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Executive Editor: Marcelo Figari, Gregorio Sánchez Aniceto

General Editor: Daniel Buchbinder

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

Mandible - Special considerations

Edentulous atrophic fractures

1. Diagnosis

General considerations

With increasing mandibular atrophy, the physical size of the mandible decreases. In the severely atrophic mandible, even very minor trauma can cause fracture. Additionally, pathologic fracture during mastication can occur. Very often, due to the fragile nature of the jaw, these fractures occur bilaterally.

Orthopantomogram (OPG), mandible series radiograph and CT scans can be used to diagnose and plan the treatment of the atrophic edentulous mandible fractures.

Clinical examination

The patient shows extraoral ecchymosis associated with an atrophic edentulous mandible fracture.

The patient exhibits pain and mobility of the anterior mandible.

Patient shows intraoral ecchymosis in the floor of the mouth associated with an atrophic edentulous mandible fracture.

Typical example of an atrophic edentulous mandible fracture.

Axial CT scan showing bilateral fractures.
Note that although there appears to be a large bone stock, this patient’s mandible has only approximately 7 mm of vertical height.

Panoramic radiograph of atrophic edentulous mandible fractures.
Note the extreme amount of vertical atrophy.

3-D reconstruction of the same case.

2. Decision/Indication

Observation and soft diet

Observation may be indicated for patients medically unfit for general anesthesia. Atrophic edentulous mandible fracture patients are often elderly with medical problems presenting severe anesthetic risks.

One major complication of observation and soft diet would be nonunion of the mandibular fracture.

Closed reduction

Historically, atrophic edentulous fractures were treated closed by wiring in the patients dentures or fabricating Gunning style splints with postoperative mandibulomaxillary fixation (MMF).
Standard treatment with closed reduction often resulted in prolonged periods of MMF which was difficult for these patients. Additionally, the fractures were often poorly aligned. Postoperative malunions and nonunions were very common.
Photograph shows a patient denture.

Photograph shows a Gunning style splint.

ORIF

Indications for ORIF are any displaced atrophic mandible fracture requiring surgical intervention.

Following the AO principles of anatomic reduction of fractures and immediate function, ORIF of atrophic edentulous mandible fractures with load-bearing osteosynthesis has a distinct advantage for these patients. The technique has evolved to provide the patient with an excellent chance for mandibular union while the ability to masticate is preserved.

Literature has supported the efficacy of this technique.

External fixation

Indications of external fixator might be the temporary stabilization of a fracture while the patient is treated medically, or if soft-tissue maturation around the fracture site is required.

Complications,including malunion and nonunion are significant when external fixators are used as they do not provide absolute stability at the fracture site.

3. Treatment of an edentulous atrophic fracture with a reconstruction plate

In the following, the treatment of an edentulous atrophic fracture with a reconstruction plate is described step-by-step.

4. Approach

Extraoral appraoch

When treating atrophic edentulous mandible fractures, the surgeon will generally find it easier to use an extraoral surgical approach. The fracture fragments can be manipulated under direct visualization and stabilized while the reconstruction plate is being bent and applied to the mandible.

Click here for a listing with all approaches described in detail.

Intraoral approach

An intraoral approach is possible but technically more difficult as the surgeon will need several sets of trained hands just to retract the soft tissues of the cheeks and tongue. Additionally, stabilization and fixation of the fractures is much more difficult via an intraoral approach. One should also be aware that the inferior alveolar nerve is located on the superior surface of the atrophic mandible. Therefore one must be extremely careful making intraoral incisions to expose atrophic fractures, or the nerve can be damaged.

5. Principles

The atrophic edentulous mandible fracture presents with several factors which make treatment very difficult. There is a lack of bone which is generally cortical in nature and has a lower healing potential. There are no teeth present to help reduce the fractures. Often the patients are elderly and medically compromised.

Atrophic mandible fractures require transfacial open reduction, load-bearing internal fixation, and often immediate bone grafting.

6. Choice of implant

General considerations

Load-bearing osteosynthesis is indicated in treatment of the atrophic edentulous mandible fracture. We currently recommend the locking reconstruction plate 2.4. The plate must be of sufficient length to place screws in adequate bone which is generally found in the symphysis and angle regions. The body region of the mandible is a common area of fracture and generally has bone of poorer quality unsuitable for screw placement. When dealing with bilateral fractures, the plate must span from angle to angle, covering the entire lateral surface of the mandible. At least three screws on either side of the fracture are recommended. Often more screws are necessary due to the poor quality of the bone.

The locking reconstruction plate is generally left in place and not removed unless clinical symptoms require hardware removal.

