craniofacial imaging-Recent advances

Ortho radio diagnosis
clinician is to apply his skills
the boundaries of these
The real task for the
and his techniques within
biologic limits.
6

Comprehensive
Diagnosis
Study cast
Analysis
Functional
Analysis
Roentgeno-
Cephalometric
Analysis
Radiographic
Analysis
Photographi
c Analysis

History
Nothing materializes as if by magic overnight.
Even Roentgen’s discovery depended upon the development and
application of three converging thoughts ;
Movement of the electrons
in a conductor.
Phenomena by which
materials exert attractive
or repulsive forces on
other materials.
Complete absence
of air.
ELECTRICITY
VACUUM MAGNETISM

Discovery of X-Rays
 While experimenting and searching
for the invisible light rays on a low
pressure Crookes tube, to his surprise a
fluorescence screen covered with
Barium Platino cyanide started to glow
brightly. The screen was on a table some
distance away.
Wilhem Conrad Roentgen
November 8th 1895

 While investigating he accidentally placed his hand between
the tube and the fluorescent screen, to be surprised by seeing a
faint image of the bones of his hand on the screen.
 Tracing back the rays to their source, he found out that the rays
were produced, whenever and wherever the cathode rays
encountered matter.

His curuosity dint end here..,
 He proceeded to make 1st radiograph of human body; he
placed his wife’s hand and exposed it for 15 minutes.
Anna Bertha

 He termed these rays as “ X- Rays ’’ after the mathematical
symbol for the unknown – X, the American way.
 These rays were ultimately called as Roentgen Rays.

Early pioneers of oral radiology:
Otto Walkhoff, Germany
 Took first dental radiograph in1896.
 He placed a photographic glass plate in his mouth for 25
minutes to expose to X-Ray beam and obtained the image of
crowns of maxillary and mandibular teeth.
William Morton and Kells -
 Made the first dental radiographs in America.

Later…
 An autopowered X-Ray was used
by physicians at the turn of the
century.
 The early X-Ray machine was
small enough to be portable, and
its tube could be operated on a
car battery.
Wires leading through a
bedroom window.

which radiograph to Prescribe ?
According to AOO for a orthodontic treatment a
minimum of lateral cephalogram, opg and 3
anterior IOPAs are essential.

Pt presents
with
orthodontic
problem
Is the Pt a
candidate for
orthodontic
Rx
Obtain lateral
Cephalogram
Evaluate
the pt
individual
radiographi
c needs


Is the Pt
heavily
restored or
exhibits PDL
problems


Obtain OPG,
Ant IOPAs
Obtain complete
mouth survey
(IOPAs & bitewing)
AJODO -1992

Does the Pt
have a
severe facial
asymmetry
Does Pt
have
significant
TMJ signs &
symptoms
If growing,
growth
modulation
or subjecting
for surgery
Diagnose
and treat
the patient
Obtain TMJ
tomograms
Obtain hand
wrist
radiograph
Obtain PA
Cephalogram




“An unobstructed or complete view of a region in every
direction”
Is based on the principle of the reciprocal movement of an X-
Ray source and an image receptor around a central point or
plane called image layer.
PANORAMIC IMAGING

 It is a technique for producing a single tomographic image of
the facial structures that include, both the maxillary and
mandibular dental arches and their supporting structures.

20
The 4 Diagnostic regions in OPG
Dentoalveolar
region
Maxillary regionMandibular region
TMJ, including retromaxillary
region

INTERPRETING:
1) Condylar process and temperomandibular joint
2) Coronoid process
3) Ramus
4) Body and angle

The maxilla can be divided into different major sites for examination:
1) Cortical boundary of the maxilla, including the posterior border and the alveolar
ridge
2) Pterygomaxillary fissure
3) Maxillary sinuses, Zygomatic complex, including inferior and lateral orbital rims,
zygomatic process of maxilla.

1) Nasal cavity and conchae
2) Temperomandibular joint

 The maxillary sinuses are well visualized on panoramic
images.
 The borders are entirely outlined with cortical bone, roughly
symmetric, and comparable in radiographic density. The
borders should be present and intact.

1) Palatoglossal air space
2) Nasopharyngeal air space
3) Glossopharyngeal air space

 The tongue arching across the film under the hard palate
 lip markings
 The nasal septum,
 Ear lobes,
 Nose, and Nasolabial folds.

1. Teeth number, position and anatomy should be evaluated.
2. Tooth germ positions.
3. Atypical sequence of eruption.
4. Ectopic tooth germs.
5. Over retained primary teeth.
6. Supernumerary teeth.

