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D E N TA L R A D I O G R A P H Y
R H C 4 0 6 3 R A D I O G R A P H I C P R O C E D U R E S I I I
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D E N TA L R A D I O G R A P H Y
Terminologies
Indications
Intra-oral radiography
Extra-oral radiography
Cephalometry
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TERMINOLOGIES Occlusal plane
Dental formula
Intra-oral
Extra-oral
Bitewing
Periapical
Panoramic view
OPG
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INDICATIONS Find problems in the mouth such as tooth decay, damage to the bones supporting
the teeth, and dental injuries (such as broken tooth roots). Dental X-rays are often
done to find these problems early, before any symptoms are present.
Find teeth that are not in the right place or do not break through the gum properly.
Teeth that are too crowded to break through the gums are called impacted.
Find cysts, solid growths (tumors), or abscesses.
Check for the location of permanent teeth growing in the jaw in children who still
have their primary (or baby) teeth.
Plan treatment for large or extensive cavities, root canal surgery, placement of
dental implants, and difficult tooth removals.
Plan treatment of teeth that are not lined up straight (orthodontic treatment).
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OCCLUSAL PLANE The imaginary curved surface on which upper and
lower teeth meet
Important especially when molding dentures
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DENTAL FORMULA The development of teeth and their arrangement in the mouth
The characteristic arrangement, kind, and number of teeth of human
at a given age
For adult human, the formula of teeth are as follows:
Incisors - 2/2
Canine - 1/1
Premolars - 2/2
Molars - 3/3
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I N T R A - O R A L D E N TA L X - R AY
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INTRA-ORAL Intra-oral: the film is inserted into patient's mouth
A basic rather than specialized equipment
Low power and low kilovoltage, but enough to
meet the demands of dental radiography
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INTRA-ORAL Designed so that
it will be easily
maneuvered
around patient'sface
Compact and light
Mounted on agimbal, which
allows rotation in
two planes
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INTRA-ORAL Scale are build in to
measure the angle of
rotation
Supported on a multi-jointed arm
Loose enough to be
flexed by slight pressure,
but tight enough to holdby friction
Commonly set at 65 kV,
with 10 mA
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GENERAL PROCEDURE Patient will be covered with a lead apron while sitting
upright on a chair. Thyroid shield may also be provided
Everyone else in the room wears a protective apron orstays behind a protective shield.
Patient will bite down on a small piece of cardboard or
plastic. The cardboard or plastic holds X-ray film.
Patient may have do this several times to get pictures
of all the teeth.
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BITEWING VIEW Shows the upper and lower back teeth and how the
teeth touch each other in a single view
These radiographs are used to:
check for decay between the teeth
show how well the upper and lower teeth lined up
show bone loss when severe gum disease or a
dental infection is present
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BITEWING VIEW The receptor is placed into the mouth parallel to
the crowns of the maxillary and mandibular
posterior teeth.
The patient stabilizes the receptor by biting on a
tab or bitewing holder. The horizontal angle of the
x-ray beam is then directed through the contacts of
the posterior teeth and at a 5 to 10 vertical
angle.
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PERIAPICAL VIEW Show the entire tooth, from the exposed crown to
the end of the root and the bones that support the
tooth
These radiographs are used to:
find dental problem below the gum line or in the
jaw
diagnose bone changes linked to some diseases
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PERIAPICAL VIEW A film will be placed into the mouth using a plastic film holding device
which has a metal rod with an attached ring that projects out of the mouth.
Radiographer will carefully place the film and holder into patient's mouth in
the required position to obtain a good-quality image. Patient must bitefirmly onto the film holding device to keep the film positioned properly and
ensure that it remains stable.
Radiographer must work quickly and employ techniques to minimize
discomfort as much as possible.
Once the film is positioned and stable, the cone of the x-ray unit will be
aligned, directing it toward the film and using the ring of the film holder to
help guide its position.
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OCCLUSAL VIEW Show the roof or floor of the mouth
Radiographs can be used to:
find extra teeth, teeth that have not yet broken
through the gum, jaw fractures, cleft in the cleft
palate, cyst, abscess, or growth
find any foreign objects
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OCCLUSAL VIEW The film packet, with the white surface facing downwards, is
placed centrally into the mouth, on to the occlusal surfaces of
the lower teeth, with its long axis crossways. The patient is
asked to bite together gently.
The patient then leans forwards and then tips the head
backwards as far as is comfortable, where it is supported.
The X-ray tubehead, with circular collimator fitted, is placedbelow the patients chin, in the midline, centering on an
imaginary line joining the first molars, at an angle of 90 to
the film
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TECHNIQUE ERRORS Error in technique will produce undesirable images
Notable errors are as follow:
Inadequate coverage
Backward placement
Bending
Tilted occlusal plane
Vertical alignment errors
Elongation
Foreshortening
Horizontal alignment errors
Horizontal overlapping
Centering errors
Double exposure
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INADEQUATE COVERAGE A common receptor placement error is inadequate coverage of the area to
be viewed.
This commonly occurs in molar projections when the patient cannot tolerate
proper receptor placement. Missing apices can also be caused by a receptorplacement error.
