Mandibular Fractures

Mandibular Fractures

Brett A. Miles

Jesse E. Smith

Mandibular fractures represent common injuries and are second only to nasal fractures with regard to frequency. The central role of the mandible in mastication, swallowing, and speech makes the surgical management and rehabilitation of mandibular fractures challenging. In addition, complications related to the management of mandibular fractures, while seldom life threatening, often result in significant morbidity for patients with these injuries. Therefore, accurate assessment of the injury and the appropriate application of the priniciples of the management of mandibular fractures is critical for sucessful outcomes.


The mandible articulates with the skull base at the paired temporomandibular joints (TMJs) and is suspended by a complex ligamentous and neuromuscular apparatus. Because of this unique, bilateral articulation with the skull base and the vector of forces contributing to mandibular trauma, a bilateral fracture pattern is commonly observed. The anatomic components of the mandible include the symphysis, parasymphysis, body, angle, ramus, coronoid process, condyle, and alveolus (Fig. 80.1). Anatomic locations with an increased propensity for fracture include the third molar area (especially if the third molar is impacted), the mental foramen region, and the condylar neck. Edentulous, atrophic mandibles are inherently susceptible to fracture in multiple anatomic locations. Additionally, pediatric patients in the deciduous phase of dentition are prone to mandibular fracture, the result of weakening of the mandible due to the presence of unerupted teeth.

Knowledge of dental occlusion is integral to the diagnosis and management of all facial fractures. In the Angle classification of occlusion, the mesiobuccal cusp of the maxillary first molar is used as a reference (Fig. 80.2). Class I occlusion is the most commonly observed pattern. Class II represents retrognathism, and class III represents prognathism. Cognizance of the three classes of occlusion and careful examination of the cuspal interdigitation and wear facets allow accurate restoration of the patient’s preinjury occlusion. Restoration of the patient’s occlusion is the primary goal during the surgical management of mandibular fractures as well as during postoperative rehabilitation. The universal dental numbering system is useful in describing the location of mandibular fractures and reporting associated dental injuries (Fig. 80.3).


Biomechanically, the mandible can be considered a cantilever beam. The beam is suspended at two points, which represent the TMJ attachments. In the mandibular body and angle, occlusal forces produce zones of relative tension along the superior border and compression along the inferior border. Mandibular tension-compression stress distribution is complex, and stress distribution can vary dramatically, depending on the magnitude and point of force application. In the symphyseal area, the situation is more complicated when the mandible is viewed and tested as a three-dimensional model. Compression is produced at the upper border, and tension and torsional forces exist along the lower border. These three-dimensional stress relationships are important to understand, because tension and compression forces dictate the type of fixation applicable to a particular fracture.

Angle and body fractures can be classified as either vertically or horizontally favorable or unfavorable (Fig. 80.4). Fractures are classified as favorable when muscles tend to draw the fragments toward each other, thus, reducing the fracture. Fractures are described as unfavorable when the
fragments tend to be displaced by muscular forces. The majority of mandibular angle fractures are horizontally unfavorable as the masseter, medial pterygoid, and temporalis muscles contribute to the superior and medial displacement of the proximal segment. Vertically unfavorable angle fractures result in medial displacement of the proximal segment by the pterygoid musculature. Vertically unfavorable fractures of the body of the mandible are distracted by the mylohyoid and suprahyoid musculature. A careful assessment of the biomechanical pattern of the fracture is paramount to guide surgical management in order to prevent displacement of fragments due to inadequate fixation techniques.

Figure 80.1 The anatomic components of the mandible include the symphysis, parasymphysis, body, angle, ramus, coronoid process, condyle, and alveolus. 1, Condylar process; 2, Coronoid process; 3, Ramus; 4, Alveolar process; 5. Parasymphysis; 6, Symphysis; 7, Mental foramen; 8, Body; 9, Inferior alveolar nerve; 10, Angle.