7. Pathological root formation.
8. Root resorption.
10. Bone loss, bony pockets.
11. Third molars – orientation, configuration of roots
and its relationship to the surrounding structures.
12. Endodontic obturations, crowns, and other fixed
restorations, should be noted.

 Although the cephalometric radiograph in standard
lateral projection was introduced into orthodontics
during 1930s, the method has become routine in recent
years.
 Today cephalometric analysis has firmly taken place in
dentofacial diagnostic procedures.

uses
1. Assessement of the facial
skeleton
2. Relationship of the jaw
bases
3. Relationship of the axial
inclination of incisors
4. Assessment of the soft
tissue morphology
5. Growth pattern and
direction
6. Localization of the
malocclusion
7. Treatment possibilities and
limitations.

Cephalometrics is used in three major areas:
 Morphological Analysis: By evaluating the
sagittal and vertical relations of dentition,
facial skeleton and soft tissue profile.
 Growth Analysis: By taking two or more
cephalograms at different time intervals and
comparing the changes.
 Treatment Analysis: By evaluating alterations
during and after therapy.

Tongue Position:
Root: It is usually flat in cases of mouth breathing.
In all other cases slight contact of the tongue usually occurs
with soft palate.
Dorsum: Is high in Class II malocclusion and in deepbite cases.
Tip: Is retracted in cases of Class II div 1 malocclusions.
In openbite, tip is forward.

The changes in the position of the tongue relate closely
to the different types of malocclusion.
In Class III the tongue is flat
and lies downward and forward.
And With Class II tongue is
backward.

 The X-Ray passes in a posterior anterior direction through the
skull.
 A cassette is positioned vertically in a holding device.
 Frontal view is particularly important in cases of
dentoalveolar & facial asymmetry, crossbites and functional
mandibular displacements.

Uses
To detect developmental abnormalities like facial asymmetries.
Used to examine the skull for presence of disease, trauma, developmental
abnormalities.
Used to detect progressive change in the mediolateral dimensions of the
skull.
It offers good visualization of facial structures including frontal, ethmoidal
sinus, nasal fossa and orbits.

 Both the dental midline
and skeletal midline is
not matching in rest and
occlusion.
LATEROGNATHY
 Here at rest dental
midline is matching but
in occlusion there is shift
of the mandible.
LATEROCLUSION
At rest At occlusion

 Transcranial Projection
 Transpharyngeal Projection
 Transorbital Projection

Film placement:
The cassette is placed flat
against the patient’s ear &
centered over the TMJ of
interest, parallel to the sagittal
plane.

Diagnostic information:
 Transcranial projection is
useful for identifying gross
osseous changes on the lateral
aspect of the joint only.
 We can see the position of the
head of the condyle within the
fossa, the shape of the glenoid
fossa & articular eminence.
Closed mouth
Open mouth

Film Placement:
 The cassette is placed flat
against the patient's ear and
is centered to the external
auditory meatus parallel to
the sagittal plane.
 Open mouth position.

Structures Shown:
 Sagittal view of the
medial pole of the
condylar head and neck,
usually taken in the
open mouth position.
 This view is effective for
visualizing erosive
changes of the condyle.

Film Position:
 The film is positioned behind
the patient's head at an angle of
45° to the sagittal plane &
perpendicular to the X-ray
beam.
Position of Patient:
 The patient head is bend 100
down so that canthomeatal line
is horizontal.
 Here patient mouth is opened
maximally to avoid
superimposition of the articular
eminence.

Diagnostic information:
 The entire mediolateral
dimension of the articular
eminence, condylar head &
condylar neck is visible, so is
particularly useful for visualizing
condylar neck fractures.

Limitations of the 2D
images
1. A conventional headfilm is a 2D representation of a 3D
object.
2. Cephalometric analyses are based on the assumption
of a perfect superimposition of the right and left sides
about the mid sagittal plane.

3. A significant amount of external error, known as
radiographic projection error, is associated with image
acquisition.
a) Magnification
b) Distortion
c) Patient positioning
4. In cephalometry, errors are most likely in locating the
landmarks due to the lack of well defined outlines,
hard edges and shadows.

52
Change is the only CONSTANT.
In orthodontics there are many ADVANCES taken place,
especially in the area of Craniofacial Imaging.