When using receptor holders, the bite block should be placed on the teeth
to be exposed and not on the opposing teeth. If the bite block is placed on
the opposing teeth and the patient is required to bite the receptor into
place, a placement error is likely to result.
Placing the receptor more lingual to the teeth where the palate and floor
are deeper will make placement easier and more comfortable for the
patient.
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BACKWARD PLACEMENT
Placing the film backwards in the mouth causes the lead foil
inside the packet to face the radiation source instead of the film.
The x-ray beam is attenuated by the lead foil before striking the
film, and embossed pattern on the foil will appear on the
processed film.
This error also results in a lighter image and confusion when
mounting the processed film.
Backwards placement is less likely with digital receptors
particularly the rigid sensors.
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BENDING Receptor bending may occur due to the curvature of the palate or lingual
arch and/or mishandled receptors
When using holders, flex the receptor into place to decrease the chances of
bending.
If the receptor is too large, bending can occur. Choose a receptor that will
adequately record the image
Bending a receptor causes the emulsion to crease, which in turn
compromises the quality of the image
Rigid digital receptors cannot be bent but phosphor plate receptors can be
creased, bent or folded. This produces a permanent artifact on the plate
and the image
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TILTED OCCLUSAL When the receptor is not placed perpendicular to the
occlusal plane, the occlusal plane will appear slanted or
diagonal.
The receptor must be placed straight or perpendicular with
the occlusal plane, or the receptor should be farther away
from the teeth to avoid this error.
Always place the biteblock in contact with the occlusal orincisal surfaces of the teeth you are imaging not on the
opposing teeth. Placement on the opposing teeth will cause
the receptor to displace when it contacts bony anatomy.
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ELONGATION Elongation or lengthening of the teeth and
surrounding structures results from
underangulation.
This error can also occur when using the bisecting
angle technique. Often the error is caused by the
x-ray beam being perpendicular to the long axis of
the teeth, rather than bisecting the angle between
the teeth and the receptor.
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FORESHORTENING Foreshortening is the result of over-angulation of the x-
ray beam.
To correct foreshortening when using the parallelingtechnique, the operator should decrease the positive
vertical angulation for maxillary projections, and
decrease the negative vertical for mandibular
projections.
This error can also occur if the receptor is not placed
parallel to the long axis of the teeth.
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HORIZONTAL OVERLAPPING
The x-ray beam should be aimed directly between
the targeted teeth in order to open interproximal
surfaces.
Horizontal alignment errors cause the image to
shift right or left, resulting in the overlapping of the
interproximal surfaces.
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CENTERING ERRORS The central ray should be aligned over the center of the receptor
with the x-ray beam directed perpendicular to the receptor.
When this alignment is not observed, a cone-cut occurs
Cone cuts appear as clear zone on traditional radiographs afterprocessing, due to the lack of x-ray exposure in the area of the
cut. When using digital imaging, the cone-cut appears as an
opaque area
The shape of the cone-cut depends on the type of collimator
used when exposing the receptor. For example, if a round
collimator or PID is used, a curved cone cut will appear
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DOUBLE EXPOSURE Double exposure results when the receptor is exposed
twice and two images appear superimposed onto each
other.
This error results in increased radiation exposure for
the patient. It is extremely important to avoid this error
because it exposes the patient to radiation twice.
To avoid this error, maintain an organized work space
in which exposed receptors are placed in one area or
turned over to separate from unexposed receptors.
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E X T R A - O R A L D E N TA L X - R AY
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EXTRA-ORAL Extra-oral: the film is outside patient's mouth
Most commonly used orthopantomography (OPG)
Offers panoramic view of patient's jaw and teeth
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EXTRA-ORAL kVp and mA can be
adjusted, as opposed
to intra-oral
equipment
Time is fixed and not
adjustable
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EXTRA-ORAL Cassette and film are
curved
The film is exposedthrough a narrow slit in
a protective metal
sheet
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EXTRA-ORAL
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EXTRA-ORAL The tube and film are
linked so that they
move in opposite
directionsimultaneously
The film moves around
the face, while the
tube moves around
the head
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EXTRA-ORAL
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EXTRA-ORAL
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PANORAMIC VIEW Show a broad view of the jaw, teeth, sinuses, nasal
area, and temporomandibular joint.
Cannot be used to find cavities
Can be used to show:
impacted teeth, bone abnormalities, cysts, solidgrowth (tumors), infections, and fractures
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C E P H A L O M E T R Y
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CEPHALOMETRY Cephalometry is the measurement of the human
head by imaging from x-ray films
Cephalometric analysis is used in dentistry, andespecially in orthodontics, to gauge the size and
spacial relationships of the teeth, jaws, and cranium.
This analysis informs treatment planning, quantifieschanges during treatment, and provides data for
clinical research.
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CEPHALOMETRY Five major components of face:
the cranium and cranial base
the skeletal maxillae
the skeletal mandible
the maxillary dentition and alveolar process
the mandibular dentition and alveolar process
These measurements will provide information to estimate the
relationships, vertically and horizontally, of the jaws to the cranial base &
to each other and the relationship of the teeth to their surrounding bone.
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