Mandible Fracture

Updated: Oct 22, 2016
  • Author: Thomas Widell, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
  • Print
Overview

Background

Maxillofacial fractures are the result of blunt or penetrating trauma. Most are blunt injuries caused by vehicular crashes, altercations, sporting-related trauma, occupational injuries, and falls. Penetrating injuries are mainly the result of gunshot wounds, stabbings, and explosions. [1, 2, 3, 4, 5, 6, 7, 8]

Shape and velocity of the striking object are the main factors that determine the type of maxillofacial injury (ie, soft tissue alone vs bony).

Mandibular fractures usually occur in 2 or more locations because of the bone's U shape and articulations at the temporomandibular joints. Fractures also may occur at a site apart from the site of direct trauma. A large percentage of mandibular fractures are open, as they often fracture between teeth and communicate with the oral cavity.

Fractures of the mandible are often associated with other craniofacial, cervical, and systemic injuries and may destabilize the airway. Therefore, the approach to emergency treatment must be to secure the airway and provide hemostasis prior to fracture management. [9, 10, 11]

Indications of the presence of mandibular fracture include the following [9] :

  • Pain
  • Bite abnormality
  • Numbness
  • Bleeding
  • Swelling
  • Dyspnea
  • Crepitus
  • Restricted function

See the image below.

Anatomy of the mandible. Anatomy of the mandible.
Next:

Pathophysiology

The amount of force needed to fracture different bones of the face has been studied, and these bones have been divided into those that require high impact to fracture (greater than 50 times the force of gravity [g]) and those that require only low impact to fracture (less than 50 g). [12]

High impact is as follows:

  • Supraorbital rim - 200 g
  • Symphysis of the mandible - 100 g
  • Frontal-glabella - 100 g
  • Angle of mandible - 70 g

Low impact is as follows:

  • Zygoma - 50 g
  • Nasal bone - 30 g

Different mechanisms are associated with varying locations. Fractures from automobile crashes most frequently occur at the condyle and symphysis, those from motorcycle accidents at the symphysis and alveolus, and those from altercations mostly at the condyles, angles, and body.

Fractures of the mandible can be stable (favorable) or unstable (unfavorable) depending on how the fracture line courses in the bone. Muscles attached to the mandible continue to exert their forces. Elevators of the mandible are the masseter, temporalis, and medial pterygoid, while depressors and retractors are the mylohyoid, geniohyoid, and anterior belly of the digastric. Lateral pterygoid is the protrusor of the mandible.

Direction of fracture determines whether it is stable or unstable. Fractures running from posterior downward to anterior (favorable) generally are stable, because muscles pull the fragments together and can be treated with soft diet and arch wires if fragments are not aligned.

For more information, see Medscape's Trauma Resource Center.

Previous
Next:

Epidemiology

The mandible is the third most fractured bone of the face. Of these fractures, approximately 20-35% are at the condyle and ramus, 20-30% at the angle, 15-30% at the body, 8-20% at the symphysis, and 1-5% at the alveolar ridge. [1]

One study placed the incidence of severe maxillofacial injury (fractures, lacerations) at 0.04-0.09% for motor vehicle crashes. Incidence of fractures due to motor vehicle injuries is higher in rural areas; altercation-related injuries are more frequent in inner cities. Incidence of other major injuries is as high as 50% in high-impact mandibular fractures, whereas it is 21% in low-impact fractures. Mortality rate in high-impact fractures is as high as 12%, yet death rarely results directly from maxillofacial injury. Patients who are involved in motor vehicle crashes are more likely to have additional injuries than patients with violence-related injuries. The incidence of associated cervical spine injuries ranges from 0.2-6%.

In one study, of 1,565 patients with 2,195 mandibular fractures, 33 (2.1%) presented with bilateral mandibular angle fractures. The average age of the cohort was 25.2 ± 1.8 years (range, 18 to 48 yr). The mechanisms of injury were assaults (30 of 33, 90.9%), motor vehicle collisions (2 of 33, 6%), and a fall (1 of 33, 3%). Twenty-seven patients (81.8%) had at least 1 mandibular third molar at the time of injury. Three patients (9.1%) had minor postoperative wound problems, with 1 incident (3.0%) of malocclusion. [13]

In a study of 363 patients with mandibular fractures, systemic illness was noted in 10.5% of the cohort, and more than 80% of the subjects had sustained their injury because of assault. The mandible angle was the most common site of fracture (56%). Most (64%) of the patients had sustained multiple fractures, and when multiple sites were involved, the angle and body were more commonly involved. [14]

Age and sex

Adult male-to-female ratio is 3:1. Suspect domestic violence or sexual assault in women as this may coexist in 30% of cases. Male predominance is reduced to 3:2 in children. In nonmotor vehicle injury, the possibility of child abuse should be a concern.

In a retrospective review of pediatric patients (age, ≤18 yr) with mandibular fractures treated at the Mayo Clinic, 122 patients were identified with 216 mandibular fractures. The prevalent mechanisms of injury were motor vehicle accidents (N = 52 [43%]), sports injuries (N = 24 [20%]), and assault (N = 13 [11%]). The most common fracture sites were subcondylar, parasymphyseal, angle, and body. [15]

According to another study of mandible fractures in pediatric patients (≤18 yr), younger patients (≤12 yr) and female patients tended to have condyle fractures caused more commonly by falls, while older patients (13-18 yr) and male patients tended to have angle fractures caused by assault. [16]

In a study of facial fractures in the elderly (>64 yr) compared with those in younger patients, elderly patients tended to experience less severe facial fractures and were more likely to have experienced injury from a fall. Compared to younger patients, the older patients sustained a higher incidence of maxillary, nasal, and orbital floor fractures and a lower incidence of mandible fractures. [17]

 

Previous
Next:

Patient Education

Instruct patient on how to release Erich arch wire if he or she has problems with airway.

Place patient on a diet of soft or pureed food.

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

Patients should be informed of the high risk of posttraumatic stress disorder and be referred to a psychiatrist should symptoms occur. [18]

Previous