Mandibular Angle Fractures 

Updated: Mar 19, 2021
Author: Jose E Barrera, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Practice Essentials

Fractures of the mandibular body may be classified by anatomic location, condition, and position of teeth relative to the fracture, favorableness, or type. Angle fractures occur in a triangular region between the anterior border of the masseter and the posterosuperior insertion of the masseter. These fractures are distal to the third molar.

Mandible fractures are also described by the relationship between the direction of the fracture line and the effect of muscle distraction on fracture fragments. Mandible fractures are favorable when muscles tend to draw bony fragments together and unfavorable when bony fragments are displaced by muscle forces. Vertically unfavorable fractures allow distraction of fracture segments in a horizontal direction. These fractures tend to occur in the body or symphysis-parasymphysis area. Horizontally unfavorable fractures allow displacement of segments in the vertical plane.

Angle fractures are often unfavorable because of the actions of the masseter, temporalis, and medial pterygoid muscles, which distract the proximal segment superomedially. Recent evidence evaluating the favorability of angle fractures shows that there is no need to apply different treatment modalities to mandibular fractures regardless of whether the factures are favorable.[1]

The image below depicts the vertical and horizontal forces acting on the mandible, as well as the relationship of muscle pull to fracture angulation.

Forces acting on the mandible and the relationship Forces acting on the mandible and the relationship between muscle pulls and fracture angulation. A: Horizontally unfavorable. B: Horizontally favorable. C: Vertically unfavorable. D: Vertically favorable.

For patient education resources, see the Breaks, Fractures, and Dislocations Center, as well as Broken Jaw.

Signs and symptoms of mandibular angle fractures

Patients with a mandibular angle fracture may exhibit the following:

  • Change in occlusion
  • Posttraumatic premature posterior dental contact (anterior open bite) and retrognathic occlusion
  • Anesthesia, paresthesia, or dysesthesia of the lower lip
  • Change in facial contour or loss of external mandibular form
  • Pain, swelling, redness, and localized calor - Signs of inflammation evident in primary trauma

Workup in mandibular angle fractures

The single most informative radiologic study used in diagnosing mandibular fractures is the panoramic radiograph.

Plain films, including lateral-oblique, occlusal, posteroanterior, and periapical views, may also be helpful, as may computed tomography (CT) scanning.

Management of mandibular angle fractures

Patients with isolated nondisplaced or minimally displaced condylar fractures may be treated with analgesics, soft diet, and close observation. Patients with coronoid process fractures may be similarly treated. Additionally, these patients may require mandibular exercises to prevent trismus.

The techniques for closed reduction and fixation of the dentulous mandible vary. Placement of Ivy loops using 24-gauge wire between two stable teeth, with employment of a smaller-gauge wire to provide maxillomandibular fixation (MMF) between Ivy loops, has been successful. Arch bars with 24- and 26-gauge wires are versatile and frequently are used. In an edentulous mandible, dentures can be wired to the jaw with circummandibular wires. The maxillary denture can be screwed to the palate. (Any screw from the maxillofacial set can be used as a lag screw.) Arch bars can be placed and intermaxillary fixation (IMF) achieved. Gunning splints have also been used in this scenario because they provide fixation and yet permit food intake. In cases of comminuted fractures, a mandibular reconstruction plate may be required to restore anatomic position and function.

Multiple approaches for open reduction and internal fixation (ORIF) exist. The intraoral approach is typically used in fractures that are nondisplaced or only slightly displaced. External incisions are usually necessary with fractures that have a high degree of dislocation or with comminuted fractures.

Problem

The angle of the mandible is the triangular region bounded by the anterior border of the masseter muscle to the posterior and superior attachment of the masseter muscle (usually distal to the third molar). This area may become fractured secondary to vehicular accidents, assaults, falls, sporting accidents, and other miscellaneous causes.

