The primary causes of mandible fractures, like other facial fractures, are vehicular accidents and assaults. Other significant causes are falls and sports injuries. In the US, the mandible is the third most fractured bone of the face. There is an adult male to female ration of 3:1. It is reduced to a ratio of 3:2 in children.
Incidence of other major injuries is as high as 50% in high-impact mandibular fractures, whereas it is 21% in low-impact fractures. This includes an associated cervical spine injury rate of 0.2-6%. Mortality rate in high-impact fractures is as high as 12%, yet death rarely results directly from maxillofacial injury.
Location of fractures
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.
Most fractures occur in the body (21-29%), condyle (26-36%), and angle (20-25%) of the mandible. The parasympheseal and symphyseal fractures account for 15-17% of mandibular fractures, whereas the ramus (3-4%) and coronoid process (1-2%) have a lower occurrence rate.
Mandibular fractures are isolated (no other facial fractures) in an average of 70% of the patients. Of the patients reported, 15% had another facial bone fracture along with the fractured mandible. A mean of 53% of patients had unilateral fractures, 37% of the patients had 2 fractures, and 9% had 3 fractures.
Mandibular fractures usually occur in 2 or more locations because of the bone's U shape and articulations at the temporomandibular joints (TMJ). 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.
Examination of the patient with a mandibular fracture should include:
- Assessment of the occlusion
- Palpation of the mandibular contours
- Bimanual manipulation of the occlusal segments to detect fracture mobility
- Voluntary mandibular mobility, including maximal opening and excursive movements. Deviations on opening should be recorded.
- Examination of dentition for injuries/avulsion of the teeth. Make sure each tooth is accounted for.
- Soft tissues adjacent to the fracture should be examined for hematoma, lacerations, and the integrity of the attached gingiva.
- Note any neurosensory disturbance in the mental nerve (lower lip and chin) distribution. Fractures that cross the inferior alveolar canal are very likely to result in a change here.
It is important in imaging of mandible fractures to obtain images that allow evaluation in at least two planes. The following types of radiographs are helpful in diagnosis of mandibular fractures:
- Panoramic radiograph--shows the entire mandible including the condyles. This combined with a posteroanterior (PA) x-ray is the most commonly used for mandible fractures. Panoramic x-rays are not available in some hospitals.
- Mandibular series (when panoramic not available)--usually includes
- Posteroanterior (PA) mandibular view
- Reverse Townes View--This is the plain film of choice for excluding condylar and subcondylar fractures.
- Bilateral Oblique Views
- Lateral Views
- Submentovertex View
- Temporomandibular joint views including tomography
- CT scan -- both axial and coronal images should be obtained if possible, if CT scans are deemed necessary.
- Occlusal views are helpful for accurate assessment of symphyseal fractures.
- Obtain periapical radiographs of the teeth on either side of the fracture to assess root fractures
Closed or Open
- Is there a fracture that communicated with the extraoral environment through a tear in the mucosa? Does the fracture run into a tooth socket?
Displaced or Nondisplaced
- The fracture may be displaced as a direct result of the trauma or may be secondary to muscle contraction with movement of the fracture. Most common sites of displaced fractures are the body, symphysis, and angle.
- Nondisplaced fractures are often seen in the condyle, coronoid process, and ramus. The large muscle masses in these areas serve to stabilize the fractures.
Complete or Incomplete
- Greenstick fractures are those in which one side of the bone is broken and the other side is bent. These are most common in children.
- Complete fractures pass entirely through both cortices of the bone. Often the periosteum will remain intact when the fracture is incomplete.
Linear or Comminuted
- Simple fractures are linear and generally produce only two bone fragments.
- Comminuted fractures involve many small fragments that are difficult to reduce and stabilize. The vascularity of the fractured segments may be compromised and can lead to nonunions.
Conservative treatment is indicated when mandibular fracture is nondisplaced and immobile. The occlusion must be normal. The patient may be placed on a soft diet and mandibular function restricted until healing is complete.
Mandibular fractures should be reduced as soon as possible to minimize pain and reduce the risk of infection.
