3. Role of radiographs
3
Clinical examination phase
Diagnosis( confirm/exclude)
Treatment planning
During treatment
Follow up
Blind screening tool-justify
Limitations-replace clinical examination
Need for further investigation
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4. Radiographs in Diagnosis
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4
Diagnostic imaging is an integral part of the
diagnostic process in clinical dentistry.
Radiographs are often obtained as part of a
complete examination.
Appropriate radiographic interpretation is used
along with clinical information and other tests
to formulate a differential diagnosis
5. Uses of radiographs
5
Loss of tooth structure
Caries(occlusal/proximal)
Non carious(attrition,fracture)
Periodontal diseases
Endodontic diseases
Impacted teeth
Trauma
Other bone pathologies
Implants
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6. 6
Radiography
Radiology
Technique
Interpretation
Interpretation:
Step by step analytical process that provides
an exact idea of the clinical problem and helps
to achieve the final diagnosis of any particular
lesion.
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8. Clinical examination
Type of radiograph
Number of
radiographs
Aids in interpretation
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Quality assurance
Inadequate quality
Inadequate number
Extraoral radiology
Biopsy/treatment-
aids in site selection
8
10. 10
Ideal radiograph:
Visual : density & contrast
Geometric : sharpness/detail,
resolution/definition, magnification, distortion
Anatomical accuracy of radiographic images
Adequate coverage of anatomical region of
interest.
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11. Viewing Conditions
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11
🞑 This should be done in a quiet, darkened room
🞑 At least two good, evenly-lit viewing boxes are
required
🞑 A bright light illuminator is required for relatively
over-exposed areas
🞑 Mounted in holder
🞑 Appropriate size of viewbox to accommodate film
🞑 Magnifying glass-detailed examination of small
regions
12. 12
A radiograph is a two dimensional image of a
three dimensional object.
Clark’s rule: The most distant object from the
cone(lingual) moves towards the direction of
the cone
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13. Three-dimensional concept
13
🞑 The radiographic image is simply a
Two-dimensional shadowgram of the patient
🞑 The third dimension must be reconstructed
mentally, preferably from two radiographic
projections made at right angles (orthogonal
projections) to each other
🞑 Oblique projections may be required to assess
anatomically complicated areas
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14. Contrast perception:
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14
Ability to distinguish b/w two areas of
radiographic image of diff densities-Weber’s
law
Minimum perceptible difference in gray level is
proportional to the brightness level to which
the subject is adapted.
All areas on a radiograph represented as:
Black
Grey
White
15. MACH BAND EFFECT
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15
Illusion consists of light or dark stripes that are
perceived next to the boundary between two regions of
an image that have different lightness gradients
Spatial high-boost filtering performed by the human
visual system on the luminance channel of the image
captured by the retina.
Mach bands are independent of orientation.
This occurs when two circles of uniform brightness are
placed side by side, separated by a sharp edge. Just
along the edge one colour looks darker than it really is,
while the other looks lighter.
17. 17
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False-positive radiological diagnosis of dental
caries
Manifest adjacent to metal restorations or
appliances, between enamel and dentin
Misdiagnosis of horizontal root fractures
because of the differing radiographic
intensities of tooth and bone.
18. 18
RADIOLUSCENT-the capability of a substance
with a relatively small atomic number to let a large
amount of x-rays pass through it, thus producing
darkened images on x-ray films.
RADIOOPACITY-the capability of a substance to
hinder or completely stop the passage of x-rays,
display as white/light areas on an exposed x-ray
film.
RADIOOPAQUE
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RADIOLUSCENT
19. Properties
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19
Atomic number
🞑 The higher the atomic number, the more
radiopaque the tissue/object:
Physical opacity
🞑 Air, fluid and soft tissue have approximately the
same atomic number, but the specific gravity of
air is only 0.001, whereas that of fluid and soft
tissue is 1
🞑 Therefore air will appear black on a radiograph,
compared with fluid and soft tissue, which appear
more grey
20. 11/15/2011
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Thickness
🞑 The thicker the tissue/object, the greater the
attenuation of X-Rays and the more white the
image .
🞑 When two tissues/objects are superimposed, the
composite shadow formed by these will appear
more opaque than either of the two separate
tissues
Bone(14;1.8)
21. Image analysis
21
Identify normal anatomic landmarks
Knowledge of normal v/s abnormal
Attention to all regions on the film
systematically
Three circuits
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22. First visual circuit: intraoral
images
22
Periapical before bitewing images
Right maxilla to left; left mandible to right
One anatomic structure at a time
Eg: posterior maxilla-maxillary
sinus,tuberosity,zygomatic process
Normal anatomy
bones, canals, foramina
Check for symmetry
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23. Use a systematic process
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23
Go back to the first quadrant and look at the
trabecular pattern. Is it:
Normal
Symmetrical when compared to the
contralateral
side
Sparse
Dense
In the direction of anatomical stress
Altered
25. Second visual circuit
Examination of bone:
Height of alveolar bone
Crest relative to teeth
Loss of height-more than 1.5 mm-periodontal
disease
Cortication
Lamina dura + PDL space + tooth roots
Carcinoma-erosion of alveolar crest+ ill defined
borders.
