Dental Academy Guide to Latest Advances in Diagnosis and Treatment Planning

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Recent
Advances in
Diagnosis and
Treatment
Planning.

Introduction
Original Diagnostic records consisted of
set of study models
and patient‘s orthodontic problems
Discovery of X-rays by Roentgen in 1895.
Traditional 2-D cephalographs also known as
Roentgenographic cephalometry
introduced by Broadbent, 36 years later.

Introduction
With the arrival of the cephalometric technique
and its increasing popularity
clarification of the anatomic basis for
malocclusions became possible.


Introduction

1.

2.

Several reasons for limited validity of the 2D
Cephalometry‘s scientific method :
A conventional headfilm is a 2D
representation of a 3D object.
Cephalometric analyses are based on the
assumption of a perfect superimposition of
the right and left sides about the midsagittal
plane.

Introduction
3.

a)
b)
c)
d)
e)

A significant amount of external error,
known as radiographic projection error, is
associated with image acquisition.
Size
Magnification
Distortion
Patient positioning
Projection distortion *

Introduction
4.

5.

Manual data collection and processing in
cephalometric analysis has been shown to
have low accuracy and precision.
Errors in location of landmarks due to the
lack of well defined outlines, hard edges and
shadows.


Introduction
Despite these limitations

Various ceph. analyses have been developed to
help diagnose skeletal malocclusions and
dentofacial deformities.


Introduction
Integration of computers and ceph
technology in the 1970‘s

Complex statistical analysis of growth patterns
and dentoskeletal relations were estb.


Introduction
Various technological aids were introduced.
IMAGING; most important tools used by an
orthodontist to measure and record the size
and form of craniofacial structures.
Traditionally used to record the status quo of
limited or grouped anatomical structures.


Introduction
Despite the diverse image acquisition
technologies currently available

Standards have been adopted in an effort to
balance the anticipated benefits with the
associated costs and risks.

Some of the recent advances which have taken
place in the field of diagnosis and treatment
planning are as follows;


radiographic image acquisition

3D radiographs
holographs

Arthrography
CT and MRI

II.

Cephalometric application
analysis and planning

Imaging and Image acquisition

Images

Conventional
ANALOG PROCESS
Contemporary
DIGITAL PROCESS


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Necessity :
Manipulation of data on a computer
Facilitating complex analysis
Organisation of data (CT and MRI imaging)
Biology:
Reduce patient radiation exposure
Practicality:
Decreases storage needs
transmission of images (teleradiology)


Digital Photography:

INPUT

PROCESSING


OUTPUT





Digital Camera:
uses a CCD (charged coupled device) or a
CMOS (complementary metal oxide)
semiconductor as a image sensor rather than
film.
CCDs are small sensors
light
electric charge

Image quality

• sensor pixel count
•Tonal range
• color purity

• Lighting etc…..

Compression using JPEG (Joint photographic
experts group format) or TIFF(Tag image file
format).


1.
2.
3.

No. of images stored depend on
Capacity of the storage device
Resolution at which the picture was taken
Amount of compression used.*
3:1 – no loss of information
upto 20:1- some loss , but clinically insigf.

Video Imaging.
With the integration of
computers and cephalometric
technology in the 1970s,
complex statistical analyses of
growth patterns and
dentoskeletal relations were
established.
The speed of computerized
cephalometric programs has
helped streamline the laborious
manual measurement of patient
cephalograms and the creation
of the visualization treatment
objective (VTO).

Video Imaging.
In the VTO of an
orthognathic surgery case,
the clinician classically has
used acetate templates of the
teeth and jaws to predict
orthodontic and surgical
movements and the final
profile is determined by the
reaction of the soft tissue to
the hard tissue movements.


Video Imaging.
Cut photographs and move the sections in a
way that somewhat simulates the surgical
outcome, but does not allow the planner to visualize
limiting factors such as the dental relationships (overjet) or
differential soft tissue reaction to hard tissue movement. Gaps
in the manipulated photographs are unavoidable.


Video Imaging.
Cephalometric digitizing programs may be
used in automating these predictions and, in
both cases, single line profile renderings serve
as the profile outline of the final treatment
goal.
Profile line renderings may represent a
reasonable feedback system for the
orthodontist, but has little cognitive value to
the patient.

Video Imaging.
Video imaging technology
allows the orthodontist to gather
frontal and profile images and
modify them to project overall
esthetic treatment goals
The video image is much more
realistic than photograph
simulation and it is much easier
for the patient to comprehend
than just the soft tissue profile of
a cephalometric tracing.


Video Imaging.






Coordinating images and cephalogram:
Digitizing the ceph and then matching the size
of the video image to it
Digitizing the ceph and then sizing the ceph to
an existing video image (loss of calibration)
Gathering the video image of a ceph through a
calibrated video camera and matching it to an
existing video image
Simultaneous image gathering and ceph.
radiography.

