The overall goal is to restore occlusion, normal anatomy and function.
Restoring and maintaining occlusion is the most important aspect of fixation of symphyseal separation and parasymphyseal fractures.
The mandibular bone at the level of the symphysis is almost completely occupied by dental roots. Therefore, invasive fixation is not recommended. Orthopedic wiring around the rostral mandibles or between the canine teeth provide adequate reduction and stabilization.
Circummandibular wiring can be done in the absence of one or both canine teeth.
Pharyngeal intubation is not needed for this procedure.
The fractured area is clipped to assess for penetrating injuries. If a penetrating wound is found, an exploratory surgery and debridement of the area is indicated to remove any foreign bodies (i.e. hair).
A comprehensive intraoral examination must be performed to assess for any injury affecting occlusion, teeth trauma and periodontal tissues.
Dental radiographs and a CT are obtained to provide details about the dentoalveolar structures in relationship to the fracture or separation.
Reduction of the separation or fracture is done digitally, bringing the teeth into normal occlusion, which realigns the bones.
The patient is placed in dorsal recumbency. A 10mm ventral incision is made over the symphysis.
The wire should be passed as close to the bone as possible, to avoid soft tissue within the wire. Place a large gauge hypodermic needle from the ventral aspect of the symphysis directing it lateral to exit distal to the canine teeth.
A pre-stretched orthopedic wire (gauge of wire depends on skull size) is passed through the needle.
The needle is removed and placed on the opposite side.
The orthopedic wire is passed through the needle on this side. This will result in the wire circling the rostral mandibles just distal to the canine teeth.
While holding the incisor teeth in occlusion, the wire is pulled and twisted until it is fully tightened on the ventral aspect of the symphysis.
The separation or fracture will be reduced and stable.
The wire is cut at the skin edge, leaving three to four twists.
Note: Care should be taken not to bend the wire due to loosening and loss of reduction.
The skin is sutured over the twisted wire.
6. Application of the composite
Irrigate the teeth to be included in the composite. Acid-etch the teeth for 20-30 seconds. Thoroughly irrigate again and dry.
Note: it is paramount that the teeth remain dry throughout the application of the composite
A composite temporization material is placed on the teeth and contoured to avoid sharp edges or projections. Care is needed to avoid contact with the gingiva.
Once the composite solidifies, smooth the composite with a Goldie bur on a surgical handpiece or a diamond bur on a high-speed handpiece.
7. Debridement and suturing
Wounds should be debrided followed by copious irrigation with sterile saline 0.9%. Soft tissue lacerations are sutured using 4.0 or 5.0 poliglecaprone 25 or other monofilament absorbable suture in a simple-interrupted fashion.
Note: in the oral cavity, due to abundant blood supply, aggressive debridement is rarely needed.
8. Case example
Wiring of a parasymphyseal fracture, in the absence of the left mandibular canine tooth.
Note: the wire can be oblique if it is anchored behind a premolar tooth.
Fixation of parasymphyseal fracture and soft tissue reconstruction in a dog.
The splint should be cleaned at least once daily using 0.12% chlorhexidine gluconate solution. Another option is to use a water-flossing device.
The patient should wear an Elizabethan collar until removal of the construct.
The wire is kept in place for 4-6 weeks and removed under general anesthesia.
A small skin incision is made exposing the wire twist. The wire is cut intraorally and straightened to prevent soft tissue damaging. The wire is gently pulled out on the ventral aspect from the twist knot.
If composite was placed, a composite removing forceps are used.
The teeth involved in the fixation should receive periodontal cleaning as moderate to severe gingivitis is seen with the presence of an intraoral splint.