The fracture gap is thoroughly cleaned and all debris removed followed anatomical reduction of the fragment Manual reduction is usually successful, but may require considerable force to replace the teeth back into their normal position. In rare cases additional force is required such as with a hammer. The mouth is closed manually to assess reduction of the fracture and occlusion of the teeth. The correct reduction of the fracture can also be assessed by applying reduction forceps to the upper and lower jaw.
In the horse 1.2 mm (18 gauge) orthopedic stainless steel wire is most commonly used for cerclage. For fractures of the incisive bone that result in loosening of the incisors, an interdental continuous wire-loop splint described by Obwegeser (1952) can be used. It allows the application of uniform tension between all the teeth that are engaged in the splint. One end of the wire is guided back and forth between all incisors to form small loops in front of the incisor teeth starting on one side of the arcade. The other end of the wire is then threaded through the loops, followed by tightening of the wire ends. Care is taken to place no loops through the fractured alveoli. The wire should always be tight and care must be taken that it is not weakened by repeated bending and kinks in the wire during insertion.
For insertion of the wire, a sharp end can be created by cutting the wire at an angle. This facilitates penetration of the gingiva. Alternatively a 2 mm (14 gauge) hypodermic needle can be used to penetrate the tissue between two adjacent teeth and to allow passage of the wire, or small holes (2.0 or 2.5 mm diameter) may be prepared using a Steinman pin or a small drill bit. This is usually required for passing a wire between the incisors and almost always for placing the wire between cheek teeth.
Subsequently each wire loop previously created in front of the incisor teeth is tightened in a uniform fashion using pliers or needle drivers. This must be completed in an even fashion, alternating between multiple loops, and under careful monitoring of the fracture site to avoid displacement after reduction.
Once the wires are tightened, the twisted ends are shortened and bent flat towards the teeth so that they do not irritate or injure the gingiva. If they are sharp, they should be protected.
Anchoring of the wire
Depending on the fracture and the degree of stability required for fixation, wires are anchored around the canine tooth or cheek teeth. If the canine teeth are used for anchoring, a notch is filed into the tooth at its base to prevent the wire from slipping.
Cheek teeth provide very good stability for tension wires, usually placed between the 06 and 07 teeth (the second and third premolar). To achieve this, the skin is clipped, surgically prepared and a short arthroscopy sleeve with a trocar or obturator is advanced into the mouth via a stab incision. This technique minimizes hemorrhage, which can be a problem when the tissue is cut with a scalpel. A drill bit is then introduced through a protective drill guide and a hole is prepared between the two cheek teeth.
Note: Special attention needs to be paid to the palatine artery, which runs under the palatine mucosa.
Once the wire has been placed to form a loop, it can be twisted together in the interdental space to increase tension.
Attention: A loose tooth within the fracture fragment should never be removed. It should be cleaned and replaced within its alveolus, followed by application of the selected wire fixation. This tooth provides stability to the fracture repair and actually may heal back into place. If the tooth is removed, the remaining teeth will loosen with time and the solid fixation will be lost.
If a tooth is lost between the time the fracture occurred and it treatment, a PMMA block should be placed between the two adjacent teeth after the placement of the loop and their tightening.
There are many other ways to place the wire loops for optimal accommodation and fixation of the fracture. Simple loops must overlap to ensure that the teeth are not pulled apart, and figure-8 loops can be used to increase stability.
At the end of the surgery, the teeth of the lower jaw are shortened to reduce pressure during eating.
During the post-surgical period, the horse is confined to stall rest for one week and fed with soft fiber feed stuff; firm feed such as hay cubes, apples or carrots should not be fed. Antibiotics and anti-inflammatory drugs are administered for 3 to 5 days or longer, if required, especially in open fractures. Intraoral cerclage and tension wires are cleaned once daily until their removal.
After 6-8 weeks the wire(s) can be removed under sedation and local anesthesia. In foals, wire removal is often done earlier because healing is very rapid and there is a risk of abnormal skeletal or dental development if the wire is left in place too long.