Video Imaging.(advantages)






Graphic method of communication with
patients
Formation of visual template in treatment
planning.
Quantification of treatment plans.
Ease of communication with others of the
similar profession
Less time consuming and more efficient .


Digital Radiographs

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


Process of data collection
RVG
Dentoptix digital radiographic system
Cephalometric applications
DIGICEPH
DIGIGRAPH
Dentofacial Planner
Vista dent
Teleradiography

Digital Radiographs

X Ray

Sensor

Data collection:
IMAGE
Electrical
charge

digitizer

• CCDs
• Amorphous Selenium

• Amorphous Silicon
• Phosphor plates

Digital Radiographs (RVG)
Basic Principles:
sensor head

object

x-ray
source

transmitter
scintillator

CCD

converter
amplifier

fibre optic
layerwww.indiandentalacademy.com

PC

quantizer

amplifier
receiver

Digital Radiographs (RVG)
CCD -analogy
The charge of the
pixel is proportional
to the amount of
light


X-ray imaging with CCD
Scintillator
- converts x-radiation to photons (light)
Fibre optic layer
- conducts photons to CCD
- stops x-radiation

pixels

CCD
- converts photons to electrons (charge)
Electronic circuit
- amplifies the signal
- converts the analog signal to digital


Dixi2 scintillation material


x-rays

crystalline




light


x-rays



amorphous 
light

new crystalline
scintillation material
no scattering
no need for fibre optic
layer
thicker scintillator can
be used
more light to CCD
better detective
quantum efficiency


Dixi2 digital intraoral radiography
real time image acquisition
view delay 1 - 4 s
pixel size: 19 / 38 µm (selectable)
very high resolution
optimal shape and size of the sensor











Dixi2

sensor thickness 4 mm
sensor cable diameter 3 mm


Dixi2 digital intraoral radiography








Dixi2

long reach, 27 m to PC
no reset between exposures
fast multiple exposures - study
templates

versatile and easy-to-use
Dimaxis software
DICOM compatible

0301

Digital Radiographs









DENOPTIX
A radiographic technique which eliminates
silver halide film
Storage Phosphor imaging plates *
High costs of scanners (laser) needed to read
the images.
Adv. over CCDs
no wires and rigid
sensors.
Available in thin flexible films.

Digital Radiographs
Phosphor plate:
PROTECTIVE LAYER
PHOSPHOR LAYER

SUPPORT
BACKING LAYER
BAR CODE LABEL


Principle of phosphor plate imaging
Phosphor particles store the x-ray information
laser beam
releases the
stored information

exposure

A/D

digital data
erasure of the plate for reuse
0301

Digital Radiographs
Cephs and OPGs : same cassettes can be used
Intensifying screen has to be removed*
Same machine and settings can be used for
DENOPTIX and regular Cephs and OPGs .


Digital Radiographs
This digital image can be then manipulated using
various software programs.

Soft tissue filtering can be done afterwards with the software

Digital Radiographs
Advantages:
1.
2.
3.

4.

Alternative to conventional film
No dark room or scanner required
No chemicals, film mounts or film
required
Saving staff time


Digital Radiographs
5.

6.
7.

Environmental friendly; no heavy metal
wastage
Transmission of images
Enlargement of any area of interest


Cephalometric Applications
Orthodontic treatment involves synthesizing
functional and esthetic treatment goals.
Ceph. applications offer various treatment
planning procedures.
Various methods of cephalometric analysis;
1.
Hand tracing and direct measurements
2.
Direct computer digitization of the ceph.
3.
Indirect computer digitization of the ceph.



Direct digitization;
Analog info. converted into digital info.
Digitizing tablet

Electronic
pen

mouse
Cross hair
cursor

Digitizing tablet with cross hair cursor.


Modes of digitization;
1.
Point mode:

Discrete location of individual landmarks

Location of landmarks in a predetermined
sequential manner

Visual ceph. generated by connection of dots
by lines and curves.

Close to accurate landmark identification

Stream mode digitization:

Stream of coordinate points recorded as the
radiographic contour is traced

Stream controlled by programmable options

Digitizing cursor or mouse to be used

More technique sensitive than point mode

Less time consuming

Landmark identification is less accurate






DIGICEPH
Method for computerized digitization, analysis
and superimposition
13 cephalometric analysis
Developed by Centre for Bio-medical
Engineering, IIT, Delhi and dept. of Dental
Surgery, AIIMS, Delhi.


Features

10 image storage data bank. (1 temp and 9
perm)

Requires a computer, printer, backlit hipad
digitizer and digiceph software

Uses point mode of digitization



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




DIGIGRAPH
Introduced by Dolphin imaging systems
Non-radiographic system
‗Digigraph workstation‘
Video images also possible
VTO
Reduces time required for records.

System design:
The DigiGraph Work Station
is about 5 feet long, 3 feet
wide and 7 feet high.
The main cabinet contains
the electronic circuitry, and
the patient sits next to the
cabinet in an adjustable chair
similar to those used with
cephalometers.