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25
27. Third visual circuit
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Examination of dentition & associated
structures
Number, Sequence, appearance, root
structure
Crowns –defective enamel, caries
Intreproximal areas & restorations
Pulp chambers-size, con
dioluscent/radio
ten
Ret
storation
Proximal caries
opaque lesions
Pulp
Dentin
Bone-ra
28. Check individual teeth
Enamel, [amelogenesis imperfecta, mulberry molar, etc.]
The dentin, [dens invaginatus or evaginatus, denticles etc.] T
Pulp chamber [dentinogenesis imperfecta, odontogenesis
imperfecta, odontodysplasia, taurodontism, individual obliteration of
nerve canals, etc.]
Apical area [root resorption, lucencies or opacities]
periodontal ligament space [widened in early osteosarcoma
(localized), scleroderma ( generalized) [ absent in
hyperparathyroidism]
Amount of bone support.
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28
29. Routine assessment of
radiographs
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🞑 Ensure that the radiograph is the one of the patient being
examined, check the date, opd/no.
🞑 Ensure two orthogonal projections are available.
🞑 The radiographic views are named according to the direction the
primary beam enters and leaves the tissue and the body part
being examined
🞑 The position of the patient during exposure should be known,
and left/right markers should be identified
🞑 The radiograph should be of high technical quality with respect to
positioning, centring, collimation, exposure and development,
and should be free from artefacts.
30. 11/15/2011
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30
Every shadow visible must be evaluated to
determine whether it is:
🞑 A feature of normal anatomy
🞑 A composite structure formed by superimposition
of structures
🞑 An artefact produced by inaccurate positioning
🞑 A pathologic lesion: must be ruled out first
31. 31
Interpretation is an orderly process
Normal
variation
Abnormal
Developmental
abnormalities
Acquired
abnormalities
Cyst Benign
neoplasia
V
ascular
analomy
Metabolic
Inflammatory
lesion
Malignant
neoplasia
Bone
dysplasia
Trauma
32. Why describe the lesion?
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32
The radiographic description can give us
indications of:
Tissue of origin
Biological behavior
Prognosis
Treatment concerns
Diagnosis or a Differential Diagnosis
33. Describing the Lesion
33
1. Size
2. Shape
3. Location
4. Density
5. Borders
6. InternalArchitecture
7. Effect on adjacent structures
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34. Aunty Minnie Approach
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34
🞑Aunt Minny represents an abnormality which
looks like one that the evaluator has seen
before, or been told about.
🞑It would be difficult to recognise new findings
using this approach
Cousin Harry represents an abnormality which
the evaluator has not seen for a long time, but
would like to see
Uncle Fred represents an abnormality which is
often present
36. Size
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Measure the lesion with a ruler. If you must
estimate, use surrounding structures as
guide
Measure in two dimensions, width and
height in mm or cm
39. Location
39
Is the lesion localized or generalized?
Unilateral or bilateral
(submandibular fossa), fibrous dysplasia
Where is the lesion in relation to other
structures and anatomic landmarks?
Use terms such as:
Mesial, Distal
Inferior, Superior
Posterior,Anterior
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40. Soft tissues or jaws:
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40
Epicentre-coronal to tooth-odontogenic
epithelium
Epicenter of the lesion is above the
mandibular canal->odontogenic in origin
Epicentre->below IAC->non
odontogenic(likely)
Cartilaginous lesions, osteochondromas -
>condyles
If the epicenter of the lesion is in the sinus, not
odontogenic in origin-alveolar process of
maxilla
41. Density
41
Is the lesion Radiopaque, Radiolucent, or
Mixed Density
Remember that opacity is relative to the
adjacent structures.
If the lesion is of mixed density, describe the
appearance
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49. Ill defined borders
49
Gradual transition-normal app bone &
abnormal app trabaculae- sclerosing osteitis
Invasive border-bone destruction-malignancy
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50. Jaw – examine the lesion in the
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jaw:
50
· Site – location, extent, solitary, multi-focal or
generalised
· Size and shape – measure and describe. This
may require one or more views.
· Symmetry – examine contralateral site. Bilateral
symmetry is suggestive of a normal variant
· Border – sclerosis, resorption, lack of continuity
· Contents – lucent or opaque. Homogenous or
varying density
· Association with other structures. Teeth
displaced or resorbing
51. Effect on adjacent structures
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51
Lesions behaviour & impact on surrounding
structures-identification of disease
Inflammatory disease-bone
resorption/formation.
A Space Occupying lesion creates its own
space by displacing other structures, such as
teeth, maxillary sinus, inferior alveolar canal,
etc.
