Imaging of mandibular fractures: a pictorial review

Abstract

Mandibular fractures are among the most common maxillofacial fractures observed in emergency rooms and are mainly caused by road accidents. The clinical features of mandibular fractures include malocclusion and loss of mandibular function. Panoramic radiography is usually limited to isolated lesions, whereas computed tomography is the tool of choice for all other facial traumatic events. No reference standard classification system for the different types of mandibular fractures is defined. Therapeutic options include a conservative approach or surgical treatment based on the anatomic area and the severity of fracture. The main purpose of this pictorial review is to illustrate a practical description of the pathophysiology of mandibular fractures and describe both the imaging techniques to recognise them and the therapeutic indications.

Keywords: Condyle; Fracture; Mandible; Panoramic radiography; Trauma.

Fig. 1

Anatomic areas of mandibular fractures

Fig. 2

Symphysis fracture. Cropped panoramic radiograph. The fracture rhyme (arrowheads) runs from the base of the mandibular symphysis to the alveolar process of the lower left first premolar. The root apex of the canine is fractured (arrow)

Fig. 3

Symphysis fracture with lambda course. Cropped panoramic radiograph. Two rhymes of fracture (arrows) converge in the area between the lower left lateral incisor and the canine

Fig. 4

Horizontal branch fractures. a Unfavourable fracture. Picture showing a fracture with a downward and posterior direction. The bone fragments are misaligned by the action of the masseter muscle (black arrow) that pulls the distal bone fragment upwards, and the mylohyoid (asterisk), geniohyoid (white arrow), and anterior belly of digastric (black arrowhead) muscles that pull the mesial bone fragment downwards. b Favourable fracture. Picture showing a fracture with a downward and anterior direction. The bone fragments impact each other with no displacement. c, d Cropped panoramic radiographs in toothless patients with unfavourable (arrow) and favourable (arrowhead) horizontal branch fractures

Fig. 5

Angle fracture. a Picture showing a vertical fracture that runs distally to the third molar (arrowheads). It is a displaced fracture since the masseter muscle (asterisk) pulls the distal bone fragment upwards and medially. b Cropped panoramic radiograph. Mandibular angle fracture involving an impacted third molar (arrow)

Fig. 6

Ramus fractures. a Picture showing that the mandibular ramus fracture can be vertical (arrowhead) or horizontal (arrow), depending on the direction of the fracture rhyme. b Cropped panoramic radiograph. Combined fracture of the left mandibular ramus. The fracture rhyme originates from the external face of the ramus and has both a vertical (arrowhead) and a horizontal (arrow) course

Fig. 7

Vertical ramus fracture. Cropped panoramic radiograph showing a fracture of the left mandibular ramus, which runs from the external face of the ramus to the sigmoid notch (arrow)

Fig. 8

Coronoid process fracture. a A straight line passing through the deepest central point of the sigmoid notch (arrow) is traced from the lower posterior portion of the condylar head (single arrowhead) to the anterior edge of the mandibular ramus (double arrowhead). The bone portion included between the arrow and double arrowhead represents the coronoid process. b Coronoid process apex fracture. The fracture is fully included in the temporal muscle. Bone fragment displacement is minimal. c Coronoid process fracture medial to the deepest central point of the sigmoid notch. The fracture approximately originates in the correspondence of the temporal muscle attachment points. d Coronoid process fracture corresponding to the deepest central point of the sigmoid notch. The fracture originates below the temporal muscular attachment

Fig. 9

Coronoid process apex fracture. a Cropped panoramic radiograph. The fracture rhyme (arrow) runs from the internal to external faces of the coronoid process. b Computed tomography 5-mm oblique reconstruction of the same patient. Note that the fracture rhyme (arrow) ends higher than the sigmoid notch

Fig. 10

Coronoid process fracture medial to the deepest central point of the sigmoid notch. a Cropped panoramic radiograph in a toothless patient. The fracture rhyme (arrow) originates from the internal face of the coronoid process and ends medially to the deepest central point of the sigmoid notch. b Computed tomography 5-mm oblique reconstruction of a different patient who underwent the examination following a road accident. The displacement of the bone fragment is remarkable (arrow)

Fig. 11

Coronoid process fracture lateral to the deepest central point of the sigmoid notch. Cropped panoramic radiograph showing a displaced fracture of the right coronoid process (arrow). The temporal muscle elevates the bone fragment upwards

Fig. 12

Picture depicting mandibular condyle fractures in according with the AO Foundation’s classification. A fracture is considered “high-neck” and “low-neck” when it is above and below Line 4, respectively. A full description is provided in the main text

Fig. 13

Picture depicting mandibular condyle fractures in according to the classification given by MacLennan et al. a No deviation. The bone fragments are in line and close to each other. The articular relation between the condylar head and glenoid fossa is maintained. b Deviation. A contact between the two bone fragments is observed but they are not in line. The articular relation between the condylar head and glenoid fossa is maintained. c Displacement. The condylar head remains within the glenoid fossa but there is no contact between the two bone fragments. d Dislocation. The articular relation between the condylar head and glenoid fossa is lost

Fig. 14

Condylar process fracture. No deviation. a Cropped panoramic radiograph. b 3D computed tomography reformation of the same patient. The bone fragments are in line and close to each other (arrows)

Fig. 15

Condylar process fracture. Deviation. Computed tomography coronal section shows that the condylar head remains within the glenoid fossa and the contact between the bone fragments is not completely lost (arrow)

Fig. 16

Condylar process fracture. Displacement. a Cropped panoramic radiograph. b Computed tomography coronal section of the same patient. The bone fragments are not in line (arrows), but the condylar head remains within the glenoid fossa

Fig. 17

Condylar process fracture. Dislocation. Cropped panoramic radiograph. The bone fragments are not in line and the condylar head moves out from the glenoid fossa (arrows)

Fig. 18

Condylar process fracture. Dislocation. a Computed tomography coronal section. b, c Magnetic resonance T2w coronal image and T1w sagittal image of the same patient. The condylar head is in the horizontal position and completely outside the glenoid fossa (arrows)

Fig. 19

Fracture of the glenoid fossa of the temporal bone. a Cropped panoramic radiograph shows a reduction of the articular space. The condylar head seems to be higher than its usual location (arrow). b, c Computed tomography coronal and sagittal sections. A slight upward movement of the mandibular condyle associated with a glenoid fossa fracture of the temporal bone is observed (arrows)

Fig. 20

Condylar head fracture. a Cropped panoramic radiograph. b Computed tomography axial section. Oblique fracture of the condylar head with involvement of the articular surface (intracapsular fracture) (arrows)

Fig. 21

Bilateral condylar process fracture with extracapsular lateral dislocation. a Panoramic radiograph shows a fracture of both condylar necks (arrows), following a violent trauma on the chin symphysis. b The lateral displacement of the condylar heads was subjected to “open” reduction and rigid internal fixations with osteosynthesis plates (arrows)

Fig. 22

Bilateral angle fracture. a Panoramic radiograph shows fractures of both mandibular angles (arrows) involving the lower third molars. b After removing the lower left third molar, rigid internal fixations with osteosynthesis plates merge the bone segments