General Principles of Mandible Fracture and Occlusion Treatment & Management

Nonoperative therapy is reserved for minimally displaced favorable fractures. Children often incur an incomplete fracture called a greenstick fracture, which is amenable to conservative therapy. Elderly edentulous patients with minimal displacements can be treated in a similar manner. Dressings help relieve the discomfort of the fracture. Minimal occlusal load is recommended when this mode of therapy is used.

The use of preoperative and perioperative antibiotics in the treatment of mandible fractures has been accepted to reduce the risk of infection, but continuing this antibiotic regimen into the postoperative period did not further improve the infection rate.^[6]

Goals of treatment include anatomic reduction of fracture segments, restoration of premorbid occlusion, and avoidance of complications. Ideally, treatment should be instituted within 7 days. Options to consider include closed or open reduction. Closed reduction maintains the segments by maxillomandibular fixation. Open reduction allows for direct evaluation of the mandibular segments and further for internal or external fixation. Internal fixation can be accomplished by wire (used more historically and in children), titanium plate, and screw fixation.

The Joe-Hall-Morris appliance is an example of an external-pin fixation device. It was used extensively in World War II but has dropped out of favor. Surgeons should be familiar with this technique and have it as part of the surgical armamentarium. It is particularly useful in edentulous patients with a comminuted fracture.

Oblique fractures, especially in the parasymphyseal region, are amenable to lag screws or to the lag technique, in which the proximal segment is drawn towards the distal segment. See the images below.

Although 3 screws are ideal, 2 screws are sufficient to hold the segments in proper reduction. When determining the mode of therapy, consideration must be given to patient age, general health, and reliability, as well as position, stability, and severity of the fracture. One must not overlook the patient's dental and periodontal status, the availability of materials and instrumentation for repair, availability of dental consultation, and the skill and experience of the surgeon.

Perioperative antibiotics are recommended, especially in fractures that go through areas with teeth. These are considered compound fractures, and should be treated as such. Chole and Yee showed a 43% infection rate in the study group without antibiotics, compared to an 8.9% infection rate in the group with antibiotics.

It is important to obtain appropriate diagnostic studies to aid in the localization of fractures. Developing a careful patient treatment plan but being prepared to deviate from the treatment plan as needed is also crucial. A dental evaluation helps to determine the condition of the teeth and allows appropriate fabrication of a dental appliance when needed.

Occlusion is always set first. The occlusion can be maintained by maxillomandibular fixation. Simply, 4 titanium screws can be placed, 1 in each dental quadrant, to permit wire fixation of the upper and lower arches. Stainless steel ligatures with eyelets can be passed interdentally to be used for MMF.

More commonly, Erich arch bars are placed and secured with wire. Stainless steel wires (24-26 gauge) are placed around available molar, premolar, or canine teeth. Anterior teeth should not be used for fixation because of their conical shape, which will cause them to be distracted out of the socket by the wire. Erich arch bars are outfitted with prongs that permit the upper and lower bars to be held together with looped wires. An alternative for attaching the arch bar to the mandible and maxilla other than wires involves light-cured resin composites. One caveat, if a subcondylar fracture is present, immobilization must not exceed 2 weeks. Physiotherapy is instituted to prevent ankylosis of the condyle.

Open reduction necessitates a mucosal or skin incision, shown below, for direct access to the fracture site.

Fixation can then be accomplished with either wires or titanium plates and screws. Open reduction is used when closed reduction is insufficient to achieve anatomic alignment and immobilization. It should also be considered when contraindications to MMF arise.

The condyle can be approached intraorally with a sulcus incision or extraorally through a preauricular incision. The angle can be addressed with a sulcus incision, percutaneous access, and/or a posterior angle incision. Sometimes a combination of access is needed, especially at the angle of the mandible. The body and parasymphyseal area is generally easily approached intraorally with a sulcus incision. With any incision, the surgeon must be cognizant of the course of the marginal mandibular branch of cranial nerve VII. The nerve is more at risk from an external access incision than percutaneous access.

Once the fracture is localized, some important concepts must be kept in mind. Mandibular tensile forces exist superiorly at the dentoalveolar area, and compressive forces exist at the inferior border. To combat the distraction of the segments, place a tension band superiorly along with an inferior plate. The tension band can take the form of an arch bar if teeth are present proximal and distal to the fracture line. If no teeth are found proximally, a small plate may be placed on the external oblique ridge of the mandible to act as a tension band. This concept is exemplified in Champy's technique. Ellis has had great success with noncompression, monocortical plates, fashioned in 2 planes at the external oblique ridge, for nondisplaced angle fractures.^[1] The 2-dimensional bend counteracts forces in both horizontal and vertical planes. See the images below.

For the inferior aspect of the mandible, a compression plate may be used. The medial screws are placed laterally in the screw hole and, as they engage the bone, they slide medially, compressing the mandibular segments together, shown below.

