This is very important topic for postgraduate students of Conservative dentistry and endodontic branch. This seminar will help them learn and understand the topic better. Thank you

1. 1
Presented by-
Dr Anuja Dhumal

2.  Introduction
 History
 Application of radiography to endodontics
 Limitations of radiographs
 Technology systems
- Traditional
- Digital technology

3. • Cone positioning- 1. Vertical Angulation
2. Horizontal Angulation
• Extraoral Film Placement-
 Digital Radiography-
• Working Principles of Digital Intraoral Systems-
1. CMOS
2. CCD
• Storage Phosphor Detectors-
3

4.  Xeroradiography
• Uses
• Advantages
• Disadvantages
 Subtraction radiography
• Working principle
• Disadvantages
 Computed tomography
• Working principles
• Advantages over conventional film
• Uses

5.  Cone beam computed tomography –
• Field of view and Spatial resolution
• Applications in endodontics
• Advantages
 Magnetic Resonance Imaging
• Operating Principles of MRI
• Use of MRI in endodontics
• Advantages and Disadvantages of MRI use
 Conclusion
 References
5

6. • Endodontic treatment relies on a series of images made at different
stages of the treatment.
• These images provide important clues about hard and soft tissues of
the teeth, including the pulp chamber and root canals.
• Radiographs are the ‘eyes’ of the dentists when performing many
procedures.
• However, conventional radiographic techniques have certain
limitations.
• Digital radiography is the latest advancement in dental imaging and is
slowly being adopted by the dental profession.
6

7.  Digital image incorporates computer technology in capture, display
enhncement, and storage of direct radiographic images.
 It offers some distinct advantages over film, but like any emerging
technology, it presents new and different challenges for the
practitioners to overcome.
7

8. • 1895- German professor Wilhelm Roentgen first developed the
cathode rays.
• Dr. Otto Walkoff took the first dental radiograph for himself.
• 1899 - Dr. C. Edmund kells gave the first clinic in the U.S.A on
the use of X-ray for dental purpose.
• 1901 – Radiographs were used to check the adequacy of root
canal filings.
• Dr. Price is credited with developing the bisecting angle
technique, whereas kells described what today is called the
Paralleling technique.
8

9. 9
Left: X-ray of Anna Bertrand Rontgen’s hand
(1895-12-22). Right: X-ray of Albert von Kolliker’s
hand (1896-01-23).
• In those days knowledge
about the dangers Of
exposing living tissues to x-
rays was very less.
• Rontgen convinced his wife as
a test subject.
• Anna rontgen, has gone down
in history as the first person
that underwent x-ray
radiography .
One can see drastic
improvements in image quality
between the two hand
radiographs, taken only one
month apart.

10.  Two weeks after the publication of Rontgen’s discovery, the German
dentist Otto Walkhoff acquired a radiograph of his own teeth with the
help of Fritz Giesel. An exposure time - 25 min was used. (diagnostic
quality)
10
Left: Otto Walkhoff. Right:
Walkhoff’s dental radiographs.

11.  In March 1896 at the Physical Society of Frankfort, Konig published an
overview of his work, containing radiographs of the anterior teeth of
upper and lower jaw.
11
Konig’s dental radiographs
The radiographs, in his words:
“are not only able to prove the position and the form of the fillings in the teeth
but we are also able to examine parts of the teeth which are sticking into the
jaw bones ...’. (W. König, as quoted by Forrai )

12. 12
Skiagraph showing upper and lower jaw teeth.
William J. Morton presented intraoral radiographs acquired of a dry
skull at a lecture for the New York Odontological Society on 24 April
1896.

13. 13
• Early X-ray tubes had to be recalibrated
before each exposure.
• Recalibration was done by placing the
operator’s hand in front of a fluoroscope
and adjusting the tube current until a clear
radiograph was shown.
• Furthermore, it occurred that dentists held
the intra-oral plate or film in place using
their own fingers during the minutes-long
exposure.
• It is to no surprise that many of the early
adopters of X-ray imaging had to pay a
heavy toll for their groundbreaking work.