The head holder is suspended from a
beam, supported by a vertical column
attached to the cabinet (Fig. 5).
more comfortable than cephalometer head
holders, allowing the patient to remain in
the holder for several minutes.
Ear rods and forehead and posterior head
pieces are used to minimize patient
movement.

The ear rods can be removed so that facial
and intraoral images can also be recorded
while the patient is sitting in the adjustable
chair.


A model board can be inserted into the
head holder, and images of various
views can be recorded (Fig. 6) .



A light box can also be attached to the
head holder for imaging headfilms,
wristfilms, laminagraphic films, and
panoramic x-rays (Fig. 7).


The video monitor (Fig. 8) is
attached that can be rotated as the
operator moves.
Images are as sharp as those on a
standard color television.
The images, text, and numerical data
can be displayed, stored, and
modified using either a light pen or a
standard computer keyboard.


Any image appearing on the screen can be
reproduced instantaneously with one of three
"hard copy" output devices:
• Sony video imager— makes 5 " x 7 " color
prints in 60 seconds (Fig. 9).
• Polaroid freeze-frame camera— produces
Polaroid prints in 10 seconds; a 35mm slide
back can be added to make slides, which can
be sent out for processing.
• Hewlett Packard Paintjet printer— makes 8 "
x 10 " paper color copies in 4 to 8 minutes.

The digitizing handpiece (Fig. 10) is used to
record cephalometric data while the patient is in
the head holder.
The removable, sterilizable tip of the handpiece
is placed directly on the patient to record a series
of facial and intraoral landmarks. As each
landmark is located, the handpiece button is
depressed and the location is recorded in threedimensional coordinates (x,y,z). Each time the
handpiece button is depressed, an audible sound
is picked up by an array of four microphones on
the beam. The time it takes the sound to reach
each of the microphones determines the
landmark location.


Some practices may need
additional work stations where
records are not taken, but can be
viewed, modified, or analyzedConsultation Station (Fig. 11)
it can be placed in the
orthodontist's private office.
It is built on casters and can
easily be moved from chair to
chair in the operatory.

procedure


Video imaging
Images can include left or right
lateral, frontal full face, standard
intraoral, or dental casts.
These can be viewed on the
monitor singly or in traditional
groupings (Fig. 14).


Procedure


Digitizing is done in this order:
1) facial landmarks,
2) mouth-closed intraoral landmarks, and
3) intraoral landmarks requiring a disposable bite opener to be inserted.
There is a fourth category that is not digitized directly:
4) extrapolated landmarks.
Such frequently used points as sella, incisor root apices, and anterior
nasal spine cannot be measured directly from the patient using the
digitizer.
Locations of these points are calculated by the program based on the
locations of other related landmarks, using specific mathematical
algorithms.

If both lateral and frontal data are being recorded,
the lateral imaging and digitizing are performed
first. Then the patient is removed from the head
holder while it is rotated to the frontal position. An
experienced operator can perform a lateral or
frontal imaging and tracing in approximately two
minutes.
At this point, the patient is no longer required to be
present. The information is ready to be analyzed by
the orthodontist.

4. Cephalometric Analysis Display
The program produces any of 14 cephalometric analyses:


•Ricketts lateral
• Ricketts frontal
• Vari-Simplex
• Holdaway
• Alabama
• Jarabak
• Steiner
• Downs
• Burstone

Additional custom analyses may be set up, using any
combination of more than 150 cephalometric
measurements programmed into the Work Station.
The observed value is shown along with the patient
norm— adjusted for age, sex, race, and head size—
and standard deviations from the norm.


5.Tracing Display
Tracings - displayed immediately;
include planes relevant to the selected
cephalometric analysis;
An advantage - is that the nonlinear
distortion associated with radiographs is
eliminated.
- all points are recorded in a direct, oneto-one manner, allowing precise
superimposition of patient tracings over
video images (Fig. 19).

6. Visual Treatment Objective
To move part of the picture, simply touch
the light pen to two points on the screen, at
opposite extremes of the area to be moved.
The computer draws a box with the two
points at opposite corners (Fig. 20A). Then,
by touching the light pen to another spot on
the screen, the boxed image is moved to
that spot (Fig. 20B). Boxes can be moved
vertically, horizontally, or diagonally, or
they can be rotated about any point.


The software automatically blends
skin tones and smoothes profile
lines so they are consistent with the
surrounding tissue.
"before and after" format
(Fig. 21).

The light pen can also be used for
freehand drawing over any video
image.

7. Finishing a DigiGraph Session
At this point, the operator saves the data onto the two 3 ½ "
patient disks . The information on the two disks is identical,
but one is a backup.
These disks - stored
All the information for one patient's treatment usually fits on
a 3½" disk.