Figure 80.2 The Angle classification of occlusion is based on the relation of the mesiobuccal cusp of the maxillary first molar to the buccal groove of the mandibular first molar.



The primary goals when treating mandibular fractures are to establish and maintain the preinjury occlusion and provide appropriate stabilization for bone healing. Surgical management of mandibular fractures varies based on the location of the fracture and severity of the injury. In general, fractures involving the tooth-bearing portion of the mandible with communication to the oral cavity are considered open. Displacement of jaw fragments is uncomfortable, impairs oral hygiene and alimentation, and contaminates exposed bone with bacterial flora from the oral cavity. These features warrant antibiotic prophylaxis starting as soon as possible after the injury as well as intraoperatively; however, the benefit of perioperative antibiotics has been questioned recently (4). Postoperative antibiotics are unnecessary in the majority of cases (5). Topical chlorhexidine rinse may also help minimize the bacterial contamination of the fracture site. Temporary partial reduction via the use of wire fixation may alleviate some mobility at the fracture site in severely displaced fractures, prior to surgical management. Although delay of fracture repair for a short duration does not markedly increase the infection or complication rate, consideration of patient comfort and prolonged environmental exposure warrants timely intervention. It should also be noted that nonmobile, nondisplaced, or incomplete fractures may be treated with careful observation and soft diet, provided the occlusion is stable and there is no mobility at the fracture site.

Figure 80.6 Fractured condyle distracted anteromedially by the lateral pterygoid muscle. This produces a shortened functional height of the ramus as the masseter, medial pterygoid, and temporalis muscles draw the ramus closer to the skull base. The ipsilateral molar teeth act as a fulcrum to produce a slight contralateral open bite.

Figure 80.7 A: Panoramic radiograph of symphyseal fracture and left subcondylar fracture. B: Panoramic radiograph of right body fracture and left parasymphyseal fracture. C: Postoperative panoramic radiograph after open reduction internal fixation of fractures in B. Note the location of the reconstruction plate along the inferior border. Small lag screw was also used in this case for oblique section of the body fracture. D: Axial CT scan of moderately displaced left mandibular body fracture. (Continued)

Figure 80.7 (Continued) E: Coronal CT of laterally displaced right subcondylar fracture.

Closed Reduction

Many favorable fractures in adult patients can be managed by means of closed reduction with arch bars, bone screws, or other means of intermaxillary fixation (IMF). Four to six weeks of IMF is generally considered appropriate for the symphysis, angle, and body. Considerable variation among experts exists regarding the duration of IMF for condylar fractures to optimize condylar mobility while achieving osseous union. Longer periods of IMF (4 to 6 weeks) have been associated with poor range of motion, ankylosis at the TMJ, muscle atrophy, and loss of interincisal opening (6). Nevertheless, many condylar fractures are successfully managed with closed techniques (7). Closed reduction techniques are still commonly used for fractures in children involving the developing dentition and in nonmobile, nondisplaced fractures. The indications for closed reduction vary widely; however, closed techniques should be utilized for cases in which an open reduction is either unnecessary or contraindicated.

Open Reduction

Table 80.2 summarizes treatment options for open reduction with internal fixation (ORIF) for mandibular fractures in adult patients according to fracture location. Internal fixation can be classified as being rigid (reconstruction plates, lag screws), semirigid (miniplates), or nonrigid (interosseous wires). Most rigid and semirigid techniques obviate the use of postoperative IMF, and the occlusion may be guided with postoperative dental elastics when required. This is an especially important consideration among patients with epilepsy, diabetes, alcoholism, psychiatric disorders, or severe disability, who may not tolerate IMF. The classic indication for open reduction and rigid internal fixation is inability to reduce or stabilize the fracture with a closed technique. Other indications include associated midface fractures, associated condylar fractures, IMF is either contraindicated or not possible, to preclude the need for IMF for patient comfort, and to facilitate the patient’s return to work or other activities. The fundamental principles of rigid internal fixation include accurate anatomic reduction, stable internal fixation, early mobilization, and careful tissue handling with preservation of the neurovascular supply. The application of appropriately stable fixation varies depending on the location and severity of the fracture. Internal fixation is the application of sufficient hardware to prevent movement across the fracture site during function; however, this is not necessarily rigid internal fixation in many situations. Thus the concept of load-bearing versus loadsharing fixation merits review. Load-bearing fixation is the application of hardware of sufficient rigidity to resist all functional forces until osseous union is achieved. When treating comminuted mandibular fractures, atrophic mandibular fractures, and those with segmental defects, load-bearing fixation is generally required. In contrast,
load-sharing fixation refers to the application of hardware that allows the functional load to be shared between the hardware and the apposed mandibular cortices after fracture reduction is achieved along the fracture site. The majority of mandibular fractures are adequately treated with load-sharing fixation.