14.  The first lesion started appearing on his left hand -1908
 Multiple lesions not responsive to the treatment- series of
amputation.- Continued his work - custom made instruments that
could be attached to the left hand- hand amputation 1926.
 Inventions- Suction apparatus,
 He suggested conservative root canal therapy using radiographs.
 published - reports on the effects of radiation, distinguishing
between early and late effects
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15.  It is made up of three components-
1. Control Panel
2. Extension Arm
3. Tube head
15

16. X-ray Tube Head
1. Metal Housing- It surrounds the x-
ray tube and transformer. It protects
the x- ray tube.
2. Insulating oil- It prevents
overheating by absorbing the heat
created by the production of x-rays.
3. X-ray tube- main X-ray generating
system.
4. Aluminium Disks- They filter out
non- penetrating longer wavelength
x-rays.
16

17.  Total filtration is regulated by the
state and federal law ( U.S.A)
1. At or below 70 kvp - 1.5mm of
Aluminium thickness.
2. Above 70 kvp- 2.5mm of Aluminium
thickness.
5. Lead Collimator- It is a lead plate with
a central hole that fits directly over the
opening of the metal housing where the
x- rays exit.
- It restricts the size and shape of the x-
ray beam and thus reduce the
exposure to the patient.
- Types- 1. Round
- 2. Rectangular.
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18. 6. Position indicating device (PID) –
-It is an extension of the tube-head and
it shapes the x-ray beam.
Types-
1. Conical
2. Rectangular
3. Round
 Conical PID appears as closed, pointed
plastic cone- It produces scattered
radiation.
 Long and rectangular PID is preferred
because of less divergence of x-ray
beam and reduces patient exposure.
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19. Short Cone
8 Inches
Long Cone
16 Inches

20.  It consists of-
 A leaded glass housing
 A negative Cathode
 A Positive Anode
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21.  Leaded glass housing-
 It is a leaded glass vaccum tube
that prevents x- rays from
escaping in all directions.
 It has a central window that
permits the x-ray beam to exit
and directs towards the
aluminium disk, lead collimator
and PID.
21

22.  A Negative Cathode-
 It is composed of two parts-
1. Filament. 2. Focusing Cup.
1. It is made up of coil of tungsten wire. It is mounted on two strong
stiff wires that carries the electric current.
The hot filament emits electrons that are separated from outer orbit of
tungsten – “Thermionic emission”.
2. It is a reflector cup of molybdenum and houses the filament.
22

23.  Positive anode-
 It consists of wafer thin tungsten plate ( target) embedded in a solid
copper stem.
 Its purpose is to convert the kinetic energy of electrons generated
from the filament into x-ray photons.
23

24.  Tungsten is usually selected as a target material because of-
1. High atomic number
2. High melting point ( 3380 degree celcius)
3. Low vapour pressure
 Methods of heat dissipation-
1. Conduction- Copper stem
2. Convention- Oil surrounding the tube.
3. Rotating Anode.
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25.  Target Size-
 Sharpness of the radiographic image increases as
the size of the radiographic source decreases.
 As the focal spot becomes smaller, heat generated
per unit target area becomes greater.
 In order to derive a benefit from small focal spot
and distribute the bombarding electrons over
greater surface area of large target, the target is
placed at an angle to an electron beam.
 Effective focal spot will be smaller than the actual
focal spot.( Sharper image and effective heat
dissipation
 Target inclination- 20 degrees- “Line focus
principle”– angle of truncation
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26.  Paralleling Technique-
 The x-ray film is supported parallel to the long
axis of the teeth and the central x ray beam is
directed at right angles to teeth and film.
 To achieve this, the film must be placed away
from the tooth and towards the middle of the
oral cavity.
 Because the film is placed away from the tooth,
image magnification and loss of definition
results.
 To compensate for image magnification the
target film distance must also be increased.
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27.  It requires the use of film holders to
stabilize the film.
 Examples of commercially available film
holders are-
1. Rinn XCP
2. Precision film holders
3. Stable bite blocks- disposable film
holders
4. EEZEE- Grip film holders
5. Hemostat with bite block
27
Rinn XCP

