Applications of a lateral cephalogram

Applications of a lateral
cephalogram
• Assessment using ceph analysis
– The superimposition a most suitable method
but can only be used in relation to a serial
study for an individual.
– For group studies it is better to use the
Reference planes like SN plane and FH plane
along with linear and angular measurements.
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cephalogram
• Comparison using ceph analysis
– The assesment of craniofacial patterns
between different races, different age groups,
sexes and dental occlusion.
– To compare the effect of two or more different
mechanotherapeutic approaches on jaws and
teeth.

cephalogram
• The expression of relationships using
cephalometrics
– It enables clinicians to express the relations
between and within the craniofacial and
dentofacial complex.
– To locate the probable causative area of
malocclusion

cephalogram
• Cephalometrics can be used to assess the
spatial relationships.
– Relationships between the cranium and jaws
– Relationships between the jaws themselves
– Relationship between the chin and the
mandible.
– Relationship of the incisors to the jaw bases
and the planes of reference with regard to
axes and position.
– Relationhips of the facial thirds to each other.

cephalogram
• Cephalometrics can be used to assess the
tongue position in the cranium and its
relationship to the various dentoskeletal
structures.
• Cephalometrics can be used to assess the glide
and rotatory movements in the closing of the
mandible and it is termed functional analysis.
• Cephalometrics can assess the patency of the
airway .
• It is also used to asses the lip incompetency with
regard to incisal position and angulation in the
craniofacial complex.

Predictions using a Lateral ceph
• A lat ceph can be used to predict the line of treatment vis
surgery.
• A number of factors must be considered before the
prediction can be accurate and they are :-
– Age.
– Sex.
– Race.
– Facial type.
– Malocclusion type.
– Spatial relatonships of the different parts of the face.
– Growth prognosis: No method has yet been devised to
accurately record this and predict the future changes.

• Cephalometrics is a useful tool to eveluate
the stage of treatment that the patient is
in.
• Many clinicians revaluate the case during
treatment with cephalometrics to see if the
treatment plan needs modification.
• The clinicians call it “Re-analysis”.www.indiandentalacademy.com

Cephalometrics and Growth
• To evaluate the remaining growth through the
comparison of chronological and biological
growth.
• To determine the time frame for growth spurts.
• To determine the direction of growth.
– To assess whether interception is required during the
mixed dentition period.
– To assess mandibular morphology for growth signs.

• To assess the rate of growth through a
comparison with standard measurements
considering age and sex.
• To predict growth which is complex and
even areas of quisence will show change
during orthdontic treament with the
following methods.

– Johnston’s method – Through the use of a
forecast grid which when placed on a ceph
can aid in growth prediction. It is said to be
65% accurate.
– Broadbent, Kilpatrick and Jacobsen
discovered an annual increase in size based
on growth using SN as the reference.

– Ricketts- arcial growth pattern for short term
prediction to distinguish between horizontal
and vertical grwoth pattern and is 80%
reliable.
– Moorees and Herbert used the mesh co-
ordinate system to help predict growth
pattern.

Growth Prediction Errors
• Growth prediction vs Weather forecast
• Growth based on certain data but numerous
unknowns:-
– Variable growth rate in various locations.
– Growth pattern in it entirety not fully taken into
account.
– The effect of persistent dysfunction on form and
function.
– The effect of age on growth(direction of growth
changes as age increases)
– The effect of discontinuation of habits or change of
functional environment on growth.

Advances in Cephalometric
Analysis
• Came to be, due to the inefficiency of
hand tracing such as:-
– Increased time.
– Difficulties in data presentation for patient
education.
– Image enlargement and distortion.
– Patient exposure to radiation.
– Chemical hazards due to developing.
– The limitations of a 2D image.

Analysis
• Digitization- Graphical information of
cephalogram is converted into numbers which
can be stored retrieved and manipulated on the
computer. It is done by a digitizing tablet or On-
screen digitizaztion.
– Digitizing tablet- A pen or stylus is used on a writing
surface or tablet. The stylus converts the graphical
format into a digital format.
• Linear or angular measurements can be made.
• The data input is either in the form of a single discrete point
in different anatomic area.
• Or by the use of a stream which allows lines to be drawn.

Analysis
– On-screen digitization- A ceph is fed into the
computer and a mouse is used to digitize the
image.
• A discrete point can be selected by clicking the
mouse on the point.
• The mouse can be used to select a series of points
to form a stream digitized image .