Pitfall: insufficiently stable implant

It may be tempting to use small plates when treating fractures in an atrophic “small” jaw. However, when using small plates, plate fracture and displacement is very common secondary to the muscle pull involved in the atrophic edentulous mandible.

X-ray shows fractured plate and fracture displacement.

Clinical photograph shows same case.

Alternatives to the locking reconstruction plate 2.4

There are fractures involving the edentulous jaws which are not atrophic in nature. When there is sufficient bone to buttress the fracture and provide adequate healing, the surgeon may choose to use a smaller reconstruction plate.

The locking plate system 2.0 (large or extra-large profile) provides all the advantages of a locking reconstruction plate 2.4 but with a smaller profile. Many surgeons have successfully used the locking system 2.0 on edentulous fractures.

 

Plate design

The locking reconstruction plate combines all the advantages of a standard reconstruction plate with the locking principle.

The thread in the plate holes provides rigid anchorage for the 2.4 mm locking screw. This construction acts as an “internal fixator”. 3.0 mm screws are also available.
The conventional 2.4 mm nonlocking cortex screw can also be used with this plate. Wide angulation of the screw is possible which, in certain clinical situations, can be an advantage.

Other advantages of the locking principle are:

  • The plate needs only limited adaptation
  • It exerts no pressure on the bone
  • The risk of screws loosening is reduced.

Click here for further details on the locking plate principles.

7. Plate bending

Templating

It is very common to use large reconstruction plates that span from angle to angle. By using a template the bending process is facilitated.

Bending

Clinical image shows the template and the reconstruction plate bent accordingly.

Click here for a detailed description of plate bending.

Pearl: reduction and temporary fixation

It can be very helpful to reduce and stabilize the fracture with adaptation plates to allow appropriate bending of the template and reconstruction plate. This is particularly applicable in fractures that are widely displaced, mobile, or unstable.

The adaptation plates are placed on the inferior border to allow excellent reconstruction plate adaption to the lateral surface of the mandible.

After the locking reconstruction plate has all planned screw holes used, the adaptation plates are removed.

Pearl: perfect adaptation

Perfect adaptation of the plate is not required as the locking reconstruction plate 2.4 acts as an “internal external fixator”.

8. Fixation

General considerations

The locking reconstruction plate 2.4 is fixed to the native mandible using either 2.4 mm or 3.0 mm screws. At least three screws must be present on either side of the fracture. In the atrophic edentulous mandible fracture, the screws are generally placed in the symphyseal region and the angular region. The bone in the symphysis is very often dense cortical bone which may require tapping of the screw hole.

Applying the plate

Apply the plate and stabilize it either with digital pressure or plate-holding forceps. One of the benefits of using a locking reconstruction plate is that perfect adaptation is not required and small discrepancies can be tolerated.

Placement of first screws

Place one screw on either side of fracture in the planned holes closest to the fracture.
A threaded drill guide must be used to allow for centric placement of the drill hole for use with the locking screw. Copious irrigation must be applied to cool the bone. A depth gauge is used to determine the appropriate screw length.

Click here for a detailed description of screw placement in a reconstruction plate.

Additional screw placement

Once the screws are placed on either side of the fracture (on the first side) the surgeon has the option of completing all screws on that one side or placing one screw on either side of the fracture (on the opposite side) before completing all screws.

Clinical image shows the plate fixed to the mandible.

Harvesting of bone graft

Due to the poor healing quality of the bone, an autogenous bone graft is often used to facilitate bony union. Common sites of bone graft harvest include the iliac crest or tibia.

Clinical images show ...

... the bone graft harvest site in the tibia.

Bone graft application

Autogenous cancellous bone grafts can be added to fracture sites and can be used to augment the native mandible to facilitate healing.

Completed osteosynthesis

X-ray shows the completed osteosynthesis.

9. Aftercare following treatment of an edentulous atrophic fracture with a reconstruction plate

If MMF screws are used intraoperatively in conjunction with the patient’s prostheses, they are usually removed at the conclusion of surgery if proper anatomic fracture reduction and fixation have been achieved.

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 fracture 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.

Follow-up appointments are at the discretion of the surgeon, and depend on the stability of the mandible on the first visit. Weekly appointments are recommended for the first 4 postoperative weeks.

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.

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. A soft toothbrush (dipping in warm water makes it softer) should be used to clean the oral cavity. 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.

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.

Long-term dental rehabilitation
An existing dental prosthesis (denture) must often be remade. Dental implants may be placed in the anterior mandible after symphyseal screws have been removed. Implant reconstruction is undertaken when bony union of the mandible has been achieved.

Appendix

Note

Always rule out contralateral compromise. This technique requires a significant amount of experience.

Shortcuts

Decision support

Additional material

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