53
“Imaging beyond imagination”

1. In terms of spatial distribution of the picture
elements.
2. In terms of different shades of grays of each of
the pixels.
The term digital refers to the numeric format of the
image content.
Images
Conventional
ANALOG
PROCESS
Contemporary
DIGITAL
PROCESS

What is an Analog image ?
An analog image, such as a radiographic film, has
virtually an infinite number of elements, with each
element represented by a continuous gray scale.
What is a digital image ?
A digital image is a matrix of square pieces, or picture
elements (pixels), that form a mosaic pattern from which
the original image can be reconstructed for visual display.

Characteristics of digital images
 A digital image is composed
of picture elements (pixels)
that are arranged in a
2-dimensional rectangular
grid.
 A pixel is the smallest
element of a digitized image.
Radiographic images
generally use gray color with
an intensity value between 8
bits (0 to 256 shades of
gray).

 Image resolution refers to the degree of sharpness of the
image. Resolution is determined by the number of pixels
per given length of an image (pixels/mm), the number of
gray levels per pixel (bits).

PRINCIPLE OF DIGITAL IMAGING
Normal X-ray Digital X-ray
Silver halide grains in x-
ray films perceived as
different shades of gray
by the human eye due to
varying densities
Silver halide grains are
replaced by small light-
sensitive electronic
sensors which produce
an electric signal
depending on the
voltage recorded by
the sensor.

CONVENTIONAL
(ANALOG)
DIGITAL
CEPHALOGRAM

INDIRECT DIRECT
a) Scanner
b) Photostimulable
Phosphor plate
(PSP)
a) Charged Coupled Device
(CCD)
b) Complementary metal
oxide semiconductor
(CMOS)
c) Charge injection device.
(CID)
METHODS OF IMAGE ACQUISITION

• X-ray source
• Intraoral sensor
• Computer
It is used to digitize, process
and store information received
from the sensor within 5 – 10
sec and display image on
computer screen.
Radiovisiography

Image enhancement:
1. Adjusted image is an improved version of
the original one.
2. Most image enhancement operations are
applied to make the image visibility more
appealing.
3. This can be enhanced by increasing
contrast, optimizing brightness.
4. Brightness & contrast
5. Color
6. Digital subtraction radiography

Color:
 Most digital systems currently provide opportunities for
color conversion of gray scale images also called
pseudo-color.
 Neither diagnostically nor educationally useful.

1. About 50% - 70% less radiation than conventional radiography
2. Immediate picture
3. Image improvable with image processing
4. Elimination of darkroom, film, and chemical processing
5. Reduce cost of daily maintenances
6. Easy to share by digital networking
7. Easy to store.
8. Easy for client education.
BENEFITS OF DIGITAL RADIOGRAPHY

1) Expensive.
2) Spare parts are expensive.
3) System, network, and database safety and security.
4) Potential training needs.
5) Cross infection.
DRAWBACKS OF DIGITAL RADIOGRAPHY

Computers With Tiny Carbon Tubes On
Silicon Chips
 It includes use of extremely tiny carbon 'nanotubes'
instead of copper conductors to interconnect parts
within integrated circuits (ICs).
 One advantage of using carbon nanotube within
integrated circuits is that these interconnects have the
ability to conduct very high currents, more than a million
amperes of current.

Digital subtraction radiography:
 Subtraction in digital radiography is another
image enhancement method.
 When 2 images of the same area in the
mouth are registered and the image
intensities of the corresponding pixels are
subtracted, a uniform difference image is
produced.

 The 1st image can be subtracted from the 2nd one to
identify changes that may have occurred during a
certain time period.
 If there is a changes seen between pre and follow up
examination, these changes show up as loss or gain of
hard tissues.

 In order for subtraction radiography to be
diagnostically useful, it is imperative that the
both the radiographs taken at different intervals
must be reproducible.
 BUT IT IS VIRTUALLY IMPOSSIBLE.
Some form of mechanical standardization if done, it
may reduce the reliance on image processing and will
generally produce better results.

Ortho radio diagnosis 71
XERORADIOGRAPH
Y

 It is a technique of making dry radiographs by a totally photoelectric
process, using metal plates coated with a semiconductor, such as
selenium.
 Special features-
1. Prononced edge enhancement.
2. High contrast.
3. A choice of positive & negative displays.
4. Good detail.
5. Does not require silver halide crystal containing films, hence no
dark room processing.
6. Reduced patient exposure.

