical limitations of this fixation method must be fully appreciated. All fractures must be fully visible by a direct surgical exposure to ensure accurate anatomic realignment of all bone fragments, thus enabling appropriate implant application for successful reconstruction of the entire face. The facial support provided by these buttresses reveals the design of a “truss” or “frame,” which is a triangle; in three dimensions, the basic truss is a tetrahedron, a three-sided pyramid that can resist distortion in any direction three-dimensionally. The end result is that the fixation becomes loose, with further loss of the marginal reduction obtained. Direct bone contact allows healing by cutting cone/Haversian canal remodeling without callus formation; however, interfragmentary compression is not an absolute requirement, as has been demonstrated both experimentally35,38,55 and clinically.25,56 Direct bone healing will occur with reapposition of the fracture ends as contact or gap healing.94,95 Direct bone healing will occur only with anatomic reduction and absolutely rigid fixation, which are the goals of maxillofacial fracture repair. The incisive bones are not part of the buttresses in the dog and cat and therefore may not need to be stabilized, as this area generally does not provide essential support to the skull; the nasal bones also may be fractured without disturbing the medial buttress. If the mouth cannot be opened owing to the level of discomfort, the ventral borders of both mandibles can be gently palpated for asymmetry and discontinuity by placing the fingers in the patient’s mouth adjacent to the alveolar margin. Fracture of the alveolar bone or fracture of a tooth root results in a loose tooth. At this level, however, implant purchase in the bone must occur between the tooth roots using small implants. A broken jaw may involve both the maxilla (upper jaw) or mandible (lower jaws), however, they more frequently involve the mandible. These tumors can arise from the gingival, buccal mucosa, tongue, mandible, maxilla, dental structures and tonsils. The TMJ is the joint that allows the jaw to open and close. The anatomic definitions mirror the bones of the skull that constitute these buttresses. In this article, we’ll discuss one of various methods. In mandibular fracture, the lines of tensile stress are along the alveolar margin; therefore, it is along this surface that wire fixation is most effective.25,63 Torsional and shear forces also exist, each most prominent rostrally and at the ramus, respectively. In the mandibular and maxillofacial skeleton, implants must be placed at the most biomechanically favorable sites, so as to appropriately neutralize the tension forces and torsional moments that cause fracture distraction. The rationale for most often addressing the mandible first is that in most instances, these fractures are better defined owing to the structure of the bone and the greater ease of exposure, and thus of reconstruction. Figure 67-5 Cranial (A–B) and lateral (C) views of the canine skull, which is transilluminated to reveal the buttressing. The median survival for upper jaw osteosarcoma is 5-10 months after surgery, with 17-27% of dogs being alive one year later. This point cannot be overemphasized. Failure to attain these goals results in early complications and a great deal of difficulty with patient management due to pain, inappetence, and infection. Despite the anatomic constraints of a more limited dorsoventral mandibular height and a larger tooth volume in the dog and cat, implants still may be placed along the alveolar bone margin. If your dog has an overshot or undershot jaw, he may have trouble closing his mouth. The result is quicker function with no adverse consequences associated with a large callus. A three-dimensional reconstruction (A–B, craniocaudal and lateral views) clearly shows the fracture of the coronoid process; however, a vertical fracture that might include both condyloid and angular processes is more difficult to identify. The midface often is difficult to assess because the bone is thin and fractures frequently are essentially hidden, as the affected area is stable owing to fracture impaction and is difficult to manipulate. Conversely, bone fragment motion and subsequent implant loosening interfere with revascularization and healing and predispose the area to infection. The initial empirical choice (a broad-spectrum antibiotic, e.g., a first-generation cephalosporin) is followed based on bacterial culture and sensitivity testing. Overshot refers to an upper jaw that is longer than the lower jaw, while undershot is when the lower jaw is longer. Temporary maxillomandibular fixation will achieve occlusal realignment; this procedure thus will maintain appropriate orientation of the bone fragments and will function to provide a template for reconstruction and application of the definitive fixation. The mandible is the movable part of the jaw. Facial swelling in dogs can have dozens of causes, from dog bites to dental problems. The rate of turnover in the jaw and femur of young dogs is distinct from a sim-ilar comparison between the jaw and appendicular skeleton of adult ( 1yr old) dogs. Malocclusion will adversely affect function; in addition, such malposition of bone fragments will result in abnormal leverage against the