52. 52
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Epicentre above crown of teeth-follicular cysts-
teeth apically
Lesion-ramus of mandible-cherubism-anterior
direction
Papilla of developing tooth-lymphoma
Widening of PDL, broken lamina dura-
periapical/periodontal abscess
Root resoption-periodontitis, trauma, tumors
Reactive bone-periphery of lesion-benign slow
growth
53. 53
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Inferior alveolar canal
Superior displacement-fibrous dysplasia
Widening of IAN-cortical boundary intact-
benign vascular/neural lesion
Irregular widening with cortical destruction,
complete length of canal-malignant neoplasm
54. Outer cortical bone/periosteal
reactions
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Slow growing-new bone-expanding lesion-
outer cortical bone maintained
Rapidly growing-periosteum does not respond-
missing cortical plate
Exudate from inflammatory lesion-lift
periosteum off surface of the surface of cortical
bone-periosteum lay down new bone.
Onion skin app-leukaemia, langerhan’s cell
histiocytosis
Spiculated new bone-osteogenic sarcoma
57. Decision 1: Normal V/S Abnormal
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Structure of interest
Variation of normal/represents abnormality
58. Decision 2: Developmental V/S
Acquired
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58
Area of interest: abnormal
Radiographic characterstics: location,
periphery, shape, internal structure, effect on
surrounding structures
Indicates developmental/acquired-external
root resorption
59. Decision 3: Classification
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59
Abnormality
Appropriate category
Treatment plan
60. Decision 4: Ways To Proceed
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Analyse images
Further imaging like CT, MRI
Biopsy
Treatment
61. SOFT TISSUE.
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61
The examination of the radiographic
appearance of soft tissue is all too often
overlooked.
This is particularly true on panoramic
radiographs.
If the clinical examination determines that soft
tissue requires radiographic examination, kVp
be reduced when the patient is exposed. Soft
tissue structures in the maxillofacial region are
often tongue, soft palate, tip and ala of the
nose
62. Correct terminology
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One examines a radiograph and NOT an X-ray. Bear in mind that
an X-ray can not be seen.An X-ray is a photon / beam of energy.
One does not see infection at the apex of a tooth. What one does
see is the well / poorly demarcated radiolucency/opacity, x mm
by y mms in size at the apex of tooth number X.
For the same reason one does not speak about a PAP in radiology.
63. 11/15/2011
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63
Periodontal bone loss is not periodontitis per
se.
Stay away from brand names. We do not
have a panorex machine here. Use the word
PANORAMIC radiograph or PAN.
In radiologic terminology, a PA is a postero-
64. EXISTING DIAGNOSTIC
RADIOGRAPHS
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An effective way to reduce unnecessary
radiation to the patient is to avoid retaking
[recent] radiographs that already exist. It is the
clinician's responsibility to obtain these records
from earlier health providers where possible.
65. The diagnostic process is far from infallible. In any
diagnostic procedure there are four possible outcomes:-
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1.True positive: The disease is present and
correctly identified.
2.False positive: The disease was absent but
something on the radiograph convinced the
clinician that it was present.
3.True negative: No disease present and
correctly determined.
4.False negative: Disease is present but not
detected. Occurs much too often
66. RADIOGRAPHIC RECORDS
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The value of radiographs as a part of the integral
records of a patient cannot be overstated.
Good radiograph is difficult to match with written
records and the radiograph is more indisputable than a
written statement in a court of law provided the name of
the patient is indicated as well as the date.
However, this is not a call to expose the patient to
ionizing radiation merely for the sake of documentation.
One may not retake radiographs for the sake of
improving one's grades. Radiographs legally must be
kept for at least 5 years; some authorities state 7 years.
67. DOCUMENTATION
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Clear medico-legal requirement for
documentation of interpretation.
Signed and dated radiographic report must be
written with patient's record.
Clinically useful in treatment planning and
case presentation.
68. Radiographic report
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Patient & general information
Imaging procedure
Clinical information
Findings
Radiographic interpretation
69. RADIOGRAPHIC
PRESCRIPTION
69
Licensed dentist may prescribe radiographs
Examination appropriate radiographic
views
Maximum amount of information
Minimum amount of ionizing radiation.
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71. References
White and pharoah,principles and
interpretation.IV edition,pg281-296
W&P. Ch.14. Oral and Maxillofacial Imaging.
Farman and NortjeNeill Serman.2000
Dr. Parish P. Sedghizadeh. Radiographic
pathology of the head and neck.
Brocklebank L, Dental Radiology, Oxford
University Press 1997.
Deforge DH and Colmery BH, An Atlas of
Dental Radiology, Iowa State University Press
2000
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72. THANK YOU
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...when you have eliminated the impossible,
whatever remains, however improbable, must
be the
truth.
Sir Arthur Conan Doyle, (Sherlock Holmes)
British mystery author & physician (1859 - 1930)