Epidemiology

Frequency

In general, incidences of fractures of the mandibular body, condyle, and angle are relatively similar, while fractures of the ramus and coronoid process are rare. The literature suggests the following mean frequency percentages based on location:

  • Body - 29%

  • Condyle - 26%

  • Angle - 25%

  • Symphysis - 17%

  • Ramus - 4%

  • Coronoid process - 1%

The mandible is involved in 70% of patients with facial fractures. The number of mandible fractures per patient ranges from 1.5-1.8. Approximately 50% of patients with a mandible fracture have more than 1 fracture.

In a series of 136 patients with angle fractures, 40% had fractures exclusive to the angle, while 60% had multiple fractures that included an angle fracture.

The mandible fracture patterns of a suburban trauma center found that violent crimes such as assault and gunshot wounds accounted for most fractures (50%), while motor vehicle accidents were less likely (29%).

Etiology

Vehicular accidents and assaults are the primary causes of mandibular fractures throughout the world.

Data from industrialized nations suggest that mandible fractures have various causes as follows:

  • Vehicular accidents - 43%

  • Assaults - 34%

  • Work-related causes - 7%

  • Falls - 7%

  • Sporting accidents - 4%

  • Miscellaneous causes - 5%

Assault most often causes mandible angle fractures. This was supported by a multicenter European study by Brucoli et al of 1162 patients, which found that angle fractures most frequently resulted from assaults and falls. It was also reported that assaults were more likely to bring about left-sided angle fractures and that a link existed between assaults and voluptuary habits, a younger mean age, and male gender. Moreover, the study indicated that that the presence of a third molar significantly correlates with an isolated angle fracture diagnosis, with the investigators suggesting that this molar allows complete force dispersal, permitting a weak point to be found upon force impact.[2]

Similarly, an evidence-based study involving 3002 patients with mandibular fractures found that the presence of a lower third molar may double the risk of an angle fracture of the mandible. Another study compared fractures with wisdom teeth to those without and found an increased infectious risk (16.6%) in fractures with wisdom teeth compared with 9.5% risk in fractures without wisdom teeth.

Pathophysiology

Optimal mandible function requires maintenance of normal anatomic shape and stiffness (ie, resistance to deformation under load). Normal occlusion can be defined when the mesiolabial cusp of the maxillary first molar approximates the buccal groove of the mandibular first molar. Fractures result secondary to mechanical overload. Torque results in spiral fractures; avulsion, in transverse fractures; bending, in short oblique fractures; and compression, in impaction and comminution.

Degree of fragmentation depends upon energy transfer as a result of overload. Therefore, wedge and multifragmentary fractures are associated with higher energy release.

Presentation

History

Obtain a thorough history specific to preexisting systemic bone disease, neoplasia, arthritis, collagen vascular disorders, and temporomandibular joint (TMJ) dysfunction.

Knowledge of the type and direction of the causative traumatic force helps determine the nature of injury. For example, motor vehicle accidents (MVAs) have a larger associated magnitude of force than assaults. As a result, a patient who has experienced an MVA most often sustains multiple, compound, comminuted mandibular fractures, whereas a patient hit by a fist may sustain a single, simple, nondisplaced fracture.

Knowing the direction of force and the object associated with the fracture also assists the clinician in suspecting and diagnosing additional fractures.

Physical examination

Pertinent physical findings are limited to the injury site.

Change in occlusion may be evident on physical examination. Any change is highly suggestive of mandibular fracture. Ask the patient to compare postinjury and preinjury occlusion.

Posttraumatic premature posterior dental contact (anterior open bite) and retrognathic occlusion may result from a mandibular angle fracture. Unilateral open bite deformity is associated with a unilateral angle fracture.

Anesthesia, paresthesia, or dysesthesia of the lower lip may be evident. Most nondisplaced mandible fractures are not associated with changes in lower lip sensation; however, displaced fractures distal to the mandibular foramen (in the distribution of the inferior alveolar nerve) may exhibit these findings.

Change in facial contour or loss of external mandibular form may indicate mandibular fracture. An angle fracture may cause the lateral aspect of the face to appear flattened. Loss of the mandibular angle on palpation may be because of an unfavorable angle fracture in which the proximal segment rotates superiorly. The anterior face may be displaced forward, causing elongation.

