Introduction

‘This is an OM/OPG/PA view x-ray of the face/mandible.’

Views

1. • Occipitomental (OM) view at 0°: frontal sinuses, orbits, maxillary antra, nasal bones and ethmoid air cells

2. • Occipitomental (OM) view at 30°: additional features – zygoma, mandible, infraorbital foramina, odontoid peg

3. • Orthopantomogram (OPG): mandible, maxilla, teeth, TMJ and inferior alveolar canal

4. • PA mandible: mandibular fractures

Anatomy

Bones

1. • Frontal bones and sinuses

2. • Orbits and orbital floor

3. • Maxilla: medial and lateral walls of maxillary antra

4. • Zygomatic arch

5. • Mandible: symphysis, body, angle, ramus, condyle and coronoid process

6. • Teeth

7. • Temporomandibular joint (TMJ)

Circles: broken circle indicates a possible fracture

1. • Frontal sinuses

2. • Orbits

3. • Maxillary sinuses

4. • Nasal and ethmoid spaces

Lines: broken line indicates a possible fracture

1. • Lines of Dolan (OM30)

2. • McGrigor's lines

3. • Elephant trunks of Rogers (zygomatic arch fractures): formed from lines of Dolan

Pathology

Fractures

1. • Maxillary fractures: alveolar process; lateral and medial walls of maxillary antra.

2. • Zygomatic arch fracture: look at ‘elephant trunks’.

3. • Tripod fractures: zygoma detachment (complex zygomaticomaxillary fracture). Suture lines involved are: 1. zygomaticofrontal suture; 2. orbital floor; 3. infraorbital rim; 4. lateral wall of maxillary sinus.

4. • Inferior orbital margin fracture.

5. • Orbital floor ‘blow-out’ fracture.

6. • ‘black eyebrow’ sign: surgical emphysema in the upper orbital rim area

7. • ‘teardrop sign’: herniation of orbital soft tissues in the maxillary antrum

8. • fluid level in antrum of maxilla

9. • Mandibular fractures.

Tumours

1. • Bone: lytic lesions and cysts

2. • Soft tissues: contour changes

Infections

1. • Sinusitis (OPG and OM): opacity of maxillary and frontal sinuses

2. • Osteomyelitis (OPG and OM): opacity of mandible and maxilla

Dislocations

1. • TMJ (OPG).

Teeth

1. • Fractures and caries.

To complete the examination…

1. • If suspecting a complex fracture or inadequate views, ask for CT face/skull to determine.

2. • Facial trauma is associated with C-spine and head injuries, so consider CT head and C-spine imaging.