Maxillary and mandibular fractures can be repaired to great effect using various techniques including plating, external fixation and direct inter-fragmentary wiring. However, with limited ‘safe corridors’ these techniques all have the potential to cause iatrogenic damage to the tooth roots, nerves and blood vessels if the surgeon is not familiar with the local anatomy.
Where fractures of the jaw bones are fully reconstructable, interdental wiring and splinting perhaps offers a safer and more versatile solution. It can be particularly useful where there are very few safe corridors within the bone itself, such as when the tooth roots are tightly packed together. Using interdental wiring techniques, a repair can often be achieved from an oral approach with very little or no dissection. Intra-oral acrylic splinting is a very useful, but much underused technique. Initial reduction is normally achieved first by intra-oral wiring and then the repair is reinforced using a cold cure, temporary crown style, dental acrylic. Note that traditional methylmethacralate acrylics are too exothermic to be used in the mouth There are a number of different techniques for interdental wiring; these include the Ivy Loop, Essig, Risdon, Stout’s Multiple Loop and Modified Stout’s Multiple Loop patterns. It is useful to know more than one different pattern as some are easier to use and indeed more effective in some parts of the mouth and for differing anatomies than others. The initial security of interdental wires depends largely on the wire’s ability to contour to the shape of the teeth, although in some cases it may be necessary to place the wire through small bone tunnels between the teeth to improve security further. 0.8mm/20g wire may be useful in large dogs, but relatively fine wires (typically 0.5mm/24g to 0.65mm/22g) are more easily worked and are suitable for most patients. These fine wires contour to the shape of the teeth better and with less force, so as well as providing greater security loss of reduction and having the wire flip out of position are both less likely to occur as the wire is tightened.
Wiring techniques do take patience to perfect and where possible, practice is strongly advised before use with a clinical patient. Dental acrylic deposited over the top of the wired repair will help to keep the wire in place and add to the mechanical strength and stiffness of the repair. For proper adherence of dental acrylic, acid-etching of the teeth is required. Dental acrylic is surprisingly user-friendly to apply. It has a consistency that allows it to flow under gravity in a controlled manner over the teeth filling the gaps and leaving a nice smooth surface finish. It can be used to cover any sharp and exposed wire twists and can be used as a refinement in this way for wiring of the mandibular symphysis.
There are two main types of dental acrylic, cold-cure and light cure. Both are available in dual barrelled cartridges which are loaded into a re usable applicator gun. As the trigger of the gun is depressed, the two components are mixed in disposable nozzles. These guns allow for very accurate deposition of the acrylic, reducing mess considerably. The volume of acrylic in each cartridge is normally sufficient for multiple uses. It is critical to ensure that the mouth can close without teeth in the opposite jaw making contact with the splint. This is uncomfortable and destabilises the splint. For mandibular fractures no splinting material should be placed on the buccal aspect of the teeth caudal to the lower carnassials. For both mandibular and maxillary splints relief should be provided to the occlusion of the canine and incisor teeth.