28.  It is also known as short cone technique.
 It is based on- “ the rule of isometry”. ( which states that the two
triangles are equal if they have two equal angles and share a common
side.)
28

29.  Horizontal angulations- it is obtained by directing the central ray
perpendicular to the curvature of the arch and through the contact
areas of the teeth.
29
Horizontal angulations for:
 Maxillary anterior teeth – straight facial
 Maxillary premolars and molars – mesial angle
 Mandibular incisors – distal angle
 Mandibular premolars – mesial
 Mandibular molars - distal

30. Mandibular Molars
A, Central ray directed at right angle to film positioned parallel to arch. B, Limited information
is gleaned from the radiograph because of superimposition of structures and canals.

31. A, Central ray directed at 20 mesially to film positioned parallel to arch. B, Two canals are
now visible in both roots of the first molar

32.  Disclosing canals by radiography.
 Figure
Right angle horizontal projection reveals
four files in separate canals
superimposed.
Horizontal angulation varied 30 mesially
reveals all four canals and file short of
working length in mesiolingual canal .

33.  A, Central ray directed at right angle to film positioned parallel to
arch. B, Radiograph reveals one canal in each premolar, although
abrupt change in density may indicate bifurcation.

34.  Central ray directed at 20 mesially to film, parallel to arch. B, In first
premolar, two canals that are clearly visible (arrow) probably reunite,

35.  A, Central ray is directed through maxillary molar at right angle to
inferior border of film.
 Malar process will superimpose over first molar. B, Superimposition
of first molar roots, sinus floor, and malar process confuse the
diagnosis.

36.  A, Central ray directed at 20 mesially skirts malar process, projecting
it distally. B, Distobuccal root is cleared of palatal root and malar
process is projected far distal, all three roots are clearly seen.

37.  A, Central beam projected 20 from the distal. B, Mesiobuccal root of
the first molar is isolated and second and third molars are cleared of
malar process, which is projected forward . Sinus floor may be
‘‘lowered’’ or ‘‘raised’’ by changing vertical angulation.

38.  A, Horizontal right-angle projection produces illusion that maxillary
first premolar has only one canal. B, Varying horizontal projection by
20 from the mesial separates two canals. Buccal canal is distal (MBD).

39.  A, Film placement for modified parallel technique. Horizontal central
beam projection at right angle to film.
 B, Single canals seen in central incisors with only suggestion of two
canals in lateral incisor.

40.  A, Film is positioned for canine radiograph. Horizontally, central
beam is projected at right angle to film. B, Canine image is single
straight canal, but incisor image reveals bifurcated canals that reunite
in narrow tapered root.

41. 41
Vertical angulations-

42. BISECTING ANGLE TEBCHNIQUE PARALLELING TECHNIQUE
Diffusion and distortion of image Sharp details are obtained
Increased chances of elongation or shortening Image is of same shape and size
Distorted images of teeth due film bending Image of the teeth anatomically accurate
Shadows of alveolar bone tend to fill the interproximal
spaces
Alveolar crest seen in true relationship to the teeth
More vertical angulation Less
Superimposition of shadow of zygomatic arch on teeth Appears above the apices of the molar teeth
Unnecessary exposure to the patient’s finger (if film is
held)
Use of film holding devices minimizes such error
Can be used in cases with shallow palate Apices of the teeth may be cut off
Buccal roots of premolars and molars are foreshortened No such errors
Coning off of the image Aiming rings minimizes such error
Cannot be reproducible Reproducible
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43. • Aid in Diagnosis- Hard tissue alterations in the teeth and periapical
structures.
• Determine the number, location, shape, size and direction of roots
and root canals.
• Assess anatomy, size and alteration of pulp chamber.
• Detect procedural errors- perforations, ledges, transportation and
instrument separation.
• Locate root tips prior to surgery.
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44. • Aid in the evaluation of obturation.
• Presence of any tooth fragment and other foreign bodies following
traumatic injuries.
• Evaluate, in follow up films the outcome of treatment.
• Confirm, following root end surgery and before suturing, that all
tooth fragments and excess filing material have been removed from
the apical region and the surgical flap.
44