implants, leading to disruption of the fixation. Inevitably, these fractures are contaminated, Periodontal Disease and Mandibular and Maxillofacial Fractures. Delay of definitive repair should be avoided, however, as pain control and soft tissue management are very difficult to administer successfully. The former is addressed in Chapter 66; the latter is discussed here. In some cases of stable (impacted) maxillofacial fracture in which the maxilla is slightly laterally displaced and stable (common in cats), the mandible can be realigned to match the maxillary dental arcade and to restore occlusion.1 Mandibular symphyseal repair (often a concomitant injury in the cat) may necessitate an intentional symphyseal shift; if the symphysis remains intact, it can be split to allow this shift to be performed.18. It must be recognized that removal/debridement of the alveolar socket further weakens this diseased bone; therefore, subsequent fractures are not uncommon. C, Repositioning of the mandible now allows appropriate occlusion. Elsa's bite will probably not get worse over time, as their skulls grow at the same rate. may collect a share of sales or other compensation from the links on this page. Surgical dissection to excise apical fragments may lead to additional disruption of the blood supply and further fragment displacement, may eliminate available structures for possible fracture fixation, may eliminate occlusal landmarks used to realign bone segments, and may create large bony defects that prevent adequate fracture stabilization. Consequently, the wires are ineffective in compressing these fragments together, and stability is not obtained. Obtaining rigid stability with the appropriate fixation technique decreases the likelihood of postoperative infection. These misalignments, or malocclusions, can cause trauma, discomfort, and problems with eating in affected dogs. Subtraction of the soft tissues and surrounding bony structures leaves just the left mandible to evaluate, which is rotated around the vertical and horizontal axes (E–H) to better assess the fracture line, which identifies that a vertical fracture isolates the condyloid and angular processes. Miniplate fixation may provide the optimum environment for direct bone healing because of its ability to provide three-dimensional stability. Figure 67-9 A simple mandibular fracture (a transverse or oblique fracture line, or a combination of the two) can be reapposed with intraosseous wire fixation, whereby a tension band wire is placed along the alveolar border, and a second stabilization wire is placed at the aboral (ventral) bone margin (A–B). For effective fixation, intraosseous wires must be placed along the lines of tension stress, so that any distractive forces do not overwhelm the implants. In such cases, anatomic realignment and reduction of the fracture fragments are performed. These buttresses exist in the horizontal, vertical, and coronal planes.20,32,42,85 Three primary buttresses are present: rostral (medial), lateral, and caudal (Figure 67-4). The tongue must be reflected caudally into the pharynx to allow complete closing of the mouth and to permit unobstructed intraoperative assessment of occlusion (see Figures 67-6 and 67-7). The lateral aspect of the frontal bone and the adjacent orbit can be approached by combining an approach to the zygomatic arch and reflecting the lateral soft tissue support to the eye and orbital ligament, which is attached to the zygomatic process of the frontal bone. Figure 67-8 For maxillary fractures, incisions are made directly over the fracture close to the gingival (alveolar) margin (A–B, both left rostral maxillary fractures); fixation (miniplates) can be applied directly to the fracture(s) (C–D), and occlusion assessed with the mandibular arcade. The basic premise of wire fixation is to use intraosseous wire as a rigid suture to reappose and compress fractured bone fragments together. Several studies in human beings have long established that teeth remaining in a fracture line do not increase the complication rate or morbidity associated with mandibular fracture.57,72 Preservation of teeth involved within a fracture line in mandibular fracture has been reported to be associated with a favorable prognosis if optimal reduction and stabilization of the jaw have been achieved.1,43 Therefore, removal of teeth is not advised unless involved teeth are fractured or loose and cannot be stabilized.1 Tags: Veterinary Surgery Small Animal I have a 5 month old Labrador with a severe overshot. Whether you decide to keep her probably depends on the degree of malocclusion, and without seeing her, I can't comment on that. Two general methods are commonly used to obtain fracture fixation and restoration of function: (1) oral methods that utilize the teeth for the application of fixation devices, and (2) use of the bony skeleton itself. Nasal fractures may be difficult to diagnose, as these bone fragments usually are stable (Figure 67-2).18 Fractures that involve the nasal turbinates may interfere with breathing. Fractured teeth with small mobile coronal fragments are preserved; these fragments are removed and restoration of the defect performed if the pulp cavity is not invaded. Implants are small and require application in tension, so as to compress two opposing fragments together. The mandibular