 In this technique instead of
conventional film, selenium
coated photoreceptor plate
with uniformly distributed
electrostatic charge is used
as the image receptor.
 The charged plate is held in
a light-tight cassette in a
plastic bag and is exposed
to x- ray.
 The X-rays beam is left as a
charged pattern on the
plate.
Selenium
plate
Selenium
plate
++ ++ + + +
X-Ray exposure
Charged pattern
on the plate
Selenium
plate
Lines of forces
++ ++ + + +
++++++++++++++++
Selenium
plate
Toner
distribution of
charges

uses
1. Mammography.
2. Sialography.
3. Height of the alveolar crest is better visualized.
4. Periodontal and periapical assessment.
5. Caries seen more readily.
6. Tmj tomography.

 The graphical information contained within the
cephalogram is transformed into numbers (digits) that
the computer can store, retrieve and manipulate.
 3 possible approaches may be used to perform a
cephalometric analysis -
Digitization

1
• Manual tracing
2
• COMPUTER AIDED ANALYSIS
• Computer aided- landmarks are located
manually & digitized into a computer system,
then the computer completes the analysis
3
• COMPLETELY AUTOMATED.
• Cephalogram is scanned into the computer
first, computer automatically locates landmark
and performs ceph analysis.

Two methods –
1) DIGITIZING TABLET –
it is a peripheral computer device that has 2
parts, tablet (writing surface) & stylus.
Data input can be 2 modes - POINT AND
STREAM MODE.
2) DIRECTLY ON THE SCREEN -
Here the image is fed directly into the
computer, and the mouse is clicked to
identify the landmark points.
Once digitization is complete, any analysis
can be performed in seconds

Spatial spectroscopy –
Image pixels that are in regions of high intensity gradient
are identified as edges, & these edges are assumed to
be object boundries:
 it involves 4 steps –
1) Remove noise
2) label pixels according to edginess
3) Connect pixels and label edges
4) Find landmarks based on position or relationship to a
labeled edge.
3
• COMPLETELY AUTOMATED
• Cephalogram is scanned into the computer first,
computer automatically locates landmark and
performs ceph analysis.

Signal to noise ratio
• The useful signal for any imaging system
needs to be compared with backround
noise.
• In analog film – backround noise is
comparable to the base density and fog.
• Signal noise ratio improves with increased
radiation dose for all systems.

 Introduced in medicine in early 70’s – Godfrey
Hounsfield.
Tomography means an image of layer of tissue, and a
computer is necessary to generate the pictures; hence
the name – COMPUTED TOMOGRAPHY

Equipment
- Scanner (movable X ray table + gantry)
- Computer system
- Display console

An image of a layer
within the body is
produced while the
images of the
structures above and
below that layer are
made invisible by
blurring.
PRINCIPLE

Remnant radiation of this
beam is
detected by scintillation crystal.
Analog signal is then fed into
computer
Digitized and analysed by
mathematical algorithm
Data is reconstructed as an axial
tomographic image.

To acquire a volume of data, 2 scanning modes are
possible-
1) SEQUENTIAL – the table with the patient is
positioned and the attenuation data are acquired.
Then the table is moved to a next position, and a new
acquisition is made.
2) SPIRAL – the table moves from the initial position
to the end position while the X-Ray attenuation data
are acquired.

 Single slice CT – From an X-Ray source, a fan beam X-
Ray is emitted through the imaged object towards a
single array of detectors.
 Multiple slice CT – Multiple slices can be produced
using adjacent detector arrays.

 Conventional radiography has the following short
comings,
1. Difficulty in assessing position (buccal/palatal)
2. Difficulty in assessing level and extent of resorption of
adjacent teeth

CT scan was advised
 Can determine the exact position of an
impacted tooth.
 Clear serial sections may be taken at
graduated depth.
 This technique allows the elimination of
superimposition of other structures.

Position for axial section Position for coronal section

96
AXIAL
Right left
Right left

98
CORONAL
RightleftRightleft

 It completely eliminates
the superimpositions of
images of structures
outside the area of
interest.
 High contrast resolution
- it can differentiate b/w
the tissues of less then
1%.
 Geometric accuracy.
 Tissue Characterization.
 Digital image
processing.
Expensive
Radiation dose.

Limitations of CT Scan
However, even though the images are obtained at
different planes, the analysis by the orthodontist
is still limited. The images are seen as 2
dimensional on film and computer screen.

 The CT images can be manipulated to undergo a three-
dimensional reconstruction of the image by a procedure
called INTERPOLATION.
 The original voxel - rectangular units, should be
dimensionally altered into multiple cuboidal voxels.

 Creation of these new cuboidal
voxels allows the image to be
reconstructed in any plane without
loss of resolution.
 The final image can be fed through
a computer aided design system
and viewed on a computer screen.