45. • Dimensions of radiographs are easily distorted through improper
technique, anatomic limitations or processing error.
• Bucco-lingual dimension is absent on single film.
• Various states of pulpal pathosis are indistinguishable on x-ray
shadows.
• Periapical soft tissue lesions cannot be accurately diagnosed by
radiographs.
• For proper diagnosis radiographic interpretation should always be
integrated with detailed medical and dental history, clinical
examination and pulp testing procedures.
45

46.  Useful for patients  cannot accommodate or tolerate intra oral films
 Gagging or trismus
 Special positioning of cone and film

47. Maxillary molar, cone is positioned a
negative 45 degree to the occlusal plane
Mandibular molar, cone is positioned a
negative 35 degree to the occlusal plane

48.  The advent of digital imaging has revolutionized radiology.
 A number of forces are driving the shift from film to digital systems.
 The detrimental effects of inadequate film processing on diagnostic
quality and the difficulty of maintaining high quality chemical
processing are well documented problems in dental radiography.

49. 49
Demonstration of the diversity of available intraoral X-ray sensors.

50. RVG system (radio visuography)
 Four main components
• An X-ray set with special timer
• An intra oral sensor
• A display processing unit
• A printer

51.  Components of the RadioVisioGraphy (RVG)-showing the solid-state electronics board with charge-
coupled device (CCD) chip, the scintillator, and the fiber optic plate used to reduce the size of the image
to the size of the CCD. Primary tooth of Mouyen’s daughter., The first ‘‘clinical’’ RVG image achieved by
Dr. Mouyen . , Commercial version of the RVG with Mouyen himself in the blue gown.
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52. Two types
 Direct digital imaging
 Indirect digital imaging

53. Digital imaging
 Components  An X-ray source, an electronic sensor, a digital
interface cord, a computer with an analog to- digital converter
(ADC), a screen monitor, software and a printer.

54.  Sensor placed in the mouth and exposed to x-rays
 Sensor captures image and transmits to computer
 Analog information is converted into digital by ADC (analog digital
converter)
 Within seconds the image appears on computer screen.
 Software used to enhance and store image

55. Indirect digital sensors are either
 A charge-coupled device (CCD)
 Complementary metal oxide semiconductor active pixel sensor
(CMOS-APS).

56.  It is so named because this technique still uses a scintillator to
convert x-rays to light.
 Charge Couple Device (CCD)
 Most common image receptor
 First developed in 1960
 Introduced to dentistry in 1987
 Used in  fax machines, home video cameras, microscopes and
telescopes
56

57. x-ray photons
Light Photons
Scintillator
Electric charge
Fiber optic plate
Electrical charge is read
out digitally before
finally being sent to an
image processor

58.  Each silicon atom in the detector chip is
covalent with another silicon atom .
 When light photon strikes the silicon and the
energy exceeds the strength of the covalent
bond, an electron hole pair is formed
 Silicon chip  usually composed of an array
of light sensitive pixels  consists of a small
electron well into which the x ray or light
energy is deposited upon exposure .
 Charge coupling is a process by which the
electrons from one well are transferred to
another in a sequential manner ( bucket
brigade)

59.  The charge of each pixel is converted from an analog electric signal
representing the energy absorbed by the solid state chip to a digital
signal representing the discrete numeric pixel values for image
display on a computer screen.

60.  Latest development in direct digital sensor technology.
 Externally, CMOS sensors appear identical to CCD detectors but
they use an active pixel technology and are less expensive to
manufacture.