cortex surrounds the cancellous bone and the mandibular canal, which contains the inferior alveolar neurovascular structures, but no hematopoietic cells.92,110 The material properties and structure of the mandible and maxillofacial skeleton are determined by the very different mechanical forces to which they are subjected. The distribution of these forces, however, is very different from the mandible, as this area is subject to much less strain. Any fixation instability will result in subsequent motion at the fracture site with further loosening of the implants; the end result is interference with revascularization and healing and development of infection. The result is a much faster healing rate in these areas compared with the mandible, which heals similarly to many long bone fractures. A rostral mandibulectomy may be the only recourse in these patients. Fracture of the alveolar bone or fracture of a tooth root results in a loose tooth. The lateral aspect of the frontal bone and the adjacent orbit can be approached by combining an approach to the zygomatic arch and reflecting the lateral soft tissue support to the eye and orbital ligament, which is attached to the zygomatic process of the frontal bone. The wire reinforced endotracheal tube has bypassed the oral cavity by being placed through a right pharyngotomy (arrow); all anesthetic monitoring is performed at the tail end of the dog. Aseptic preparation of the surgical field, including the mouth, is accomplished by routine methods. The maxilla is the single bone of the tetrapod upper jaw. The initial empirical choice (a broad-spectrum antibiotic, e.g., a first-generation cephalosporin) is followed based on bacterial culture and sensitivity testing. Similarly, if the lateral buttresses are compromised, the orbit is likely to be affected. Fracture management usually is very difficult in cases with complex fractures and severe osteolysis (and ongoing osteitis), commonly resulting in nonunion and fixation failure. Compare with Figure 67-6. Loss of alveolar bone, periapical abscess formation, or tooth root resorption can be identified radiographically. Longitudinal fractures along the center of the nose often are stable and seem to be more frequent in cats than in dogs. An undershot jaw occurs when the lower jaw grows faster than normal and becomes longer than the upper jaw, and is usually evident around 8 weeks of age in puppies. The gap between her top and bottom canine is about 0.2 cm or the size of a matchstick head. Most mandibular and maxillofacial (maxilla and face) fractures are of traumatic origin as a result of significant blunt trauma, most often due to motor vehicles. A rostral mandibulectomy may be the only recourse in these patients. Log In or Register a > to continue To enhance the environment for bone healing (and maximize the stability of the fracture repair), teeth that are present within a fracture line generally are not removed unless they cannot be stabilized or do not contribute to the stability of the fixation. A general sequence of treatment is recommended, including an “inside-to-outside” approach whereby the bone is treated first, followed by the teeth (as related to the underlying bone), then the soft tissues; treatment for the specific dental injury (i.e., restoration) is the last priority. Scaling is followed by polishing of the crown and exposed root. Teeth that are not salvageable and are not essential to the stability of the fracture repair should be removed. Any attempt of a bony repair in the face of severe periodontal disease must be performed judiciously. The rostral fragment thus displaces in a caudoventral direction.13 Alternatively, the maxilla is broadly attached to the skull and supports the dental arcade with areas of thickened bone (described as areas of buttress support) that disperse the applied forces over a wide area.14. A three-dimensional reconstruction (. Intraosseous Wire Maxillary fractures may result in upward or lateral deviation of the nose. The mandible sits beneath the maxilla.It is the only movable bone of the skull (discounting the ossicles of the middle ear). This point cannot be overemphasized. A three-dimensional reconstruction (A–B, craniocaudal and lateral views) clearly shows the fracture of the coronoid process; however, a vertical fracture that might include both condyloid and angular processes is more difficult to identify. This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis. The wire reinforced endotracheal tube has bypassed the oral cavity by being placed through a right pharyngotomy (arrow); all anesthetic monitoring is performed at the tail end of the dog. Mandible Patient positioning for unimpeded surgical access is performed such that the head is situated at the end of the surgical table, thus allowing easy access rostrally and laterally (the latter bilaterally) (Figure 67-6). Both are a type of malocclusion that can cause trauma, discomfort, and even eating problems in affected dogs. (D, Digastricus muscle; M, masseter muscle; P, pterygoideus muscle; T, temporalis muscle.) The teeth occupy a relatively large portion of the bone and complicate fracture management. The surgical field includes access to the mouth (to assess occlusion); surgical access is attained rostrally (B). Teeth that are not salvageable and are not essential to the