Lacerations, hematoma, and ecchymosis may be associated with mandibular fractures. Their presence should alert the clinician that thorough investigation is necessary to exclude fracture. Do not close facial lacerations before treating underlying fractures except in the case of life-threatening hemorrhage.

Pain, swelling, redness, and localized calor are signs of inflammation evident in primary trauma.

Indications

Use the simplest means possible to reduce and fixate a mandibular fracture. Because open reduction can carry an increased morbidity risk, use closed techniques for the following conditions:

  • Nondisplaced favorable fractures

  • Grossly comminuted fractures

  • Edentulous fractures (using a mandibular prosthesis)

  • Fractures in children with developing dentition

  • Coronoid and condylar fractures

Indications for open reduction include the following:

  • Displaced unfavorable angle, body, or parasymphyseal fractures

  • Multiple facial fractures

  • Bilateral displaced condylar fractures

  • Fractures of an edentulous mandible (with severe displacement of fracture fragments in an effort to reestablish mandible continuity)

Relevant Anatomy

The angle of the mandible is the triangular region bounded by the anterior border of the masseter muscle to the posterior and superior attachment of the masseter muscle (usually distal to the third molar).

Contraindications

Evaluate and monitor the patient's general physical condition prior to treating mandibular fractures.

Any force capable of causing a mandibular fracture may also injure other organ systems. Case reports have documented concurrent posttraumatic thrombotic occlusion of the internal carotid artery and basilar skull fractures.

Bilateral cervical subcutaneous emphysema, pneumothorax, pneumomediastinum, and spleen lacerations have also been associated with mandible fractures after trauma.

Patients should not undergo surgical reduction of mandible fractures until these issues are addressed.

 

Workup

Imaging Studies

See the list below:

  • The single most informative radiologic study used in diagnosing mandibular fractures is the panoramic radiograph.

    • Panorex provides the ability to view the entire mandible in one radiograph.

    • Panorex requires an upright patient, and it lacks fine detail in the TMJ, symphysis, and dental/alveolar process regions.

  • Plain films, including lateral-oblique, occlusal, posteroanterior, and periapical views, may be helpful.

    • The lateral-oblique view helps in diagnosing ramus, angle, or posterior body fractures. The condyle, bicuspid, and symphysis regions often are unclear.

    • Mandibular occlusal views show discrepancies in the medial and lateral position of the body fractures.

    • Caldwell posteroanterior views demonstrate any medial or lateral displacement of ramus, angle, body, or symphysis fractures.

  • CT scanning may also be helpful.

    • CT scanning allows physicians to survey for facial fractures in other areas, including the frontal bone, naso-ethmoid-orbital complex, orbits, and the entire craniofacial horizontal and vertical buttress systems.

    • Reconstruction of the facial skeleton is often helpful to conceptualize the injury.

    • CT scanning is also ideal for condylar fractures, which are difficult to visualize.

 

Treatment

Medical Therapy

Patients with isolated nondisplaced or minimally displaced condylar fractures may be treated with analgesics, soft diet, and close observation. Patients with coronoid process fractures may be similarly treated. Additionally, these patients may require mandibular exercises to prevent trismus. If the fractured coronoid restricts mandible movement, medical therapy is contraindicated. Administer prophylactic antibiotics for compound fractures. Penicillin remains the antibiotic of choice.

The techniques for closed reduction and fixation of the dentulous mandible vary. Placement of Ivy loops using 24-gauge wire between 2 stable teeth, with use of a smaller-gauge wire to provide maxillomandibular fixation (MMF) between Ivy loops, has been successful. Arch bars with 24- and 26-gauge wires are versatile and frequently are used. In an edentulous mandible, dentures can be wired to the jaw with circummandibular wires. The maxillary denture can be screwed to the palate. (Any screw from the maxillofacial set can be used as a lag screw.) Arch bars can be placed and intermaxillary fixation (IMF) achieved. Gunning splints have also been used in this scenario because they provide fixation and yet permit food intake. In cases of comminuted fractures, a mandibular reconstruction plate may be required to restore anatomic position and function.

Surgical Therapy

Multiple approaches for open reduction and internal fixation (ORIF) exist. Consider fracture location, nerve position, and skin-crease lines when choosing the appropriate approach.

