Authors of section


Ricardo Cienfuegos, Carl-Peter Cornelius, Edward Ellis III, George Kushner

Executive Editors

Marcelo Figari, Gregorio Sánchez Aniceto

General Editor

Daniel Buchbinder

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ORIF, reconstruction plate (basal triangle)

1. Principles


The basal triangle decreases the bone buttressing and the interfragmentary support. This condition demands a degree of stability beyond the level of low degree load sharing.
Symphyseal basal triangular fractures therefore should be considered comminuted fractures requiring a level of high degree load-sharing or load-bearing fixation across the basal triangle. This can be provided one of two ways:

Using one reconstruction plate or ...

Usage of a reconstruction plate.

... using two plates , but the one along the inferior border being a heavy locking plate 2.0 of large or extra-large profile.

Sequence of plate insertion
The superior plate is inserted first. This will prevent inadvertent displacement of the fragments during the subsequent contouring and insertion of the inferior border plate.

Usage of two plates.

Special considerations

2. Selection of approach

These fractures can often be approached and treated through the intraoral approach.

orif one plate and arch bar

However, depending on the difficulty or severity of the fracture, and/or the presence of a laceration suitable, an extraoral approach via the submental route may be indicated.

revision orif

3. Reduction


In symphyseal fractures with basal triangular fragments, an arch bar is preferred for MMF.

The application of the arch bar is unproblematic because only one fracture line runs through the alveolar process and is not affected by the triangular fragmentation.

Click here for a description of MMF application.

Symphyseal fracture with basal triangular fragment.

Reduction of the main fragments

Reduction of the fragments is done manually with the use of elevators, bone hooks, or bone screws inserted as handles. Gross reduction is done prior to the MMF application. Fine tuning for precise anatomical reduction is best done with MMF in place.

The main fragments are reduced as a first step. Ensure that the basal triangle is loose enough be reduced secondarily into the remaining bone gap.

From evaluating the preoperative x-rays it is assumed that the basal triangle is a single and solid bony triangle. It becomes apparent from CT scanning that basal triangles are often divided into an outer and inner table fragment which makes the reduction more difficult. The inner fragment will not usually be accessible using an intraoral approach that only exposes the anterior surface of the mandible.

Reduction of the basal triangle

The basal triangle itself must be repositioned by pushing and dragging with an appropriate instrument. Bone screws inserted into the basal triangle function well as a handle on the fragment and are useful for reduction. Using a transoral approach the lingual cortex of the mandible can be accessed only with addition of a percutaneous hook.

To keep the basal triangle in position it can be compressed between the greater fragments. An alternative is the preliminary fixation with a miniplate that does not interfere with the planned position of the inferior border plate.

How to reposition the basal triangle.

Maintaining the reduction

The maintenance of the reduction of the alveolar portion of the fracture with a conventional clamp becomes more difficult the higher the basal triangle is located. If the basal triangle segment is large and extends superiorly, the reduction clamp can actually “squeeze out” the fragment. If possible, a clamp is applied into tiny predrilled holes in the outer cortex.

How to reposition the basal triangle.

4. Fixation

Plate selection

For load-bearing fixation, a locking reconstruction plate 2.4 should be used. The plate must be long enough so that there can be a minimum of three or preferably four screws on each side of the fracture. The screws adjacent to the fracture should be at least 7 mm away from the fracture line. Most commonly there will be one or two holes without screws located over the fracture. There are advantages to using a locking reconstruction plate system. Click here to learn about them.

Locking reconstruction plate

Plate adaptation

The plate must be contoured to the surface of the mandible flush with the inferior border to avoid injuring the mental and inferior alveolar nerves.

Click here to see a step-by-step description of plate bending using locking reconstruction plate.

Different types of plate adaptation

Screw insertion

Threaded drill guides should always be used to center the screw within the locking reconstruction plate.

For a step-by-step description of screw insertion into locking reconstruction plates follow this link.

Large fragments (like the triangular one in this illustration) can be secured to the plate to hold them in position.