Steps :-
1. Image which is obtained
consists of individual pixels
along with the face of the
volume called VOXEL .
2. Cuboid voxels can be
created from the original
rectangular voxel by
INTERPOLATION.

104
Magnetic Resonance Imaging

MECHANISM OF MRI
 The theory of MRI is based on the magnetic properties
of an atom.
 Atomic nuclei spin about their axis much as the earth
spins about its axis.
 In nuclei in which protons and neutrons are evenly
paired, the spin of each nucleon cancels that of another,
producing a net spin of zero.
 Where as the nucleus of the element hydrogen contains
a single, unpaired proton and therefore acts as a
magnetic field.

 To produce an MR image, the patient is placed
inside a large magnet, which induces a
relatively strong external magnetic field.
 This causes the nuclei of many atoms in the
body, including hydrogen, to align themselves
with the magnetic field.

108
N
S
Externally applied magnetic
field
Higher energy
state
Lower energy
state

 Energy in the form of an electromagnetic
wave in the radiofrequency range from an
antenna coil is directed to tissue.
 Those protons that have a larger
frequency matching that of the
electromagnetic wave absorb energy and
shift or rotate away from the direction
induced by the magnet.

 After removing the application of an radiofrequency
signal, 2 events occur simultaneously-
1) The radiation of energy is released from the body.
T1 relaxation time
2) Return of the nuclei to their original state.
T2 relaxation time
 This energy is detected by the sensors and used to
construct the MR image by computer.

 When images are displayed, intense signals
show as and weak ones as and
intermediate as shades of gray.
 Cortical bone and teeth with low presence of
hydrogen are poorly imaged and appear black.

 Indications
 Assessing diseases of the TMJ
 Cleft lip and palate
 Tonsillitis and adenoiditis
 Cysts and infections
 Tumors
 Contraindications
 Patients with cardiac pacemakers.
 Patients with cerebral metallic aneurysm clips.
 Stainless steel and other metals produce artifacts.

Advantages
 Magnetic forces - does not produce any biological side
effects.
 Non invasive technique and can be used in most patients.
Short comings
 Inability to identify ligament tears or perforations
 Cannot be used in patients suffering from claustrophobia.

The limiting factor in the use of MRI
in Orthodontics
Apart from economic cost, the functional modality of
MRI depends on the presence of large numbers of
hydrogen nuclei in the tissues being imaged.
Because hard tissues such as bone, enamel and dentin
contain few if any free hydrogen nuclei, the use of this
diagnostic tool is restricted in orthodontics to the
visualization of the cartilaginous components of
temperomandibular joint.

 For 3D imaging, 3D CT imaging is needed to
volumetrically measure the patient’s anatomy.
 However for cephalometric analysis, the availability of 2D
lateral and frontal is beneficial to indicate landmarks
accurately and repeatably in a 3D scene.

 To avoid extra radiation dose, and to achieve this
geometric relationship, lateral and frontal
cepahlograms are computed from the CT data.
 In this way an unlimited number of virtual X-Ray
images of the skull can be computed.
 To compute an virtual image, a bundle of parallel
rays are cast through the CT volume.

 The orientation of the virtual X-Ray image plane is
perpendicular to the bundle of rays. Therefore, this X-Ray
image can be added to the 3D scene as a textured
rectangle.
Virtual cephalogram computed
from the CT volume

Pre op -, mandibular asymmetry with chin deviated to Rt. (
Early loss of right condylar process )

Pre op 3D surface hard tissue
representation
Linked frontal & lateral virtual ceph
Right Left

Virtual planning of a reverse L – osteotomy
in the right ramus was planned.
Planning for reconstruction of right
condylar process & placement of
unilateral distractor & osteotomy of
coronoid process

Post distraction –
1 week after distractor
removal
Lengthening of the vertical ramus and
improvement in chin projection,
and increase in Anterior and Posterior
facial height.

124
Teleradiography

 Electronic transmission of radiologic images from one
location to another for the purpose of interpretation,
consultation or both.
 Teleradiology system allow direct digital or digitized film
images to be transmitted to distant locations, where
they can be viewed and downloaded to hard copy for
reading and interpretation.
 Transmission of images requires that the image files be
in a digital format.

TRANSMISSION OF IMAGES
Digital images may be saved in a variety of file formats.
Commonly used are -
TIFF – tagged image format file.
WAN- wide area network.
IP - Internet protocol.
JPEG – joint photographic expert group.

