This document provides information on lateral oblique radiographs of the mandible and maxilla. It describes the indications for this type of x-ray, which include assessing unerupted teeth, fractures, and large lesions. The positioning of the patient, cassette, and x-ray tube is explained to capture the desired area while minimizing overlapping structures. Modifications for different areas of interest and using an angle board are also outlined. Key criteria for image quality like alignment, contrast and the absence of artifacts are listed.

1. Lateral Oblique of the Mandible and
Maxilla
Amila Abeyweera

2. Introduction
• The lateral oblique radiograph is an extra-oral projection produced
using conventional intra-oral X-ray equipment that reveals a larger
area of the jaws than intra-oral radiography. It can also be produced
using a skull unit.

3. Indications
• Assessment of the presence/absence of teeth and also the position of
un-erupted teeth (especially third molars).
• Detection and assessment of fractures of the mandible.
• Assessment of large pathological lesions (e.g. cysts, tumours,
osteodystrophies).
• When intra-oral radiography is impossible (e.g. trismus, severe
gagging).
• Patients with physical and/or medical conditions in which large
coverage and a rapid imaging technique is needed.

4. General imaging principles
• The head is rotated to ensure that the area under examination is
parallel to the film.
• The film and the median plane are not parallel.
• To avoid superimposition of the opposite side of the jaws, the
combined angulation of the angle between the median plane and the
film plus the angulation of the X-ray beam must not be less than 20
degrees.
• The central ray is perpendicular to the film but oblique to the median
plane.

5. Position of Patient and Cassette
• The patient sits comfortably, with the head supported. The median plane is
vertical.
• A 13 * 18-cm cassette is used with a removable film marker attached to
designate the side of the mandible to be imaged.
• The cassette is positioned against the patient’s cheek overlying the region
of the mandible under investigation, with the lower border parallel to the
inferior border of the mandible but lying at least 2cm below it.
• The positioning achieves a 10-degree angle of separation between the
median sagittal plane and the film.
• The patient is instructed to stabilize the cassette in this position.

6. • The patient’s head is rotated to the side of interest. This positions the
contralateral ascending ramus forwards and increases the area
between the neck and the shoulder to provide space for the X-ray
tube.
• The chin is raised slightly to increase the space between the posterior
aspect of the mandible and the cervical spine.
• The patient is asked to protrude the mandible.

7. Cassette and the X-ray tube positions for a right lateral oblique
radiograph of the body of the mandible and maxilla. Note the rotation
of the head with flattening of the nose against the cassette

8. Direction and centring of the X-ray
beam
• Direct the central ray at a point 2cm below and behind the angle of the
contralateral side of the mandible (see figure).
• Positioning of the tube is dependent upon the area of clinical interest,
o Third molar region for assessment of the position of third molars and possible
pathology in this region
o Premolar region for assessment of the developing dentition
o Lower canine region if there is evidence of mandibular fracture or other pathology.
• The choice of beam angulation varies between 10 degrees upward and 10
degrees downward .
• The central ray is perpendicular to the plane of the film.

9. Schematic to illustrate the direction of the beam
for a lateral oblique radiograph of the body of the
mandible and maxilla

10. Lateral oblique radiograph of the body of the mandible
and maxilla

11. Modifications

12. • The choice of a downward beam angulation is related to the (clinical)
need to avoid superimposition of the hyoid bone on the body of the
mandible.
• To image the maxillary and mandibular canine/incisor region requires
further rotation of the head to a point where the patient’s nose is
flattened against the cassette.
• It is important to ensure that the area of interest is parallel to the
film. This technique reduces the angle of separation between the
median sagittal plane and the film to five degrees.

13. Lateral oblique of the ramus of the mandible
• This projection gives an image of the ramus from the angle of the
mandible to the condyle.

14. Position of patient and cassette
• The patient sits comfortably, with the head supported. The median plane is
vertical.
• A 13 * 18-cm cassette is used with a removable film marker attached to
designate the side of the mandible to be imaged.
• The cassette is positioned against the patient’s cheek overlying the
ascending ramus and the posterior aspect of the condyle of the mandible
under investigation.
• The cassette is positioned so that its lower border is parallel with the
inferior border of the mandible but lies at least 2cm below it.
• The positioning achieves a 10-degree angle of separation between the
median sagittal plane and the film.

15. • The patient is instructed to support the cassette in this position.
• The mandible is extended as far as possible.
• Limit rotation of head (~ 10 degrees) towards the cassette.

16. Direction and centring of the X-ray
beam
• The central ray is directed posteriorly with upward angulation
(cephalad) of 10 degrees towards the centre of the ramus of the
mandible on the side of interest.
• The centring position of the tube is the contralateral side of the
mandible at a point 2cm below the inferior border in the region of the
first/second permanent molar.

17. Cassette and the X-ray tube positions for a right lateral oblique
radiograph of the ramus of the mandible

19. Essential image characteristics
• There should be no removable metallic foreign bodies.
• There should be no motion artefacts.
• There should be no antero-posterior positioning errors.
• There should be no evidence of excessive elongation.
• There should be no evidence of incorrect horizontal angulation.
• There should be minimal superimposition of the hyoid bone on the region
of (clinical) interest.
• There should be good density and adequate contrast between the enamel
and the dentine.
• There should be no pressure marks on the film and no emulsion scratches.

20. • There should be no roller marks (automatic processing only).
• There should be no evidence of film fog.
• There should be no chemical streaks/splashes/contamination.
• There should be no evidence of inadequate fixation/washing.
• The name/date/left or right marker should be legible.

21. Modifications

22. Patient - Supine
• Patient supine on the X-ray couch.
• Use a 10-degree wedge-shaped foam pad to achieve separation of
one side of the mandible from the other.
• Attach a removable film marker to the cassette to designate the side
of the mandible to be imaged.
• With the cassette on the pad, the patient’s head is rotated so the
side of the jaw to be examined is parallel to the film, with the median
sagittal plane parallel to the cassette.
• The head is tilted back on the spine to achieve further extension of
the contralateral mandible away from the region of interest.

23. Direction and centring of the X-ray
beam
• The central ray is angled 30 degrees cranially at an angle of 60
degrees to the cassette and is centred 5cm inferior to the angle of the
mandible remote from the cassette.
30 °
Patient lying supine on the X-ray couch and positioned for a right lateral

24. Using an angle board

25. Position of patient and cassette
• The head is positioned parallel to the angle board and cassette, but
with the sagittal plane inclined to the vertical by the degree of
angulation set by the device.
• Some angle boards incorporate ear rods to ensure accurate
localization of the patient.
• A small forward tilt of the chin avoids superimposition of the cervical
vertebrae on the ramus.

26. Direction and centring of the X-ray
beam
• The tube is positioned below the angle of the mandible, remote from
the film, and the central ray is directed towards the vertex.
• To avoid superimposition of the opposite side of the face, there must
be an effective separation of 20 degrees.
• For example, with a sagittal plane angled at 15 degrees by the angle
board, the central ray must be angled five degrees to the vertex to
achieve the required separation of 20 degrees.

28. Reference
• Clark’s Positioning in Radiography 12th Edition

29. Thank You!!!!!!!!!