Teleradiology
INTRODUCTION AND DEFINITION
Teleradiology is the electronic transmission of
radiological images from one location to another
for the purposes of interpretation and/or
consultation.


Teleradiology
When a teleradiology system is used to produce the official
authenticated written interpretation,there should not be a significant loss of spatial or contrast
resolution from image acquisition through transmission to
final image display.


Teleradiology
GOALS
A. providing consultative and interpretative radiological
services in areas of demonstrated need;

B. making services of radiologists available in medical
facilities without on-site radiologist support;
C. providing timely availability of radiological images
and radiologic image interpretation in emergent and nonemergent clinical care areas;

Teleradiology
GOALS
D. enhancing educational opportunities for practicing
radiologists;
E. promoting efficiency and quality improvement; and
Teleradiology is an evolving technology. New goals will
continue to emerge.


Teleradiology
EQUIPMENT GUIDELINES
Equipment guidelines cover two basic categories of
teleradiologic systems when used for rendering the
official authenticated written interpretation:
small matrix size and
large matrix size.


Teleradiology
A. Specific Guidelines
1. Small-matrix systems (computed tomography
(CT), magnetic resonance imaging (MRI),
ultrasound, nuclear medicine, and digital
fluorography):
a. Digitization system: These systems require 0.5k x 0.5k x 8 bits
array or better.
b. Display System: These systems require a 0.5k x 0.48k x 8 bits
array or better.

Teleradiology
2. Large-matrix systems (digitized radiographic films and
computed radiography):
a. Digitization system: These systems require a 2k x 2k
x 12 bits array or better.
b. Display system: These systems should be 2k x 2k x 8
bits array or better.
.


Teleradiology
B. General Guidelines
1. IMAGE MANAGEMENT
Teleradiologic require the use of image management
for optimal performance.
Both matrix systems should include:


Teleradiology
a. capability for the selection of the image sequence for
transmission and display at the receiving site;

b. capabilities for use at the transmitting station that must
include patient name, identification number, date and time
of examination, institution of origin, type of examination,
degree of compression (if any), and brief patient history;
and

Teleradiology
2. TRANSMISSION OF IMAGES AND PATIENT DATA
New technology systems should include the current
version of the ACR image data format standard and the
DICOM network standard.


Teleradiology
PATIENT DATABASE
For radiological images transmitted by teleradiology, a
database should be available, at either the transmitting or
receiving site, that includes:
a. patient name, identification number, and date;
b. type of examination; and
c. type of images.

Teleradiology
SECURITY
Teleradiology systems should provide network
and software security protocols to protect the
confidentiality of the patient images and data.


Teleradiology (USES)
1. Teleradiology allows timely interpretation of
radiological images
2. Gives greater access to secondary consultations
and to improved continuing education.
3. Users in different locations may simultaneously
view images.
4. Appropriately utilized: can improve access to
quality radiological interpretations and thus
significantly improve patient care.

The introduction of digital image sources in the
1970‘s and the use of computers in processing
these images led the American College of
Radiology (ACR) and the National Electrical
Manufacturers Association (NEMA) to form a
joint committee in order to create a standard
method for the transmission of medical images
and their associated information.

•This committee, formed in 1983,
•in 1985 published the ACR-NEMA Standards
Publication ..

• with the release of version 3.0 a name change
- Digital Imaging and Communications in
Medicine (DICOM)


The DICOM standard today uses a specific network
protocol utilizing TCP/IP
created a mechanism for identifying Information
Objects as they are acted upon across the network.


• DICOM defined Information Objects not only for
images but also for patients, studies, reports, and other data
groupings.
• With the enhancements made in DICOM (Version 3.0),
came the development and expansion of picture archiving
and communication systems (PACS) and its interfacing
with medical information systems.


DICOM is used or will soon be used by virtually
every medical profession that utilizes images within
the healthcare industry.
These include cardiology, dentistry, endoscopy,
mammography,
opthamology,
orthopedics,
pathology, pediatrics, radiation therapy, radiology,
surgery, etc. DICOM is even used in veterinary
medical imaging applications.

Transmission of images done :
•using various forms of Ethernet
• virtual private networks (VPNs),
• within a metropolitan area (often using
ATM),
• by modem
• and via satellite

DICOM does not specify functional requirements for an
entire system,
For example, storage of image objects is defined only in
terms of what information must be transmitted and retained,
not how images are displayed or annotated.
DICOM can be considered as a standard for communication
across
the
―boundaries‖
between
heterogeneous
applications, devices and systems.

Dentofacial Planner Plus is a powerful treatment
visualization software system.
DFP Plus links digitized lateral cephalograms to digital
facial images - move the skeletal and dental components
of the cephalometric tracing - the cephalometric profile
and the facial image are automatically transformed to
represent the predicted facial form.