An eccentric compression plate also exists, in which the medial screws bring the inferior portion of the mandible together while the lateral screws draw the superior aspect of the mandible together. Various sizes of plates and screws exist, and newer resorbable plates are currently under investigation. At present, the resorbable plates are being used in non–load-bearing areas, such as the periocular area. The surgeon should be familiar with the many plate sizes as well as the specifications of the different companies' products.

Patients left in MMF should have a nasal trumpet until fully awake. Wire cutters should be taped to the head of the bed, and a tracheotomy tray should be in the room.

Teach patients to use a 60-cc syringe, with a 3-inch trimmed red rubber catheter attached at the end of the syringe, for feeding. The catheter is placed into the sulcus adjacent to the fixated arches so liquids and pureed food can then be easily delivered from the syringe.

Patients must practice strict oral hygiene. Chlorhexidine (Peridex) oral rinses after meals and at bedtime should be prescribed if an intraoral incision is used.

Patients should be seen on a weekly basis. The condition of the arch bars, as well as the tension on the MMF wires, can be checked and tightened as necessary. Children are kept in MMF for 4 weeks, adults for 6 weeks, and elderly patients for 8 weeks. Patients with condylar fractures must be taken out of MMF by 2 weeks, and aggressive physiotherapy must be instituted to prevent ankylosis. Measure the oral opening on each follow-up visit. Normal interincisal distance is 40 mm. If open reduction and internal fixation is performed, many feel that MMF is not needed. By not having the patient in MMF, the ill effects are avoided and the patient's comfort level is increased.

Complications can arise with delayed treatment, inadequate treatment, poor patient constitution, or poor postoperative care. Acute complications are the result of trauma itself. Intermediate complications are caused during MMF, and late ones occur after MMF. The overall complication rate is 3 times as high if the fracture is treated more than 10 days after initial injury.

The greatest potential for respiratory distress occurs with bilateral body, parasymphyseal, or condylar fractures. Muscular action pulls the distal mandibular segment posteriorly, causing the tongue to obstruct the oropharynx. Depending on the degree of neural injury, nerve function may or may not return. In neurapraxia, function returns in 4-6 weeks, whereas in neurotmesis, function may or may not return for approximately 18 months.

An infection increases the chance of delayed union, nonunion, osteomyelitis, and loss of teeth and bone structure. Infection prolongs hospitalization and disability and increases the financial burden. With any open fracture or fractures involving teeth, antibiotics are recommended.

A bony union is expected to result within 4-8 weeks with proper reduction and immobilization. Any time longer than 8 weeks is considered a delayed union and is seen when MMF is released prematurely. Pain and mobility require MMF to be reinstituted and within 8 weeks, a union is eventually formed.

Nonunion occurs when no future potential exists for the bone to ultimately heal. Usually, a pseudoarthrosis is present, in which surgery is required to allow for union. Approximately 2.4% of fractures result in nonunion. Malunion occurs when the bone heals with improper alignment.

Ankylosis is seen with an interincisal opening smaller than 5 mm. The normal oral opening is 40 mm, measured from incisal edge to incisal edge of the anterior teeth. The ankylosis is either fibrous or bony. Aggressive physiotherapy may release a fibrous ankylosis, but surgery is required in the latter case.

With proper treatment planning and surgical technique, mandible fractures have a favorable prognosis. The overall infection rate is 6-6.5% for rigid fixation and around 12.9% for conservative treatment. Ultimately, more than 90% of mandible fractures that are treated achieve a bony union.

Although great success has been seen with the titanium plate and screw systems, the use of resorbable plate and screw systems is currently being investigated. Initial studies were started over 40 years ago. Resorbable plates are used in craniofacial reconstructive surgery. Their greatest benefits include the lack of translocation as the child grows and, with resorption, lack of interference with the growth centers. Indications include fractures of bones that are non-weightbearing in the periocular and midface regions. Due to the great muscular forces, success has been limited in the mandible. Current efforts will determine if the new generation of resorbable plates will be strong enough to maintain reductions in mandibular fractures.

Studies, such as the report from Mizuhashi, have investigated the characteristics of resorbable plates under dynamic loading.^[7] Neither dynamic loading nor degree of load were shown to clearly affect the degree of hydrolytic degradation. The original shape and bending strength were maintained for up to 4 weeks.

Another area that has gained increased reports in the literature is the treatment of fractures of the condyle. This is still an area of controversy.^[8] Treatments have been conservative or surgical. Eulert et al reviewed 1812 patients treated between 1981 and 2001.^[9] Their statistical analysis revealed that surgical osteosynthesis was superior to conservative therapy. Schoen reported functional results of endoscopic-assisted open treatment of bilateral condyle fractures.^[10] The conclusion of the report was that surgical therapy was reliable, and the long-term results revealed good temporomandibular joint (TMJ) function without risk of facial nerve damage and visible scarring.

Intermaxillary fixation screws have been gaining more and more popularity. A 2007 article by Coletii et al concluded that the IMF self-drilling/tapping screws have been shown to be a useful modality to establish MMF.^[11] It was felt to be safe, and time sparing; however, it was not without limitations or potential consequences.

These are exciting areas that the reader should gain more experiences in for the care of the fractures of the mandible.