DENTAL
RADIOGRAPHY
Azka Asghar
Lecturer MIT
Introduction
• Dental radiography is the most common
radiographic examination, comprising 33% of
all medical examinations.
Radiographs are used in dentistry for many reasons,
summarized below:
• To detect pathology associated with teeth and their
supporting structures, such as caries, periodontal disease and
periapical pathology.
• To detect anomalies/injuries associated with the teeth, their
supporting structures, the maxilla and the mandible.
• To determine the presence/absence of teeth and to localize
unerupted teeth.
• To measure the length of the roots of teeth before
endodontic therapy.
• To detect the presence/absence of radio-opaque
salivary calculi and foreign bodies.
• To detect anomalies/injuries/pathology of adjacent
facial structures.
• To evaluate skeletal and/or soft tissues before
orthodontic treatment.
• To monitor the progression of orthodontic treatment
and dental disease.
• To enable a preoperative assessment of skeletal and
soft tissue patterns before orthognathic surgery.
• To assess bony healing and effectiveness of surgical
treatment of the patient postoperatively.
Dental radiography involves techniques in which the film
is placed either inside the mouth (intra-oral radiography)
or out side the mouth (extra-oral radiography).
Intra-oral radiography
• The most frequently requested intra-oral projections are bitewing
radiography, periapical radiography and occlusal radiography.
• Bitewing radiography is a lateral view of the posterior regions of the
jaws. The view demonstrates the crowns of the teeth and the alveolar
crestal bone of the premolar and molar regions of both the maxilla and
mandible.
• Periapical radiography is a lateral projection displaying both the crown
and the root of the tooth and the surrounding bone. Occlusal
radiography comprises a number of views in which the film is positioned
in the occlusal plane.
Extra-oral radiography
• The most frequently requested extra-oral projections are dental
panoramic radiography, oblique lateral radiography and cephalometry.
• Dental panoramic radiography is a projection that produces an image of
both jaws and their respective dentitions on a single extra-oral film.
• Oblique lateral radiography demonstrates large areas of the maxilla and
mandible, with the region imaged dependent on the technique chosen.
• Cephalometry employs techniques to produce standardized and
reproducible films of the facial bones for use in orthodontic,
orthognathic and implant treatment.
Terminology
• Mesial represents that surface of the tooth adjacent to the
median plane following the curvature of the dental arch.
• Distal represents that surface of the tooth furthest away
from the median plane following the curvature of the dental
arch.
• Lingual or palatal refers to the inner aspect of the teeth or
dental arches adjacent to the tongue or palate, respectively.
• Buccal or labial refers to the outer aspect of the teeth
or den tal arches adjacent to the cheeks or lips,
respectively.
• Occlusal refers to the biting surface of both premolar
and molar teeth.
• Incisal refers to the horizontal flat surface of the
incisor teeth.
Recommended kilovoltage operating
range
• The use of a higher kilovoltage (60–70kVp) in dental
radiography represents a prudent compromise
between minimizing surface dose to the patient and
obtaining sufficient contrast to allow radiological
diagnosis of dental and bony tissue.
Rectangular collimation
• The use of rectangular collimation for intra-oral dental radio
graphy has been shown to reduce patient dose by up to 50%
compared with a 6-cm round beam. Rectangular collimation
is available as:
• manufactured component of the X-ray tube head;
• ‘removable’ universal fitting to open-ended cylinder type of
equipment;
• additional component of some types of film holders.
Film-holding devices
• The use of a film holder, incorporating an extra-oral aiming
arm to ensure accurate alignment of the X-ray tube relative to
the intra-oral film, is mandatory when using rectangular
collimation in order to prevent ‘cone-cut’.
• Image quality is improved when employing rectangular colli
mation and longer focus-to-film distance (FFD) by reducing
the amount of scattered radiation and reducing the
penumbra effect, respectively.
Image receptors
• The following types of image receptors are used in
dental radiography:
• Intra-oral radiography:– direct or non-screen film;–
digital receptors.
• Extra-oral radiography:– film-screen (usually rareearth);– digital receptors: storage phosphor and solidstate.
Direct or non-screen film
• Dental radiography uses direct film. For the
dental clinician, direct (or packet) film has the
advantage of producing a high resolution image
that provides the fine detail needed to assess
pathological change.
The contents of the film packet consist of the
following:
• Outer plastic wrapper to prevent moisture
contamination. The reverse side of the outer wrapper
has a two-toned appearance to differentiate it as the
non-imaging side of the film packet.
• Black paper that is wrapped around the film to
protect it from light ingress and damage during
handling.
• Lead foil with an embossed pattern is positioned at
the back of the film to reduce film fogging from
scattered radiation. If the packet is inadvertently
positioned back-to-front, the foil pattern is evident on
the processed film, identifying the cause of
underexposure.
• A single sheet of film comprising a plastic base with
emulsion adherent to both surfaces.
Key Techniques & Positioning
Paralleling Technique
•X-ray Beam: Directed perpendicular to both the tooth and
the sensor.
•Advantage: Produces accurate, undistorted images.
•Tip: Use a beam alignment device to maintain correct
angles.
•Film/Sensor: Placed parallel to the long axis of the tooth.
Bisecting Angle Technique
•Film/Sensor: Placed close to the tooth, not parallel.
•X-ray Beam: Directed perpendicular to an imaginary line
that bisects the angle between the tooth and the sensor.
•Used When: Patient anatomy makes paralleling difficult.
Bitewing Radiographs
•Purpose: Detect interproximal caries and bone
levels.
•Positioning: Sensor is placed horizontally with the
patient biting down; beam is directed through the
contacts.
Occlusal Radiographs
•Purpose: Capture larger areas like the floor of the
mouth or palate.
•Sensor: Placed flat inside the mouth; beam directed at
a steep angle.
Pro Tips
•Head Position: Align the patient’s head so the occlusal
plane is parallel to the floor.
•Stabilization: Use cotton rolls or gauze to help hold the
sensor in place.
•Avoiding Errors: Watch for cone cuts, elongation, or
foreshortening by adjusting beam angulation properly.