Transmission and receiving
console system
Staff monitoring the
transmission system.

Prototype; Derived from Latin - "first form"
 Rapid Prototyping is a method in which the part is
created by a layer-additive process.
 By using a specialized software a 3-D CAD model is
obtained.
 Then the RP machine constructs the part layer by
layer until a solid replica of the CAD model is
generated.

 Rapid prototyping takes virtual designs (from CAD
model), which transforms them into cross sections, and
then create each cross section in physical space, one
after the next until the model is finished.
 It is a WYSIWYG process where the virtual model and
the physical model correspond almost identically.
WYSIWYG acronym for
What You See Is What You Get.

Techniques in Rapid
Prototyping
131
Most commercially available RP machines use one of six
techniques.
They are:
1. Stereolithography (STL)
2. Laminated object manufacture (LOM)
3. Selective laser sintering (SLS)
4. Fused deposition modeling (FDM)
5. Solid ground curing (SGC)
6. 3-D ink jet printing

Basic steps in Prototyping
1. CAD model creation
2. Conversion to STL format
3. Slice the STL format
4. Layer by layer construction
5. Clean & finish

Pre treatment – elevation in
palatal mucosa

Image from STL file after elimination of all the
tissues and structures

Findings from prototype models
 Crown of canine was tipped toward the palate
 Was 2.1mm away from the root of maxillary right
lateral incisor
 Root apex was over the apex of maxillary right
first premolar
 The model was used as an aid during surgical
exposure.

Advantages
 Diagnosis & treatment
planning
 Communication with
patients
 Surgical access made
easier
Disadvantages
 Exposure to CT
radiation
 Conventional
radiographs still
required for records
 The COST

Digigraph
Equipment -
 Computer system
 Video camera with light source
 Sonic digitizing probe with receptor
microphones and
 Patient seat with a head holder.
 With digigraph, any point can be located in
3 planes of space.

Head holder
 More comfortable
 Ear rods and forehead
clamp.
Attached video monitor
Images, text, numerical data can be
displayed, stored, modified using a light
pen or computer keyboard

 Digitizing handpiece with
removable, sterilizable tips
 Landmark location is recorded
in 3 dimensional coordinates (x,y,z)
 The time it takes the sound to
reach each of the microphones
determines the landmark location.

Digitization
142
 4 microphones are arranged strategically above the Pt’s
head. A sound emitting probe is placed on various
landmarks directly on the Patient’s head.
 Each landmark is recorded by emitting a sound.
 The computer calculates the exact position of landmark
in 3D by analyzing the sound arriving at each
microphone.

With the Pt in position, lateral
and frontal cephalometric points
are easily digitized.

The 2 principle differences that
distinguishes CBCT from
traditional CT are –
1) The type of imaging source
detector complex.
2) Method of data acquisition.
14

146
• X-Ray source is a high
output rotating anode
generator.
• Uses a fan shape X-
Ray beam.
• Image sensors used
solid state detectors
arranged in a 360
degree array around
patient.
• In contrast to CT it uses
a low energy fixed anode
tube similar to that used
for OPG machines.
• Uses a cone shaped X-
Ray beam.
• The image sensors used
are special image
intensifier & solid state
sensor.

 CBCT uses 1 rotation sweep of the patient. Image data
can be collected for a complete maxillofacial volume or
limited area of interest.
 Scan times vary from 10 – 90 sec.
 Dose is also reduced.

Possible Fields of View Include
(A) 3 Inches, (B) 6 Inches, (C) 9 Inches, And (D) 12
Inches.

• Extended FOV scanning incorporating the craniofacial region
is difficult to incorporate into cone-beam design because of
the high cost of large-area detectors.
• The expansion of scan volume height has been accomplished
by one unit (iCAT Extended Field of View model) by the
software addition of two rotational scans to produce a single
volume with a 22-cm height.

IMAGE DISPLAY
• The availability of CBCT technology provides the dental
clinician with a great choice of image display formats.
• The volumetric data set is a compilation of all available
voxels and, for most CBCT devices, it is presented to the
clinician on screen as secondary reconstructed images in
three orthogonal planes (axial, sagittal, and coronal),
usually at a thickness defaulted to the native resolution

STANDARD DISPLAY MODES OF CBCT VOLUMETRIC DATA. (A) VOLUMETRIC 3D REPRESENTATION OF
HARD TISSUE SHOWING THE THREE ORTHOGONAL PLANES IN RELATION TO THE RECONSTRUCTED
VOLUMETRIC DATA SET; EACH ORTHOGONAL PLANE HAS MULTIPLE THIN-SLICE SECTIONS IN EACH
PLANE. (B) REPRESENTATIVE AXIAL IMAGE. (C) REPRESENTATIVE SAGITTAL IMAGE, AND (D)
REPRESENTATIVE CORONAL IMAGE