Fracture Location


Symphysis and parasymphysis

Inferior plate and arch bars

Inferior locking or nonlocking reconstruction plate

Inferior locking or nonlocking 2.0-mm mandible plate and superior border monocortical tension band

Two 2.0-mm miniplates (8)

Two lag screws (9)


Inferior plate and arch bars

Inferior locking or nonlocking reconstruction plate

Inferior locking or nonlocking 2.0-mm mandible plate and superior border monocortical tension band

Two 2.0-mm miniplates (8)

Multilag screw technique, if oblique


Single malleable superior border miniplate (11)

Two biplanar or monoplanar miniplates (12)

Inferior locking or nonlocking reconstruction plate with superior tension band

Ramus and condyle

One 2.0-mm miniplate

Two 1.5/2.0-mm miniplates

Comminuted fractures are defined as a fracture pattern in which a single anatomic region is broken into pieces. Comminuted fractures of the mandible have been treated in a variety of fashions, including closed reduction, external pin fixation, internal wire fixation, and ORIF with titanium plating systems (8, 9, 10). Most nonunions in these fractures result from inadequate immobilization of comminuted fragments. Investigations have revealed that periosteal stripping during ORIF does not lead to increased infections as long as fragments are properly stabilized (9, 10). Comminuted mandibular fractures treated with formal ORIF using reconstruction plates exhibit lower complication rates and decreased recovery time when compared to external pin fixation and closed reduction techniques (Fig. 80.8) (9, 10).

In terms of soft tissue approaches, similar complication rates have been observed when comparing transoral versus extraoral reduction of mandible fractures (11). The majority of mandibular fractures may be treated via the transoral approach, which allows direct occlusal visualization during reduction and internal fixation, eliminates facial scarring, and limits the risk of facial nerve injury. In many instances, posterior body, angle, ramus, and condyle fractures can be addressed through combined intraoral and extraoral approaches utilizing trocars to reduce external scars. The main advantage of the extraoral approach is enhanced visualization and access for complex or comminuted fractures. Extensive comminution or fractures in the severely atrophic mandible often require an external approach to appropriately address the fracture.

Figure 80.8 Reconstruction plates (2.4 or 2.7-mm) are used in comminuted, gap, and infected fractures. Small fragments may be reduced and stabilized with smaller (2.0-mm) plates prior to application of the reconstruction plate.

Selection of Hardware

In comminuted, segmental, and infected fractures, when load-bearing fixation is required, large reconstruction plates using 2.4 or 2.7-mm screws are advised (Fig. 80.8). In general, these reconstruction plates require placement of at least three to four screws on either side of the fracture within stable portions of the mandible. Locking reconstruction plates retain their yield load, yield displacement, and stiffness even when imprecise contouring to the bone has occurred, whereas nonlocking reconstruction plates demonstrate significant differences in these factors even with as little as 1 mm of displacement from the bone (12). For this reason, many now prefer the use of locking reconstruction plates in these situations. The benefit of locking technology may be less apparent in load-sharing fixation schemes and nonlocking plates are often sufficient (13).

May 24, 2016 | Posted by in OTOLARYNGOLOGY | Comments Off on Mandibular Fractures
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