Examination

External examination of the face will reveal areas of swelling, bruising and wounds overlying a fracture. A tilted or asymmetrical position of the mandible may indicate a displaced mandibular fracture or unilaterally dislocated TMJ. A bilaterally dislocated TMJ is indicated by an open mouth that the patient is unable to close.

The image shows gum laceration and displacement indicating an open mandibular fracture (Click on the image to enlarge).

It is important to look inside the mouth, if trismus allows, for swelling, bruising and fractured or missing teeth. Haematoma in the sublingual space is indicative of a mandibular fracture. Lacerations to the gum mucosa almost always indicate an open fracture of the mandible.

Finally, look for evidence of bleeding from the ear. Falls onto the point of the chin, often accompanied by a wound to the underside of the chin, may fracture the tympanic plate of the temporal bone [6] and tear the auditory canal membrane, producing bleeding from the ear. Mandibular condyle fractures are also associated with this mechanism of injury.

Other causes of bleeding from the ear must also be considered:

• Basal skull fracture
• Tears of the canal mucosa from foreign body insertion
• Rupture of the tympanic membrane

Learning Bite

Bleeding from the ear, in addition to other causes, may arise from a fall onto the chin and an associated tympanic plate fracture.

The external mandible, the TMJ and the internal surface of the mandible must be palpated with a gloved finger. Gentle palpation of the TMJ can also be achieved by insertion of the gloved little finger in the external auditory meatus.

Sensation should be checked over the lower lip and chin. This area is supplied by the mental nerve, a branch of the inferior alveolar nerve, which is vulnerable to injury as it exits through the mental foramen. Always assess and clearly document IAN status when examining patients with mandibular fractures [18].

Movements of the mandible at the TMJs are commonly reduced in both fracture and dislocation and may be due to:

• Muscle spasm
• Effusion in the TMJ
• Depression of the zygomatic arch obstructing movement of the coronoid process of the mandible

If the patient is able to close the mouth they should be asked to bite down and to indicate whether the teeth ‘fit correctly’. Malocclusion most commonly indicates either a fracture or unilateral dislocation of the mandible.