Advantages of Digitization
• The superimpositions of different
exposures can be done much more
efficiently.
• More advantageous to the clinician for
patient education.

Method for Patient Education
• Paste a ceph on a wall
• Project a photo ontothe ceph till the
borders match.
• Trace the photos on a blank tracing sheet.
• Superimpose the ceph on the photograph.
• Construct the relevant hard and soft tissue
changes.
• Final picture is readied which can even be
superimposed on an old photograph.

Video Imaging
• The imaging software allows for movements of
various sections in the image thereby simulating
the expected profile or frontal changes.
• Advantage- Quantification of the treatment plan
thereby improving the chances of achieving the
proposed treatment plan.
• Disadvantage- Inability to let the clinician view
the underlying dento-osseous relationships.

Method of Video Imaging
• Graphic Imaging softwares were used to modify
image.
• Co-ordination of calibrated profile images with
facial profile images to permit precise
measurements of bony and dental movements.
• The application of logarithmic prediction ratios to
produce images that expose the expected
surgical and orthodontic outcome.

Digigraphy
• Created by Dr. Marc Lenscher and Mr. Gary
Engel
• Based on a videoimaging computer capable of
generating 2D and 3D facial analyses.
• Components:-
– Computer
– Monitor
– Keyboard
– RGB video camera with light source
– Sonic digitizing probe with receptor phones capable of
producing any ceph landmark in 3D.

Disadvantages of Digigraphy
• Increased cost .
• The technology is still in its primitive
stages.

Facial Analysis in 2D and 3D
• Head and face is scanned by laser an
ultrasonic scanner thereby recording hard
and soft tissue on a computer.
• Increased cost.
• Conventional manual measurements are
taken along with cephalometric data with
the use of videoimaging and MRI.

Xeroradiography
• Started for the evaluation of breast lesions,
however in dentistry it is used to evaluate the
larynx and TMJ.
• Components-
– Panographix cephalometer- 90 Kv and 15Ma with
exposure of 1sec.
– System 125 processor of radiogaphy.
• Uses Se coated Al pates in a plastic cassette,
when charged it becomes sensitive.

Xeroradiography
• Developing occurs in a processing
machine.
• An electrically charged powder is sprayed
on a exposed plate.
• Image is formed by the static attraction or
repulsion of th epowder particles.
• The image is then transferred from plate
to paper.

Xeroradiography
• Se= -ve charge= dark blue
• Se= +ve charge= light blue to white
• Advantages:-
– Can be viewed without transillumination
– Radiograph need not be traced.
– Density of soft and hard tissue directly displayed over
headfilm.
– Image quality is superior with a high degree of
contract and an edge enhancement effect(mirror
image).

McNamara Jr. Components of class II
malocclusion in children 8-10 yrs of age
AO 1981; 51: 177-202
• His data sowed marked differences in the
maxillary development of patients with Cl
II div 1 type of malocclusion.
• The range covers maxillary prognathism
and retrognathism which should not be
encountered inthis malocclusion.
• Only 23.8% showed an ideal SNA while
50% showed a retruded SNA and 26.2%
showed the appropriate prognathic values.

Point A revisited- Jacobson and
Jacobson AJO jan 1980;77: vol 1
• Locating point A is hard due to extreme
range of radiolucency between bone and
soft tissues making it difficult to locate
point A consistently.
• Point A is not an ideal reference point but
a valid one and possibly the best there is
in this area of the maxilla.

Point A revisited- Jacobson and
Jacobson AJO jan 1980;77: vol 1
• A point is plotted 3mm labial to point A
between the upper third and lower two
thirds of the long axis of the root of the
maxillary central incisors was found to be
a suitable point through which to draw the
NA line and one which most closely
approximates the true NA plane

Conclusion
• Cephalometrics has given us a way of
placing the historical dental problem within
the dentofacial complex.
• It is not very accurate and the simplest
readings can cause the case to take a turn
for the more complex.
• It has allowed us to quantify what was a
subjective problem.

Conclusion
• The future of cephalometrics as it
becomes more integrated with computer
technology is inordinately bright.
• It allows us use of the data in a 3D way.
• Currently though not feasible the promise
of cephalometrics as a diagnotic and
prognostic tool may yet be fulfilled.

Applications of a lateral cephalogram

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Applications of a lateral cephalogram