Fig. F4G: Tension band wiring of a fracture to the canine teeth. Note, an indentation (arrow) was created with a rasp in the nuchal aspect of the canine teeth to anchor the wire.
Fig. F4H: The drill guide is used to protect the cheek and gingiva as a drill bit is used to create a hole for passing the wire between P2 and P3 at the gum line. The wire for inclusion of the first cheek tooth in cerclage wire bridging of the interdental space is passed through this hole.
The advantages of wire are that it is easy to use, versatile, and inexpensive, and it confers a secure fixation. Disadvantages include loosening of the fixation and, in certain instances of molar fractures, exposure. Application may involve several stab incisions through the cheek, with its abundant neurovascular network.
Application of cerclage wires to the molar arcades is facilitated by stab incisions through the cheek.
Fig. F4I: Figure-8 wiring of a transverse fracture of the interdental space. The holes are created with a 2.5 mm drill bit or a Steinmann pin.
Fig. X4C: Long oblique fracture through the diastema of one ramus of a Shetland pony.
Fig. X4D: The fracture in Fig. X4C was repaired with two cerclage wires supported by a tension band wire fixation between the incisor and premolar teeth. The picture was taken 4 months after the surgery at the time of implant removal, which was necessary because of a persistent draining tract.
Fig. X4E: A bilateral mandible fracture in a 3-week-old foal was repaired with a Steinmann pin along each horizontal ramus.
Steinmann pins
Steinmann pins are rarely employed as a sole mode of fixation, except possibly in young foals [1]. They can be used in fractures of the diastema (Fig. X4E), but trauma to the tooth buds may present a problem. In most cases, this fixation is not stable. In suckling foals, the fixation may be adequate but may traumatize the udder of the dam.
Place a screw transversly into the diastema to provide anchorage for wire fixation.
Screws
Screws may be used in fractures of the symphysis or in oblique fractures where good interfragmentary compression may be achieved through cortex screws applied in lag fashion [4, 5] (Fig. F4J). Screws may also be used to anchor cerclage wires in the region of the diastema [ 1] (Fig. X4F).
Fig. X4F: A rostral mandible fracture was repaired with cerclage wires anchored to two cortex screws placed into the diastema.
Fig. F4J: Lag screw repair of a unilateral fracture of the mandible containing a large osseous fragment. The fixation is protected with tension band wiring of the incisors to P2.
Fig. X4G: Laterolateral radiographic view of an unstable mandible fracture in a 1-month-old foal.
The U-bar
An aluminum U-bar, rounded rostrally, and flattened toward the premolars and molars can be used in very unstable fractures of both rami of the mandible [6] (Fig. X4G). It should be fixed with wire loops around the incisors and, further caudally, around the premolar and/or molar teeth on both sides of the cheek (Fig. F4K). Position the animal in dorsal recumbency to allow simultaneous access to both sides of the jaw. U-bars can be cumbersome, requiring several incisions to secure them to the molar arcades [6] (Fig. S4F). To add stability, dental acrylic may be applied as described below.
Fig. F4K: Intraoral splint made from aluminum bar and molded around the contours of the mandible. The bar has a round cross-section in front and a flattened cross-section on either side. The aluminum bar is attached to selected teeth with cerclage wires.
Fig. S4F: An aluminum bar was applied to a very unstable bilateral fracture of the mandible shown in Fig. X4G. The U-bar is attached to the mandible with wires. (Photo courtesy JP Watkins, Texas A&M University.)
Dental acrylic
Dental acrylic may be applied intraorally to serve as a buttress and enhance stability [7, 8]. In its softened state, the acrylic is molded to the contours of the mandible or maxilla. It is important to select an acrylic that does not produce an exothermic reaction during the hardening process. Such a reaction can be harmful to the gingival tissues. In selected cases, wires may be incorporated into the acrylic while it is still soft. When the acrylic hardens, these wires are firmly anchored to the neighboring teeth. This type of fixation has the function of a stent [2, 7, 8] (Fig. F4L).
Enhance stability by the application of dental acrylic.
Plates
Plates may be applied directly to the bone, or attached to the teeth. It may be difficult to identify the ideal location for the plate [9, 10] (Fig. F4M). Underlying teeth may cause a problem and may be traumatized. It is also difficult to apply a plate to the tension side because this tension side is, in fact, the occlusal surface. Therefore, the plate is typically applied in a less than ideal location, in terms of biomechanics, with resultant reduction in stability (Fig. X4H). Care has to be taken to avoid insertion of screws through tooth roots. Plates can be applied in the rostral mandible and possibly on the caudal rim of the ramus if it is large enough to accept the screws