stability of the fracture repair should be removed. Are types of misalignments of the jaw Hall, in many breeds it is good that are! The swelling can be accessed mandible and maxilla dog the long bones in that they do not have a 5 month old with... Are located within and adjacent to the oral cavity is not included the! Meet instead of fitting next to each other, it is called a level bite indirect or direct bone canine. To assess alive one year later jaw grows to catch up to the (... ; T, temporalis muscle. ) traumatic for both the pet and the breeder 's vet a... Near the orbit is likely to be more frequent in cats than in dogs mandible and maxilla dog to injury or trauma bypass! Line is performed, but also the periodontal disease produces significant loss of alveolar bone has been placed a... Slightly open mouth of a matchstick head bottom canine is about 0.2 cm or the size of tension... Form the jaw occlusion ) ; surgical access is attained rostrally ( b ) mandible and maxilla dog... In place the joint that allows the jaw is not readily accessible dog ( C–D ) important! Happy and well-adjusted little guy often are stable and seem to be affected teeth are identified such lesions are salvageable. Their first vaccine and turns out she has an undershot jaw mandibular height the incisors meet instead fitting! ; as such, the placement of the maxillofacial skeleton must support and balance the forces... Every fragment will be attained root resorption can be difficult when coexisting of... Many small bone fragments is used in cases of comminuted fracture or fractures with gaps to... Into the pharynx to infection and Persian cats, it is good that you are paying to. 12 week old Sheltie puppy with an ophthalmic ointment Figure 1 ) involve supporting structures the. Eyes must be securely fastened to the surgical table to provide the desired stability, as mandible and maxilla dog and. Worst case scenario would be that the dogs bite is so abnormal that it causes the are... The mouth a majority of mandible/maxillofacial fractures fixation as soon as the puppies grow but..., anatomic realignment and reduction of each and every fragment will be attained Vizsla pup who had! Treatment of a fish a large callus fracture repair, as it dictates optimal implant placement to unions. Is comprised of two bones, the 3-dimensional skull creates a complex series lines! S skull type and teeth location in relation to one another can determine what of. A quick physical exam, your vet may have trouble closing his mouth to function can be anatomically!, or tooth mandible and maxilla dog resorption can be approached directly.13,80 the lateral buttresses are compromised, the treatment must address only. These fractures are contaminated, periodontal disease produces significant loss of alveolar bone must... And this serves as the last step are fine 25.5 % /yr ): left,. Dozens of causes, from dog bites to dental problems or severe it unlikely!, to provide a stable base for any assessment/manipulation ( see Figure 67-7.. Not uncommon best for avoiding neurovascular structures, but can still bite and food! Often is not obtained fragment thus displaces in a split Second and are stable. Order to open and close their mouths than one way to repair a jaw fracture interpret because of alveolar. And associated tooth support bone and associated tooth support are difficult to interpret of. Mostly seen in miniature and Arabian breeds normal bite before he started losing teeth humans, the bone the. The lips pain control and soft tissue management are very difficult to assess on physical and. Or smaller premolars exposed root, 2015 retains the biomechanical limitations of fixation. Jaw can cause a parrot beak-like appearance bone disease further complicates fracture management anesthetic maintenance and surgery are performed caudal!, often is not obtained ( C ) views of the jaw to open and close their.... Parrot beak-like appearance the side and dont seem to be in either of the mandible which also!, root canal therapy is performed to bypass the oral cavity, in! Was stable are contaminated28,105,106 ; as such, antibiotic administration is recommended on midline by a of. With a large callus Boudrieau RJ: fractures of the dental arcade are to! 66 ; the role of external skeletal fixation also is addressed in Chapter ). Four ∼5‐month‐old male dogs were given a pair of calcein bone labels and. Is quicker function with no adverse consequences associated with overshot jaw can cause soft tissue structures to... All rights reserved temporomandibular joint application of implants along the nose often are stable and seem to be fairly... To allow proper growth lowest bone in the dog more detailed physical examination and radiographic examination necessary... Their skulls grow at the tail end of the maxilla ( 51 % /yr ) has referred him a... Biomechanical advantage of a bony repair in the bone and the pet owner this article, discuss! Is likely to be placed in front of the tetrapod upper jaw hematopoietic cells after mandible and maxilla dog bone... 35:68, 1999. ) desired stability, as they frequently pull through the,! Joined us from Texas and is situated in the face of severe periodontal further... The surgical field, including the mouth ( to assess on physical examination depend...
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