This table of SUGGESTED MANAGEMENT of Mandibular Fxs is from the Selected Readings in Plastic Surgery, 1994,
|Location of Fx||Displacement||Reduction/ Fixation|
Open, plating or wiring
Open, plating or wiring
Open, wiring and plating
Open, plating or lag screw (combo)
Open, plating or lag screw
Open, lag screw or plating
Open, lag screw or plating
Some caveats for closed reduction
- Nondisplaced favorable fractures: Open reduction carries an increased risk of morbidity, thus use the simplest method to reduce and fixate the fracture.
- Grossly comminuted fractures: Generally, these are best treated by closed reduction to minimize stripping of the periosteum of small bone fragments.
- Severely atrophic edentulous mandibles: These have little cancellous bone remaining and minimal osteogenic potential for fracture healing. Closed reduction with the use of circummandibular wires offers a more conservative approach.
- Fractures in children involving the developing dentition: Such fractures are difficult to manage by open reduction because of the possibility of damage to the tooth buds or partially erupted teeth. A special concern in children is trauma to the mandibular condyle. The condyle is the growth center of the mandible, and trauma to this area can retard growth and cause facial asymmetry. Early mobilization (7-10 d of intermaxillary fixation) of the condyle is important. If open reduction is necessary because of severe displacement of the fracture, the use of resorbable fixation or wires along the most inferior border of the mandible may be indicated.
- Coronoid fractures: These fractures usually require no treatment unless impingement on the zygomatic arch is present.
Some caveats for open reduction
Condylar fractures: Although strong evidence supporting open reduction of condylar fractures is lacking, a specific group of individuals benefit from surgical intervention. Careful evaluation of each case on an individual basis is crucial.
- Absolute indications
- Displacement of the condyle into the middle cranial fossa
- Inability to obtain adequate occlusion by closed techniques
- Lateral extracapsular dislocation of the condyle
- Relative indications
- Bilateral condylar fractures in an edentulous patient when splints are unavailable or impossible because of severe ridge atrophy
- Unilateral or bilateral condylar fractures when splinting is not recommended because of concomitant medical conditions or when physiotherapy is not possible
- Bilateral fractures associated with comminuted midfacial fractures
The primary concern in patients with mandibular fractures who have been treated with maxillomandibular fixation is the airway. If the cause of the injury was an accident, a nasogastric suction tube is inserted at surgery and left in place for 6 hours to prevent aspiration. It is recommended that the patient not be extubated until fully awake.
It is important for the patient to maintain adequate nutrition. Feedings should progress from a clear-liquid diet to a high-protein, full-liquid diet, to a blended fractured-jaw diet.
- Delayed healing and nonunion--most common cause is infection, second most common cause is noncompliance, and then there is inadequate reduction, metabolic &/or nutritional deficiencies.
- Nerve paresthesia--(Inferior Alveolar nerve) occur in 2%
- Malocclusion and malunion
- TMJ problems
Facial Trauma, Mandibular Fractures by Adel R Tawfilis, DDS and Patrick Byrne, MD-- eMedicine Article, March 10, 2006
Fractures, Mandible by Thomas Widell, MD -eMedicine Article, April 24, 2005
Craniofacial Trauma; Supplement to Plastic & Reconstr Surgery, Vol 120, No 7, Suppl 2, Dec 2007; Larry H Hollier, Jr MD and James F Thornton MD
Facial and Mandibular Fractures, Approaches To Differential Diagnosis In Musculoskeletal Imaging by Michael L. Richardson, M.D.; University of Washing School of Medicine
Mandible Fractures by Karen Stierman, MD and Byron J Bailey, MD --UTMB Grand Rounds, June 14, 2000 (PDF File with nice slides)
CLASSIFICATIONS OF MANDIBULAR FRACTURES-REVIEW; Journal of IMAB - Annual Proceeding (Scientific Papers) 2006, book 2; Hristina Mihailova, Department of Maxillo-facial radiology and oral diagnostic, Faculty of Stomatology, Medical University-Sofia, Bulgaria (PDF file)