Intraoral approach

The intraoral approach is usually used in fractures that are nondisplaced or only slightly displaced. The mandible base may require additional stab incisions to place screws for plate fixation. Intraoral lacerations may be used for access in fixation of mandible fractures. Local anesthesia may be sufficient for simple or nondislocated fractures when 1-plate fixation is required.

The minimally invasive fixation of angle fractures has been described.[3] Using a trocar penetration of the masseter at the focus of interest greatly facilitates plate fixation while obviating the need for an additional facial incision. Cole et al reported that trocar excursion within local subcutaneous tissue routinely yields more than 1-2 cm movements.

However, when engaged within the masseteric sling, trocar mobility typically falls to less than 4 mm. By maneuvering the percutaneous trocar within the subcutaneous tissue, rather than within the mesenteric sling as usual, much greater instrument range-of-motion is achieved. Upon review of their 5-year experience with minimally invasive mandible angle repair, this simple refinement significantly decreased operative challenge, improved instrument range-of-motion, and eased the steep learning curve of minimally invasive repair of mandible angle fractures while optimizing aesthetic outcome.[3]

A retrospective study by Hsueh et al found, in propensity-weighted analysis, no statistically significant difference in the complication rates for intraoral and extraoral approaches in patients who underwent ORIF of mandibular angle fractures. The study, which included 155 patients, also found that the intraoral approach required a significantly shorter operating time.[4]

Extraoral approach

External incisions are usually necessary with fractures that have a high degree of dislocation or with comminuted fractures, since placing longer and stronger plates is difficult via the intraoral approach. Although not impossible, reducing and securing angle and ramus fractures are difficult; therefore, these fractures usually require an extraoral approach. General anesthesia is indicated in the extraoral approach. Give careful attention to the marginal mandibular branch of the facial nerve.

Transverse fracture line without displacement

Semirigid fixation using miniplates and monocortical screws may be used in a transverse fracture line with limited exposure.

Although 1-plate fixation is possible using a 2.0 miniplate, the forces that occur during function are usually too great to be neutralized by a single plate.

This fracture is better managed using two 2.0 miniplates (4-6 holes, 2-3 screws on each side), the first in the area of the oblique line and the second at the inferior border. Fixation is also possible using a single lag screw in the anteroposterior-oblique approach in nonosteoporotic bones. Transverse fracture and its fixation are seen in the image below.

A transverse fracture of the mandible angle withou A transverse fracture of the mandible angle without displacement. A: Transverse fracture of the right mandible with fixation using miniplates at the superior and inferior borders. B: Postoperative radiograph demonstrating fixation.

Transverse fracture line with displacement

With dislocation, the medial pterygoid and masseter muscles cause vertically and horizontally unfavorable vector forces, which make reduction more difficult. For a minimally displaced fracture, achieve reduction by fixing a 2.0 miniplate of suitable length to the proximal fragment on the medial aspect of the anterior border of the ramus using 2-3 screws. Reduce the fracture using the plate as a handle to complete IMF. Bend the free end of the plate to conform to the distal oblique ridge and fix with monocortical screws.

A widely displaced fracture may require stabilization by using a reconstruction plate. Following IMF, widely displaced or comminuted angle fractures can be reduced with clamps and stabilized by splinting with a reconstruction plate (ie, 2.4 low-contact dynamic compression plate [LCDCP] at the inferior border, well anchored with 3 screws on each side of the fracture). A 2.0 miniplate may be placed at the oblique line.

No difference in short-term complication rates can be found when comparing 2.0 mm locking plates with 2.0 mm monocortical plates. In a prospective randomized clinical study at Harborview Medical Center, 90 patients with 122 fractures were stratified to 64 treatment sites that received locking plates and 58 sites that received standard plates.[5] No statistically significant difference was found between the plates used.

Angular fractures with basal triangle

As with displaced fractures, use an angulated 2.4 reconstruction plate with 6-8 holes at the base of the mandible after IMF. The triangle can be fixed to the plate, or lag screws (2.0, 2.4) can be placed. Use a 2.0 miniplate along the oblique line.