Specifications
Recommended hardware:
Pentium computer, Windows 95, MS-DOS 5.0 or higher
1 GB hard drive, 16 MB RAM (expandable to 32 MB)
Tseng ET-4000 graphics adapter
Microsoft bus mouse
backup system - tape or zip drive
2 serial ports, a parallel port
800 x 600, 1024 x 768 graphics resolution
Supported digitizers:

Video Cameras;
Recommended features;
S-video output, also known as super VHS or Y-C
video
high pixel count (over 320,000 pixels)
charge coupled device (CCD); generally found in Hi-8
cameras
through-the-lens (TTL) macro auto-focus for ease of
focus when acquiring intraoral images
white balance control

Cephalometrics
DFP Plus contains all of the cephalometric functionality of
Dentofacial Planner,
A digitized radiograph is used as the starting point for a
wide variety of cephalometric analyses and
superimpositions, growth estimation, orthodontic treatment
planning and surgical prediction.
Soft tissue profile changes are automatically computed and
displayed during treatment planning manipulations.

Flexible Cephalometric Analysis
DFP and DFP Plus share the unique functionality of
Tools(tm), that provides flexibility in customizing the
work.
Tools - mix and match measurements from several
different analyses into one or more personalized
cephalometric analyses.
easily add new landmarks, measurements and graphical
reference lines.

- automated lateral facial image manipulation through
linkage to digitized lateral cephalograms. Facial form is
automatically transformed in response to interactive hard
tissue manipulations:
Incisor retraction, advancement
Maxillary orthopedics
Functional appliance therapy
Mandibular auto- or counter-rotation
LeFort 1 maxillary surgery
Mandibular advancement, setback
Total or anterior sub-apical osteotomy
Genioplasty

Image Review:
• simultaneously showing pretreatment and predicted
images:

Other functions;
•Ceph superimposition and narrow review
•Overlay ceph tracing on image
•Semi-transparent image superimposition


Cephalometric Hardcopy
generate precise cephalometric hardcopy through the use
of pen plotters, laser printers or ink-jet printers.
Tracing size can be varied so that multiple tracings can be
generated per page, in either portrait or landscape
orientation.


VISTADENT Image management
system
VISTADENT COMPLETE™
ability to modify an image that is stored in the program,
as well as the ability to do Visual Treatment Objective
(VTO).
Images can easily be manipulated to show treatment
objectives by using standard editing features such as cut
and paste or more advanced features like the Smile
Library.

system
Ideal system requirements;
 win 98 operating system or above
 pentium processor II
64 MB RAM
1GB hard disk space


Other attachments

 digital camera or scanner
 RGB camera
Printer ( color)
 CD ROM drive


system
Easy to calculate cephalometric analysis.
The Ceph program allows one to trace and
identify your points directly from a
scanned X-RAY.
After points and tracings are entered they can
easily be edited for accuracy purposes. Then
Tracings, Analysis and Measurements can all
be printed on one page with the image.

system
The VTO feature automatically illustrates soft
tissue changes based on measurements for most
orthodontic treatment as well as many
surgeries.


Procedure;

 input - scanner / digital camera
Photographs and x –rays (tracing) are scanned
separately
 digitizing the ceph - stream mode
i) Using a digitizing tablet

ii) On screen tracing

 Aligning the ceph on the photograph
 Calibration
 Ready for use


Arthrography (TMJ)
 Radiographic invasive technique
 uses a radio opaque substance (Tc99 / Ba )
 injected into the joint space to enhance the
contrast between disc and the space


Arthrography (TMJ)
Equipment required;
 dental X ray unit
 Syringes ( 27 gauge needle )

 L.A.
 Contrast medium


Arthography (TMJ)
Procedure:

1. Anesthesia;
 27 gauge needle with 1ml of 2% lignocaine
 Subcutaneously - 5 mm anterior to tragus
 Open mouth 1 finger – forward, inward and
upward - till contact with posterior lateral
aspect of the condyl.
 Inject 0.4ml in the lower compartment

Arthrography (TMJ)
For the upper compartment;
 5 mm superior to the lower compartment
insertion site.
 The mouth opening should be more


Arthrography (TMJ)
Patient Positioning ;


Arthrography (TMJ)
Opacifying the Lower joint;
 a new 27 gauge needle is used
 insert 1cm posterior to the tragus of the ear

 Needle is placed on skin overlying the condyl
 mouth should be open at this time
 0.5 – 1ml injected


Arthrography (TMJ)
Opacifying the upper joint;
 27 gauge needle is used
 insert 5mm superior to insertion of the lower
compartment needle
 mouth should be open more than halfway
 After contacting bone, withdraw 1 -2mm and
inject 1- 1.5ml

Arthrography (TMJ)
Exposure factors;
 65 kVp for speed of 400 (film)
 40 degree angle ( tomograph)

 Distance of 42‖ from source


Arthrography (TMJ)


Arthrography (TMJ)
Post – Op;
 contrast media aspirated and the spaces should
be irrigated with saline
 patient should be informed about the pain and
if it remains persistent - medication


Arthrography (TMJ)
This procedure is not used now a days because
of:
 Patient discomfort
 allergic reactions
 chances of disc perforation
 time consuming

 relatively high radiation exposure

Arthrography (TMJ)
More recent techniques for TMJ imaging
1. Bones - CT Scanning
2. Joint spaces and disc - MRI


Magnetic Resonance Imaging
Principles:
Magnetism is a dynamic
invisible phenomenon
consisting of discrete
fields of forces.
Magnetic fields are caused by
moving electrical charges
or rotating electric
charges.
Images generated from protons
of the hydrogen nuclei.*
Essentially imaging of the
water in the tissue.