Available CBCT Imaging Systems – Worldwide
Unit Model(s) Manufacturer/Distributor
Accuitomo 3D Accuitomo - XYZ Slice View
Tomograph/Veraviewpacs 3D
J. Morita, Japan
AUS: Henry Schein Halas
Galileos Galileos Sirona Dental Systems, Germany AUS:
Sirona Dental Systems
Hitachi CB MercuRay / CB Throne Hitachi Medical Systems, Japan AUS:
Unknown
iCAT i-CAT* / Platinum Imaging Sciences Int'l, USA AUS: Body Logic
Australia
ILUMA Ultra Cone Beam CT Scanner MTEC Imaging, USA/Kodak
AUS: Currently unavailable
KaVo 3D exam
* Announced at IDS 2007
KaVo, Germany
AUS: Currently unavailable
Newtom 3G / NewTom VG/5G QR, Inc. Verona, Italy AUS: Inline Systems
Picasso Series Trio / Pro / Master E-Woo Technology, Korea AUS: Integradent
PreXion 3D TeraRecon Inc., USA AUD: Currently
unavailable
Promax 3D Planmeca OY, Helsinki, Finland AUS: Henry
Schein Halas
Scanora 3D CBCT Soredex , Helsinki, Finland AUS: Currently
unavailable
SkyView 3D Panoramic Imager My-Ray Dental Imaging, Italy AUS: Currently

FOV 8 cm x 8 cm FOV 16 cm x 4 cm FOV 16 cm x 6 cm
upper jaw TMJ
FOV 16 cm x 6 cm
lower jaw
FOV 16 cm x 8 cm FOV 16 cm x 10 cm
FOV 16 cm x 11 cm FOV 16 cm x 13 cm FOV 23 cm x 17 cm

3D Facial photo
• Planmeca ProFace® is an exclusive 3D facial photo system
available for all of Planmeca 3D X-ray units.
• This integrated system produces a realistic 3D facial photo and
CBCT image in a single imaging session.
• can also take a separate 3D face photo without exposing your
patient to any radiation.

Create a 2D photo series automatically
Pre and post-operative comparisons Measure distances and relationships between bone
and soft tissue
Superimpose images for comparison Deviate images for instant viewing of changes

Impacted Canines
• In the past, orthodontists have used the tube shift technique to compare two
periapical radiographs taken at different beam angles to determine the facial/lingual
position of the impacted canine.
• This same lingual, opposite buccal rule is helpful in determining whether the
impacted canine is labial or lingual to the incisor roots; however, the degree of
displacement is difficult to determine
• These 3D images are beneficial in determining the proximity of adjacent incisor and
premolar roots.
• Which can be invaluable in determining the ease of uncovering and bonding and the
vector of force that should be used to move the tooth into the arch with a lesser
chance of adjacent root resorption

Root Resorption
• Most root resorption involved in orthodontic treatment can be readily
viewed on periapical radiographs.
• However, resorption that occurs on the facial or lingual side of the
tooth is difficult to ascertain and quantify with this 2D view.
• CBCT scanning allows for better viewing of resorption on either of
these surfaces.
• Removal of the deciduous canine adjacent to the impacted permanent
canine has been shown to be effective if accomplished early.

Orthodontic Temporary Anchorage Device Placement
• CBCT images allow more accurate and dependable views of the interradicular
relationships than panoramic radiographs.
• These images allow not only more successful placement but also better treatment
planning of where these TADs should be placed so that proper force vectors can be used
during orthodontic treatment.
• CBCT data can be used to construct placement guides for positioning mini-implants
between the roots of adjacent teeth in anatomically difficult sites.
• The quality of the bone in the proposed placement sites can be evaluated before
insertion of the mini-implants.
• Quantifying the thickness of the palatal bone can aid in determining the size and
location of any TADs that may be treatment planned for the palate.

Asymmetry Evaluation
• It can be difficult to evaluate the bony asymmetry of orthodontic patients using
cephalometric and panoramic radiographs.
• Direct measurements can be made of these structures with CBCT imaging by
comparing the right and left sides.
• Software companies are adding the ability to extract (segment) the mandible or
maxilla from the CBCT image and evaluate the bone independent of the other
structures.
• In addition, the unilateral nature of posterior cross bites can be diagnosed more
specifically.
• A determination of an asymmetric maxilla or mandible can be accomplished
more easily by viewing and measuring the bones in 3D.