Details on emergency screws/systems can be found here.

Final check

One should then release the MMF and check the occlusion for accuracy before proceeding with closure.

Completed plate fixation

5. Case example


Panoramic and ...

Large basal triangular fracture of mandibular symphysis.

... PA x-rays show a large basal triangular fracture of mandibular symphysis.

Large basal triangular fracture of mandibular symphysis.


Fracture-related preoperative malocclusion.

Fracture-related preoperative malocclusion.

Large basal triangle

Intraoperative photograph shows large basal triangle that has not yet been reduced. Note that the alveolar components have been reduced.

Large basal triangle that has not yet been reduced

Fracture reduction

Intraoperative photograph shows bone clamps used to reduce basal triangle.

Bone clamps used to reduce basal triangle.

Completed osteosynthesis

Intraoperative photographs show completed osteosynthesis.

Final fixation

Note that small miniplates were used to maintain position of basal triangle after it was reduced with clamps.

Final fixation

Postoperative x-rays

Postoperative x-rays show ...

Reduction and fixation

... reduction and fixation.

Reduction and fixation

6. Aftercare following ORIF of mandibular symphysis, body, angle and ramus fractures

If arch bars or MMF screws are used intraoperatively, they are usually removed at the conclusion of surgery if proper fracture reduction and fixation have been achieved. Arch bars may be maintained postoperatively if functional therapy is required or if required as part of the fixation.

Postoperative x-rays are taken within the first days after surgery. In an uneventful course, follow-up x-rays are taken after 4–6 weeks.

The patient is examined approximately 1 week postoperatively and periodically thereafter to assess the stability of the occlusion and to check for infection of the surgical wound. During each visit, the surgeon must evaluate the patients ability to perform adequate oral hygiene and wound care, and provide additional instructions if necessary.

Adequate dental care is required in most patients having suffered a mandibular fracture.

If a malocclusion is detected, the surgeon must ascertain its etiology (with appropriate imaging technique). If the malocclusion is secondary to surgical edema or muscle splinting, training elastics may be beneficial. The lightest elastics as possible are used for guidance, because active motion of the mandible is desirable. Patients should be shown how to place and remove the elastics using a hand mirror.

If the malocclusion is secondary to a bony problem due to inadequate reduction or hardware failure or displacement, elastic training will be of no benefit. The patient must return to the operating room for revision surgery.

Follow-up appointments are at the discretion of the surgeon, and depend on the stability of the occlusion on the first visit. If a malocclusion is noted and treatable with training elastics, weekly appointments are recommended.

Postoperatively, patients will have to follow three basic instructions:

1. Diet
Depending upon the stability of the internal fixation, the diet can vary between liquid and semi-liquid to “as tolerated”, at the discretion of the surgeon. Any elastics are removed during eating.

2. Oral hygiene
Patients having only extraoral approaches are not compromised in their routine oral hygiene measures and should continue with their daily schedule.
Patients with intraoral wounds must be instructed in appropriate oral hygiene procedures. The presence of the arch-bars and any elastics makes this a more difficult procedure than normal. A soft toothbrush (dipping in warm water makes it softer) should be used to clean the surfaces of the teeth and arch-bars. Any elastics are removed for oral hygiene procedures. Chlorhexidine oral rinses should be prescribed and used at least three times each day to help sanitize the mouth. For larger debris, a 1:1 mixture of hydrogen peroxide/chlorhexidine can be used. The bubbling action of the hydrogen peroxide helps remove debris. A Waterpik® is a very useful tool to help remove debris from the wires. If a Waterpik is used, care should be taken not to direct the jet stream directly over intraoral incisions as this may lead to wound dehiscence.

3. Physiotherapy
Physiotherapy can be prescribed at the first visit and opening and excursive exercises begun as soon as possible. Goals should be set, and, typically, 40 mm of maximum interincisal jaw opening should be attained by 4 weeks postoperatively. If the patient cannot fully open his mouth, additional passive physical therapy may be required such as Therabite or tongue-blade training.