The technique is based on the presence of
specific magnetic properties found within
atomic nuclei containing protons and neutrons,

Inherent property of rotating about their axis
Causes a small magnetic field to be generated
around the electrically charged nuclei.

When dipoles exposed within a strong electric
field
Orientation in response to the field
Depending on density and spatial relation

Signal interpreted and image produced

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


Equipment;
1.
The Gantry ;houses the
patient. Patient is surrounded
by magnetic coils
2.
Operating console ; where the
operator controls the
computer and scanning
procedure
3.
Computer room network.

(TMJ)
The objectives of MRI imaging of the TMJ are;

Determine relationship between the disc and
Temporal and mandibular components of the TMJ

Detect inflammation, hematoma and effusion for
the soft tissue components


(TMJ)
MRI clearly differentiates the soft tissue components .
Short and long echo imaging of the TMJ enables
identification of the positional relationships
between the disc and the condyl


(TMJ)
The contrast and appearance of images can be varied
by selecting the field strength and other factors.
Special head holders have been designed which
facilitates orientation of the patient and reduces
patient movement during imaging.


Complications;
Magnetic forces and radio waves - not know
to produce any biological side effects in
man.
Non invasive technique and can be used in
most patients.










Contraindications;
Patients with cardiac pacemakers.
Patients with cerebral metallic aneurysm
clips. Slight movement of the clip could
produce bleeding
Stainless steel and other metals produce
artifacts ; obliterate image details of the
facial area.*









Indications
Assessing diseases of the TMJ
Cleft lip and palate
Tonsillitis and adenoiditis
Cysts and infections
Tumors









Short comings;
Inability to identify ligament tears or
perforations
Dynamics of tissue joint not possible
Cannot be used in patients suffering from
claustrophobia.


Computed Tomography




Invented by Sir Godfrey Hounsfield who
was awarded a Nobel prize in 1979
CT is an image display of the anatomy of
a thin slice of the body developed from
multiple x- ray absorption measurements
made around the body‘s periphery.


Computed Tomography
Parts of the Equipment;
1.
Scanner ( movable x
ray table + gantry)
2.
Computer system
3.
A display console


Computed Tomography
Principle;
A x ray source and array of detectors
mounted within the gantry rotate around
the patient during each scan.
Detectors record the attenuation values of the
beam emerging from the patient
Information from each traverse is a Profile

Computed Tomography
The tube and detectors are
further angled and
another traverse is
made.
A series of Profiles is built
up.
The computer analyses the
data and an image is
produced.

Computed Tomography
Early scanners

translate and rotate system.

Recently developed scanners
stationary
detectors and x ray tube rotates around the patient
both the
detectors and x ray tube rotate in synchrony


Computed Tomography
Radiation dosage

1.536 rad for
a single section
1.8432 rad for
multiple sections

Estimated dose to the centre of the condyl
with CT is 180mR

Computed Tomography
(TMJ)
CT for the evaluation of the TMJ was introduced
by Wegener and colleagues for demonstrating
bone abnormalities within the TMJ.


Computed Tomography
(TMJ)






Useful in determining changes in
bone density
Primary imaging method when
internal derangement or arthrosis is
suspected – clinical diagnosis is not
always sufficient.
Has advantages when planning
treatment or operations on jaws and
TMJ diseases and deformities.


Computed Tomography
Although CT scans are too expensive and the
radiation dose too high to be appropriate
for orthodontic applications
Certain situations, benefits outweigh the risks


Computed Tomography






In the treatment of certain craniofacial
deformities. 2D diagnostic records inadequate.
To visualize outcome of certain surgical
procedures
3D reconstruction of images and viewing of the
final images via Monitor or processed via
Milling machines or Stereolithography.


Microcomputed Tomography
Principally the same as CT, except that the
reconstructed cross sections are confined
to a much smaller area.
Significantly reduces radiation dosage.
Used to measure bone connectivity in all 3
dimensions and even record anisotropy –
till now not possible even with histology.