TMJ Degenerative Changes
• Conventional tomography has been used extensively for the evaluation of TMJ hard
tissues; however, technique sensitivity and the length of the examinations made it a
less attractive diagnostic tool for the dental practitioner.
• CBCT images of the TMJ have been shown to provide greater reliability and
accuracy than tomographic or panoramic views in detecting condylar erosions.
• With temporomandibular dysfunction continuing to be a haunting pathology in some
orthodontic cases, it is important to view the anatomy of these patients’ joints
carefully before, during, and after orthodontic treatment.
• Current software solutions allow the visualization of TMJ osseous elements isolated
(segmented) from other surrounding structures.

Soft Tissue
• Frontal photographs are used to judge symmetry, but without numerous
views from different angles, it is difficult to gain a good feel of facial
symmetry.
• Using the soft tissue data gathered in the CBCT scan, it is possible to rotate
and tilt the head in an infinite number of positions to evaluate symmetry of
the soft tissue.
• It is difficult to gain a good view of the nose with some CBCT machines
because this area is at the edge of the image package.
• Recently, various companies have offered photographic imaging packages
to coordinate with the CBCT data, using multiple camera locations.

Airway
• Using lateral cephalometric radiographs, the orthodontist may
evaluate the airway in a 2D manner.
• Many studies have been accomplished and various analyses
established in this way.
• All this evaluation, however, is limited by the fact that we are
looking at a flat projection seen in a sagittal or coronal plane.
• A 3D view of the airway can be readily available with CBCT
imaging.

CBCT airway view displaying the volume of the airway and sinuses. The
most constricted region has been located and the minimum axial area
calculated

ADVANTAGES
• Ray sum or ray casting
• Multiplanar reformation
• Interactive display modes unique to
maxillofacial imaging
• Reduced patient radiation dose compared to
conventional CT
• Image accuracy
• Beam limitation
• Rapid scan time

DISADVANTAGES
1. It is definitely more expensive than classic two-dimensional
radiologic investigations.
2. The dose of ionising radiation generated is greater than in a
pantomography investigation.
3. Any movement artefacts affect the whole data set and the
whole image rather than just one part.
4. It provides limited resolution of deeper (inner) soft tissues, and
MRI and classic CT are better for soft-tissue imaging.
5. It has low contrast range (dependent on the type of x-ray
detector).
6. It has increased noise from scattered radiation and
concomitant loss of
contrast resolution.

LIMITATIONS
• Noise and contrast
• Image noise
• Poor soft tissue contrast

 Orthodontic imaging has come a long way since the
“PLASTER ERA” during the times of E.H Angle and Calvin
case when plaster was recording medium for dentition as
well as facial form.
 With advent of impression material, radiographic and
photographic film – the orthodontic patient evolved into
“FILM ERA”. Despite their limitations, these methods have
served orthodontists well as research tools, diagnostic aids
and medico-legal records.

We are now in “DIGITAL ERA” in which digital
technologies are being used to resolve previous
limitations.
Continuing evolution in orthodontic imaging and
treatment of patients is such that these
techniques will be key to future orthodontic
practice.

1) Oral radiology principle & interpretation.
White and Pharoah – 5th edition.
2) Craniofacial imaging, 2nd chapter.
Graber Vanarsdall & Vig – 4th edition.
3) 3D Cephalometry.
Swennen, Schutyser & Hausamen.
4) Color atlas of Radiology. - Klaus and H.F.
Wolf.
5) Radiographic cephalometry –
Alexander Jacobson. 1st and 2nd edition.
6) Basics of radiography & radiology –
Eric whaites.
7) Color atlas, orthodontic diagnosis –
T.Rakosi, Irmtrud jonas & T.M.Graber.

7) Current status and feature needs in
craniofacial imaging – orthodontic
craniofacial research -2003.
8) Digital imaging in dentistry -DCNA 2000.
9) An algorithm for ordering Pre treatment
orthodontic radiographs – AJODO 1992.
10) Rapid prototyping as a tool for
diagnosis & treatment planning -
AJODO 2006.
11)Automatic computerized radiographic
identification of ceph landmarks.
AJODO-1998.
12) Reliability of digital cephalometric
landmark identification – SEMI IN
ORTHOD 2005.

craniofacial imaging-Recent advances

craniofacial imaging-Recent advances

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