|Principles: general considerations|
Rigid fixation techniques in the dentate patient begin with fixation of the occlusion. This ensures that the patients maintain their preoperative occlusal status. There are several techniques to providing mandibulomaxillary fixation (MMF). Many surgeons agree that the gold standard in MMF is the use of arch bars. However, there are various methods of MMF to be used in specific clinical situations.
Common MMF methods are:
- Arch bars (described in this document)
- Ernst ligatures (click here for a detailed description)
- Bone supported devices including intermaxillary fixation (IMF) screws, hanger plates and interarch miniplates (click here to learn more about bone supported devices)
There other methods of wire fixation such as Ivy loops, Gilmer wiring, Stout wiring and Kazanjian buttons to name but a few.
Click here for the AO Teaching video on mandibulomaxillary fixation (MMF).
|Arch bars: indications|
Arch bars are preferred:
- For temporary fragment stabilization in emergency cases before definitive treatment
- As a tension band in combination with rigid internal fixation
- For long-term fixation in conservative treatment
- For fixation of avulsed teeth and alveolar crest fractures
|Arch bars: general considerations|
There are important points to consider before starting.
The occlusion must be checked. In the case of jaw malformations, such as a deep bite deformity, it may be impossible to use arch bars.
There should be calculable tension forces on both bars, so the hooks should be symmetrically positioned in the upper and lower jaw. This symmetry is essential for functional training with elastics.
One pitfall when using arch bars is the risk of contamination of bloodborne infection from patients. Passing the wires to secure the arch bar can result in a puncture or tear in the surgeon’s glove and the possibility of disease transmission to the surgeon.
|Arch bars: preparation|
Before inserting the arch bars, check the occlusion. There should be full interdigitation of the teeth with regular contacts.
Determine if the patient has a normal occlusion or a preexisting malocclusion before taking the patient to the operating room.
Adjusting the shape
The prefabricated arch bar must be adjusted in shape and length according to the individual situation. The arch bar should not damage the gingiva.
Firstly, the bar is adapted closely to the dental arch. The bar should be placed between the dental equator and the gingiva.
Trimming the bar
The bar should be trimmed to allow ligation to as many teeth as possible. The bar should not extend past the most distal tooth or protrude into the gingiva as this will be an irritation to the patient.
|Arch bar: bar position|
Symmetric bar position
To achieve calculable tension forces on both bars, the hooks must be positioned symmetrically in the upper and lower jaw. This symmetry is essential for functional training with elastics.
|Arch bars: bar fixation|
To fix the arch bar in place, prepare a ligature in the premolar region of each side. The wire ends should not damage the surrounding soft tissues.
Attaching the bar
Position the arch bar and fix it using the wire twister.
In the premolar and molar regions one end of the wire is above the arch bar and the other end below it.
Cut the wire with the cutter and turn the ends away from the gingiva to prevent damage.
Make sure the wire rosettes do not protrude away from the arch bar as this will be an irritation to the patient.
Photographs show arch bars applied to mandible and maxilla.
|Mandibulomaxillary fixation (MMF)|
|Arch bars: mandibulomaxillary fixation (MMF)|
Mandibulomaxillary fixation (MMF) can be used either intraoperatively to establish the correct occlusion or as part of postoperative management of the patient’s injury. MMF may be accomplished with wires or training elastics depending on the overall treatment plan for this patient.
The wire loop is placed over the maxillary and mandibular lugs of the arch bar and the wire loop is tightened.
MMF completed with wire fixation. At least three wires, a posterior wire loop in each side, and an anterior wire loop will provide stable fixation.
Some surgeons prefer MMF with elastics for intraoperative management of the occlusion. Additionally, postoperative training elastics can be used to manage condylar fractures in a closed manner.