Computerized tooth width
analysis


Introduced by Christopher T.C. Ho and Terrence Freer



Named as Ho-Freer Graphical analysis of tooth width
Discrepancy (GATWD)



Base line data obtained from pre treatment orthodontic
casts
9 percentage ratios relating max teeth to mand. teeth
were derived.




analysis







Direct input using digital calipers or manual
input using visual basic 3.0
Upto 24 tooth width measurements can be done
Caliper used is a Mitutoyo 6‖/ 150mm , with
tapered beaks
Connected to a Mitutoyo digimatic mini
processor IBM compatible computer


analysis


1.
2.

3.

4.

Advantages:
Less time consuming
Use of digital calipers reduces errors during
transfer of measurements
Mathematical calculations done by the
computer
Eliminates reference to standard value tables

What is Invisalign®?
Invisalign® is the invisible way
to straighten teeth without
braces.
uses a series of clear
removable aligners to straighten
teeth without metal wires or
brackets.


Invisalign







co-founded by Zia Chishti and Kelsey Wirth in 1997
Based in Sunnyvale, California.*
Align Technology
the treatment procedure is handled by the computer
technicians in Pakistan - process takes 3 weeks to a
month.
After approval from the orthodontist, specifications
are transmitted to the manufacturing plant in Mexico

Invisalign






Patient gets the first aligner 6 weeks after the
1st visit
Most treatments require 20 – 60 aligners
worn for 2 weeks each
Should be taken off only for eating and
brushing


Impressions are
made using
Polyvinyl Siloxane

Impression and bite
send along with a
detailed treatment
plan.

advanced imaging
technology transforms
plaster models into a
highly accurate 3-D
digital image.

A computerized movie called ClinCheck® depicting the movement
of teeth from the
beginning to the final
position is created.

Procedure

After wearing all of
the aligners in the
series,

customized set of
From the approved file,
aligners are made from
laser scanning to build a
these models, sent to the
set Invisalign® uses of
doctor, and given to the
actual models that reflect
patient. Pt to wear each
each stage
aligner for about two
www.indiandentalacademy.comof the
treatment plan.
weeks.

Using the Internet, the
doctor reviews the
ClinCheck file - if
necessary, adjustments
to the depicted plan are
made.

Invisalign
Contraindications;
 patients with severe malocclusions
 All children – growing jaws and erupting teeth
too complicated for the computer to model


A comparison of sonically derived
and traditional cephalometric values
Daniel Langford Hall, Anne-Marie Bollen.
Angle Orthodontist
1997 No. 5, 365 - 372:
The cephalometric technique is the standard used by
orthodontists to assess skeletal, dental, and soft-tissue
relationships.
However, this technique exposes patients to radiation,
preventing orthodontists from taking frequent
cephalograms to assess growth and to monitor
treatment.


the Dolphin Imaging Company developed the
DigiGraph™, a nonradiographic cephalometric
method that uses sound waves and
mathematical algorithms
But its accuracy as a cephalometric alternative
has not been adequately investigated.



The purpose of this study was to compare the
values obtained by traditional cephalometrics
with those obtained by the DigiGraph
technique,for 30 well-known measurements,
and then to assess the repeatability
(intraobserver comparison) and reproducibility
(interobserver comparison) for both
techniques.






Materials and methods
Patients starting or finishing orthodontic
treatment at the University of Washington lateral cephalogram.
a DigiGraph analysis was performed for each
consenting patient.





There were no exclusionary criteria.
The sample consisted of 70 patients, 41 males
and 29 females, with a mean age of 18.2 years













Standard cephalograms were obtained using the following
criteria:
Anode-to-subject distance of five feet.
Subject-to-film distance of five inches.
A kVp setting of 78 and a mA setting of 100.
Kodak Lanax Regular film with an exposure of 0.1 second.
A cephalostat with a light indicator was used to orient the
patient‗s head so that Frankfort horizontal was parallel to the
ground.
A dodger was used to enhance the soft tissue profile.









The patients closed their teeth together (centric occlusion) and
relaxed their lips to provide the most correct reproduction of
lip morphology.
The lateral cephalograms were traced by hand on acetate paper
using a mechanical pencil with a 0.5 mm diameter lead.
Landmarks were identified for each cephalogram, and 30
angular and linear measurements were calculated by hand,
using a protractor and millimeter ruler.
Measurements were made to the nearest 0.5 mm or degree.




Each subject was digitized in the manner
described in the DigiGraph operations manual.








Patients were asked to bring their teeth together (centric
occlusion) and to relax their lips.
The appropriate landmarks were digitized in the following
order: (1) facial landmarks, (2) mouth-closed intraoral
landmarks, and (3) mouth-open intraoral landmarks. The
fourth category of landmarks cannot be digitized directly (e.g.,
sella turcica) and are computed by mathematical algorithms.
The desired analysis (e.g., Steiner, Downs) was selected and
the linear and angular measurements were computed by the
DigiGraph system. The average time to digitize a patient once
was approximately 10 minutes.