Comminuted angular fractures

These often occur in association with other mandibular and maxillary fractures. After temporary IMF, reduction and fixation of fragments within simpler fractures can be accomplished using 1.5 or 2.0 miniplates and lag screws and then bridging with a 2.4 reconstruction plate. Miniplates are often used to reduce large fragments of a comminuted angular fracture. However, miniplates may not be strong enough to bridge severely comminuted fractures. Comminuted angular fracture and its fixation are seen in the image below.

Comminuted angular fracture of the left mandible. Comminuted angular fracture of the left mandible. A: Transverse and longitudinal fractures. B: A lag screw and reconstruction plate used to provide fixation. C: Radiograph depicting fixation.

Comminuted fractures of the ascending mandibular ramus

In the case of concurrent fractures of the ascending ramus, a combined submandibular and preauricular approach may be warranted.

Simplify the fracture using 2.0 miniplates and subsequent bridging and then stabilize it with a 2.4 universal fracture plate or reconstruction plate. Comminuted fracture of the ascending mandibular ramus and its reduction is seen in the image below.

Comminuted fracture of the ascending mandibular ra Comminuted fracture of the ascending mandibular ramus. A: A comminuted fracture of the left ascending ramus. B: Reduction using miniplates of the superior aspect of the ascending ramus. C: Bridging of the comminuted area using a reconstruction plate.

Preoperative Details

Approach mandibular fractures methodically. Patients rarely die solely from mandibular fractures. Diagnose and treat in an efficient manner. As with all trauma patients, strictly adhere to advanced trauma life support (ATLS) protocols. Particular attention to the airway is of critical importance to any patient with craniofacial trauma.

Use prophylactic antibiotics for compound fractures. Penicillin remains the antibiotic of choice. Evaluate nutritional needs.

Intraoperative Details

The goal of treatment is to reestablish occlusion. Function is compromised with malunion. Most mandibular fractures can be treated by closed reduction. Nondisplaced favorable fractures can be managed with closed reduction and IMF alone. Arch bars or Ernst ligatures may be placed and supplemented with an autopolymerizing resin.

The 3 separate techniques for rigid fixation of the mandible that have been developed are (1) the bicortical Luhr system, using vitallium plates, (2) the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) system of stainless steel compression or reconstruction plates with bicortical screws, and (3) the Champy miniplate technique placed along the line of ideal osteosynthesis, using monocortical screws.

A prospective randomized clinical trial comparing 2.0-mm locking plates to 2.0-mm standard plates in the treatment of mandible fractures found no statistically significant difference between the plates. In addition, mandible fractures treated with 2.0-mm locking plates and 2.0-mm standard plates present similar short-term complication rates.

A prospective study by Pattar et al reported good results from the use of a single noncompression miniplate in the ORIF of noncomminuted mandibular angle fractures. The study involved 30 patients, with only relatively minor complications reported regardless of the open-reduction surgical approach used (intraoral, transbuccal, or extraoral).[6]

A retrospective study by Ribeiro-Junior et al also reported that a single miniplate can be successfully used in the ORIF of mandibular angle fractures, particularly long miniplates, frequently without postoperative maxillomandibular fixation. The study involved 50 patients (53 mandibular angle fractures), with morbidity and rate of postoperative complications found to be low. The investigators stated, however, that postoperative maxillomandibular fixation should be considered when little contact exists between bone segments or when the patient demonstrates malocclusion or extensive tooth loss.[7]

With multiple facial fractures, usually treat mandibular fractures first, since the mandible is the foundation on which other facial bones may be repaired to restore form and function. Perform intraoral surgery prior to an extraoral approach. IMF time varies according to type, location, number, and severity of fracture(s). Generally, 6 weeks of IMF are prescribed, although this is only an empiric approximation.

Treat dental injuries concurrently with the fracture. Fractured teeth may become infected or jeopardize bone union and should be removed in consultation with a dentist. Mandibular cuspids help determine occlusion and should be preserved if possible.

Respect the third molar in angle fractures. Removal of the third molar is associated with conversion of a closed fracture to an open fracture, loss of the bony buttress on the tension side, and loss of the possibility for a tension band plate. Extract the third molar only when the apex is open to the fracture line, the root is fractured, or the molar is partially erupted.

