What is Mandible Fracture?
Facial fractures aren’t a common reason for visiting the Emergency Department, but when they do occur, they usually involve the nose or the lower jaw (the mandible). Most people with a broken nose don’t need surgery, but fractures of the lower jaw often do, because this bone’s shape and function are complex. The lower jaw is movable and shaped like a ring, so it can break in more than one spot. These fractures can become infected due to oral bacteria, may be complicated by teeth in the fracture line, and in some cases, can interfere with the patient’s ability to breathe.
What Causes Mandible Fracture?
The mandible, or the jawbone, is one of the facial bones most often broken, along with the nose and cheekbones. These fractures frequently occur due to injuries such as car accidents, fights, work accidents, falls, and contact sports. Because of this, it’s crucial to check patients who have jawbone fractures for other related injuries, including those to the neck and the brain.
Risk Factors and Frequency for Mandible Fracture
Car accidents and fights are the main reasons for broken jaws in the United States and all over the world. In cities, fights cause about half of these fractures, while car accidents account for less. Men are about three times more likely to break their jaw than women, and this often happens when they are in their thirties.
Jaw fractures aren’t very common in children under six years old. This is probably because their foreheads stick out more than their chins. When kids do break their jaws, the fractures are often ‘greenstick’ fractures, which means the bone bends and cracks rather than snapping completely.
Signs and Symptoms of Mandible Fracture
People with a broken jaw may experience pain in the jaw, a change in their facial shape, difficulty in swallowing, and other potential signs such as problems with aligning their teeth, limited movement in the jaw joint, muscle spasms in the jaw, or loss of feeling in the lower lip. The cause of the injury is also important. For instance, in car accidents, people often end up with several complex jaw fractures. However, if someone was injured during a physical fight, the fracture is likely to be simpler and perhaps not as severe.
During a physical check-up, doctors will look for signs of injury such as swelling or bruising in the facial area. They will also examine inside the mouth for signs of any injury or abnormalities. An injury-related collection of blood under the tongue may suggest a hidden jaw fracture. They will also look for any misalignment of teeth, muscle spasms in the jaw, or irregularities in facial symmetry.
It’s often difficult for doctors to understand a patient’s usual dental alignment before the injury. But, if dental records are available, they can help guide treatment. Dentists use something called the Angle classification system to describe how the upper and lower teeth align. This system includes:
- Class I occlusion, here the upper and lower back teeth correctly align.
- Class II occlusion, also known as an overbite, where the upper back teeth sit ahead of their lower counterparts.
- Class III occlusion, or an underbite, where the upper back teeth sit behind their lower counterparts.
A simple test, known as the tongue-blade bite test, can help predict if the jaw is fractured. The patient is asked to bite down on a tongue depressor. If the jaw is not broken, the doctor should be able to snap the tongue depressor by twisting it. If the jaw is fractured, the patient will feel pain and will release the bite, therefore the tongue depressor will stay intact. This test is quite reliable; it correctly identifies a fracture 88.5% of the time and accurately rules out a fracture 95% of the time.
Testing for Mandible Fracture
To diagnose a fracture in the lower jaw, or mandible, various types of medical imaging are required. These can include a mandibular series, a panoramic X-ray of the mouth (known as a panorex), and a computed tomography scan (commonly known as a CT scan).
The mandibular series is a set of X-rays from different angles. It includes a front-to-back view, side views, and a specific view known as a Towne view. These images are mainly useful for looking at the joints that connect the jaw to the skull (known as the condyles) and the top part of the jawbone.
The panorex gives a full view of the jaw. It’s particularly useful for assessing the front section and main body of the jawbone.
A CT scan might be necessary if the doctors suspect there might be other fractures in the face. If a patient is unconscious and teeth are missing, a chest X-ray is necessary to check that they haven’t been inhaled into the lungs, which could cause serious problems. Generally, lab tests aren’t needed for a jaw fracture unless the patient might need surgery urgently or in an emergency. In those cases, doctors should order standard screening tests – a complete blood count, a check of the body’s electrolyte balance, a blood typing test, and a test to check the blood’s clotting time, particularly important for patients taking blood-thinning medication like warfarin.
Treatment Options for Mandible Fracture
People with jawbone (mandibular) fractures often have other injuries as well. The first step in treatment is to address any immediate, life-threatening issues such as difficulty breathing, heavy bleeding, spinal injury, or brain injury. If a patient can’t be placed on a breathing tube orally, surgery may be needed to establish an airway. It’s important to avoid inserting the breathing tube through the nose if there’s a chance the patient has fractures in the middle of the face, nose, or front of the skull base. Patients with jawbone fractures should take precautions to protect their neck until a specialist has confirmed it’s safe for normal movement.
If the jawbone fracture has disrupted the lining of the mouth, gums, or tooth sockets, it’s considered an open fracture. These patients should be given antibiotics that can fight mouth-related bacterial infections to reduce the risk of subsequent infection. Suitable antibiotics include ampicillin/sulbactam, amoxicillin/clavulanate, and clindamycin for patients allergic to penicillin. It’s also wise to consider giving a tetanus vaccine in open fractures. Pain can be managed with acetaminophen, NSAIDs (nonsteroidal anti-inflammatory drugs), and/or opioids. Steroids and cold packs can help decrease swelling.