61.  In a CMOS chip, more of the electronic components controlling the
conversion of photon energy into the electronic signal are
incorporated into the chip itself.
 This simplifies the manufacturing process and thus, reduces the
costs of production.
 However, most digital cameras on the consumer market are based on
CCD technology.

62.  The APS technology reduces by a factor of 100 the system power
required to process the image compared with the CCD.
 In addition, the APS system eliminates the need for charge transfer
and may improve the reliability and lifespan of the sensor.

63.  The image is captured in an analog or continuous format and then
converted into a digital format.
 As with any data conversion, this analog to digital conversion (ADC)
results in the loss and alteration of information.

64.  Consequently, many edges are lost or distorted in an analog to digital
conversion.
 The original indirect digital imaging technique was to optically scan a
conventional film image (analog) and generate a digital image.
 As imaging systems became more sophisticated, other techniques for
capturing the digital image from an analog were developed.

65.  The image is captured on a phosphor plate as analog information
and is converted into a digital format when the plate is processed.

67.  First introduced in 1981 by the Fuji
Corporation (Tokyo, Japan).
 The PSP consists of a polyester base
coated with a crystalline halide emulsion
that converts X-radiation into stored
energy.
 The crystalline emulsion is made up of a
europium-activated barium fluorohalide
compound.
The sequence involved in the formation of a
photostimulable phosphor (PSP) image.

68.  The energy stored in these crystals is released as blue fluorescent
light when the PSP is scanned with a helium-neon laser beam.
 The emitted light is captured and intensified by a photomultiplier
tube and then converted into digital data.

69.  Not all of the energy stored in the PSP is released during scanning
and consequently, the imaging plates must be treated to remove any
residual energy.
 Finally, the receptors must be erased by exposure to white light
before reuse.

70.  A major advantage of the PSP image receptor is that it is cordless.
 This significantly impacts the ease of receptor placement.
 The receptor is approximately the same size as conventional film and
is somewhat flexible.

71.  These sensors must also be kept in an infection control barrier
because the imaging plate cannot be sterilized.
 PSP technology is used for intraoral as well as extraoral imaging.
 Most studies report comparable utility when evaluating conventional
film images with PSP images.

72.  Reduced time between exposure and image formation.
 Reduced radiation dose per image.
 Multiple exposures, from various angles.
 Elimination of chemical processing and disposal of spent chemicals.
 Images can be duplicated any number of time without any loss of
image quality.
 Images can be stored and retrieved electronically and can be
transmitted electronically for referrals and other purposes.
 Dynamic nature of the image with the ready option of post-imaging
enhancements.
72

73.  Digital systems also have measurement tools. (e.g., an endodontic
instrument of known length placed in a root canal) can accurately
measure, for example, the root canal working length.
 Reusable detector reduces expenditure on consumables.
 With DICOM image file usage, digital images can provide greater
security regarding radiographic image integrity and tags include such
information as patient name, date of exposure.
 Wired detectors have an advantage when working on special need
patients as the wire makes swallowing or ingesting the detector
unlikely.
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74.  Relatively high initial investment cost .
 Issues related to infection control as the detectors cannot be
autoclaved.
 Solid-state detectors are somewhat thicker and more rigid (however,
this can also be an advantage in preventing disproportionate
distortion from film bending).
 Packaged PSP imaging plates (IPs) are thinner than prepackaged
analog intraoral X-ray films and may not be held firmly in position in
film holders.
74

75.  As most current versions of CCD and CMOS detectors are wired, this
could create patient psychological discomfort.
 Competency using software may take time to master .
 With PSPs, the intraoral imaging plates have been prone to mechanical
degradation necessitating replacement of plates to sustain image
quality.
 Mishandling can cause mechanical damage with high replacement
costs for CCD and CMOS detectors.
75

76.  Digital subtraction radiography is a technique that allows us to
determine quantitative changes in radiographs.
 A radiographic image is generated before a particular treatment is
performed.
 At some time after the treatment, another image is generated.
 The two images are digitized and compared on a pixel-by-pixel
basis.

