When a bone breaks or cracks, the injury is called a fracture. Jaw fractures are the third most common type of facial fractures, after fractures of the nose and cheekbone. They can be caused by many different types of impacts to the lower face, including:
An accidental fall, especially in children who are playing and in adults who faint
Hitting the dashboard during a car accident
A fall from a motorcycle or bicycle
A fall or collision during contact sports
A punch to the jaw
The jaw bone is also called the mandible. It is a long bone that includes your chin and angles up toward your ear on both sides of your face. On each side, the end of the jawbone is rounded like a ball. This "ball," called the condyle, is the part of the jaw joint right in front of your ear. It lets you open and close your mouth. The jaw joint is also called the temporomandibular joint or TMJ.
A fracture can happen anywhere along the jawbone. In more than 50% of cases, the jaw fractures in at least two places — a "direct" fracture where the jaw was hit and an "indirect" fracture somewhere else along the jaw. Most often, this second fracture is near one of the ends of the mandible, close to the jaw joint. The second fracture occurs when the force of impact travels upward along the jaw and snaps the relatively thin part of the jawbone just below the ear.
Fractures of the condyles are the most common type of jaw fracture in children. They usually happen when a child falls and strikes his or her chin against the ground or some other hard surface. In teenagers and young adults, jaw fractures more commonly occur on the side of the face nearer the chin because this area is often struck during fights or attacks.
An impact with a dashboard during a car accident can fracture any part of the jaw, including the condyles. The force of the impact can dislodge teeth, and cause fragments of the broken jaw to pierce the gum or damage nearby blood vessels and nerves.