Mandibular Fracture
A break in the lower jawbone
Quick Facts
- Type: Facial bone fracture
- Common causes: Assaults, falls, crashes, sports
- Bone involved: Mandible (lower jaw)
- Seek urgent care: Airway trouble, heavy bleeding, can't swallow saliva
Overview
A mandibular fracture is a break in the mandible, the U-shaped lower jawbone that holds the lower teeth and forms the joint that lets you chew and speak. It is one of the most common facial fractures because the jaw projects forward and is exposed to direct blows.
The mandible often breaks in more than one place at the same time, since force applied at one point can crack the bone on the opposite side. The fracture may involve the body of the jaw, the angle, the area near the joint (condyle), or the chin region. Prompt treatment restores the bite, protects the airway, and allows the bone to heal in proper alignment.
Symptoms
Common symptoms include:
- Pain and swelling of the lower jaw that worsens with movement
- A bite that feels off or teeth that no longer meet correctly
- Difficulty or inability to open or close the mouth fully
- Loose, broken, or missing teeth
- Numbness of the lower lip or chin
- Bleeding inside the mouth or a tear in the gum
- A visible step, gap, or deformity along the jaw
- Drooling or trouble swallowing
Trouble breathing or an inability to manage saliva are signs of a possible airway problem and need emergency care.
Causes
Mandibular fractures result from a direct impact to the jaw or face. Common causes include:
- Physical assault, the leading cause in many adults
- Motor vehicle and motorcycle crashes
- Falls, particularly in young children and older adults
- Sports injuries from contact and collision sports
- Industrial accidents
Conditions that weaken bone, such as some cysts, tumors, or severe bone loss, can occasionally make the jaw break with less force.
Diagnosis
A clinician examines the jaw for tenderness, swelling, an abnormal bite, and any step or gap in the bone, and checks the teeth and sensation of the lip and chin. Imaging confirms and locates the break.
- Panoramic dental X-ray (orthopantomogram): A wide view that shows the whole jaw and teeth.
- CT scan: Provides detailed images, especially for the joint region and complex breaks.
Because the jaw often breaks in two places, doctors look carefully for a second fracture.
Treatment
Treatment aims to realign the bone, restore a normal bite, and keep the fracture stable while it heals.
- Airway protection: In severe injuries, securing the airway and controlling bleeding come first.
- Closed reduction: The upper and lower teeth may be wired or banded together for several weeks to hold the jaw in position while it heals.
- Open reduction and internal fixation: The fracture is surgically realigned and fixed with small titanium plates and screws, often allowing earlier jaw movement.
- Pain control and antibiotics: Fractures that open into the mouth are usually treated with antibiotics to prevent infection.
- Soft or liquid diet during healing.
Most jaw fractures heal over about six weeks, with the approach chosen based on the fracture location and how displaced it is.
Complications
Possible complications include:
- A persistent change in the bite (malocclusion)
- Infection of the bone or surrounding tissue
- Lasting numbness if the nerve to the lip and chin is injured
- Stiffness or pain in the jaw joint
- Nonunion or malunion if the bone heals poorly
Prevention
- Wear a mouthguard and helmet with a faceguard for contact and collision sports
- Use seatbelts and keep airbags functional
- Reduce fall risks at home, especially for children and older adults
- Address dental and jaw bone problems that could weaken the bone
When to See a Doctor
Seek medical care for any suspected jaw fracture, since an untreated break can heal in the wrong position. Call emergency services or go to the emergency department immediately if you have:
- Trouble breathing or managing saliva
- Heavy bleeding from the mouth
- Inability to open or close the mouth
- A jaw that is clearly out of shape, or loss of consciousness after the injury
Frequently Asked Questions
What are the main signs of a broken lower jaw?
Typical signs include jaw pain and swelling, a bite that suddenly feels wrong, trouble opening or closing the mouth, loose teeth, and numbness of the lower lip or chin. A visible step or gap along the jaw is also suggestive.
Will my jaw be wired shut?
Sometimes. The upper and lower teeth may be wired or banded together for a few weeks to keep the jaw aligned. Many fractures are now fixed with small plates and screws instead, which can allow the jaw to move sooner during healing.
How long does a broken jaw take to heal?
A mandibular fracture usually heals in about six weeks, though complex breaks can take longer. A soft or liquid diet, good oral hygiene, and follow-up visits support proper healing and bite recovery.
When is a broken jaw a medical emergency?
Seek emergency care immediately if you have trouble breathing, cannot manage your saliva, have heavy bleeding, cannot open or close your mouth, or lost consciousness. These can signal airway compromise or a serious associated injury.
References
- American Association of Oral and Maxillofacial Surgeons. Facial injury and trauma.
- Mayo Clinic. Broken nose and facial fractures.
- MedlinePlus, U.S. National Library of Medicine. Broken or dislocated jaw.
- American Academy of Otolaryngology-Head and Neck Surgery. Facial trauma.