77.  The resultant image shows only the changes that have occurred and
“subtracts“ those components of the image that are unchanged.
Image comparing baseline to follow-up images made at 3, 6, and 12 months following
endodontic therapy . Column 3 indicates subtraction of respective follow-up images from
the baseline radiograph. Progressive remineralization of the radiolucency at the apex of
the distal root of the first molar .

78.  Areas with mineral loss  displayed in darker shades of gray, while
areas of gain appear lighter than the background
 A subtraction image is a two dimensional display of 3-D structures.
 In order for DSR to be diagnostically useful, it is imperative that the
baseline projection geometry and image intensities be reproduced.

79.  If the exact projection geometry and receptor placement are not
recreated, the changes in the subtracted image will demonstrate the
effects of mis-registration rather than the effects of therapeutic
intervention.

80. Xeroradiography
• It is made up of 9.5 by 14 inch
sheet of aluminium.
• A thin layer of amorphous
selenium photoconductor.
• An interface layer- Aluminium
oxide.
• An overcoating-cellulose acetate.
•It uses Photoelectric process
instead of photochemical process.

81. 81
The XC plate Is charged to a high positive potential by corotron.
It is then placed in a cassette and used in manner similar to a conventional film.
When x rays strike the selenium , photoconduction occurs and this produces a
charge image Of the part to be examined.
The image is made visible in a processor by using a liquid toner.
The resultant powder image is subsequently transferred to a special paper
And fixed there to form a permanent image.

83.  soft tissues on xeroradiographic films have well defined outlines that
may permit confident evaluation of the soft tissue height and
contour.
 Xeroradiographs provide greater overall soft tissue detail making
possible evaluation of its density, texture, and contents.
 The technique reveals soft tissues calcifications which are not easily
discerned in conventional radiographs. This property may be
employed in endodontics to visualize early pulpal calcifications.
 It gives detailed visualization of lamina dura, bony trabeculae, fine
metal instruments like files, broaches etc, root apices, PDL spaces.
83

84.  Wide applications-Management of neoplasm of laryngopharyngeal
area, joint region, as well as an aid in cephalometric analysis.
 Reduced exposure to radiation hazards- Because there is no need to
make multiple exposures as tissues of different densities and
thicknesses can be recorded in one exposure, patient is at a very low
risk of radiation hazards.
 Economic benefit- An eight fold increase in cost is saved over
conventional radiography.
84

85.  Better ease and speed of production-So far as no special skills are
required for office copying machine.
 High resolution- The strengths of the fields are smaller at the centre
of charged ones than at the edge, resulting in a greater number of
powder particles collections peripherally than in central charged
areas. This greatly enhances local contrast which, in turn, improves
resolution and image quality.
85

86.  Fragile selenium coat-the layer is quite easily scratched.
 Slower speed-Comparatively, xeroradiography has a lower speed than
halide radiographs.
 Technical limitations-
 -> High radiation dose is needed for extraoral techniques
 -> Positioning difficulties especially in the most posterior areas of
the mouth
 -> Image artifacts are more.
86

87. • In 1972 Godfrey hounsfield invented
Computerized axial transverse scanning.
• A CT scan makes use of computer
processed combinations of many x-ray
images taken from different angles to
produce cross sectional (tomographic)
images.

88.  Claimed to be 100 times more sensitive
than conventional x-ray system.
 CT scanner consists of a radiographic tube
that emits a finely collimated, fan shaped
x-ray beam directed to a series of
scintillation detectors or ionization
chambers.
 Depending on the scanner's mechanical
geometry, both the radiographic tube and
detectors may rotate synchronously about
the patient

89.  The detectors forms a continuous ring
about the patient and the x-ray tube may
move in a circle within the detector ring.
 More recently CT scanners have been
developed that acquire image data in a
spiral or helical fashion.
 lt is reported that, compared with
incremental CT scanners, spiral scanners
provide improved multiplanar image
reconstructions, reduced examination
time (12 seconds versus 5 minutes) and a
reduced radiation dose (up to 75%).