Patients with minor nonsurgical jaw fractures can be managed as outpatients and should eat a soft diet, take painkillers, and follow up urgently with a specialist for an operative repair that can be done in an outpatient setting a few days later. This wait allows some of the swelling to decrease and makes the surgery easier. A special dressing referred to as a Barton dressing can be used to stabilize the jaw and help with pain. These less complicated fractures are often treated with a procedure known as maxillomandibular fixation (MMF), where the upper and lower jaw are wired together to stabilize the fracture as it heals. There are several techniques to yet to achieve MMF, but all involve some form of wire or fastening system. Patients with this treatment need to cooperate and follow a strict diet often resulting in weight loss. As it’s dangerous if the patient vomits whilst the jaws are locked together, they are provided with wire cutters for such an eventuality.
In patients who are likely to disregard the wire-cutters and cut the MMF wires unnecessarily or not likely to follow aftercare instructions, an alternative procedure called open reduction and internal fixation (ORIF) should be considered. ORIF, which involves attaching plates and screws to the jaw, is also opted over MMF if it’s not practical to have the patient’s jaws wired together for a long time, or when the fractures can’t be addressed adequately with MMF.
Patients with fractures on both sides of the jaw present a unique challenge, especially if they have no teeth. Jaw-clasping techniques can’t be used because there are no teeth. Instead, a pair of devices known as Gunning splints or external fixators can be used to spark healing. In some cases, these double fractures can cause the front part of the jaw to retract, potentially impairing the patient’s airway. If the airway becomes compromised, the patient may need to be intubated or undergo surgery immediately. Children with jaw fractures can mostly be treated with a soft diet, and only very rarely require MMF or an operation. If surgery is needed, many surgeons prefer to use resorbable plates and screws instead of titanium to minimize the risk of future growth abnormalities or damage to developing teeth.
Patients with major dislocated fractures may need to be admitted to the hospital. This is typically the case for patients with breathing difficulties, those who can’t tolerate feeding or handling secretions orally, and those unable to manage their pain adequately.
What else can Mandible Fracture be?
When trying to identify the cause of a jaw injury, doctors might consider several possibilities such as a bruised jawbone, a jaw dislocation, or a single tooth injury. If your jawbone is dislocated, your jaw will lean away from the side where the dislocation happened. On the other hand, if there’s a break below the rounded ends of your jawbone, typically your jaw will tilt towards the side of the fracture. This can cause your teeth to touch prematurely on the side where the break occurred while leaving a gap on the other side when you bite.
What to expect with Mandible Fracture
Patients who experience mandible (jawbone) fractures generally have a good outlook, especially if there are no other associated injuries. The complex nature of the surgery (known as ORIF) to repair these fractures means that there is a fairly high chance (~20%) of complications happening during or immediately after the operation. However, in the long run, the outcome is usually positive, with only 7% of patients experiencing lasting issues, such as abscess (pus-filled cavity), improper bone healing, and hardware exposure.
It’s important to note that habits such as smoking and alcohol use, which often contribute to the cause of the fracture in the first place, are linked to a higher chance of complications. But factors like the patient’s age, gender, and type of injury don’t seem to greatly influence the overall results.
Possible Complications When Diagnosed with Mandible Fracture
Regardless of how it’s treated, the most commonly faced problem after a mandibular (jaw) fracture is misalignment of the teeth, also referred to as malocclusion. One type of treatment, called ‘open reduction and internal fixation’ (ORIF), has a slightly higher risk of complications (21%), as compared to ‘closed reduction’ (17%), especially if the surgeon is not experienced in dealing with facial trauma. Numbness in the lower lip and chin, known as hypesthesia, is also extremely common, often reported in about 50% cases. Other complications, while less common, include infection, improper joining or non-union of the broken bone, protruding hardware, limited jaw mobility or deviation when opening the mouth, and facial nerve damage. Complications are most likely when the fracture is located at the angle of the jaw.
Common Complications:
- Teeth Misalignment (Malocclusion)
- Numbness in the Lower Lip and Chin (Hypesthesia)
- Infections
- Improper Bone Healing (Bony Malunion/Nonunion)
- Protruding Hardware (Hardware Extrusion)
- Limited Jaw Mobility or Deviation (Persistent Trismus)
- Facial Nerve Injuries
Recovery from Mandible Fracture
If a patient has been on MMF treatment for a long time, they might need some physical therapy to regain their full movement. This could involve using a device like a Therabite. Also, if a patient is experiencing slight misalignment of their teeth after surgery, orthodontic treatment can help restore their teeth to the way they were before the illness.
Preventing Mandible Fracture
Luckily, the number of jaw fractures caused by car accidents has dropped thanks to the introduction of seatbelts, airbags, and helmet laws. However, interpersonal violence still remains a major cause of such injuries. Many of these violent incidents are often stimulated by the use of recreational drugs, from alcohol to illegal substances. Thus, educating people about the dangers of drug use may further help decrease the occurrences of jaw fractures in the future.