To assess the intraobserver error, 15 randomly
selected subjects were immediately digitized a second
time by the primary examiner. The corresponding
cephalograms were traced a second time after a 2week interval.
To assess interobserver error, 15 subjects were
chosen at random, and immediately following the
initial procedure, a second examiner, independently
digitized the patients. The second examiner also
independently traced the corresponding
cephalograms.





Results
Differences in techniques
The means, mean differences, and standard
deviations of the differences for the two
techniques are listed in Table 1.


There

was a
statistically significant
mean difference for 18
of the 30 measurements
(p >.0067).
 Eighteen of the
measurements had
standard deviations
equal to or greater than
+/- 4.0
degrees/millimeters.





Correlation of methods
Correlation coefficients between both methods
were calculated (Table 1). Twenty-eight of the
30 variables had statistically significant
correlation coefficients (r> .37), but only four
had correlation coefficients greater than 0.80.









Repeatability / Reproducibility
the DigiGraph angular and linear mean error values were
two to three times that of the cephalogram mean error values.
For both angular and linear measurements, the interobserver
error for the two methods was greater than the intraobserver
error.
For all the intraobserver measurements, there was greater
agreement for the traditional cephalometric values than for the
DigiGraph values. Except for Steiner's soft-tissue convexity,
interoperator measurements for the cephalogram show greater
reproducibility.




Discussion;
Sixty percent of the variables had mean
differences between methods that were
statistically significant. The greatest
differences were found for the measurements
involving sella, orbitale, A-point, and incisor
position.



Measurements relying on soft-tissue
landmarks, which were digitized directly,
showed no difference between techniques.




The sonically generated values consistently
showed less agreement between examiners.



-while two consecutive digitizations were

taken for each patient, only one cephalogram
was taken. - a single cephalogram was traced
twice.





patients were asked to remain in the DigiGraph head
positioner between digitizations. - a head-holder can
minimize movement but cannot prevent it
superficial skeletal landmarks such as orbitale are
not digitized directly, but necessitate palpation and
firm pressure.- not being able to directly visualize a
landmark increases the likelihood of identification
error.



deep skeletal structures, such as sella turcica and the
root apices, are derived from mathematical
algorithms, which can only estimate the position of
the true landmark.



only the subject's right-sided structures are digitized,
any asymmetry that is projected on the cephalogram
will not be represented by the DigiGraph.



The concept of a nonradiographic technique to
perform cephalometric analyses is encouraging, but
the diagnostic information must be comparable to the
traditional technique



If a three-dimensional analysis can be developed
based on landmarks that can be digitized directly,
perhaps the DigiGraph can be an adjunct to the lateral
cephalogram.

Conclusions
1. Eighteen of 30 sonically generated measurements
were statistically different from the radiographically
generated measurements; however, the differences for
some measurements may not be clinically significant.
The soft tissue variables revealed no significant
difference between the two techniques.
2. The regression analyses showed low correlations for
all measurements except lower incisor to NB (mm),
Ricketts' esthetic line, and Steiner‗s soft tissue
convexity.

3. Intraobserver and interobserver errors were found
with both techniques, but overall repeatability and
reproducibility were greater for the radiographically
generated measurements.
4. The DigiGraph's soft tissue measurements involving
landmarks that were digitized directly were
comparable to those obtained by the radiographic
cephalometric analysis.

Arthroscopy
First arthroscopic examination of the TMJ
reported by Ohnishi in 1975
Invasive technique
One of the several diagnostic methods and not a
substitute for a thorough case history, clinical
examination and indirect imaging.


Arthroscopy
Indications;
1.
Internal derangements
2.
Osteoarthrosis
3.
Examination and biopsy of suspected
neoplastic disease and
4.
Investigation of post traumatic complains

Arthroscopy
Equipment;
1.
Small diameter arthroscope (needlescope)
2.
Sharp and blunt trocars
3.
Arthoroscopic sheath
4.
Fiber optic cable
5.
Light source
6.
Video documentation sets

Arthroscopy
Anesthesia
frequently done under G.A – diagnostic
arthroscopy may be done under LA

Auriculotemporal nerve is blocked, posterior
to the condylar neck.


Arthroscopy
Technique;

Patient asked to open mouth

Joint space distended by injection of isotonic
saline in to joint space

3ml for upper compartment and 1.5 for lower
compartment

Arthroscopy






3mm vertical skin incision made at the
injection site using a sharp trocar surrounded
by the arthroscopic sheath
The lateral capsule is punctured
Resistance felt as the capsule is penetrated
Sharp trocar is exchanged for a blunt one

Arthroscopy








Trocar pushed further
Then exchanged for an arthroscope
2nd puncture created on the canthaltragal line
5mm ant. And 3mm inferior the arthroscope
sheath
A 2mm diameter cannula is inserted .
Joint continuously irrigated during the
procedure with saline or Ringer‘s solution.

Arthroscopy
Provides valuable data that cannot be obtained
by other methods – direct visualization.
Shows a high diagnostic accuracy and low risk
of postoperative complications


Thank you
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