90.  Many scans are progressively taken as the object is gradually
passed through the gantry. They are combined together by a
mathematical procedure known as tomographic
reconstruction.
90

91.  Completely eliminates the superimposition of images of structures
outside the area on interest.
 Because of the inherent high contrast resolution of CT, differences
between tissues that differ in physical density by less than 1% can be
distinguished; conventional radiography requires 10% difference in
physical density to distinguish between tissues.

92.  Time consuming
 Expensive for routine clinical use.
 High radiation exposure.
 Expensive equipment hence not always accessible.
92

93.  Evaluation of extent of any suspected
pathology in the head and neck, including
tumors, cysts and infection.
 Presence and absence of root canal filling
materials and metal posts.
 Extension of the maxillary sinus and its
proximity to root apices.
 Determination of location and extent of
facial fractures.
 Radiographic presurgical evaluation for
implant placement.
Axial CT and coronal CT of the mandible showing the
brown tumour as a mass of the left hemimandible.

94.  It uses a round or rectangular cone shaped x-ray beam where
an x-ray source and a reciprocating array of detectors
simultaneously moves around the patients head.
 Single projection image – “Basis image”.
 Series of such basis images – projection data software
converts this data into 3D volumetric data. Final image.
94

95. 95

96.  Fan shaped x-ray Beam  Cone shaped x-ray Beam
96

97.  Traditional CT uses high output,
rotating anode x-ray tube.
 CBCT utilizes a low power,
medical fluoroscopy tube that
provides continuous imaging
throughout the scan.
97

98.  Produces a single slice image
per scan. Each slice must
overlap slightly in order to
properly reconstruct the
images.
 Produces the complete volume
image in a single rotation.
98

99.  CT is slower due to spiral
motion. Scan time is longer.
 CBCT-The single turn motion
image- quicker than traditional
CT.
99

100.  CT has high radiation dose.
 The average medical CT can
reach levels of 1,200-3300
Microsiv.
 CBCT has lower radiation dose
as a result of no overlap of
slices.
 Radiation exposure- 36
microsieverts.
100

101.  CT- To collect adequate
information there is overlapping
of radiation.
 No overlap of slices.
101

102.  CT- only one jaw can be
visualized at one time.
 - High contrast resolution.
 - Cost is high.
 -Can cause claustophobia.
 CBCT- Both jaws can be imaged
at the same time.
 - Poor contrast resolution, thus
soft tissues cannot be viewed.
 - Cost is less.
 Open design of CBCT eliminates
claustophobia and greatly
enhances patient comfort and
acceptance.
102

103.  Uses non ionizing radiation- to produce high quality cross sectional
images of the body.
 Patient  placed inside large magnet  induces strong external
magnetic field
 Nuclei of many atoms in the body  align with the magnetic field- to
transverse plane.
 This produces a rotating magnetic field from the body, detectable by
the scanner and used to construct image by a computer.

104.  Loosely bound hydrogen atoms- soft tissues and liquids- can
align with external magnetic field and produce a detectable
signal.-Bright color
 Hard dental tissues fail to produce a usable signal as they
cannot align themselves.-dark color
104
MRI IMAGE CBCT IMAGE

105. Advantages of MRI
 It offers the best resolution of soft tissues.
 No ionizing radiation is involved with MRI.
 Direct multiplanar image is possible without reorienting the patient

106. Disadvantages
 Long imaging times, reducing patient comfort.
 Requires high financial resources for setup.
 Different types of hard tissues such as enamel,dentine cannot be
differentiated from each other and from metallic restorations.-
radiolucent.
 A strong magnetic field has the capability to pull heavy objects
towards the scanner at very high velocity- “projectile effect”.