Postoperative Details

Administer analgesic medications in the postoperative period. Administer antibiotic therapy covering gram-positive organisms to patients with open fractures. Keep wire cutters at the bedside in case of emesis. Reevaluate nutritional needs.

Follow-up

Maintain IMF for 4-6 weeks. Tighten wires every 2 weeks. After wires are removed, a Panorex radiograph is usually taken to ensure complete fracture union.

Complications

Complications following repair of a mandibular fracture are rare.

The most common complication is infection or osteomyelitis. Malunion and nonunion of the mandible occur because of failure to observe treatment goals as previously outlined. Malunion is described as delayed, incomplete, or faulty union following a fracture. More specifically, delayed union is characterized as no clinical evidence of bone union after 8 weeks.

Several factors contribute to malunion, including infection (the greatest factor), injury severity, inadequate reduction, lack of fracture stability, lack of compliance, alcoholism, and metabolic and nutritional deficiencies.

Nonunion describes improperly healed fractures. Nonunion may be due to delay in treatment, inadequate immobilization, and osteomyelitis of the fracture before and after surgery.

Contributing factors include oral sepsis, teeth in the fracture line, alcohol abuse and chronic disease, prolonged time prior to treatment, poor patient compliance, and displacement of fracture fragments.

In addition, plate fracture has been identified as a complication. Material analysis of AO plates used in mandible fractures revealed titanium plate fracture in 4 out of 110 mandibular reconstructions. The plate fracture was most common in angle-type plates due to constriction on the internal side of the plate.

In the aforementioned multicenter European study project by Brucoli et al, the investigators, assessing patients with unilateral, isolated mandibular angle fractures, found fewer complications associated with the Champy miniplate technique than with other methods employed in maxillofacial surgery departments. The Champy method was also the most commonly used technique for osteosynthesis. Among all of the surgical treatments utilized, in 489 patients, 60 complications occurred (12.3% complication rate), with a correlation found between complications and the absence of third molars.[8]

A literature review by Falci et al indicated that in the fixation of mandibular angle fractures, the placement of one plate on the lateral border in the tension zone carries less risk for infection or the need for plate removal than does fixation with one plate on superior border in the tension zone.[9]

Outcome and Prognosis

Both closed and open reductions of mandibular fractures cause favorable results for bony union. In a study of 922 mandibular body and angle fractures that were repaired using an intraoral approach without IMF, solid bony union was achieved in more than 99% of patients.

Future and Controversies

Controversy exists regarding open versus closed reduction for angle fractures. Traditionally, MMF has been the mainstay of treatment. Plating techniques have revolutionized open reduction as a treatment modality.

Advantages of closed reduction include proven efficacy, low complication rate, and short operating time. This technique may be performed as an office procedure. Disadvantages include long fixation (ie, 3-6 wk), poor nutrition associated with MMF, risk of TMJ ankylosis, and airway problems.

Advantages of ORIF include earlier mobilization and nearly exact bone-fragment reapproximation. Disadvantages include increased treatment cost and need for operating room time.

Another controversy involves disposition of teeth located in the fracture line. In the postantibiotic era, infection of involved teeth is less troublesome. Many teeth may be retained, and they can be useful in reduction and stabilization of fractured segments. Extract teeth if they prevent proper reduction and fracture stability or if they have significant periodontal disease or caries.

The use of miniplates for treatment of mandibular fractures has been controversial.[10] A 2010 study using 0.55 mm-thick miniplates with 1.2 mm monocortical miniscrews showed that 2-point fixation with microplates is appropriate for the internal fixation of simple, isolated mandibular fractures.[11] Its advantages include a high adaptability to the fracture site, occlusal self-adjustment, a minimal mass effect, and a relatively strong holding power of 2-point fixation. In 54 patients, 8 complications where found, which include 7 patients with a double fracture, including mild malocclusion (n = 3), paresthesia (n = 3), asymptomatic delayed union (n = 1), and asymptomatic plate fracture (n = 1).