Mandibulomaxillary fixation (MMF) - Ernst ligatures

AO Teaching video on mandibulomaxillary fixation (MMF)

Principles

Indication
The major indication for Ernst ligatures are temporary fixation prior to definitive operative treatment, and intraoperative MMF during surgery for simple fractures.

Contraindication
Comminuted and displaced fractures and unstable, segmented fractures.
Ernst ligatures do not provide adequate stability when dealing with complex fractures.

General considerations

• There are important points to consider before starting:
• The occlusion must be checked.
• In patients with jaw malformations (dysgnathias) it may be impossible to use Ernst ligatures.
• Mobile teeth should not be included in the ligatures.
• The ligatures of the upper and lower jaw must be in opposite, symmetric positions for correct immobilization.
• There is a risk of contamination via wire puncture injuries from infected patients.

Ligature application

General consideration
An Ernst ligature is based on two neighboring teeth in the same segment of one dental arch.

If possible, the premolars are used in the maxilla and mandible.

Passing the wire through the interdental space
Use a 0.4 mm wire of approximately 15 cm length.
Pass one end of the wire through the interdental space between molar no. 6 and premolar no. 5.

Thread it back from the lingual to the buccal side via the interdental space of premolars 4 and 5.

Pass the other end between premolar no.4 and canine no. 3.

Closing the loop
This end also goes through the interdental space of 4 and 5.

One wire end must pass below, the other end must pass above, the horizontal portion of the wire on the buccal side.

Tighten the wire
Then tighten the wire with the twister.

Add ligatures in the same way in the other three sections of the dental arches to form two symmetrical pairs.

It is of major importance to preserve wire ends of at least 4-5 cm length.

Fixation of occlusion

Combining the wires
After assuring correct occlusion, twist the wire ends of each pair of ligatures together with the twisters.

Take care at this point not to break the wires; otherwise the procedure would have to be started again.

Cut the wire ends and bend them towards the teeth to protect the oral mucosa and the surgeons from accidental injuries.

Additional methyl methacrylate (MMA)
Additional stabilization can be obtained by using methyl methacrylate to reinforce the ligature.

Place the methyl methacrylate around the wire. Use monomer for the final molding.

Flexible occlusion

If complete immobilization is not tolerated or if less stability is needed, elastics can be inserted.

To accommodate elastics bend together the wire ends to form little hooks.