107.  Differential diagnosis between a granuloma and a cyst may be
important in the management and predicting the outcome of
the endodontic treatment.
 Traditional radiographs, CT, CBCT are not good guides.
 In recent years ultrasound real time echotomography, safer
method used to supplement traditional radiology, in the study
of apical periodontitis.
107

108. 108
When quartz or a synthetic ceramic crystal is exposed to AC
current. Electrons cause a change In the structure of its grid.
This change emits mechanical Energy in the form of US waves.
As the US waves passes through or interacts with tissues It is
attenuated by a combination of absorption, Reflection,
refraction and diffusion.
Sonic waves that are reflected back(echoed) towards the
transducer cause a change in the thickness of piezoelectric
crystal, which in turn produces an electrical Signal, that is
amplified , processed and finally displayed as an image on a
monitor.

109. 109
The production of ultrasound images is based on the
generation and reflection of ultrasound waves.

110. 1. Alveolar bone, if healthy, is hyperechoic because it exhibits a total
reflecting surface that appears white in the image.
2. The roots of the teeth are also hyperechoic and appear as an even
whiter shade than bone .
3. Solid lesions in the bone are echogenic or hypoechoic presenting
various intensities of echoes and appear as different shades of gray .
4. A bone cavity filled with clear fluids (i.e., serous) is anechoic (or
transonic) because it has no reflection and it appears dark .
110

111. 5. A bone cavity filled with fluids - degrees of darkness, depending on
the contents of the fluid.
6. The irregular bone (resorbed) around a lesion shows a
dishomogeneous echo .
7. The reinforced bony contour of a lesion is usually very bright
(hyperechoic) .
8. By applying the CPD to the examination procedure, the presence and
direction of blood vessels around and within the lesion can be
detected.
9. The mandibular canal, the mental foramen, and the maxillary sinus
can often be distinguished and appear mostly transonic.
111

112. 112
Ultrasound real-time imaging of two different lesions in the jaws. A1, Periapical lesion (granuloma)
as seen in the ultrasound image it is an ‘‘echogenic’’ area where echoes are reflected at different
intensities. A2, The same lesion after the application of color power Doppler. The colored spots
represent the vascularization within the lesion.
B, Ultrasound image of a cystic lesion ,it shows an ‘‘anechoic’’/’’transonic’’ cavity; the reinforced
lower bone contour of this lesion is hyperechoic’’ .

113.  Advantages
 Ultasound imaging showed enough potential sensitivity to
allow the disctinction between a cyst and a granuloma, to
define a mixed type of lesion.
 Immediate and long term response to the treatment-The
application of CPD has the sensitivity to detect the presence
of newly formed vessels.
 Non-invasive painless method and has lower biological
adverse effects.
113

114.  Drawback-
 Images interpretation is very critical and needs an expert eye,
and there are not landmarks to help distinguish the position
of a lesion within a given area of mouth.
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115.  Recent advances in imaging technologies have revolutionized
dental diagnostics and treatment planning. Correct use of
technology and their correct interpretation following ALARA
principle and cause effectiveness, newer radiographic techniques
can help to detect pathologies in very early stages, which
ultimately help to reduce morbidiy and mortality and improve the
quality of life of the patient.
 Digital radiography is a reliable and versatile technology that
expands the diagnostic and image sharing possibilities of
radiography in dentistry.

116.  Endodontics –Ingle 5th and 6th edition
 Pathways of pulp—Cohen , 10th edition
 A guide to dental radiography—Rita and Bourne
 Oral radiology—White and Pharoah, 5th edition

117.  Digital Radiography:An Overview. The Journal of Contemporary Dental
Practice, Volume 3, No. 4, November 15, 2002
 Dental Imaging - advances in conventional and digital radiography.
Clinical Update, 2003, Vol. 25, No. 4
 Filmless imaging: The uses of digital radiography in dental practice.
PAUL F. VAN DER STELT, J Am Dent Assoc 2005;136;1379-1387

118. 118